bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of Complex Ligands, LXV. Vinylidene and Methoxy(alkynyl)carbene Molybdenum Complexes: Competitive Formation During Fischer Carbene Complex Synthesis and Crystal Structure Determination
Authors: Dötz Karl Heinz , Christoffers Carmen , Christoffers Jens , Böttcher Dirk , Nieger Martin , Kotila Sirpa 
Published: July 2007

AbstractReaction of [(η5‐C5H5)(CO)2(NO)Mo] (1) with alkynyllithium and [(CH3)3O]BF4 affords the vinylidene‐molybdenum complex 2 along with the methoxy(alkynyl)carbene molybdenum complex 3. Both compounds are characterized by an X‐ray crystal structure analysis. Due to axial and central chirality in the LnMCCR2 moiety complex 2 is formed as a 2 : 1 mixture of two diastereomers. The formation of 2 and 3 can be understood in terms of a competitive attack of alkynyllithium at the carbonyl ligand and the molybdenum center.
Ligand‐Induced Directionality Shift in the Fe+‐Mediated Dehydrogenation of 1,8‐Diphenyloctane
Authors: Raabe Norbert , Karraß Sigurd , Schwarz Helmut 
Published: July 2007

AbstractThe presence of a cyclopentadienyl ligand brings about a complete shift of regioselectivity in the Fe+‐mediated dehydrogenation of 1,8‐diphenyloctane (1). While “bare” Fe+, due to the formation of an intramolecular sandwich‐like complex, activates the internal C‐4/C‐5 positions of the alkyl chain, this chelate effect is no longer operative in the gas‐phase chemistry of Fe(C5H5)+ with 1. Labeling experiments demonstrate that the C‐1/C‐2 and (to a minor extent) the C‐2/C‐3 methylene groups are activated, and a possible origin of this remarkable ligand effect is discussed.
Synthesis, Structure, and Ligand Behavior of the 1,2‐Diphosphaferrocene [η5‐1,3‐tBu2C5H3)(η5{3,4‐(Me3Si0)2‐5‐(Me3Si)P2C3} Fe]
Authors: Weber Lothar , Sommer Oliver , Stammler Hans‐Georg , Neumann Beate , Kölle Ulrich 
Published: July 2007

AbstractReaction of equimolar amounts of (η5‐1,3‐tBu2C5H3)(CO)‐{3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe]2‐FeP(SiMe3)2 with bis(trimethylsilyl)methylenechlorophosphane afforded the 1‐metallo‐1,2‐diphosphapropene (η5‐1,3‐tBu2C5H3)(CO)2 FeP (SiMe3)P = C(SiMe3)2 (1b). Treatment of 1b with an excess of [(Z)‐cyclooctene]Cr(CO)5 furnished 1,2‐diphosphaferrocene (η5‐1,3‐tBu2C5H3)(η5‐{1‐[Cr(CO)5]‐3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe (4b). Chromium complex 4b was freed from the pentacarbonylchromium fragment by heating with 1.5 equiv. of [Fe2(CO)9] in toluene solution at 80–90°C affording sandwich 5. In contrast, treatment of 4c with [Fe2(CO)9] in refluxing n‐pentane yielded the trinuclear complex (η5‐1,3‐tBu2C5H3){η5‐1,2‐[Fe2(CO)7]‐3,4‐(Me3SiO)2‐5‐(Me3Si)P2C3}Fe (6). The ligation of sandwich 5 to the [Fe(CO)4] unit in 7 was achieved by irradiation with [Fe(CO)5] in n‐pentane solution. A tricarbonylnickel adduct 8 resulted from the reaction of 4b with an excess of [Ni(CO)4] in toluene at ambient temperature. The molecular structures of the complexes 6 and 8 were established by single‐crystal X‐ray structure analyses. Cyclovoltammetric studies with 4b, 5, and 8 revealed an anodic shift of the oxidation potential when changing from 5 to 8 and 4.
1,1′‐Bis(methylphenylphosphanyl)ferrocene: Synthesis and Complexes with the Tetracarbonylchromium Fragment
Authors: Herberich Gerhard E. , Moss Stefan 
Published: July 2007

Abstract1,1′‐Bis(methylphenylphosphanyl)ferrocene (mppf) (2) was synthesized from dilithioferrocene and PMePh(OC6H4‐4‐Me). The diastereomers rac‐2 and meso‐2 were separated by fractional crystallization from ethanol. The tetracarbonyl‐chromium complexes (rac‐2)Cr(CO)4 (rac‐5) and (meso‐2)Cr(CO)4 (meso‐5) were obtained photochemically from hexacarbonylchromium and mppf in near quantitative yield. The structures of rac‐2, rac‐5, and meso‐5 were determined by X‐ray crystallographic analysis.
Synthesis and Complexation Behavior of the Functionalized Tripodal Phosphane cis,cis‐1,3,5‐Tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)‐cyclohexane (tdppcycn)
Authors: Mayer Hermann A. , Stößel Philipp , Fawzi Riad , Steimann Manfred 
Published: July 2007

AbstractThe synthesis of the novel potentially bistripodal ligand cis‐cis‐1,3,5‐tris(cyano)‐1,3,5‐tris(diphenylphosphanyl)cyclohexane (tdppcycn) (6) is described. Starting from the tricarboxylic acid cis,cis‐1,3,5‐C6H9(COOH)3 (1), which is converted stepwise into the triacid chloride cis,cis‐1,3,5‐C6H9(COCl)3 (2), the triphenyl ester cis,cis‐1,3,5‐C6H9(COOPh)3 (3), the tricarboxamide cis,cis‐1,3,5‐C6H9(CONH2)3 (4), and the tricarbonitrile cis,cis‐1,3,5‐C6H9(CN)3 (5), we obtained tdppcycn (6) by α‐deprotonation of 5 followed by treatment with ClPPh2 in good yield. Treatment of 6 with Mo(CO)3(‐C7H8) and Ir(PPh3)2(CO)Cl gave octahedral Mo(tdpp‐cycn)(CO)3 (7) and pentacoordinate Ir(tdppcycn)(CO)Cl (8), respectively, with a facially P‐coordinated tdppcycn ligand. The stereochemistry of compounds 2–8 was established by 1H‐, 13C‐, 31P‐NMR, and IR spectroscopy. An X‐ray crystal structure analysis of complex 8 confirms the trigonal‐bipyramidal ground‐state structure in the solid state.
A Direct Route to Halogenated Arsaborane Clusters: Crystal Structure of 3,4,5,6‐Tetrachloro‐1,2‐diarsa‐closo‐hexaborane(4)
Authors: Schäfer Ronald , Einholz Wolfgang , Keller Willi , Eulenberger Günther , Haubold Wolfgang 
Published: July 2007

AbstractCopyrolysis of B2Cl4 and AsCl3 at 330°C leads to the formation of closo‐1,2‐As2B4Cl4 (1) and further products the mass spectral evidence of which suggests that they are perchlorinated arsaboranes As2B5Cl5, As4B8Cl6, and As2B10Cl10. The pyrolysis temperature and the molar ratio of the reactants exert an essential influence on the type and distribution of the products. At temperatures above 400°C and higher B2Cl4/AsCl3 ratios the formation of As2B10Cl10 is preferred to that of smaller arsaboranes. A single‐crystal X‐ray study of 1 confirmed that, consistent with its 14‐skeletal electron count, the arsaborane adopts a slightly distorted octahedral structure with the arsenic atoms in adjacent cis positions.
Synthesis of Structures of (Acyloxy)boranesSynthesis of Structures of (Acyloxy)boranes
Authors: Lang Andreas , Nöth Heinrich , Schmidt Martin 
Published: July 2007

Abstract9‐Borabicyclo[3.3.1]nonane (9‐BBNH) reacts with monocarboxylic acids to afford 9‐(acyloxy)‐9‐borabicyclo[3.3.1]nonanes which are dimers in the solid state as shown by X‐ray crystal structures of the benzoate and pivalate. More complex reactions were observed by allowing 9‐BBNH to react with dicarboxylic acids in THF or monoglyme. Thus, (9‐BBN)2 oxalate 3 contains a fully delocalized oxalate unit with equal C‐O and B‐O bond lengths. Traces of water convert it into the tetrakis(9‐BBN) oxalate 5. A rather unusual structure is veryfied by 9‐BBN 2,2‐dimethylmalonate 7 which according to its molecular structure is a tetramer featuring a 32‐membered ring system. In contrast, reactions of oxalic acid with thexylborane leads to reduction of the acid and formation of a bicyclic dioxaborolo‐dioxaborolane 10. Several intermediates were detected by 11B‐NMR spectroscopy as well as in reactions of BH3 · THF or BH3 · SMe2 with oxalic acid. — It follows from the present study that (acyloxy)boranes derived from dicarboxylic acids are strong Lewis acids with an unexpected variety of structural features.
Chalcogen Polycations with Mononuclear Divalent Anions from Chalcogen Subhalides and Tetrachlorides of Zr and Hf: Syntheses and Crystal Structures of Se4(MCl6) (M = Zr, Hf) and Te4(HfCl6)
Authors: Beck Johannes , Schlitt Klaus‐Jürgen 
Published: July 2007

AbstractSelenium, SeCl4, and MCl4 (M = Zr, Hf) react in a sealed evacuated glass ampoule at 130°C to afford red, moisture sensitive crystals of Se2+4(ZrCl2‐6) and Se2‐6(HfCl2‐6). The isotypic crystal structures (tetragonal, P42/ncm, Z = 4) consist of square‐planar Se2+4 cations and slightly distorted octahedral MCl2‐6 (M = Zr, Hf) anions. The ions are packed corresponding to the NaCl structure type with the centres of gravity of the Se4 rings and the metal atoms of the MCl6 octahedra in the Na and Cl positions. From Te, TeCl4, and HfCl4 one obtains under similar conditions at 200°C Te2+4 (HfCl2‐6) in form of dark violet crystals. The crystal structure (triclinic, P1, Z = 1) is built of nearly square‐planar Te2+4 ions and octahedral HfCl2‐6 ions. The packing of the ions corresponds to a rhombohedrally distorted CsCl structure type.
β‐Alkoxy‐ and β‐Hydroxyalkylphosphanes as Ligands in the Stereoselective Hydrogenation — A Comparison
Authors: Börner Armin , Kless Achim , Kempe Rhett , Heller Detlef , Holz Jens , Baumann Wolfgang 
Published: July 2007

AbstractOptically pure 1,4‐bis(diphenylphosphanyl)‐2‐hydroxy‐butane (2) and its methyl ether 1 can be conveniently prepared by starting from chiral pool substances such as malic or L‐ascorbic acid. Different pathways to these compounds were elucidated. In one case an interesting migration of an acetalic OH‐protective group was observed. The reaction of the bisphosphanes with Rh1 or PdII gave uniform metal complexes. On the basis of X‐ray structural analysis, NMR and IR data it was concluded that in the investigated precatalysts of the type [Rh(COD)(bisphosphane)]BF4 a coordination of the alkoxy or hydroxy oxygen to the metal does not take place. Nevertheless, significant differences in enantioselectivity and activity could be observed when several prochiral substrates were hydrogenated.
Zinc Complexes of Drugs Containing Nitrogen Heterocycles
Authors: Koppenhöfer Alrik , Hartmann Uwe , Vahrenkamp Heinrich 
Published: July 2007

AbstractFour drugs whose actions have a relation to the status of zinccontaining species in the human body were used as ligands in zinc complexes. Captopril (H2Cap) forms the compound [ZnCap] (1) presumed to be a coordination polymer with O and S coordination. Isoniazid, in the presence of zinc salts, is converted to 1,2‐diisonicotinoyl hydrazide (H2Nih) which forms polymeric [Zn(Nih)NH3] (2) with trigonal‐bipyramidal ZnO2N3 coordination. Nalidixic acid (HNal) and zinc perchlorate yield [Zn(HNal)2(H2O)2](ClO4)2 · 2 H2O (3) containing zinc in an octahedral ZnO6 environment. Mercaptopurine (H2Mer), in the presence of ammonia, forms [Zn(Mer)(NH3)2] . H2O (4) which is a coordination polymer containing tetrahedral ZnN4 units. The structures of [Zn(Nih)NH3], [Zn(HNal)2(H2O)2](ClO4)2 . 2 H2O, and [Zn(Mer)(NH3)2] . 2 H2O were determined diffractometrically.
Locating the Position of Lithium in Solution by Combined 13C,6Li and 1H,6Li HOESY Measurements
Authors: Berger Stefan , Müller Frank 
Published: July 2007

Abstract13C,6Li HOESY Measurements were developed and performed for the first time on the 13C‐labeled benzyllithium compound 1. 1D NOE difference, 1H,6Li HOESY, and spin lattice relaxation measurements were used to obtain information on the position of the lithium, ion in solution.
Enantioselective Deprotonation of Benzyl Phosphates by Homochiral Lithium Amide Bases — Configurational Stability of Benzyl Carbanions with a Dialkoxyphosphoryloxy Substituent and Their Rearrangement to Optically Active α‐Hydroxy Phosphonates
Authors: Hamerschmidt Friedrich , Hanninger Achim 
Published: July 2007

AbstractBenzyl dialkyl phosphates are deprotonated enantioselectively by homochiral lithium amides of isopropyl(1‐phenylethyl)amine or bis(1‐phenylethyl)amine. The short‐lived benzylic carbanions formed are virtually configurationally stable relative to the rearrangement to optically active phenyl‐hydroxymethylphosphonates. The enantiomeric excesses are up to 50%. The pro‐(S) hydrogen is removed by amides having (S) configuration. Homochiral diethyl (S)‐phenyl[D1]‐methyl phosphate [(S)‐16c] is deprotonated by both LDA and n‐BuLi with a high primary kinetic isotope effect (kH/D ≈︁ 50) and isomerizes to the corresponding α‐hydroxy phosphonate with an enantiomeric excess of up to 85%.
Tris(1,10‐phenanthroline)iron(II) Complexes — Broad Variation of the Redox Potential by 4,7‐Substitution at the Phenanthroline Ligands[1]
Authors: Schmittel Michael , Ammon Horst , Wöhrle Clemens 
Published: July 2007

AbstractThe new 4,7‐donor‐substituted phenanthrolines 2a‐h were synthesized and the corresponding tris(1,10‐phenanthroline)iron(II) complexes 3a‐h studied by cyclic voltammetry. In more detail three novel aza‐crown ether‐linked (phenanthroline)iron complexes were investigated, the redox potentials of which could be fine‐tuned by the addition of group‐Ia,IIa metal cations. All iron(II) complexes showed reversible waves at scan rates between 50 and 500 mV · s‐1 and could be reversibly oxidized and reduced by chemical means.
Synthesis of Allenes by 1,6‐Addition of Organocuprates to Acceptor‐Substituted Enynes: Scope and Limitations
Authors: Hohmann Michael , Krause Norbert 
Published: July 2007

AbstractAcyclic acceptor‐substituted conjugated enynes bearing sulfonyl sulfinyl, sulfonate, nitro, amide, cyano, and oxazolidino groups at the double bond were synthesized and the regioselectivity of their reaction with organocuprates was examined. All Michael acceptors except enynes with nitro and amide functions underwent 1,6‐additions, and the allenyl enolates thus formed were trapped with electrophiles in order to obtain the corresponding allenes. A qualitative reactivity scale for these reactions was established. The dependence of the regioselectivity of both the cuprate addition and the subsequent electrophilic capture on the acceptor group and the substitution pattern of the allenyl enolate were studied. Cyclic 2‐en‐4‐ynoates with endocyclic double bonds were synthesized and treated with organocuprates to afford an exocyclic allene in one case.
Thiono, Selenothiono, and Dithiocarboxylic Ester Complexes from Pentacarbonyl(thiobenzaldehyde)tungsten and π‐Donor Substituted Alkynes and Decomplexation of the Esters
Authors: Fischer Helmut , Treier Kornelia , Troll Carsten 
Published: July 2007

AbstractPentacarbonyltungsten‐coordinated thiobenzaldehyde, [(CO)5W{S=C(Ph)H}] (1), reacts with 1‐methylthio‐1‐propyne, 1‐ethylseleno‐1‐propyne, and alkoxyethynes by insertion of the CC into the S=C bond to form in a highly regio‐and stereoselective manner the α,β‐unsaturated dithio, selenothiono, and thionocarboxylic ester complexes (E)(CC)‐[(CO)5W{η1‐SC(XR′)C(R)=C(Ph)H}] (3) (R = Me: XR′ = SMe (a), SeEt (b); R = H: XR′ = OEt (c), OtBu (d)). The analogous reaction of 1 with bis(alkylthio)ethynes affords mixtures of the (E) and (Z)(C=C) isomers of [(CO)5W{η1‐S=C(SR)C(SR)=C(Ph)H}] (6) [R = Me (a), tBu (b)]. The Z isomers are the initially formed products. Formation of (Z)‐6 is followed by Z → E isomerization until an equilibrium [E/Z = 1 (6a), 1.5 (6b)] is obtained. For R = tBu isomerization is significantly faster than for R = Me. The dithio and thiono ester ligands can be cleaved intact from the metal by treatment with [NEt4]Br as shown by the examples of 3a, 3c, and 6a. Complex 3c has been characterized by an X‐ray structural analysis.
Metal Tetrahydroborates and Tetrahydroborato Metalates. 20. Reactions of Cadmium Tetrahydroborate with Alcoholates and Phenolates ‐ X‐ray Structure of [MeCd(OCMe3)]4
Authors: Nöth Heinrich , Thomann Martina 
Published: July 2007

AbstractCadmium tetrahydroborate reacts with alkali metal alcoholates or phenolates in THF solution either with formation of addition products [Cd(BH4)2OR]‐ or by ligand exchange to produce Cd(BH4)OR. Different oligomers of the latter are formed depending on concentration. The reaction of Cd(BH4)2 with Cd(Omes)2 (mes = mesityl) leads to an equilibrium of the starting materials with Cd(BH4)(Omes) as shown by 113Cd‐NMR spectroscopy. The crystal structure of Me‐Cd(OCMe3), a molecule which can be regarded as a model for Cd(OCMe3)(BH4), proved to be a tetramer with a cubane‐type Cd4O4 core.
Silicon Compounds with Strong Intramolecular Steric Interactions. LVII. Oxidation and Cycloaddition Reactions of an Unsymmetrically Substituted Disilene
Authors: Weidenbruch Manfred , Pellmann Andrea , Pohl Siegfried , Saak Wolfgang , Marsmann Heinrich 
Published: July 2007

AbstractReaction of the unsymmetrically substituted disilene R2Si=SiR′2 (4; R = 2,4,6‐Me3C6H2, R′ = 2,4,6‐iPr3C6H2) with m‐chloroperbenzoic acid (mCPBA) or oxygen furnished the correspondingly substituted 1,2,3‐oxadisilirane 5 or 1,3,2,4‐dioxadisiletane 6, respectively. The [2 + 2] and [2 + 4] Cycloaddition reactions of 4 with benzophenone and 3,5‐di‐tert‐butyl‐1,2‐benzoquinone, respectively, proceeded with a high degree of regioselectivity to yield the 1,2,3‐oxadisiletane 9 and the 2,3‐dihydro‐1,4,2,3‐benzodioxadisiline 7. The latter product was isolated together with a small amount of an isomeric compound 8 in which the substituents at the silicon atoms are reversed. The molecular structures of the products 5, 6, and 7 were determined by X‐ray crystallography.
Norbornadiene(bipyridyl)molybdenum(II) Complexes: Synthesis, Structure and Reactivity of [Mo(CO)(C7H8)(C10H6R2N2)X2] (X = I, Br)
Authors: Daniel Thomas , Nagao Hirotaka , Tanaka Koji , Nakamura Akira 
Published: July 2007

AbstractThe reaction of [Mo(CO)4(C7H8)] (1) with I2 gave the norbornadienemolybdenum(II) complex [Mo(CO)2(C7H8)I2]n≥1 (2), which existed in an equilibrium of two isomeric forms. In acetonitrile, 2 reversibly formed the adduct [Mo(CO)2‐(C7H8)(NCCH3)I2] (3), whereas on treatment with 2,2′‐bipyridine or 4,4′‐di‐2,2′‐tBu‐bipyridine, it gave stable 7‐coordinated molybdenum(II) complexes, [Mo(CO)(C7H8)‐(C10H8N2)I2] (4) and [Mo(CO)(C7H8)(C10H6tBu2N2)I2] (5), in good yield. In similar reactions, the related dibromomolybdenum compounds [Mo(CO)(C7H8)(C10H8N2)Br2] (6) and [Mo‐(CO)(C7H8)(C10H6tBu2N2)Br2] (7) were prepared by oxidation of 1 with two equivalents of CuBr2. The X‐ray structural analysis of 6 reveals that the geometry around the molybdenum atom is nearly perfectly pentagonal bipyramidal, with the CO and one of the bipyridyl rings perpendicular to the plane formed by the other ligands. The compounds 5 and 6 react with AgSbF6 by halogen abstraction to give cationic complexes, {[Mo(CO)(C7H8)(C10H8N2)Br]SbF6}n≥1 (8) and {[Mo(CO)(C7H8)(C10H6tBu2N2)I]SbF6}n≥1 (9): In acetone, 8 and 9 reversibly formed the adducts [Mo(CO)(C7H8)(C10H8N2)(acetone)Br]SbF6 (8′) and [Mo(CO)(C7H8)(C10H6tBu2N2)(acetone)I]SbF6 (9′); while on treatment with PMe3, the stable monomeric complexes, [Mo(CO)(C7H8)(C10H8N2)(PMe3)Br]SbF6 (10) and [Mo(CO)(C7H8)(C10H6tBu2N2)(PMe3)I]SbF6 (11), were isolated in almost quantitative yield. In the presence of KBr, compound 8′ reverted to the dibromo complex 6, whereas 9′ reacted to produce a 1:1:2 mixture of 5, 7 and the bromo(iodo) complex [Mo(CO)(C7H8)(C10H6tBu2N2)BrI] (12). The same mixture is available from the reaction of 5 with one equivalent of 7.
Functionalized Diorganozinc Compounds: Key Reagents for the Synthesis of Enantiomerically Pure 2,5‐Disubstituted cis‐ and trans‐Tetrahydrofurans
Authors: Berninger Jörn , Koert Ulrich , Eisenberg‐Höhl Christina , Knochel Paul 
Published: July 2007

Abstract1,4‐Diol derivatives 4a‐i were synthesized stereoselectively by either reagent‐ or catalyst‐controlled routes using the addition of functionalized diorganozinc reagents to aldehydes. The stereoselectivities along the reagent‐controlled synthetic path were in the range between 80:20 and 95:5. The stereoselectivities along the catalyst route exceeded 95:5. The 1,4‐diol derivatives 4 thus obtained were transformed into enantiomerically pure cis‐ and trans‐2,5‐disubstituted tetrahydrofurans (16‐20) by means of an intramolecular Williamson reaction.
Titanocene Complexes Based on Benzenehexathiolate Derivatives and 2,3,6,7‐Tetrachloronaphthalenetetrathiolate
Authors: Fanghänel Egon , Bierwisch Jörg , Ullrich Andreas , Herrmann Anett 
Published: July 2007

AbstractThe synthesis and properties of the new (dithiolato)titanocene complexes 4a‐d, 6, 9 are described. The ligands of these complexes are derived from sodium benzenehexathiolate or 3,4,7,8‐tetrachloronaphthobis[1,2]dithiole. Complexes with one, two and three (dithiolato)titanocene units were prepared by use of these dithiolato ligands.
Amino Substituted Tricarbonyl(cyclobutadiene)iron Complexes: Pd‐Catalyzed Coupling of Iodocyclobutadiene Complexes with Amines
Authors: Wiegelmann‐Kreiter Jutta E. C. , Enkelmann Volker , Bunz Uwe H. F. 
Published: July 2007

AbstractThe coupling of the iodides 1 with amines under palladium catalysis affords the novel aminated cyclobutadiene derivatives 2 in preparative useful yields.
Metallocenophanes, VII. Preparation and Characterisation of the Disilver(I) Complexes of Conjugated Polyenes with [2.2.2]Paracyclophanyl End Groups
Authors: Heirtzler Fenton R. , Hopf Henning , Bubenitschek Peter , Jones Peter G. 
Published: July 2007

AbstractThe preparation of the disilver(I) complexes 3 and 4, polyene metal complexes that are terminally substituted with [2.2.2]paracyclophanyl units, is described. NMR spectro‐scopic studies on the disilver perchlorate complex 3b showed that (a) the sites of complexation are the cyclophane groups and (b) the olefinic spacers do not overly perturb the overall complexation properties of the individual [2.2.2]paracyclo‐phanyl groups. The crystal structures of the disilver hexafluo‐roantimonate complexes 4a–b were determined. The use of the hexafluoroantimonate counterion and solvent mixtures containing toluene both proved crucial in obtaining single crystals; toluene is incorportated into the crystal lattices.
Unusual Complexation Behavior of Metallomacrocycles Based on Isothiosemicarbazides with Respect to Alkali and Alkaline Earth Metal Ions: Novel 2:1 Associates
Authors: Reetz Manfred T. , Arion Vladimir B. , Trültzsch Rainer , Buschmann Hans‐Jürgen , Cleve Ernst 
Published: July 2007

AbstractThe reactions between alkali and alkaline earth metal ions and nickel(II) macrocycles based on S‐alkylated isothiosemi‐carbazides with different crown ether cavity size were studied in propylene carbonate by spectrophotometric and calorimetric titrations. Metallomacrocycles 1 and 2 exhibit normal behavior on 1:1 complexation with alkali‐ and alkaline earth metal ions and resemble in this respect 15C5 and 18C6, respectively. The most stable complexes are formed by these “ligands” when the diameter of the cation and the crown ether hole have approximately the same size. The most striking feature of the complexation processes studied is the formation of 1:2 metal‐ligand associates even in the case of the smallest cations. These associates are very different from “normal” crown ether sandwich complexes. In reality, the particle formed is an associate between a 1:1 complex, in which the corresponding metal ion is well accommdated inside the ligand cavity, and a second metallomacrocyclic ligand. Their formation is disfavored by enthalpic contributions. A special kind of “switch” from these associates to normal sandwich complexes takes place in the case of 1, when the cation diameter compared to hole size increases. The macrocycle 2 forms this kind of associates with all akali and alkaline earth ions.
Thiaaza‐arachno‐pentaboran SNB3H2tBu3R
Authors: Müller Matthias , Englert Ulli , Paetzold Peter 
Published: July 2007

Thiaaza‐arachno‐pentaborane SNB3H2tBu3RThe azadiboriridine [‐B(tBu)‐N(tBu)‐B(tBu)‐] (1) gives 1:1 adducts with the mercaptoboranes BH2(SR), which can be generated from their cyclotrimers by the action of THF. The adduct 4a (R = Ph), a nido cluster with an NB3 skeleton, forms an equilibrium with an adduct 5a, an arachno cluster with an SNB3 skeleton, whose S‐bound ligand Ph is found in an endo position by an X‐ray structural analysis. The equilibrium 4a · 5a involves a Lewis acid‐base reaction, which is electronically coupled to a reduction of a three‐center to give a two‐center π bond. The reaction of 1 with BH2(SPr) gives the corresponding arachno cluster 5b only.
[MeO(CH2CH2O)3(CH2)3C5Me4]FeCl: A Halfsandwich Iron (II) Chloride Complex of Remarkable Stability
Authors: Siemeling Ulrich 
Published: July 2007

AbstractReaction of iron(II) chloride with one equivalent of [MeO‐(CH2CH2O)3(CH2)3C5Me4]Li in THF yields the title halfsand‐wich complex 1, which is stable in solution up to room temperature. Compound 1 reacts with C5H5Li and CO to give [MeO(CH2CH2O)3(CH2)3C5Me4]Fe(C5H5) (2) and [MeO‐(CH2CH2O)3(CH2)3C5Me4]Fe(CO)2CI (3), respectively, in high yields.