bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Structure of a Binuclear [Bis(ethane-1,2-diamine)nickel(II)]-μ-(ethane-1,2-dithiolato)-[(ethane-1,2-dithiolato)Nickel(II)] Complex [Ni(en)2(μ-C2O2S2)Ni(C2O2S2)], and the Related 3,4-Dimercaptocyclobutene-1,2-dionato Complex
Authors: Boyd PDW , Hope J , Raston CL , White AH
Published: September 2010

The reaction of planar bis nickel(II) chelates of the ethanebis ( thioate ) ( dithiooxalate ) dianion (C2O2S22-, dto ) or the 3,4-dimercaptocyclobutene-1,2-dionate(2-)( dithiosquarate ) dianion (C4O2S22-, dts ) with bis (ethane-1,2-diamine)nickel(II) dinitrate [NiII (en)2(NO3)2 ]leads to the formation of neutral binuclear complexes of the form [Ni(en)2Ni(L)2] (L= dto or dts ), (1) and (2). An X-ray crystal structure of the dithiooxalate complex has been performed which confirms the formulation of a μ- dithiooxalato bridged binuclear complex based on analytical, magnetic and spectroscopic data. The crystals of [Ni(en)2Ni( dto )2] are orthorhombic, space group Pcnn a 8.371(8), b 17.65(1), c 23.37(2)Ǻ and Z 8; a total of 853 unique data with I > 2σ(I) were refined to R 0.073. The molecule is found to be binuclear with a dithiooxalate dianion bridging a six-coordinate Ni(en)2O2 moiety and a planar four-coordinate Ni( dto )S2 group.
The Effect of Cetyltrimethylammonium Bromide on the 2-Iodosyl-5-octyloxy-benzoate-Catalyzed Hydrolysis of Active Esters and Related Compounds
Authors: Leslie DR , Pantelidis S
Published: September 2010

Enhancements provided by micellized cetyltrimethylammonium bromide ( ctab ), to the rates of reaction between 2-iodosyl-5-octyloxybenzoic acid and 4-nitrophenyl diphenyl phosphate (3), 4-nitrophenyl acetate (4), 1-methylethyl methylphosphonofluoridate (5), 1,2,2-trimethylpropyl methylphosphonofluoridate (6) and ethyl N,N- dimethylphosphoramidocyanidate (7) are determined over a range of ctab concentrations. The maximum enhancements observed for substrates (5)-(7) are greater than predicted by the phase-separation model.1 The suitability of themodel to describe these reactions is considered.
The Chemistry of Laurenene. XI. A Deep-Seated Rearrangement of the Laurenane Skeleton
Authors: Eaton PJ , Hayman AR , Simpson J , Weavers RT
Published: September 2010

A trifluoroacetic acid induced rearrangement product of laurenan-2β-ol (3) has been shown to have the 4H-pentaleno[6a,1-c]indene skeleton. This combination of one six- membered ring and three five-membered rings has been encountered once previously, again as a rearrangement product of the laurenane skeleton. The structure was determined by n.m.r. studies and by X-ray crystallography conducted primarily on a stable ozonide (6).
The Chemistry of Laurenene. XII. The Structure of a Minor Product From the Formic Acid Induced Rearrangement of Lauren-1-ene
Authors: Hayman AR , Perry NB , Weavers RT
Published: September 2010

Rearrangement of lauren-1-ene (1) with formic acid gives a trisubstituted alkene (4) in addition to the previously characterized tetrasubstituted alkene (3). The structure was determined by n.m.r . Studies on (4) and the derived diol (5). Alkene (4) contains a new tetracyclic carbon skeleton which comprises one six- membered ring and three five- membered rings.
A Synthesis of (-)-12,15-Epoxylabda-8(17),12,14-trien-16-yl Acetate and (-)-Pumiloxide
Authors: Cambie RC , Moratti SC , Rutledge PS , Weston RJ , Woodgate PD
Published: September 2010

Sclareol (7) and manoyl oxide (8) have each been converted into the (-)-enantiomers of the naturally occurring diterpenoids 12,15-epoxylabda-8(17),12,14-trien-16-yl acetate (2) and pumiloxide (1).
Potential Antimalarials. X. Di-Mannich Bases of 4-(7'-Trifluoromethyl-1',5'-naphthyridin-4'-ylamino)phenol and N-(4'-Diethylamino-1'-methylbutyl)-7-trifluoromethyl-1,5-naphthyridin-4- amine
Authors: Barlin GB , Jiravinyu C
Published: September 2010

The syntheses of some di-Mannich bases derived from 4-(7′-trifluoromethyl-1′,5′-naphthyridin-4′-ylamino) phenol and of N-(4′-diethylamino-11′-methylbutyl)-7-trifluoromethyl-1,5-naphthyridin-4- amine from 3-chloro-5-trifluoromethylpyridine via4-chloro-7- trifluoromethyl-1,5-naphthyridine are described. In tests in vitro against the FCQ-27 strain of Plasmodium falciparum these compounds were slightly less active than their 7-bromo analogues.
The Synthesis of (2S,3R)-2-Hydroxymethylpiperidin-3-ol, a Fragment of the Alkaloid Swainsonine
Authors: Mocerino M , Stick RV
Published: September 2010

Methyl α- and β-D-galactopyranoside have been converted into methyl 4,6-di-O-benzyl-2,3-dideoxy-α- and -β-D-threo-hexoside , and subsequent treatment with ethanedithiol gives the same alcohol. Tosylation and azide displacement gives, after hydrolysis, an azido aldehyde which is transformed under reducing conditions into the title piperidine . The synthetic piperidine is an ineffective inhibitor of α-D- mannosidase.
The ortho Metalation of N,N,N',N'-Tetramethyl-P-phenyl-phosphonothioic Diamide
Authors: Craig DC , Roberts NK , Tanswell JL
Published: September 2010

The reaction of C6H5P(S)(NMe2)2 (2) with BuLi in diethyl ether/hexane mixture gives the ortho-metallated species o-LiC6H4P(S)(NMe2)2 (3), which has been characterized by 31P and 13C n.m.r . spectroscopy, and by preparation of the derivatives R{o-C6H4P(S)(NMe2)2}n (where R = Me3Si or Ph2P, n = 1; R = PhP , n = 2; R = P, n = 3). A single-crystal X-ray structure determination of one derivative, phosphinetriyltris (N,N,N′,N′- tetramethyl-o-phenylenephosphonothioic diamide ), P{o-C6H4P(S)(NMe2)2}3 (6), is reported.
Quinquedentate Coordination of 6-Methyl-1,11-dithia-4,8-diazacyclotetradecan-6-amine to Cobalt(III). X-Ray Crystal Structure of the [Co(N3S2)(OOCCH3)] (ClO4)2.H2O Complex
Authors: Lawrance GA , Martinez M , Skelton BW , White AH
Published: September 2010

The pendant arm macrocycle 6-methyl-1,11-dithia-4,8-diazacyclotetradecan-6-amine (7) can coordinate to cobalt(III) as a quinquedentate N3S2 ligand . Spectroscopy indicated a geometry with the macrocycle folded and the pendant amine and the unidentate donor in cis dispositions for the [Co(7) Cl ]2+ and [Co(7)(OOCCH3)]2+ products isolated. An X-ray crystal structure analysis of [Co(7)(OOCCH3)](ClO4)2.H2O characterized the cis stereochemistry. The complex crystallized in the Pbca space group, a 10.620(9), b 13.926(9), c 32.35(2)Ǻ, and analysis defined a distorted octahedral geometry with the primary and two secondary nitrogen donors occupying an octahedral face with relatively short Co-N bonds [1.937(7)-1.950(7)Ǻ], the acetate ion [Co-O 1.905(6)Ǻ] trans to one of the secondary amine donors and thioether donors [Co-S 2.223(3), 2.227(3)Ǻ] trans to the other nitrogen donors. Significant angle distortions occur around the metal ion. Base hydrolysis of the chloro complex is slow and stereoretentive , with a rate constant of 1.08×103 dm3 mol-1 s-1 at 25°C, 15-fold faster than for the pentaaza analogue.
Synthesis of Casein-Related Peptides and Phosphopeptides. VII. The Efficient Synthesis of Ser(P)-Containing Peptides by the Use of Boc-Ser(PO3R2)-OH Derivatives
Authors: Perich JW , Alewood PF , Johns RB
Published: September 2010

A new approach to the synthesis of Ser(PO3R2)-containing peptides by using five protected Boc-Ser(PO3R2)-OH (R=phenyl, ethyl, methyl, benzyl, t-butyl) derivatives is described. The five Boc-protected derivatives are prepared by a simple three-step synthetic procedure which features the use of either (A) diphenyl or dialkyl phosphorochloridate/pyridine, or (B) dialkyl N,N-diethylphosphoramidite/1H-tetrazole-m-chloroperoxybenzoic acid for the phosphorylation of the serine hydroxy group. The five derivatives were utilized in the Boc mode of peptide synthesis with the use of the mixed-anhydride coupling procedure, and led to the synthesis of the protected tripeptides, Boc-Glu(OBzl)-Ser(PO3R2)-Leu-OBzl, in high yield and purity. In peptide deprotection studies, the phenyl and benzyl phosphate protecting groups were readily removed from the protected Ser(PO3Ph2) and Ser(PO3Bzl2) tripeptides by hydrogenolysis and gave Glu-Ser(P)-Leu in near quantitative yield. The t-butyl phosphate groups were cleaved from the Ser(PO3But2) dipeptide by mild acidolysis and gave Ser(P)-Leu in quantitative yield. However, attempts to cleave the ethyl or methyl phosphate groups by acidolytic or silylitic treatment of the Ser(PO3Et2) and Ser(PO3Me2) tripeptides resulted in decomposition of the O-phosphoseryl residue.
The Bastadins Revisited: New Chemistry From the Australian Marine Sponge Ianthella basta
Authors: Butler MS , Lim TK , Capon RJ , Hammond LS
Published: September 2010

A specimen of Ianthella basta, collected from the Great Barrier Reef, Australia, has been found to contain the recently reported tetramer of bromotyrosine , bastadin-9 (6a), along with a new example of this structure class, bastadin-12 (9a). The structure for bastadin-12 (9a) was confirmed by detailed spectroscopic analysis and derivatization, and represents the first reported example of this structure class derived from an alternative oxidative cyclization . As earlier biosynthetic arguments to the structure elucidation of some bastadins were based on the premise that only one cyclization pathway was possible (leading to 13,32-dioxa-4,22-diazabastarane), the discovery of (9a) introduces an added dimension to the identification of new and known bastadins. Also isolated and identified as their methyl ethers were two new dimers of bromotyrosine, hemibastadin-1 (10) and hemibastadin-2 (11).
Coordination of Hydrazone Derivatives of 2,2'-Bipyridine-6-carbaldehyde. Electronic and Structural Aspects of the Iron(II), Cobalt(II) and Nickel(II) Complexes
Authors: Onggo D , Craig DC , Rae AD , Goodwin HA
Published: September 2010

Iron(II), cobalt(II) and nickel(II) [MN6]2+ type complexes of the tridentate terimine ligands 2,2′-bipyridine-6-carbaldehyde phenylhydrazone ( bph ) and 2,2′-bipyridine-6-carbaldehyde 2-pyridylhydrazone ( bpyh ) have been prepared. The electronic spectrum of the [NiN6]2+ species indicates that the field strength of these ligands is near that at the iron(II) singlet/quintet crossover. Magnetic and Mossbauer spectral data reveal that salts of [Fe( bph )2]2+ are essentially low spin, while those of [Fe( bpyh )2]2+ are high spin. Salts of [Co( bph )2]2+ have strongly temperature-dependent magnetic moments which indicate a thermally induced doublet ↔ quartet spin transition in the metal atom. The structure of [Ni( bph )2][ClO4]2 reveals meridional coordination of the tridentate units, the azomethine nitrogen of the hydrazone moiety being bound to the metal atom. There is significant twisting (8.3°) of the two pyridyl rings in each ligand molecule about the interring bridge. The [NiN6]2+ fragment is tetragonally compressed and the mean Ni-N distance is 2.09 Ǻ. [Ni( bph )2][ClO4]2 is monoclinic, space group C2/c, Z = 4, a 23.949(3), b 7.868(1), c 21.303(3)Ǻ, β 117.95(2)°.
MoO(S2)(S2CNR2)2 Complexes (R = Me, Et, Pr, Bu): Improved Syntheses and Thermogravimetric and Nuclear Magnetic Resonance Studies
Authors: Yan XF , Young CG
Published: September 2010

The reactions of MoO (S2CNR2)2 [R=Me, Et, Pr, Bu; formed in situ from the reactions of cis-MoO2(S2CNR2)2 and PR′3 (R′= Ph, Bu)] and propylene sulfide in 1,2-dichloroethane (for R = Me) or dichloromethane (others) constitute convenient, high-yield syntheses for the blue, seven-coordinate complexes MoO (S2)(S2CNR2)2 The complexes have been characterized by elemental analysis, infrared, electronic and 1H and 13C n.m.r. spectroscopy, and mass spectrometry. Thermogravimetric analyses indicate decomposition of the complexes to Mo2O2(μ-S)2(S2CNR2)2 at temperatures greater than 160°C.
Preparation and Properties of Sodalite-Type Aluminophosphates Containing Silicon, Cobalt and Zinc
Authors: Rajic N , Stojakovic D , Kaucic V
Published: September 2010

The SAPO, MeAPO and MeSAPO microporous materials (Me=Co2+ and/or 2n2+) having a sodalite structure have been obtained hydrothermally at 200°C in the presence of tetramethylammonium ion as the template. The SAPO and MeSAPO products prepared at lower template concentrations are formed through a partial replacement of both aluminium and phosphorus by silicon in the parent aluminophosphate lattice; at higher pH only phosphorus is replaced. While the Me2+ ions are in all cases constituents of the framework, most zinc-containing materials have a fraction of the Zn2+ ions located in the cavities. T.g.a . shows that complete removal of the trapped organic component can not be easily accomplished. This can be explained by the small size of the openings in the sodalite cages. Powder diffraction analysis shows that replacement of aluminium by silicon, cobalt and zinc, and phosphorus by silicon leads to an expansion of the parent aluminophosphate unit cell. Kinetic studies suggest that crystallization of the silicon-containing products is preceded by an induction period of about 2 h, the nucleation taking place both in the liquid and solid phase.
Crystal Structure of a Centrosymmetric Trinuclear Cadmium(II) Complex Containing Metal Atoms in Two Different Coordination Environments
Authors: Mak TCW , Chen XM
Published: September 2010

The complex [Cd3( pybet )4Cl6] ( pybet = C5H5N+CH2COO-) crystallizes in the triclinic space group Pī (No. 2), with Z = 1, a 8.3228(8), b 10.290(2), c 12.199(2)Ǻ, α 66.44(1), β 77.65(1), γ 71.59(1)°; structure was refined to R = 0.027 for 5242 observed MoKα data. In the centrosymmetric trinuclear molecule the metal atoms exhibit trans-octahedral Cd (1)O4Cl2 and tetrahedral Cd (2)O2Cl2 coordination geometries; the central Cd (1) atom is doubly bridged to each of the terminal Cd (2) atoms by a pair of pybet ligands which function in an uncommon syn-skew mode.
New Macrocyclic Ligands. II. Pendant Hydroxyethyl, Cyanoethyl and Carbamoylethyl Arm Systems Derived From O2N2-Donor Rings: the X-Ray Structure of a Pendant Hydroxyethyl Derivative
Authors: Chia PSK , Ekstrom A , Liepa I , Lindoy LF , Mcpartlin M , Smith SV , Tasker PA
Published: September 2010

The syntheses and characterization of 12 new 14- to 17-membered macrocycles incorporating pendant hydroxyethyl cyanoethyl or carbamoylethyl groups are reported. The macrocyclic ring in each of these new ligands contains an O2N2-donor set. The X-ray structure of the di(hydroxyethyl) derivative of the 14-membered macrocycle is described.
Mono-α-carbamoylethylthio-Substituted Pyrazolo[3,4-d]pyrimidines: the Position of Substitution
Authors: Quinn RJ , Scammells PJ , Tucker DJ
Published: September 2010

Pyrazolo [3,4-d] pyrimidines are a general class of compounds which exhibit adenosine receptor affinity. One particular compound, α-{6-(1α-carbamoylethylthio)-1-phenylpyrazolo-[3,4-d]pyrimidin-4-ylthio} propionamide (1a), has been shown to have antagonist activity an order of magnitude greater than theophylline at the A1 adenosine receptor. The synthesis, structural elucidation by n.m.r. spectroscopy, and adenosine receptor affinity of the mono-α- carbamoylethylthio analogue is now reported.
The Stereochemistry of Organometallic Compounds. XXXVII. Regio and Stereo-control in the Rhodium-Catalyzed Hydroformylation of Some Alkenylphosphines
Authors: Jackson WR , Perlmutter P , Suh GH , Tasdelen EE
Published: September 2010

Good to excellent regiocontrol can be obtained for the internal product of rhodium- catalysed hydroformylation of a range of alkenylphosphines. Excellent stereo- as well as regio-control can also be obtained for reactions of some cyclic alkenylphosphines.
The Chemistry of Laurenene. XIII. Formation of a New, Bridged, Tetracyclic Ring System
Authors: Corbett RE , Guild JR , Lauren DR , Weavers RT
Published: September 2010

Attempted reduction of a laurenene-derived keto ester with sodium borohydride or lithium tri-t-butoxyaluminium hydride at 110° gave rise to products containing a new tetracyclic carbon ring system made up of one seven- and one six- membered ring and two five- membered rings.
Studies in Porphyrin Chemistry: A Synthetic Approach
Authors: Clezy PS
Published: September 2010

This review summarizes porphyrin synthesis in the author's laboratory, and deals mainly with the preparation of porphyrins substituted with electron-withdrawing groups. Oxidative cyclization of 1,19-dimethylbilenes-b has provided the most successful avenue to porphyrins of this class, and the procedure works best when the terminal rings of the bilene -b are substituted with electron-withdrawing groups. This methodology has yielded a wide range of porphyrins carrying this class of substituent on adjacent pyrrolic rings, and has led to the preparation of many biologically important molecules including porphyrin a and the chlorophylls c1 and c2. Also described are the necessary modifications which are required to adapt the general strategy to the synthesis of porphyrins carrying electron-withdrawing groups on opposite pyrrolic rings as well as for cases where only one such substituent occurs. All these procedures were designed specifically to handle the preparation of porphyrins which were unsymmetrically substituted. However, some biologically significant members of the porphyrin series have a symmetrical arrangement of substituents in part of the molecule, and an adaption of the general synthetic procedure allows advantage to be taken of this substitution pattern. A mechanistic study of the oxidative cyclization of bilenes -b, which has been the reaction central in all the above synthetic endeavours, has produced a broad understanding of the manner in which the cyclization proceeds. Very recent studies involving the synthesis of petroporphyrins, besides consolidating the structure of many of these compounds, have provided sufficient material to allow an investigation of the properties of these porphyrins to commence, and in some cases this had led to a clearer understanding of their orgin.
Pigments of Fungi. XXIV. New Trihydroxylated Tetrahydroanthraquinones From an Australian Fungus Belonging to the Genus Dermocybe
Authors: Burns CJ , Gill M , Gimenez A
Published: September 2010

The pigments (9)-(11), the first trihydroxylated tetrahydroanthraquinones from Basidiomycetes, are isolated from an Australian toadstool belonging to the genus Dermocybe and the structure and relative stereochemistry of each one is established by spectroscopy. The absolute stereochemistry of each pigment is determined by synthesis from dihydroxylated tetrahydroanthraquinones of known absolute configuration.
Practical Synthesis of 2'-5'-Linked Oligoadenylates (2-5A Oligomers)
Authors: Noyori R , Uchiyama M , Nobori T , Hirose M , Hayakawa Y
Published: September 2010

A general, facile synthesis of 2'-5'-linked oligonucleotides (2-5A oligomers ) has been achieved based on the second-order regioselective protection of adenosine, one-pot formation of the 2'5' internucleotide linkage, and O-selective phosphorylation of N-unblocked nucleosides. Standard t- butyldimethylsilylation of 5'-O-p-methoxytrityladenosine followed by careful recrystallization from a mixture of triethylamine , methanol, ethyl acetate and ether (4 : 4 : 5 : 100 v/v) gives the 3',5'-di-O-protected adenosine in high yield. Magnesium alkoxide -mediated condensation of the 2'-O-free adenosine with o-chlorophenyl p-nitrophenyl phosphorochloridate followed by 2',3'-di-O-t-butyldimethylsilyladenosine produces the N-free and fully O-protected adenylyl (2'-5')adenosine. The resulting adenylyl dimer, after removal of the 5'-O-trityl protector, is elongated to the protected trimeric compound through a similar reaction sequence. Deprotection of the product furnishes the 2-5A core. Condensation of the 5?-0-detritylated core and bis (2,2,2-trichloroethyl) phosphorochloridite assisted by 2,6-lutidine and subsequent oxidation with aqueous iodine produces, after deblocking, 2-5A 5'-monophosphate (p5'A2'p5'pA2'p5'A). The 2-5A 5'-monophosphate is converted into 2-5A 5'-triphosphate (ppp5'A2'p5'A2'p5'A) by reaction with N,N'-carbonyldiimidazole in the presence of triethylamine followed by tributylammonium diphosphate. This procedure allows ready synthesis of 2-5A oligomers and related compounds on a multigram scale.
New Spatane-Derived Diterpenoids From the Australian Brown Alga Dictyota fenestrata
Authors: Vanaltena IA , Mcgivern J
Published: September 2010

The secondary metabolites of the brown alga Dictyota fenestrata were investigated. It was shown that two of the major metabolites were the previously unknown acetylated spatane (1) and the secospatane (5). Their structures were determined by spectroscopic and chemical means.
Synthesis of the Simple Peptide Model Ac-Abu(PO3H2)-NHMe
Authors: Valerio RM , Perich JW , Alewood PF , Tong G , Johns RB
Published: September 2010

The simple model substrate AC-L-Abu(PO3H2)- NHMe was prepared by the use of the protected 4( diethylphosphono ) butanoic acid derivative Boc -Abu(PO3Et2)-OH in the Boc mode of solution phase peptide synthesis. The protected peptide model Ac-Abu(P03Et2)- NHMe was prepared by initial reaction of the isobutoxycarbonyl mixed anhydride of Boc-Abu(PO3Et2)-OH with N-methylamine followed by cleavage of the Boc group from Boc -Abu(PO3Et2)- NHMe with 4 M HCl/dioxan and N- acetylation of H-Abu(PO3Et2)-NHMe.HCl with the isobutoxycarbonyl mixed anhydride of acetic acid. Cleavage of the phosphonate ethyl groups was effected with 33% hydrogen bromidelacetic acid or 10% bromotrimethylsilane/acetonitrile to give AC-L-Abu(PO3H2)-NHMe in near-quantitative yield.
The Intermediacy of Free Aryl Radicals in the Reaction of o-Alkenyloxybenzenediazonium Salts With Ferrocene
Authors: Beckwith ALJ , Jackson RA , Longmore RW
Published: September 2010

The formation of 3-ferrocenylmethyl-2,3-dihydrobenzofuran (5a) and similar products bearing cyclized substituents, when ferrocene or mixtures of ferrocene and ferrocenium ion are treated witho - allyloxybenzene - or o-but-3-enyloxybenzene-dimonium salts, provides unequivocal evidence for the intermediacy of free aryl radicals in the reaction of ferrocene with arenediazonium salts. The results are consistent with a mechanism involving electron transfer and dediazoniation followed by homolytic attack on ferroce nium ion.
Imidazo[1,2-b]pyridazines. XII. Syntheses and Central Nervous System Activities of Some Substituted Imidazo[1,2-b]pyridazines and Related Imidazo[1,2-a]pyridines, Imidazo[1,2-a]pyrimidines and Imidazo[1,2-a]pyrazines
Authors: Barlin GB , Davies LP , Ireland SJ , Ngu MML , Zhang JK
Published: September 2010

Syntheses are reported for some 6-chloro(alkoxy,alkylthio and pheny1thio)-3-benzamidomethyl-(acetamidomethyl and methoxy)-2-arylimidazo[1,2-apyridines and some corresponding imidazo- [1,2- b]pyridazines, imidazo[1,2-a[pyrimidines and imidazo[l,2-a]pyrazines. IC50 values (or percentage displacement) are reported and discussed for the displacement of [3H]diazepam from rat brain membrane by each of these compounds. The imidazo[l,2-a[pyridines were generally slightly less potent than the imidazo[l,2- b]pyridazines but considerably more potent than the corresponding imidazo[1,2-a]pyrimidines or imidazo[1,2- a[pyrazines. Substitution of a 2-aryl group by a 2-alkyl group in imidazo[l,2- b]pyridazines led to a significant loss of activity.
Studies in the Cycloproparene Series: Attempted Cycloadditions With Tricyclo-[5.4.1.03,5]dodeca-2,5,7,9,11-pentaene
Authors: Halton B , Russell SGG
Published: September 2010

4,4-Dichlorotricyclo[5.4.1.03,5]dodeca-7,9,11-triene (18a) undergoes cycloaddition with 4-phenyl-1,2,4 triazoline-3,5-dione via its norcaradiene valence-bond isomer (18b) to give adduct (21)in 86% yield. By comparison the aromatic tricyclo [5.4.1.03,5]dodeca-2,5,7,9,11-pentaene (6)and its 12-chloro stereoisomer (20) fail to react; this contrasts with the behaviour of other 1,6-methano[10] annulene derivatives.
Stereochemistry of α-Amino Oximes From the Monoterpene Hydrocarbons Car-3-ene, Limonene and α-Pinene
Authors: Tkachev AV , Rukavishnikov AV , Chibiryaev AM , Denisov AY , Gatilov YV , Bagryanskaya IY
Published: September 2010

The conformation and configuration of the α-amino oximes derived from the terpene hydrocarbons car-3-ene, limonene and α- pinene have been determined by n.m.r. spectroscopy (high-field 1H n.m.r., 13C n.m.r., INADEQUATE technique), molecular mechanics calculations and X-ray crystallographic analysis. The crystal structure of (lS,3S,6R)-3-dimethylamino-caran-4-one (E)-oxime has been determined by X-ray diffraction; crystals are orthorhombic, space group P 212121 with a 11.421(2), b 13.223(2), c 16.992(4) �, Z 8. Refinement on 1730 observed reflections measured with Cu K α radiation converged at R 0.053.
Fast Atom Bombardment Mass Spectrometry of Arene-Chromium Complexes: Cr(η6-C6-Ph6)2, Cr{η6-PhPh[Cr(CO)3]}2 and Fe(η-C5H4-η6-PhCr(CO)3)n(η-C5H4Ph)2-n (N = 0-2)
Authors: Bruce MI , Zaitseva NN
Published: September 2010

The fast atom bombardment mass spectra of several high molecular weight η- arene -chromium complexes have been measured and analysed. Interesting features include the observation of loss of C2Ph2 from [Cr(C6Ph6)2]+ to give [Cr(C10Ph10)]+ as the base peak, which appears to be derived from pentaphenylcyclopentadiene; the ready loss of Cr(CO)3 moieties from complexes containing this group; and the formation of ions containing CrFe groups in the spectra of the ferrocene derivatives.
Densities and Excess Molar Volumes of 2-Methoxyethanol/Water Binary Mixtures
Authors: Corradini F , Franchini G , Marcheselli L , Tassi L , Tosi G
Published: September 2010

Densities (ρ) are reported for the 2-methoxyethanol (component l)/water (component 2) solvent system, over the full composition range (0 ≤ X1 ≤ 1) at temperatures (t) from -10 to +80�C. The experimental data have been fitted by three empirical relations that represent the functions ρ = ρ(t), ρ = ρ(X1), ρ = p(t,X1), and the excess volume values by a Redlich-Kister equation. The 1:2 2-methoxyethanol/water adduct appears to be stable throughout the temperature range.
Rhodium-Catalyzed Reactions of Propargylamines With CO/H2. Formation of Pyrroles and Butenolides
Authors: Campi EM , Fallon GD , Jackson WR , Nilsson Y
Published: September 2010

Rhodium- catalysed reactions of ( arylpropargyl ) arnines with CO/H2 give P- arylpyrroles in good yields. Reactions of ( alkylpropargyl )amines gave alkylpyrroles together with butenolides which are formed in an unusual reaction that probably involves double carbonylation, reduction of one carbonyl function and removal of the amine function by hydrogenolysis. The single-crystal X-ray structure of 5-methyl-N,3-diphenylpyrrole-2-carboxamid is recorded.
Chlorosulfination With Thionyl Chloride of Aromatic Methyl Ethers Containing Other Functional Groups
Authors: Bell KH , Mccaffery LF
Published: September 2010

Further studies on the direct chlorosulfination with thionyl chloride of aromatic methyl ethers are described. In some cases (e.g. 1,6-dimethoxynaphthalene, 1,2,4 trimethoxybenzene, ethyl 3,5- and 3,7-dimethoxy-2-naphthoate, 3,5-dimethoxyphenyl benzoate) good yields of the sulfinyl chlorides were obtained but in others (e.g. 1,2-dimethoxybenzene, 3,5-dimethoxybenzyl acetate) the products (e.g. thiosulfonates, sulfides) were those from further reactions of the initial sulfinyl chloride. Aromatic methyl ethers containing functional groups which normally undergo reaction with thionyl chloride (e.g. aldehydes, ketones, acetals) showed only the usual reactions of those functional groups and no aromatic chlorosulfination.
Cometins (A-C), New Furanosesterterpenes From an Australian Marine Sponge, Spongia sp.
Authors: Urban S , Capon RJ
Published: September 2010

The known marine furanosesterterpene furospinosulin-1 (1), together with three new furanosesterterpenes, namely cometin-A (2), cometin-B (3) and cometin-C (4), were isolated from a marine sponge, Spongia sp., collected during commercial trawling operations in the Great Australian Bight. The structures of these metabolites were determined by detailed spectroscopic analysis and chemical derivatization . The antibiotic property of the crude ethanol extract of this sponge was attributed solely to the furanosesterterpene tetronic acid cometin -A (2).
On Diffraction Patterns of Structures Containing Regular Crystallographic Shear Planes
Authors: Harburn G , Parry BH , Tilley RJD , Williams RP
Published: September 2010

The appearances of the diffraction patterns expected for the phases derived from tungsten trioxide by crystallographic shear have been deduced by Fourier analysis. Study of electron- diffraction patterns and optical analogues confirms the predictions of the theory. The results have been generalized to a two-dimensional continuum of 'infinitely adaptive structures' by use of the shift lattice, of which the crystallographic shear structures are a special case.
Polymer-Fraction Dependence of Entry Rate Coefficients in Emulsion Polymerization
Authors: Leslie GL , Napper DH , Gilbert RG
Published: September 2010

Data on the rate of approach to steady state in a series of studies of the seeded emulsion polymerization of styrene yield the dependence of the rate coefficient for entry of free radicals into latex particles as a function of the weight-fraction polymer and hence of monomer concentration in the aqueous phase. The results are in accord with a model for the entry process (i.e., for the initiator efficiency) based on aqueous-phase propagation and termination being the rate-controlling events.
Imidazo[1,2-b]pyridazines. XIV. Syntheses and Central Nervous System Activities of Some 6-(Methoxy-, dimethoxy-, methylenedioxy-, chloro- and fluoro-)-3-alkoxy-2-phenyl(and substituted phenyl)imidazo[1,2-b]pyridazines
Authors: Barlin GB , Davies LP , Ireland SJ , Zhang JK
Published: September 2010

Syntheses are reported for 28 new 3-alkoxy-6-(3′-methoxy-,3′,4′-dimethoxy, 3′,4′-methylene-dioxy-, 2′- and 4′-chloro- and 4′-fluoro-benzylamino)-2-phenyl(and substituted phenyl) imidazo -[1,2-b] pyridazines from the corresponding 6-substituted pyridazin-3-amine 2-oxides with α- bromoacetophenones, followed by alkylation of the intermediate 3-hydroxyimidazo[1,2-b] pyridazines. In tests of the ability of these compounds to displace [3H]diazepam from rat brain membrane, 3-(2′-ethoxyethoxy)-6(3′-methoxybenzylamino)-2-phenyl- and 6(3′,4′-methylenedioxybenzylamino )-2-(3″,4″-methylenedioxyphenyl)-3-methoxy-imidazo[1,2-b] pyridazine bound most strongly, with IC50 values of 1nM.
The Thermal Isomerization of Coordinated Thiocyanate in Crystalline trans-[Co(NH3)4(15NH3)SCN](N14CS)2
Authors: Buckingham DA , Clark CR , Liddell GF , Simpson J
Published: September 2010

Heating crystalline trans-[Co(NH3)4(15NH3)SCN](N14CS)2 in the dark at c. 60°C results in the following immediate products (partial formulae are shown): 39% trans-CoNCS2+ (without incorporation of ionic thiocyanate ), 31% cis-CoS14CN2+ and 30% cis-CoN14CS2+ (with incorporation of ionic thiocyanate ). A crystal structure of the unlabelled reactant [Co(NH3)5SCN](NCS)2 [a 14.001(5), b 14.176(5), c 14.774(5) Ǻ, β 117.12(3)°, P21/n, Z = 8, 2898 reflections with I > 2σ(I), R 3.85%, Rw 4.10%] identifies two independent cobalt(III) cations in the asymmetric unit, and a consideration of the four distinct lattice thiocyanates identifies one of these, S(4)C(4)N(4)-, as that most likely to be involved in replacing the originally coordinated SCN-; S(4) at Co(1), and N(4) at Co(2). Intramolecular (as distinct from intermolecular) isomerization of coordinated thiocyanate is suggested for the formation of trans-CoNCS2+. The solid-state incorporation of lattice N14CS- and S14CN- is compared to that found in aqueous solution where ion-paired N14CS- and S14CN- as well as H2O compete in a solvent-cage, intramolecular , exchange process. The structure of the coordination isomer [Co(NH3)5NCS]SO4.1.5H2O, containing the product CoNCS2+ cation [a 6.621(9), b 7.123(21), c
26.906(19) Ǻ, Pnma, Z = 4,524 reflections with I > 2σ(1), R 6.34%, Rw 7.67%], is reported. A
reexamination of the crystal structure of [Co(NH3)5SCN]Cl2.H2O (ref. 1) suggests that hydrogen bonding to ammine ligands, rather than a more open structure or poorer positioning of lattice Cl-, is the reason for the non-incorporation of ionic Cl- on heating this material.
Compounds of Nickel(II) With trans-6,13-Dinitro- and trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane, with Structural Studies of Five (trans-6,13-Diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II) Compounds
Authors: Curtis NF , Gainsford GJ , Siriwardena A , Weatherburn DC
Published: September 2010

Compounds of NiII with the macrocyclic ligand trans-6,13-dimethyl-6,13-dinitro-1,4,8,11-tetraazacyclotetradecane ( dino ), which is formed by condensation of bis (ethane-1,2-diamine)nickel(II) salts, nitroethane and formaldehyde, are described, together with homologues formed by substituting propane-1,2-diamine and/or 1-nitropropane. The nitro functions of [Ni( dino )]2+ were reduced by catalytic hydrogenation to form (trans-6,13-diamino-6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane)nickel(II), [Ni( diam )]2+, isolated as approximately equal amounts of two isomeric forms; designated α (with the R,S,R,S configuration of the chiral nitrogen centres, overall configuration 1α,4α,6β,8α,11α,13α), and β (with the R,R,S,S, 1α,4β,6α,8β,11α,13β configuration). The α-isomer is metastable, and in solution isomerizes to the β-isomer, with rate constant of 5.0(5)×10-5 s-1 in 2 mol l.-1. NaCl solution at 50°C, the rate of this reaction increasing in both acid and base. Protonation constants (pK at 25°C in 0.1 mol l.-1 NaClO4) for diam are 11.2(1), 9.7(1), 6.2(1), 5.3(1), and for the isomeric nickel(II) cations are α 4.94(2), 2.4(5); and β 4.5(1), 4.0(1). Compounds of diam with the β-configuration were prepared with triplet ground state NiII with diam in hexadentate coordination (e.g. β-[Ni(diam-N4)] Cln ) and in tetradentate coordination with the neutral (e.g. trans-β-[Ni(diam-N4)(NCS)2]) or diprotonated ligand (e.g. trans-β-[Ni(diamH2-N4)(NCS)2](CNS)2). Compounds prepared with the α-configuration with triplet ground-state NiII had pentadentate diam with the neutral (e.g. trans-α-[Ni(diam-N5)(H2O)]Cl2) or monoprotonated ligand (e.g. trans-α-[Ni(diamH-N5) Cl ] (ClO4)2). Singlet ground-state NiII compounds with the square planar diprotonated ligand were prepared for both configurations. Structures are reported for β-[Ni(diam-N6)](ClO4)2(H2O), R 0.062 for 5708 reflections; β-[Ni(diam-N6)] [ZnCl4].1.5H2O, R 0.064 for 4332 reflections; β-[Ni(diam-N6)]Cl2.6H2O, R 0.044 for 2001 reflections; trans-β-[Ni(diam-N4)(NCS)2] R 0.056 for 1521 reflections; and trans-α-[Ni(diamH-N5) Cl ](ClO4)2(H2O), R 0.047 for 2667 reflections.
The Synthesis of Some Pyrrolidines as Potential Precursors to Retronecine
Authors: Ferro V , Skelton BW , Stick RV , White AH
Published: September 2010

Methyl β-D-galactopyranoside was converted into methyl 4-azido-3-O-benzyl-6-O-t-butyldiphenylsilyl-2,4-dideoxy-β-D-arabino-hexoside, but subsequent transformation of the anomeric centre into a dithioacetal was unsatisfactory. Alternatively, methyl β-D- galactopyranoside easily gave methyl 4-azido-3,6-di-O-benzyl-2,4-dideoxy-β-D-arabino-hexoside, and this could be transformed by a reductive amination into two pyrrolidines as potential precursors to retronecine. Related chemistry gave (4S,5S,6R)-6-benzyloxy-4-benzyloxymethyl-3-oxa-1-azabicyclo[3.3.0]octan-2-one, the structure of which was confirmed by a single-crystal X-ray structure determination. Finally, the synthesis of a potential precursor to heliotridine (an epimer of retronecine ), namely methyl 4-azido-3-O-benzyl-6-O-t-butyldiphenylsilyl-2,4-dideoxy-α-D-ribo-hexoside, from methyl α-D- mannopyranoside is reported.
Molten Calcium Nitrate Tetrahydrate: Spectroscopy of Chromium(III), Cobalt(II), Nickel(II) and Copper(II) Nitrates and Some Complexes of Nickel(II) and Cobalt(III)
Authors: Kerridge DH , Tariq SA
Published: September 2010

The hydrated nitrates of chromium(III), cobalt(II), nickel(II) and copper(II) dissolved in molten calcium nitrate tetrahydrate at 43°C to form clear coloured solutions. Their spectra, between 30000 and 11000 cm-1, showed maxima closely similar in wavenumber to those of the corresponding aqueous solutions, and indicated similar octahedral coordination by oxygen from the ligands. However, slightly higher molar absorption coefficients of the metal cations in the molten solutions than those of the aqueous solutions suggested the possibility of mixed coordination by both aqua and nitrato groups. Nickel(II) complexes were rapidly solvolysed in the melt but cobalt(III) displayed more varied behaviour, intriguingly different from those of their aqueous solutions.
Metal Ion Promoted Hydrolysis of Polyphosphates
Authors: Geue RJ , Sargeson AM , Wijesekera R
Published: September 2010

Various CoIII amine aqua hydroxo complexes have been evaluated for their ability to hydrolyse pyrophosphate to phosphate rapidly. Two very effective reagents have emerged, [Co( trpn )(OH)(OH2)]2+ ( trpn = 3,3′,3″-nitrilotris(propan-1-amine)) and [Co( tamen )(OH)-OH2)]2+ ( tamen = 6-(4-amino-2-azabutyl)-6-methyl-1,4-diazacycloheptane), and the latter has been examined closely to assess details of the mechanistic path for hydrolysis. The study shows substitution of the reagent on the substrate is fast and not rate determining. Two moles of the reagent are required to bind to [(en)2Co(P2O7)]- (en = ethane-1,2-diamine) to effect rapid hydrolysis. One supplies the coordinated OH- nucleophile to cleave the phosphorus anhydride, and the other binds as a chelate to the leaving group to assist bond rupture. An unproductive side path, to form a symmetrical dichelate of the form [(en)2Co(P2O7)Co( tamen )]2+, becomes rate limiting. However, if this path can be reduced in significance or eliminated, the study implies that polyphosphates and phosphate esters should hydrolyse on the subsecond time scale.
Group 15 Complexes With Carboxylic Acids. V. The Preparation and Crystal Structures of {Ag5As4(C4H2O6)4(H2O)5(X)}n[(C4H2O6) = (+)-Tartrate(4-); X = NO3-, ClO4-]
Authors: Bott RC , Smith G , Sagatys DS , Mak TCW , Lynch DE , Kennard CHL
Published: September 2010

The structures of two isomorphous silver(I) complexes with arsenic(III) (+)- tartrate [Ag5As4(C4H2O6)4(H2O)5(X)]n [X = NO3- (1), ClO4- (2)] have been determined by X-ray methods and refined to residuals R of 0.045 (1) and 0.028 (2) for 3822 and 3849 observed reflections respectively. Crystals are monoclinic, space group P21 with Z 2 in cells of dimensions a 12.057(3), b 10.651(1), c 12.496(3)Ǻ, β 93.37(2)° for (1), and a 12.170(5), b 10.570(1), c 12.634(4)Ǻ, β 92.74(2)° for (2). The two complexes are isostructural , with polymer framework structures based upon two configurationally identical [As2(C4H2O6)2]2- dimer ions, analogous to these in the tartar emetic structure [As-O (hydroxyl): 1.790(7)-1.804(8)Ǻ(1); 1.768(4)-1.818(4)Ǻ(2). As-O (carboxyl): 1.966(9)-2.118(8)Ǻ(1); 1.940(5)-2.127(5)Ǻ(2)]. However, an arsenic of one of the dimers forms a short bond to a silver atom [As-Ag, 2.729(2)Ǻ(1), and 2.723(1)Ǻ(2)], completing a trigonal-bipyramidal coordination about arsenic. The arsenic dimers are in turn linked by a chain of five silver cation centres through both carboxyl and hydroxyl oxygens which also form intrachain links. All five water molecules are bonded to silver ions, with three of them bridging silver centres. The main difference between the two structures arises from the replacement of the nitrate group in (1) by a perchlorate in (2).
Heterocyclic Ambident Nucleophiles. V. Alkylation of Benzimidazoles
Authors: Howell JR , Rasmussen M
Published: September 2010

Alkylation of 5-substituted benzimidazole anions with a variety of primary alkyl halides in both protic and aprotic solvents showed only small regioselectivity , with a slight preference for reaction at N1 for 5-nitro and N3 for 5-methoxy systems. With 4-substituted benzimidazole anions, alkylation gave more divergent results with the N1 to N3 regioselectivity varying between 100:0 and 29:71. These alkylation patterns are interpreted as deriving from an interplay of electrostatic, thermodynamic, steric and associative control factors within the variable SN2 transition state structures involved. In the 4-substituted series, proximity effects, both electrostatic field and steric non-bonded, are clearly dominant.
Structural Studies of Three Sesquiterpenes From Litsea spp. (Lauraceae)
Authors: Hakim EH , Achmad SA , Effend y , Ghisalberti EL , Hockless DCR , White AH
Published: September 2010

Isocurcumol (1) and a diepoxygermacranolide (2) have been isolated from Litsea cassiaefolia (Lauraceae), and valenc-1(10)-ene-8,11-diol (3) from L. excelsa. The structures of these new sesquiterpenes have been determined by X-ray crystallographic methods. It is suggested that (2) is identical to a compound described previously and originally assigned the epimeric configuration at C8.
Trunculin-F and Contrunculin-A and -B: Novel Oxygenated Norterpenes From a Southern Australian Marine Sponge, Latrunculia conulosa
Authors: Butler MS , Capon RJ
Published: September 2010

A specimen of Latrunculia conulosa from southern Australian coastal waters, previously observed to contain conulosin-A (6) and conulosin-B (7), has also been found to yield the known marine natural product trunculin-C methyl ester (14), along with three new norterpenes, trunculin-F (10), contrunculin-A (11) and contrunculin-B (12). Trunculin-F (10) was isolated, characterized and identified as its methyl ester (13), and its absolute stereochemistry determined by Horeau analysis. The structures for all new compounds were secured by detailed spectroscopic analysis.
X-Ray Crystal Structure Determination of Some Sodium Anthraquinone Sulfonate Derivatives
Authors: Gamag e , Gamag e , Peake BM , Peake BM , Simpson J , Simpson J
Published: September 2010

The crystal structures of sodium 9,10-dioxo-9,10-dihydroanthracene-2-sulfonate hydrate (1) and sodium 9,10-dioxo-9,10-dihydroanthracene-1,5-disulfonate trihydrate (2) have been determined by single-crystal X-ray diffraction at 253 K and refined to R 0.03 for (1) (1535 reflections) and R 0.04 for (2) (1409 reflections). Crystals of (1) are monoclinic, P21, a 17.395(5), b 6.625(2), c 5.537(1)Ǻ, β 91.87(2)°, Z 2, and those of (2) are orthorhombic, Pnma, a 11.332(4), b 20.048(5), c 7.634(3)Ǻ, Z 4. The results of molecular mechanics calculations on these two molecules were in general agreement with those determined by X-ray methods. The effect of sulfonate substitution in the 1-position compared with that in the 2-position include a small lengthening of the C-S bond and a displacement of the sulfur and quinone oxygen atoms to opposite sides of the plane of the substituted aromatic ring. However, these differences do not appear to be of sufficient magnitude to account for the much greater differences in the electrochemical and photochemical behaviour of these two classes of anthraquinone sulfonate derivatives.
Potential Antimalarials. XVIII. Some Mono- and Di-Mannich Bases of 3-[7-Chloro(and trifluoromethyl)quinolin-4-ylamino]phenol
Authors: Barlin GB , Ireland SJ , Nguyen TMT , Kotecka B , Rieckmann KH
Published: September 2010

Syntheses are reported for mono- and di-Mannich base derivatives of 3-[7-chloro(and trifluoro-methyl)quinolin-4-ylamino]phenols by Mannich reaction on 3-[7-chloro(and trifluoromethyl )-quinolin-4-ylamino]phenols or by condensation of Mannich base derivatives of 3-aminophenol, prepared from 3-nitrophenol, with the appropriate 4-chloroquinoline. The antimalarial activity of 3-(7′-chloroquinolin-4′-ylamino)-2,6-bis[ pyrrolidin-1″-ylmethyl -(or piperidin-1″-ylmethyl)]phenol against the FC-27 isolate of Plasmodium falciparum was comparable to that of chloroquine, and it was not significantly diminished in tests against the chloroquine -resistant K-1 isolate.
Preparation and Characterization of Porphyrin c Analogs as Agents for Photodynamic Therapy
Authors: Karagianis G , Reiss JA , Scourides PA
Published: September 2010

The porphyrin c analogues (4)-(10) were prepared by reaction of the appropriate thiol with the dibromohematoporphyrin adduct (3). The porphyrins were obtained in high yield and purity and were characterized by 1H and 13C n.m.r. spectroscopy and f.a.b. mass spectrometry.
Studies on Crown Ether Complexes. XXXI. Synthesis, Properties and Structure of the Complexes of Lighter Lanthanide Nitrates With (Z)-2,3-Diphenyl-1,4,7,10,13-pentaoxacyclopentadec-2-ene (Stilbeno-15-crown-5)
Authors: Lu TB , Tang N , Tan MY , Liu Y , Yu KB , Inoue Y , Hakushi T
Published: September 2010

Complexes of the lighter lanthanide nitrates with stilbeno-15-crown-5 (L) have been prepared in ethyl acetate. These new complexes with the general formula Ln (NO3)3.L.H2O ( Ln = La, Ce , Pr, Nd ) have been characterized by means of elemental analyses, i.r . spectra, 1H n.m.r. spectra and conductivity measurements. The crystal structure of La(NO3)3.L has been determined by X-ray methods, and refined to a residual R 0.0513 for 4937 independent reflections with I ≥ 1.5σ(I). It crystallizes in the monoclinic space group P21/a with a 16.090(5), b 15.654(8), c
22.687(2) Ǻ, β 93.96(4)°, V 5700(4)Ǻ3, and Z 8. There are two independent La(NO3)3.L monomers in one asymmetric unit; in each the coordination number is 11.
A Comparison of Chemical Reactivity in Some Benzo[b]Naphthyridines (Azaacridines)
Authors: Chen QP , Deady LW , Mackay MF
Published: September 2010

Some comparisons between four series of benzo [b][1,x] naphthyridines (x=5-8) have been made. Bromination in acetic acid gave almost exclusive reaction β to the nitrogen in the outer pyrido ring. Basic silver oxide oxidation of the centre ring occurred in the order x = 6 > 8 > 7 > 5. Methylation occurred on the pyrido nitrogen, the relative nucleophilicities paralleling those of the corresponding naphthyridines . One methiodide (x = 6) underwent an interesting dimerization in solution and the structure of the product was determined by X-ray crystallography.
The Synthesis and Structure of Encapsulating Ligands: Properties of Bicyclic Hexamines
Authors: Bottomley GA , Clark IJ , Creaser II , Engelhardt LM , Geue RJ , Hagen KS , Harrowfield JM , Lawrance GA , Lay PA , Sargeson AM , See AJ , Skelton BW , White AH , Wilner FR
Published: September 2010

Template syntheses based on tris (ethane-1,2-diamine)cobalt(III) lead to cobalt(III) complexes of cage hexamines of the ' sarcophagine ' type ( sarcophagine = sar = 3,6,10,13,16,19- hexaazabicyclo [6.6.6] icosane ) rapidly and in high yield. Reduction of these species to their cobalt(II) forms enables the ligands to be removed in concentrated acids at elevated temperatures, and in hot aqueous solutions containing excess cyanide ion. The free sarcophagine and 1,8-diaminosarcophagine [(NH2)2sar or diamsar] ligands are strong bases, accepting up to four and five protons, respectively, in aqueous solution. In chloride medium, I = 1.0, at 298 K, pK1 = 11.95, pK2 = 10.33, pK3 = 7.17, pK4 ≈ 0 for sarcophagine , and pK1 = 11.44, pK2 = 9.64, pK3 = 6.49, pK4 = 5.48, pK5 ≈ 0 for diaminosarcophagine , with very similar values being found for triflate medium. Crystal structure determinations for both free bases, the chloride, sulfate, perchlorate and nitrate salts of diamsar , the complex of zinc chloride with sar, and the magnesium nitrate complex with diamsar show remarkably small variations in the cavity defined by the bicyclic ligands, though relatively subtle bond length and bond angle changes can be rationalized in terms of the effects of proton and metal ion binding. Exhaustive methylation of sarcophagine produces the highly lipophilic, hexatertiary base hexamethylsarcophagine , which, in the solid state, adopts quite different conformations and nitrogen-atom configurations to those of sar itself. All the ligands rapidly form metal ion complexes of generally exceptional kinetic and thermodynamic stability.
Structural Systematics of Rare Earth Complexes. VII. Crystal Structure of Bis(2,2'/6',2␛-Terpyridinium) Octaaquaterbium(III) Heptachloride Hydrate
Authors: Kepert CJ , Skeleton BW , White AH
Published: September 2010

The room-temperature single-crystal X-ray structural characterization of the title compound (tpyH2)2[Tb(OH2)8]Cl7.~2⅓H2O is recorded. Crystals are triclinic, Pī , a 17.063(5), b 16.243(3), c 7.878(3) Ǻ, α 84.78(2), β 84.39(3), γ 87.81(2)°, Z = 2 formula units; 3167 'observed' diffractometer reflections were refined by full-matrix least-squares procedures to a residual of 0.057. Notable features of interest of the compound are the 'chelation' of chloride ions by the terpyridinium cations , and the existence of a free [Tb(OH2)8]2+ cation in the presence of an abundance of chloride ions.