bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Pair Charge‐Transfer Complexes of Dithiolene Metalates with Diquaternary 2,2′‐Biimidazoles
Authors: Lemke Matthias , Knoch Falk , Kisch Horst , Salbeck Josef
Published: July 2007

Cycloalkylated biimidazolium dications (A2+) of reduction potentials from ‐0.4 to ‐1.4 V form ion pair charge‐transfer complexes {A2+ [M(mnt)2]2−} with dithiolene metalates, M = Zn, Ni, Pd, Pt, mnt2− = maleonitrile‐2,3‐dithiolate. X‐ray analyses of {P2BBIm2+[Ni(mnt)2]2−} [P2BBIm2+ = 1,1′,3,3′‐bis(propane‐1,3‐diyl)bibenzimidazolium] and {B2Blm2+ [Pd(mnt)2]2−} [B2BIm2+ = 1,1′,3,3′‐bis(butane‐1,4‐diyl)biimidazolium] reveal that the solid‐state structure is largely determined by the geometry of the acceptor. When the latter is strongly twisted, the usually observed mixed donor‐acceptor columns are modified to a chain‐like arrangement. In the case of the bibenzimidazolium dication P2BBIm2+ the otherwise planar [Ni(mnt)2]2− becomes tetrahedrally distorted. By the application of the Hush model a reorganization energy of about 67 kJ/mol is estimated for the thermal electron transfer from [M(mnt)2]2− to A2+ when M = Ni, Pd, Pt, but considerable deviations from this model are observed when M = Zn. Irradiation of the free biimidazolium acceptors in the presence of EDTA affords the strongly reducing radical cations which reduce water to hydrogen in the presence of colloidal platinum. Attempts to sensitize this reaction by irradiating into the charge‐transfer band of {A2+ [M(mnt)2]2−} have failed until now. The molar absorptivity of one biimidazolium radical cation is measured by spectroelectrochemistry.
Erste strukturelle Charakterisierung eines 3‐Silaoxetans und 3‐Silathietans im Kristall und in Lösung
Authors: Strohmann Carsten
Published: July 2007

First Structural Characterisation of a 3‐Silaoxetane and a 3‐Silathietane in the Crystal and in Solution

The 3‐silaoxetane 3,3‐dimethyl‐2,2,4,4‐tetraphenyl‐1‐oxa‐3‐silacyclobutane (1) and the 3‐silathietane 3,3‐dimethyl‐2,2,4,4‐tetraphenyl‐1‐sila‐3‐thiacyclobutane (2) were synthesized and studied in the solid state and in solution. The crystal structures of 1 and 2 were investigated by X‐ray diffraction. Furthermore, 1 and 2 were characterized by solid‐state NMR spectroscopy (13C and 29Si CP/MAS). The cyclobutane ring of 1 is planar with a C‐Si‐C angle of 75.07(9)° and a C‐O‐C angle of 105.3(2)°. 2 crystallizes with a non‐planar cyclobutane ring with a C‐Si‐C angle of 89.00(11)° and a C‐S‐C angle of 93.25(11)°. The Si‐O distance of 241.5(3) pm for 1 and the Si‐S distance of 263.9(3) pm for 2 are shorter than the sum of the van der Waals radii of these atoms. The results obtained by X‐ray diffraction are consistent with those from solid state 13C‐NMR spectroscopy for 1 and 2. Different 29Si‐NMR spectra in solution and the solid state indicate unusual electronic or steric effects around the silicon atom of 2 in the solid.
Reactions of Diazo Compounds and Chiral Rhenium Alkylidene Complexes of the Formula [(η5‐C5H5)Re(NO)(PPh3)(CHR)]+ PF A Versatile and Highly Stereoselective Route to Alkene Complexes
Authors: Wang Van , Gladysz John A.
Published: July 2007

The methylidene complex [(η5‐C5H5)Re(NO)(PPh3)(CH2)]+ PF or the ReCD2 analog react with diazo compounds N2CHR [R  H, Si(CH3)3, COPh, CO2C2H5] in CH2Cl2 at −80°C to give alkene complexes [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHR)]+ PF or D2CCHR analogs. The two ReC geometric isomers of benzylidene complex [(η5‐C5H5)Re‐(NO)(PPh3)(CHPh)]+ PF and CH2N2 react to give opposite configurational diastereomers of styrene complex [(η5‐C5H5)Re(NO)(PPh3)(η2‐H2CCHPh)]+ PF. Stereochemical features of these reactions are analyzed in detail, and are interpreted in terms of models involving (a) attack of the diazo compound upon the ReC face opposite to the bulky PPh3 ligand, (b) an antiperiplanar disposition of the ReC and CN2 bonds in the transition state, utilizing the diazo carbon face that minimizes interactions of the substitutent (R) and cyclopentadienyl ligand, and (c) N2 loss from the resulting intermediate [(η5‐C5H5)Re(NO)(PPh3)(CHR′CHRN2)]+ PF via a conformer with antiperiplanar PReCHR′C and ReCHR′CHRN linkages, with anchimeric assistance of the rhenium fragment d orbital HOMO from the backside.
Tripodal Amides Containing a Totally Silicon‐Based Ligand Framework
Authors: Schubart Martin , Findeis Bernd , Gade Lutz H. , Li Wan‐Sheung , McPartlin Mary
Published: July 2007

A novel type of tripodal amido ligand with a totally siliconbased (trisilylsilane‐derived) ligand framework has been synthesized and coordinated to tetravalent titanium and zirconium. The key compound in the ligand synthesis is the chlorosilane H3CSi{Si(CH3)2CI}3 (2) which upon condensation with a range of primary amines R‐NH2 (R = aryl, alkyl) yields the amino‐functionalized ligand precursors H3CSi{Si(CH3)2NHR}3 (3a–e). Their corresponding trilithium salts have been found to be the appropriate amide transfer reagents in the subsequent syntheses of the transition metal complexes. Single‐crystal X‐ray structure analyses of the trilithium triamide H3CSi{Si(CH3)2N(Li)tBu}3 (4a) and the Ti complex H3CSi{Si(CH3)2N(p‐Tol)}3TiBr (5b) have established their respective adamantane‐ and [2.2.2]bicyclooctane‐related cage structures.
Carbohydratocarbene Complexes of Manganese and Rhenium
Authors: Fischer Helmut , Schleu Joachim , Roth Gerhard
Published: July 2007

The cationic carbyne complexes [Cp(CO)2MCR]+ [BX4]− [M = Mn, X = F: R = Ph (1), Tol (2); M = Re, X = 3,5‐C6H2(CF3)2: R = Ph (3)] add the anion of monodeprotonated protected mannofuranose (4a), glucofuranose (4b), and fructopyranose (4c) to the carbyne carbon atom to form the carbohydratocarbene complexes 5a–c, 6a, b, and 7a. With 5b, 5c, and 6b the addition proceeds with retention of configuration at the anomeric center. Due to inversion of configuration in the deprotonation step the complexes 5a, 6a, and 7a are obtained as β‐glycosides. The carbene ligand is oxidatively cleaved from the metal by trimethylamine N‐oxide or air. Cleavage of the C(carbene)O bond with reformation of the cation of the carbyne complex 2 is achieved by reaction of 6a with BCl3. Photolysis of [Cp(CO)2MnC(Ph)OEt] in the presence of L affords the carbene complexes [Cp(CO)(L)MnC(Ph)OEt] [L = P(OMe)3 (11), P(Tol)3 (12)]. Ethoxide abstraction from 11 and 12 by BF3 gives the chiral cationic carbyne complexes [Cp(CO)(L)MnCPh]+[EF4]− (13, 14) which add 4a to form the corresponding mannofura‐nosylcarbene complexes (15, 16). When 0.5 equivalents of 4a are employed in the reaction with 13, 14 the ratio of diastereomers is 3:2, both for 15 and 16. Complex 11 was characterized by an X‐ray structural analysis.
Synthesis and Characterization of β‐Phosphaenones An Investigation on the Conjugative Properties of the PC Bond
Authors: Sluis Marcel Van Der , Bickelhaupt Friedrich , Veldman Nora , Kooijman Huub , Spek Anthony L. , Eisfeld Wolfgang , Regitz Manfred
Published: July 2007

Thermally and air‐stable β‐phosphaenones were synthesized by functionalization of Mes*PCCl2 (1; Mes* = supermesityl = 2,4,6‐tri‐tert‐butylphenyl). At low temperature, 1 was lithiated by halogen‐metal exchange with n‐butyllithium to give the phosphanylidene carbenoid (Z)‐Mes*PC(Cl)Li [(Z)‐2] which reacted with acid chlorides to furnish the C‐carbonyl‐substituted phosphaalkenes (Z)‐Mes*PC(Cl)R (3: P = COtBu; 4: R = COPh; 5: R = COOEt). The reaction of (Z)‐2 with carbon dioxide furnished the carboxylate 6, which was converted by treatment with pivaloyl chloride or trimethylsilyl chloride into the phosphaalkenes 7 and 8 functionalized at the carbon atom by an anhydride or a trimethylsilyl ester function, respectively. Acidification of 6 or hydrolysis of 8 with water in chloroform solution afforded the novel carboxylic acid (Z)‐Mes*PC(Cl)COOH (9). Spectroscopic investigations (NMR, UV, IR) of 3–9 and the X‐ray structures of 3 and 4 are presented. Based on these properties and on theoretical calculations, the occurrence of conjugation in the β‐phosphaenone system is discussed and compared with the well‐known conjugation in normal enones.
Synthesis of Bis(trichloromethyl)tetra‐ and ‐heptasulfane from Titanocene Polysulfide Complexes and Structure of (CCl3)2S7
Authors: Steudel Ralf , Pridöhl Markus , Buschmann Jürgen , Luger Peter
Published: July 2007

CCl3SCl reacts with (C5H5)2TiS5 to give the heptasulfane (CCl3)2S7 which forms colorless crystals of m.p. 38°C. An X‐ray structural analysis revealed that the C‐S7‐C chain is helical but the CCl3 groups are slightly tilted. In the triclinic crystals the molecules are arranged parallel to each other. Decomposition of (CCl3)2S7 provides other members of the homologous series with 4–12 sulfur atoms as shown by HPLC analysis. The reaction of CCl3SCl with (C5H4‐CH3)4Ti2S4 yields colorless crystals of (CCl3)2S4, demonstrating the usefulness also of dinuclear titanocene polysulfide complexes for the synthesis of organic polysulfanes. Infrared, Raman, and 13C‐NMR spectra of (CCl3)2S7 and (CCl3)S7 are reported.
Electronic Structure of Planar‐Tricoordinated Phosphorus in Titanium‐Boron Complexes
Authors: Gleiter Rolf , Silverio Sandro Johannes , Binger Paul , Sandmeyer Frank , Erker Gerhard
Published: July 2007

The electronic structure of the recently synthesized complex 5 obtained by the reaction of Cp2Ti(PMe3)(tBu‐CP) with (Et2BH)2 was analyzed by means of molecular orbital (MO) calculations. The methods applied were the extended Hückel and the ab initio Hartree‐Fock procedures. The highest occupied MOs were derived from molecular fragments. The geometrical parameters calculated for a simplified model (6) are close to those obtained from an X‐ray investigation of 5. The analysis of the results shows a strong donor‐acceptor interaction between the P‐B ó bond and the Ti center. The phosphorus lone pair is not involved in bonding.
Substituted Variants of the Cluster Type Fe3(CO)9(μ3‐η2‐RCN)
Authors: Suter Pierre , Vahrenkamp Heinrich
Published: July 2007

Various aromatic nitriles were used for the preparation of the nitrile‐capped clusters Fe3(CO)9(μ3‐η2‐RCN) (2) by reaction with Fe3(CO)12 under hydrogen. Electron‐rich nitriles decrease, electron‐poor nitriles increase the thermal stability of clusters 2. With CN‐substituted pyridines only traces of clusters 2 could be obtained. CO replacement in Fe3(CO)9(PhCN) (2a) by isonitriles also causes a lowering of the stability. Conversely, more stable products were obtained by substitution reaction with trimethyl phosphite. One PPh3 and two dppm derivatives were also obtained. The structure of Fe3(CO)8‐P(OMe)3(μ3‐η2‐PhCN) (5a) was determined.
Stereoselective Substitution at Phenyl‐Substituted γ‐Lactols with Organometallic Compounds
Authors: Schmitt Andreas , Reißig Hans‐Ulrich
Published: July 2007

A variety of monosubstituted γ‐lactols 4–6 were prepared in good yields by DIBAL reduction of the corresponding γ‐lactones 1–3. The monophenyl‐substituted lactols 4b–6b were transformed into disubstituted tetrahydrofuran derivatives by replacement of the hydroxyl group by the alkyl residue of organometallic compounds used as nucleophiles. The diastereoselectivity of the substitution was found to depend strongly on the substitution pattern of the γ‐lactols. For the reaction of the 3‐ and 4‐substituted derivatives 4b and 5b, respectively, good to excellent trans selectivity was observed, while the 5‐substituted derivative reacted without any diastereoselectivity. These results were interpreted by means of the Felkin‐Anh model.
Synthesis and Structure of a Cyclic Complex of Digold Sulfide Au2S and of Related Compounds
Authors: Hofreiter Stefan , Paul Martin , Schmidbaur Hubert
Published: July 2007

1,4‐Bis(diphenylphosphanylmethyl)benzene (1) was converted into its bis[chlorogold(I)] complex [1 · (AuCl)2] upon treatment with two equivalents of chloro(dimethyl sulfide)‐gold(I). The reaction of 1 · (AuCl)2 with one equivalent of silver tetrafluoroborate afforded a cyclic di[gold(I)]chloronium tetrafluoroborate [1 · Au2Cl+ BF‐4]. Substitution of chloride in 1 · (AuCl)2 by sodium methanethiolate in wet chloroform, gave the bis[methylthiogold(I)] complex 1 · (AuSMe)2], while with sodium sulfide a cyclic complex 1 · Au2S was obtained. Reaction of 1 · (AuCl)2 with two equivalents of AgBF4 followed by treatment with diphenyldisulfide or sodium methanethiolate yielded the cyclic methyl/phenylsulfonium tetrafluoroborates 1 · Au2SPh+ BF‐4 and 1 · Au2SMe+BF‐4, respectively. All compounds were identified on the basis of their analytical and spectroscopic data. The crystal structures of 1 · (AuCl)2, 1 · (AuSMe)2, and 1 · Au2S have been determined. The Au2S complex has a cyclic structure with a narrow Au‐S‐Au angle of 86.7(1)° indicating a significant intraannular Au…Au interaction.
Organometallic Aqua Complexes, III. Olefin Aqua Complexes of Rhodium(I)
Authors: Kölle Ulrich , Görissen Ralf , Wagner Trixie
Published: July 2007

Dehalogenation of halide precursors [(olefin)RhCl]2 [olefin = ethylene, 1,5‐cyclooctadiene (COD], norbornadiene (NBD), 2,3‐dimethylbutadiene (DMB)] in water gave the respective cis‐diolefin aqua ions, characterized by NMR spectroscopy in solution. Attempted isolation of the tosylate salt [(COD)Rh‐(H2O)2]OTs yielded crystals of (COD)Rh(H2O)(η1‐OTs) characterized by X‐ray structural analysis. [(NBD]Rh(H2O)2]SbF6 in the presence of adventitious toluene decomposed into [(NBD])Rh(η6‐toluene)]SbF6 and [(NBD]2Rh]SbF6, both complexes were isolated and structurally characterized. Ethylene exchange in [(C2H4)2Rh(H2O)2]+ is fast with k2 of the order of 104–105 s‐1 · M‐1. The rate constant for water exchange in [CODRh(H2O)2]+ is estimated as 104 s‐1 (ΔDLG ≈︁ 25 kJ/mol) at 173 K.
A Molybdenum‐Catalysed Electrocyclisation‐Cycloaddition Sequence: Synthesis and Structure of a Pentacyclic Unsaturated Ketone
Authors: Schmidt Thomas , Lutz Frank
Published: July 2007

The pentacyclic unsaturated ketone 3 is obtained as the sole product by the reaction of pinocarvone (1) with cycloocta‐triene in the presence of catalytic amounts of dicarbonyl‐bis(η4‐pinocarvone)molybdenum (2). Compound 3 formally resulting from a [4 + 2] cycloaddition reaction of bicy‐clo[4.2.0]octa‐2,4‐diene with the alkene fragment of pinocarvone was characterised by means of spectroscopy (1H, 13CNMR, IR, MS) as well as by X‐ray crystal structure analysis. A mechanism is proposed involving rigid molybdenum complexes as intermediates in order to explain the stereospecificity of the reaction.
Controlled Conversion of the Transient 2‐Mesityl‐1,1‐bis(trimethylsilyl)silene into a Tetrahydro‐2,3‐disilanaphthalene, a 1,2‐Disilacyclobutane, or a 1,3‐Disilacyclobutane
Authors: Krempner Clemens , Reinke Helmut , Oehme Hartmut
Published: July 2007

Mesityl[tris(trimethylsilyl)silyl]methanol (1) reacts with strong bases with elimination of trimethylsilanolate according to a Peterson‐type mechanism, the outcome of the reaction being dependent on solvent, temperature, and nature of the organometallic base applied. Thus, 1 was converted by treatment with MeLi in ether at –78°C to (E)‐1,2,3,8a‐tetra ‐hydro‐1‐mesityl‐5,7,8a‐trimethyl‐2,2,3,3‐tetrakis (trimethylsi‐lyl)‐2,3‐disilanaphthalene (3), formally a [2 + 4] cyclodimer of the transient silene (Me3Si)2Si=CHMes (2). The reaction of 1 with PhMgBr in THF after some days resulted in the formation of (Z)‐3,4‐dimesityl‐1,1,2,2‐tetrakis(trimethylsilyl) ‐1,2‐disilacyclobutane (6) as the main product besides small quantities of 3, the polysilane (Me3SiSi(SiMe3)2CH2Mes (10), and the alkoxysilane (Me3Si)3SiCH(Mes)OSi(Si‐Me3)2CH2Mes (7). Compound 6, the formal [2 + 2] cycloadduct of 2, can also be obtained by thermal treatment of 3 and is considered to be the thermodynamically more stable silene dimer whereas 3 is the kinetically preferred product. At high LiBr concentrations in the reaction mixture 1 was converted by PhMgBr in THF to (E)‐2,4‐dimesityl‐1,1,3,3‐tetrakis(tri‐ methylsilyl)‐1,3‐disilacyclobutane (13) besides 6 and [bis(tri‐methylsilyl)silyl]mesityl(trimethylsiloxy)methane (11). The unforeseen formation of 13 is discussed as proceeding via the silene‐lithium bromide adduct (Me3Si)2Si(Br)CH(Li)Mes (12). In the absence of LiBr 1 was converted by MeLi in THF at –78°C to 11 and the trisilane (Me3Si)2Si(Me)CH2Mes (4b). Probable pathways of the formation of all new compounds are discussed. For 6 and 13 the results of the X‐ray structural analyses are given.
Synthesis and Reactivity of Silicon Transition Metal Complexes, 34. Pentachlordisilanyl‐ und Disilanyl‐Komplexe von Molybdän und Wolfram: Darstellung, Struktur und spektroskopische Charakterisierung
Authors: Malisch Wolfgang , Lankat Reiner , Seelbach Wolfgang , Reising Joachim , Noltemeyer Mathias , Pikl Ralf , Posset Uwe , Kiefer Wolfgang
Published: July 2007

Synthesis and Reactivity of Silicon Transition Metal Complexes, 34[*]. — Pentachlorodisilanyl and Disilanyl Complexes of Molybdenum and Tungsten: Synthesis, Structure, and Spectroscopic Characterization

Reaction of the lithium metallates Li[M(PMe3)(CO)2C5R5] [M = Mo, W; R = H (1a, b), Me (1c, d)] with Si2Cl6 (2) leads to the formation of the pentachloro(metallo)disilanes 5R5(OC)2(Me3P)M—SiCl2—SiCl3 (3a—d), which are transformed into the metallo disilanes C5R5(OC)2(Me3P)M—SiH2—SiH3 (4a—d) on treatment with LiAlH4. The disilanes 4a—d are reconverted into 3a—d in the presence of tetrachloromethane. Extensive spectroscopic investigations (NMR, Raman, and IR spectroscopy) were performed to establish the transition‐metal effect especially with respect to the H5Si2 ligand. The molecular structure of C5Me5(OC)2(Me3P)W—SiCl2—SiCl3 (3d) was determined by single‐crystal X‐ray diffraction.
Synthesis and Reactivity of Silicon Transition Metal Complexes, 33. Metallo Silanols and Metallo Siloxanes, 8. Metallo‐silanole vom Typ C5R5(OC)2(Me3P)M—SiPh2OH (M = Cr, Mo, W): Darstellung nach der Dimethyldioxiran‐Methode und Überführung in funktionalisierte Metallo‐disiloxane
Authors: Malisch Wolfgang , Schmitzer Siegfried , Lankat Reiner , Neumayer Michael , Prechtl Frank , Adam Waldemar
Published: July 2007

Synthesis and Reactivity of Silicon Transition Metal Complexes, 33

32. Mitteilung: Lit.

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— Metallo Silanols and Metallo Siloxanes, 8

7. Mitteilung: Lit.

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— Metallo Silanols of the Type C5R5(OC)2(Me3P)M‐SiPh2OH (M = Cr, Mo, W): Preparation According to the Dimethyldioxirane Route and Conversion into Metallo Disiloxanes

Herrn Professor Max Schmidt zum 70. Geburtstag gewidmet.

The metallo silanes C5R5(OC)2(Me3P)M‐SiPh2H (4a‐c), are converted into the corresponding metallo silanols C5R5(OC)2‐(Me3P)M‐SiPh2OH [R = H, M = Cr (6a); R = Me, M = Mo (6b); M = W (6c)] by oxofunctionalization with dimethyldioxirane (5). Treatment of 6b, c with the chlorosilanes Me2Si(R)Cl [R = H (3b), [R = Cl (3c)] in the presence of triethylamine gives access to the metallo disiloxanes C5Me5(OC)2(Me3P)M‐SiPh2OSiMe2R (M = Mo, R = H (7a); M = W, R = Cl (7b)]. The structure of tungsten silanol 6c is determined by X‐ray diffraction analysis.
P8 and P12 as Complex Ligands
Authors: Scherer Otto J. , Berg Gerald , Wolmershäuser Gotthelf
Published: July 2007

The thermal and/or photochemical reaction of [Cp‴Co(CO)2] (1), Cp‴ = 1,2,4‐tBu3C5H2, with white phosphorus, P4, gives besides [(Cp‴Co)2 (P2)2] (2) the trinuclear complexes [(Cp‴Co)3P8] (3) and [(Cp‴Co)3P12] (4), the Pn ligands of which form P5–P3 and P5–P7 skeletons, structural motifs, which formally can be derived from Hittorf's phosphorus. The X‐ray crystal structure analysis of 3 confirmed its P5–P3 framework.
Komplexe von Halogenid‐Ionen mit 1‐Halogen‐2‐phenylacetylenen. Kristallstrukturen von PPh4[X(I—CC—Ph)4] mit X = Cl, Br, I, von PPh4[Br(Br—CC—Ph)4] und von NMe4[F(I—CC—Ph)2]
Authors: Ghassemzadeh Mitra , Harms Klaus , Dehnicke Kurt
Published: July 2007

Complexes of Halide Ions with 1‐Halogen‐2‐phenylacetylenes. Crystal Structures of PPh4[X(I—CC—Ph)4] with X = Cl, Br, I, of PPh4[Br(Br—CC—Ph)4], and of NMe4[F(I—CC—Ph)2]

Herrn Prof. Dr. H. Brunner zum 60. Geburtstag gewidmet.

The complexes PPh4[X(I—CC—Ph)4] with X = Cl (1), Br (2), I (3), PPh4[Br(Br—CC—Ph)4] (4), and NMe4[F(I—CC—Ph)2] (5) were prepared from the corresponding salts PPh4X and NMe4F, respectively, with the 1‐halogen‐2‐phenylacetylenes X—CC—Ph (X = Br, I) in dichloromethane solutions. 1—5 form colourless crystals, which were characterized by vibrational spectroscopy. According to the crystal structure determinations the halide ions in 1—4 are coordinated by the halogen atoms of the 1‐halogen‐2‐phenylacetylenes in a tetragonal‐pyramidal fashion. The fluoride ion in 5 is only twofold coordinated with a bond angle I—F—I of 110.45°.
Komplexe von Halogenid‐Ionen mit Diiodacetylen. Die Kristallstrukturen von PPh4[X(I‐CC‐I)2] mit X = Cl, Br, I
Authors: Ghassemzadeh Mitra , Harms Klaus , Dehnicke Kurt
Published: July 2007

Complexes of Halide Ions with Diiodoacetylene. The Crystal Structures of PPh4[X(I‐CC‐I)2] with X = Cl, Br, I

The complexes PPh4[X(I‐CC‐I)2] with X = Cl (1), Br (2), and I (3) have been prepared from the phosphonium salts PPh4X and 1‐CC‐I in dichloromethane solutions. 1–3 form colourless crystals, which according to crystal structure analysis crystallize isotypically in the space group P421m with two formula units per unit cell. The diiodacetylenes are coordinated by the halide ions X− in a distorted tetragonal fashion, the I‐CC‐I molecules being in μ2‐bridging function. Thus, a polymeric anionic network [X(I‐CC‐I)2]nn− with a layered structure results.
Compounds of Germanium and Tin, 18. Cleavage Reactions of Hexa‐tert‐butylcyclotrigermane: Racemate versus Conglomerate Crystallization
Authors: Weidenbruch Manfred , Hagedorn Annette , Peters Karl , von Schnering Hans Georg
Published: July 2007

Treatment of hexa‐tert‐butylcyclotrigermane (3) with CCl4, Br2, and I2 furnishes the correspondingly substituted 1,3‐dichloro‐ (4), 1,3‐dibromo‐ (5), and 1,3‐diiodotrigermanes (6). The symmetries of the molecules of 5 and 6 are very similar (point group C1) revealing gauche‐anti conformations and different GeGe bond lengths. However, while 5 crystallizes as a racemate, 6 forms a conglomerate of enantiomerically pure crystals. The X‐ray structure analysis of the 1,3‐dimethyltrigermane (7) derivative, derived from 6 by a sequence of metalation and methylation reactions, reveals more symmetrical molecules of the point group C2 which also crystallize as a racemate. Irradiation of 3 leads to tetra‐tert‐butyldigermene (8) and di‐tert‐butylgermylene (9) which could be trapped by addition and cycloaddition reactions with selenium, tellurium, and 3,5‐di‐tert‐butyl‐1,2‐benzoquinone.
The effect of substituting phosphorus for a ring carbon atom in the valence isomers cyclobutene, bicyclobutane, and 1,3‐butadiene. a quantum‐chemical investigation
Authors: Schoeller Wolfgang W. , Tubbesing Ulrike
Published: July 2007

Cyclobutene, bicyclobutane, and 1,3‐butadiene are valence isomers within the concept of the Woodward‐Hoffman rules. According to thermochemical considerations and in agreement with energy optimized quantum‐chemical calculations at the ab initio RHF and MP2/6‐31G(d,p) levels bicyclobutane is the least and 1,3‐butadiene the most stable valence isomer. Phosphorus substitution exerts a considerable effect on the relative stabilities of the various valence isomers. Bicyclobutanes containing phosphorus atoms in the bridgehead positions are considerably more stable than the other phosphorus‐substituted valence isomers. This conclusion was confirmed by an analysis of the natural bond populations.
Azolylborane adducts. Structural and conformational analysis by x‐ray diffraction and NMR. Protic‐hydric (CHδ+‐δ–HB) and Protic‐Fluoride (CHδ+‐δ–FB) interactions
Authors: Padilla‐Martińez Itzia Irene , Rosalez‐Hoz Maria De Jesús , Tlahuext Hugo , Camacho‐Camacho Carlos , Ariza‐Castolo Armando , Contreras Rosalinda
Published: July 2007

The preparation, NMR and X‐ray diffraction studies of a series of azolylboron hydrides derived from pyrrole, indole, and carbazole coordinated with tetrahydrofuran, pyridine, and imidazole are reported. The azolyl substituents are very electroattractive leading to an acidic boron atom which strongly coordinates with the Lewis bases. The stabilization of the BH2groups against disproportionation could be explained in terms of the interactions found between the acidic hydrogen atoms of the heterocycles (CHδ+ acceptor) and the hydrides (BHδ– donors).
Metal hydroborates and hydroborato metalates, 21. Solvates of lithium (dimethylamino)trihydroborate
Authors: Nöth Heinrich , Thomas Steffen , Schmidt Martin
Published: July 2007

Li(Me2NBH3) (1) was prepared by deprotonation of Me2NH BH3 with LiBu and its solubility determined in various solvents. Compound 1 is unstable in most ethereal solvents and decomposes in a reversible reaction into LiH and Li‐(Me2NBH2NMe2BH3) (2). Five solvates of 1 were characterised by X‐ray structure analysis. Li(Me2NH3) · TMEDA is a dimer in the solid state, and two units are connected to one another by BH…Li bonds. The crystal structure of Li(Me2NBH3) · 0.5 dioxane is represented by layers consisting of tetrameric Li(Me2NBH3) units connected via dioxane molecules. Each Li atom is coordinated to one oxygen atom, one nitrogen atom, and two hydrogen atoms. Also Li(Me2NBH3) · 0.5 O2C3H6 forms an extended layer, however with pentacoordinated Li atoms which bear one oxygen, one nitrogen, and three hydrogen atoms. A similar layer structure was also found for Li(Me2NBH3) · O3C3H6 where each Li atom is bound to two oxygen atoms of different trioxane molecules, one nitrogen atom, and two hydrogen atoms. Finally, Li(Me2NBH3) · 12‐crown‐4 retains its molecular integrity in the solid state. Its Li atom is pentacoordinated by four oxygen atoms and one nitrogen atom.
Analysis of 13C and 17O Chemical Shift Tensors and an ELF View of Bonding in Fe2(CO)9 and Rh6(CO)16
Authors: Kaupp Martin
Published: July 2007

Carbon and oxygen chemical shift tensors for bridging and terminal carbonyl ligands in Fe2(CO)9 and Rh6(CO)16 were calculated by sum‐over‐states density‐functional perturbation theory (SOS‐DFPT). Agreement with experimental 13C shift tensors is excellent, and 17O shift tensors are predicted. The reduced anisotropy values of the shift tensors for the bridging compared to terminal carbonyl ligands are due to large deshielding contributions to δ33 from non‐bonding or bridge‐bonding orbitals. Comparison to recent computational results for a series of unusual piano‐stool and bent‐sandwich group‐4 complexes is made. The electronic structures of the clusters are discussed by using plots of electron localization functions (ELF). Bonding electrons within the Rh6 cluster are mainly localized on the unbridged octahedral faces. This leads to a heterocubane‐like arrangement of ELF maxima above all octahedral faces (four bridging CO ligands, four M‐M 3‐center‐bonding maxima), in analogy to previous results for B6H62‐.
Synthesis and Reactivity of Bis(ethene) Rhodium(I) and Iridium(I) Carboxylato Complexes
Authors: Werner Helmut , Poelsma Sybo , Schneider Michael E. , Windmüller Bettina , Barth Dietmar
Published: July 2007

[Rh(μ‐O2CCH3)(C2H4)2]2 (3) and analogous carboxylatobis‐(olefin)rhodium(I) complexes [Rh(μ‐O2CR)(olefin)2]2 (4–6) were almost quantitatively prepared under heterogeneous conditions from [RhCl(C8H14)2]2 (1) or [RhCl(C2H4)2]2 (2) and CH3CO2Na · 3 H2O or RCO2H/NaOH, respectively. The X‐ray crystal structure analysis of 3 confirmed the bridging position of the acetato ligands. The synthesis of [Ir(μ‐O2CCH3)(C2H4)2]2 (10) was carried out similarly by using [IrCl(C2H4)2]2 (8) and CH3CO2Na · 3 H2O as starting materials. The monoethene complex trans‐[Ir(η1‐O2CCH3)(C2H4)‐(PiPr3)2] (11) was obtained from 10 and PiPr3; it reacted with H2 and HCCPh by oxidative addition to give [IrH2(η2‐O2CCH3)(PiPr3)2] (12) and [IrH(CCPh)(η2‐O2CCH3)(PiPr3)2] (14), respectively. Compound 12 was also prepared from [IrH2Cl(PiPr3)2] (13) and CH3CO2Na · 3 H2O. The new bis‐(ethene)complexes 3, [Rh(μ‐O2CC6H5)(C2H4)2]2 (6) and 10 are catalytically less active than 2 in the reaction of C2H4 and Ph2CN2 and gave as C–C coupling product not only 1,1‐diphenylpropene (16) but also mixtures of 16 and 1,1‐diphenylcyclopropane (17) in different ratios.
Structure of O‐Methyl‐N,N‐bis(trifluoromethyl)hydroxylamine, (CF3)2NOCH3
Authors: Casper Bernd , Jakob Jens , Minkwitz Rolf , Oberhammer Heinz
Published: July 2007

The molecular structure of (CF3)2NOCH3 was determined by gas electron diffraction. The molecular intensities were reproduced by use of a single conformation with syn orientation of the O–CH3 group relative to the nitrogen lone pair. This was confirmed by ab initio calculations (HF/3‐21G(*), polarization functions only on nitrogen, and MP2/6‐31G*). The observed structure demonstrates that the generalized anomeric effect is of minor importance to this compound. The following skeletal geometric parameters (bond lengths [pm] and angles [°] with 3‐s̀ uncertainties) were derived: N–C 142.9(7), N–O 142(3), O–C 145(3), CNC 118.0(9), CNO 108.1(17), and NOC 109.4(17). The experimental structure is well reproduced by the ab initio calculations.
Neue Phospholen‐ und Phosphepin‐Derivate aus λ3‐Phosphorverbindungen und Hexafluoraceton oder perfluorierten α‐Diketonen
Authors: Kadyrov Alexander , Neda Ion , Kaukorat Thomas , Sonnenburg Ralf , Fischer Axel , Jones Peter G. , Schmutzler Reinhard
Published: July 2007

New Phospholene and Phosphepine Derivatives from λ3‐Phosphorus Compounds and Hexafluoroacetone or Perfluorinated α‐Diketones

The reaction of the bis(2‐chloroethyl)amino‐substituted benzoxazaphosphorinone 1 with hexafluoroacetone (HFA) proceeds with insertion of the carbonyl group of HFA into the heterocycle of 1 to form the oxazaphosphepinedione 2. Triethyl phosphite (3) and triphenyl phosphite (4) react with the perfluorinated diketones 5 and 6 with formation of the pentaoxyphosphoranes 7–10 containing a dioxaphospholene ring system. The reaction of the (2‐chloroethyl)amino‐ and bis(2‐chloroethyl)amino‐substituted 1,3,5,2‐triazaphosphorinanediones 11–14 with the perfluorinated diketone C2F5C(:O)C(:O)CF3 (15) furnishes spirophosphorane derivatives with the dioxaphospholene ring system, 16 and 17, in two cases only. Compound 1 and 2‐[bis(2‐chloroethyl)‐amino]‐4H‐1,3,2‐benzodioxaphosphorin‐4‐one (18) react with the perfluorinated α‐diketones 5 and 6 with insertion of the diketones into the heterocycle of 1 and 18 with formation of compounds 19–22 containing dioxa‐ and oxazaphosphepinone ring systems. The expected oxidative addition of the diketones to λ3P with formation of spirophosphoranes was not observed. Compounds 19–22 were obtained as mixtures of isomers (19a/b–22a/b). Single crystal X‐ray structure analyses were conducted on 2 and 9. The seven‐membered ring of 2 displays a “tub” conformation, with the O and benzo C atoms lying out of the plane of the other four atoms. The two independent molecules of 9 are similar, but differ in the degree of distortion from trigonal‐bipyramidal geometry of phosphorus.
Isolation and Spectroscopic Characterization of Heteroleptic, Anionic and Neutral (Phthalocyaninato)(tetra‐4‐pyridylporphyrinato)lanthanide(III) Double‐Deckers
Authors: Jiang Jianzhuang , Mak Thomas C. W. , Ng Dennis K. P.
Published: July 2007

Treatment of 5,10,15,20‐tetra‐4‐pyridylporphyrin [(TPyP)H2] with europium(III) or gadolinium(III) acetylacetonate [Ln(acac)3 · nH2O] (Ln = Eu, Gd) in 1,2,4‐trichlorobenzene produced Ln(acac)(TPyP), which reacted with dilithium phthalocyaninate [Li2(Pc)] to give Li[Ln(Pc)(TPyP)] in moderate yields. Upon exposure to air, solutions of these compounds converted slowly to the corresponding neutral complexes Ln(Pc)(TPyP). The new compounds were spectroscopically characterized.
Komplexe mit Metall‐Phosphor‐Dreifachbindungen als mögliche Intermediate der Umsetzungen von Chlorophosphiniden‐Komplexen mit Metallaten verschiedener Übergangsmetalle
Authors: Scheer Manfred , Schuster Kay , Krug André , Hartung Helmut
Published: July 2007

Complexes with Metal‐Phosphorus Triple Bonds as Possible Intermediates in the Reactions between Chlorophosphinidenes and Metalates of Various Transition Metals

The reaction of [{M′(CO)5}2PCl] (M′ = Cr, W) with various metalates ([Cp′Mo(CO)3]−, [Cp * Ni(CO)]−, [Cr2(CO)10]2−) yields the M2P2 tetrahedral complexes [(MLn)2(μ,η2‐ P2){M′(CO)5}2] (MLn = Cp*Ni, M′= Cr (1), W (2); MLn = Cp′Mo(CO)2, M′ = Cr (4); Cp* = η5‐C5Me5, Cp* = η5C5H3tBu2) and the cyclo‐P4 compound [{Cr(CO)4}(η4‐P4){Cr(CO)5}4] 6. As side products the distorted prismane [(Cp*Ni)2{μ4,η4‐(P2‐O‐P2)}{W(CO)5}2] 3 and the diphosphino‐methanone complex [{Cp′Mo(CO)2}2{μ4η2‐PC(O)P}‐{Cr(CO)5}2] 5 are formed. The complexes are characterised by NMR, IR, MS, and X‐ray structure analysis (1‐5). Studying the reaction pathway provided evidence of phosphido intermediates of the type [LnMP→M′Ln].
Metal Complexes with Tetrapyrrole Ligands, LXXII Cerium(IV) Sandwich Complexes with Porphyrin Ligands Linked by Aliphatic and Quinone‐Containing Bridges
Authors: Buchler Johann W. , Heinz Georg
Published: July 2007

Starting from 5‐(4‐hydroxyphenyl)‐10,15,20‐tris(4‐methylphenyl)porphyrin (1a), the new bis(porphyrinylphenoxy)alkanes 4a–c were synthesized by ether formation with the α,ω‐dibromoalkanes Br(CH2)nBr (n = 9,10; 3a, b) and 1,4‐bis(3‐bromopropyl)‐2,5‐dimethoxybenzene (3c). The bis‐[(porphyrinylphenoxy)propyl]hydroquinone dimethyl ether 4c derived from 3c was converted into the diporphyrin‐quinone 4e by methyl ether cleavage with BBr3 and subsequent oxidation with ammonium cerium(IV) nitrate. The bisporphyrins 4a–c, e were metalated with cerium(III) acetylacetonate to yield the new cerium porphyrin sandwich complexes 5a–c, e which carry the alkane links in vicinal positions at the porphyrin rings. 5a–c, e were characterized by UV/Vis, IR, 1H‐NMR spectroscopy and cyclic voltammetry. The quinone‐bridged cerium sandwich complex 5e contains the quinone moiety in a distinct non‐coplanar orientation relative to the porphyrin ligands of the double‐decker system. The length of the lateral chains may have a dramatic effect on the first and second oxidation potentials, E3 and E2, of the porphyrin rings: for 5b having 10 aliphatic C atoms in the chain, E3 and E2 are higher by 0.26 and 0.24 V, respectively, as compared with 5a having only 9 aliphatic C atoms. E3 and E2 for the latter are rather close to values for species with dipropylbenzene chains (i.e. in 5c and 5e) or without lateral bridges.
Structural Studies on Indium and Tin Thiobenzoates
Authors: Singh P. , Gupta Vishnu D. , Bhattacharya S. , Nöth Heinrich
Published: July 2007

Indium(III) and tin(IV) thiocarboxylates were prepared and characterized on the basis of their IR,13C‐ and19Sn‐NMR data. Indium tris(thiobenzoate) (1) decomposes into a sulfido complex In (S)[S(O)CPh] (2a). The corresponding tris(thioacetate) In[S(O)CMe]3is thermally too unstable to be isolated. The anionic tetrakis complex [Et3NH]{In[S(O)CPh]4} (3) was characterized by X‐ray crystallography which revealed a distorted tetrahedral coordination at the In atom. X‐ray diffraction analysis of the complexes BuSn[S(O)CPh]3(4) and Cl2Sn[S(O)CPh]2(7) showed distorted tetrahedral andcis‐octahedral structures, respectively.
Interaction Modes of Titanium Tetrachloride with the Carbonyl Functionality
Authors: Cozzi Pier Giorgio , Solari Euro , Floriani Carlo , Chiesi‐Villa Angiola , Rizzoli Corrado
Published: July 2007

Mesityl aldehyde binds TiCl4leading to the first structurally characterized TiCl4‐aldehyde adduct,cis‐[(MesCHO)2TiCl4] (Mes = 2,4,6‐Me3C6H2) (1), which contains a pseudooctahedral titanium and two aldehyde carbonyl groups in acisarrangement. However, in the case of 1:1 TiCl4–acetone adduct [(Me2CO)TiCl3)2(μ‐Cl)2] (3) the solid‐state structure of this acid‐base complex is that of a chloro‐bridged dimer. Both kinds of structures were suggested for the products [{(PhCOMe)TiCl3}2(μ‐Cl)2] (4) and [cis‐(PhCOMe)2TiCl4] (5) formed by the reaction of TiCl4with acetophenone in 1:1 and 1:2 molar ratio. Thioesters behave like acetone in that they give adducts8and9with TiCl4, where9, [{(PhSC(Me)O)TiCl3}2(μ‐Cl)2], exhibits a solid‐state dimeric structure like3. The bidentate bonding mode of the chiral propionyloxazolidone12with TiCl4was revealed by an X‐ray analysis of13.
A Search for Thionitrosyl Chloride (Cl–NS) in the Gas Phase
Authors: Nguyen Minh Tho , Flammang Robert
Published: July 2007

Ab initio MO calculations at the QCISD(T)/6‐311++G(3df,2p) + ZPE level show that the thionitrosyl chloride ion, ClNS+•, is 36 kJ/mol more stable than the thiazyl chloride ion, NSCl+•, whereas neutral NSCl is 77 kJ/mol more stable than ClNS [IEa (ClNS) = 9.2 ± 0.3 eV, IEa (NSCl) = 10.5 ± 0.3 eV]. Mild flash‐vacuum pyrolysis of the thiazyl chloride trimer (NSCl)3 followed by electron impact ionization resulted in the formation of [N,S,Cl]+• ions (m/z 81). The fragments observed in the CA spectrum of these ions indicate the formation of both NSCl+• and ClNS+• ions. A very weak recovery signal is observed in a neutralizationreionization experiment. This signal is tentatively assigned to the neutral thionitrosyl chloride.
Synthesis and Reactivity of Some Nitroaryl Complexes of HgII and AuIII — Synthesis of a Substituted Biphenyl by C–C Coupling – Crystal Structure of [Hg(C6H4NO2‐3, OnBu‐6)2]
Authors: Vicente Jose , Bermúdez María‐Dolores , Carrión Francisco‐José , Jones Peter G.
Published: July 2007

4‐Butoxynitrobenzene reacts with [Hg(O2CCF3)2] and LiCl to give [Hg(R)Cl] [R = C6H3NO2‐3, OnBu‐6 (1)] which is symmetrized by Me4NCl to give [HgR2] (2), the crystal structure of which has been determined. The reaction of 2 with Me4N[AuCl4] affords Me4N[Au(R)Cl3] (3) by a facile transmetallation process. Complex 3 reacts with PPh3 (1:1) to give cis‐[Au(R)(PPh3)Cl2] (4). The diaryl complex [‐Ph‐2)(R)Cl] (5) is obtained by reaction of 3 with [Hg‐(C6H4N=NPh‐2)2] through a second transmetallation reaction. Complex 5 and PPh3 (1:1) give [AuClPPh3] and the C–C coupling biphenyl RC6H4N=NPh‐2 (6).
Compounds of Germanium and Tin, 20. Stannylene Complexes of Iron and Nickel without Donor Stabilization
Authors: Weidenbruch Manfred , Stilter Artur , Peters Karl , Schnering Hans Georg Von
Published: July 2007

Treatment of [Fe2(CO)9], [Fe3(CO)12] or [Ni(CO)4] with the alkylarylstannylene RR′Sn: [R= 2,4,6‐tBu3C6H2, R′ = CH2C(CH3)2‐3,5‐tBu2C6H3] furnishes the stannylene complexes [(OC)4Fe=SnRR′] (5) and [(OC)3Ni=SnRR′]. The X‐ray structure analysis of 5 reveals a trigonal‐bipyramidal environment of the iron atom with the tricoordinated tin atom occupying an axial site, thus indicating that RR′Sn: is a strong σ‐donor but weak π‐acceptor.
Characterization of a [4Fe‐4S]‐Ferredoxin Model Based on a Concave Tetradentate Thiol Ligand System
Authors: Martens Constantinus F. , Bongers Mathias M. G. , Kenis Paul J. A. , Feiters Martinus C. , Nolte Roland J. M. , Czajka Ryszard , Linden Johannes G. M. Van Der
Published: July 2007

NMR and Mössbauer spectroscopy show that a novel tetrathiol ligand, based on the cavitand diphenylglycoluril, encapsulates a 4Fe‐4S cluster and induces asymmetry in it. The cluster gives a weak electrochemical current response in DMF, with a half‐wave potential for the 2−/3− reduction vs. Fc+/Fc of ‐1.7 V. Ba2+ ions are adsorbed, according to X‐ray analysis of the SEM image of the electrode, and act as modulator and promoter of the electrochemical response. On the basis of cyclic voltammograms it is proposed that this adsorption creates electroactive sites, changing the type of diffusion controlling the mass transport to the electrode from radial to linear, and that it helps the negatively charged complex, which contains a dipole, to approach the negative electrode in an orientation favourable for electron exchange. This feature makes the complex an important model for ferredoxins, in spite of a difference in redox potential.
Hydrogen Bonding and Conformational Analysis of Chelate‐Stabilized Alkoxopalladium(II) Complexes Derived from Amino Alcohol Ligands
Authors: Kapteijn Gerardus M. , Baesjou Patrick J. , Alsters Paul L. , Grove David M. , Koten Gerard Van , Smeets Wilberth J. J. , Kooijman Huub , Spek Anthony L.
Published: July 2007

The reaction of palladium acetate with two equivalents of di‐ and triethanolamines RN(CH2CH2OH)2 in the presence of a base affords the new chelate‐stabilized alkoxo Pd(II) complexes [Pd(OCH2CH2N(R)CH2CH2OH)2] [R = Me (1), Et (2), n‐Bu (3), benzyl (4) or CH2CH2OH (5)]. These N,O‐ligated complexes are isolated in high yield as yellow, crystalline solids and are thermally stable despite the presence of several β‐hydrogen atoms in the ligand system. Both complexes possess a square‐planar palladium coordination geometry with the two oxygen atoms positioned mutually trans. The most notable difference in the molecular structures is that 1 forms a two dimensional network of intermolecular O–HO hydrogen bonds, whereas 5 forms intramolecular O–H ⃛O hydrogen bonds, which cage the palladium center. In solution 1–4 exist as a diastereoisomeric mixture (a racemic enantiomeric pair SNSN, RNRN and a mesomeric form RNSN) in a 1:1 molar ratio, and this ratio is independent of temperature in nonalcoholic solvents, When complexes 1–4 are dissolved in protic solvents (e.g. MeOH) the diastereomeric excess is temperature‐dependent due to an exchange process between the meso diastereoisomer and the (racemic) enantiomeric pair. Thermodynamic parameters for this process in a mixture of MeOH‐toluene have been determined with NMR and show this process to be influenced by the steric nature of the alkyl substituent (R) on nitrogen. A conformational analysis based on 1H‐NMR coupling constants within the N,O‐chelate ring of complexes 1–4 provides details on the solution structure of the ring in both diastereoisomers.
The Synthesis, Crystal Structures and Magnetic Properties of Cu4(AsO4)2(O) and Ba2Cu7(AsO4)6
Authors: Adams Richard D. , Layland Ralph , Payen Christophe
Published: July 2007

Two new compounds Cu4(AsO4)2O (1) and Ba2Cu7As6O24 (2) were obtained from a mixture of CuO and As2O5 · xH2O heated to 1090°C for 72 h in a BaCO3 flux. Compound 1 was obtained as dark green crystals, belonging to the orthorhombic crystal system. Compound 2 was obtained as light gray to colorless crystals belonging to the triclinic crystal system. The structure of 1 contains two copper ions with distorted trigonal bipyramidal geometries and a third with a distorted square pyramidal geometry. One ‚oxide’︁ ion is surrounded by four copper ions in a distorted tetrahedral arrangement. Compounds 2 consists of two chains with alternating units of trigonal bipyramidal CuO5 and square planar CuO4 units, with the oxygen atoms derived from the AsO4 groups. Magnetic susceptibility measurements of 1 and 2 both show effective magnetic moments, μeff1.90–1.95 B.M./Cu at 25°C, which is consistent with Cu2+ ions having one unpaired electron. Significant antiferromagnetic coupling was revealed by variable temperature measurements. At very low temperatures (15–25 K) samples of both 1 and 2 undergo a transition to a weak ferromagnetic state.
Tris(phenylthiomethyl)phosphane Sulfide and Selenide, (PhSCH2)3PX (X = S, Se), as Ambidentate Ligand Systems in Copper(I) Complexes
Authors: Fuchs Stefan , Angermaier Klaus , Bauer Andreas , Schmidbaur Hubert
Published: July 2007

Triphenylphosphite has been converted into tris(phenylthiomethyl)phosphane (1) by reaction with LiCH2SPh/DABCO, and subsequently into the corresponding sulfide (2) and selenide (3) by treatment with elemental sulfur or selenium, respectively. Ligands 2 and 3 react with copper(I) halides CuX (X = Cl, Br, I) in polar organic solvents to give either 1:1 (X = Cl: 4, 7, X = Br: 5, 8 ) or 1:2 complexes (X = Br: 9, X = I: 6, 10). The crystal structures of five of these complexes have been determined by single crystal X‐ray diffraction studies. All compounds of the type [(PhSCH2)3PS/Se]CuX (X = Cl, Br) form centrosymmetrical dinuclear complexes featuring a four‐membered ring core Cu2[S/Se], fused to two five‐membered rings Cu[S/Se]PCS through common trans edges. Only one of the three phenyl‐thiomethyl functions is involved in coordination to a metal center. The compound [(PhSCH2)3PS](CuI)2 (6) is associated into a centrosymmetrical tetranuclear complex containing two four‐membered rings (ICu2S) bridged via iodine atoms in 1,3‐cis positions. The ligand is found to employ two of its PhSCH2 functions for metal coordination, giving rise to two five‐membered rings fused to the four‐membered rings via neighbouring edges. In all cases, therefore, the PS/Se functions of the ligands are the preferred donor sites, which are used for the building of bridgehead structural units of polynuclear complexes.
Design of Self‐Adapting N‐Heteroaromatic Substituted Claw Ligands as E−/M+(E = P‐Block Element, M = Main‐Group Metal) Charge Spacers
Authors: Kottke Thomas , Stalke Dietmar
Published: July 2007

Monoanionic bi‐ and tridentate ligand systems emulating the structural features of the well‐known poly(pyrazolyl)borates are created by bridging heteroaromatic rings with formally negatively charged p‐block elements. Their properties and versatility are exemplified by their complexes with main group metals. Due to their N(σ)‐donating and π‐interacting ability, as well as the flexibility of the substituent bonding, these ligand systems have the potential to adapt both geometrically and electronically to the coordination requirements of the complexed metal. Within these complexes, the heteroaromatic substituents operate as charge spacers between the formally anionic center and the metal cation without encapsulating either site. This provides possible applications in the creation of reactive soft/hard bimetallic reagents, the realization of multinuclear arrays, and the design of preorganized CVD precursors, particularly en route to III/V‐semiconducting thin films.
Diastereoselectivity in the Reaction of RCH2C[CH2P (Ar)(Lr)]3 with Electrophiles: Enhancement of Diastereoselective Control by η3‐Coordination in {RCH2C[CH2P(Ar)(Li)3}Mo(Co)3
Authors: Büchner Michael , Huttner Gottfried , Winterhalter Ute , Frick Axel
Published: July 2007

Following a procedure developed for H3CC[CH2P(Ph)2]3 (1a) as the starting compound, various tripod ligands RCH2C[CH2P(Ar)2]3 (1) have been transformed into the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 with various electrophiles R′ — Hal leads to the two diastereomers of RCH2C[CH2P‐(Ar)(R)]3 (6) with an (RRR/SSS : RRS/SSR) ratio close to the statistical value of 1:3, except when ArPh and R′Bzl, where the RRS/SSR diastereomer is obtained almost exclusively. In contrast, the reaction of [RCH2C[CH2P(Ar)(Li)[3]‐Mo(CO)3 (4) with electrophiles R′ — Hal tends to favour the formation of the homochiral RRR/SSS diastereomers. The triphosphide coordination compounds 4 are available by two different routes: either the complexes (RCH2C[CH2P‐(Ar)(H)]3Mo(CO)3, obtained from 2 and (CH3CN)3Mo(CO)3, are deprotonated by MeLi, or the trilithiotriphosphides RCH2C[CH2P(Ar)(Li)]3 are reacted with (CH3CN)3Mo(CO)3 to produce 4 in high yields. The ration in which the two diastereomeric forms of 5 are obtained depends on the nature of the electrophile: the greatest diastereomeric discrimination is obtained for ArPh, RPh, R′Bzl, where the homochiral relative to the RRS/SSR pair. Two‐dimensional NMR spectra and simulations of one‐dimensional spectra are used to ascertain the diastereomeric excess in each case. X‐ray analyses of three compounds of type 5 (5d, ArPh, RH, R′Ph, R′Bzl) indicate the remarkable conformational stability of the tripod metal scaffolding, with the conformations observed for these three compounds in three different solid‐state environments being closely similar, even with respect to the torsional arrangement of the phosphorus‐bound benzyl groups.