Bildung siliciumorganischer Verbindungen. 110. Reaktionen von (Cl3Si)2CCl2, seiner Si-methylierten Derivate,von (Cl3Si)2CHCl, (Cl3Si)2C(Cl)Me und Me2CCl2 mit Silicium (Cu-Kat.)

Formation of Organosilicon Compounds. 110. Reactions of (Cl₃Si)₂CCl₂ and its Si-methylated Derivatives as well as of (Cl₃Si)₂CHCl, (Cl₃Si)₂C(Cl)Me and Me₂CCl₂ with Silicon (Cu cat.) The reactions of (Cl₃Si)₂CCl₂ 1 , its Si-methylated derivatives (Me₃Si)₂CCl₂ 8 , Me₃Si? CCl₂? SiMe₂Cl 9 , (ClMe₂Si)₂CCl₂ 10 , Me₃Si? CCl₂? SiMeCl₂ 11 , Cl₂MeSi? CCl₂? SiCl₃ 12 as well as of (Cl₃Si)₂CHCl 38 , (Cl₃Si)₂CClMe 39 and of Me₂CCl₂ with Si (Cu cat.) in a fluid bed reactor ( 38 and 39 also in a stirred solid bedreactor) arc presented. While (Cl₃Si)₂CCl₂ 1 yields C(SiCl₃)₄ 2 the 1,1,3,3-tetrachloro-2,2,4,4-tetrakis(trichlorsilyl)-1,3-disilacyclobutane Si₆C₂Cl₁₆ 3 and the related C-spiro linked disilacyclobutanes Si₈C₃Cl₂₀ 4 , Si₁₀C₄Cl₂₄ 5 , Si₁₂C₅Cl₂₈ 6 , Si₁₄C₆Cl₃₂ 7 this type of compounds is not obtained starting from the Si-methylated derivatives 8, 9, 10, 11 They Produce a number of variously Si-chlorinated and -methylated tetrasila- and trisilamethanes. However, Cl₂MeSi? CCl₂? SiCl₃ 12 forms besides of Si-chlorinated trisilamethanes also the disilacyclobutanes Si₆C₂Cl₁₅Me 34 and cis- and trans Si₆C₂Cl₁₄Me₂ 35 as well as the spiro-linked disilacyclobutanes Si₈C₃Cl₁₉Me 36 , Si₈C₃Cl₁₈Me₂ 37 . (Cl₃Si)₂CHCl 38 mainly yields HC(SiCl₃)₃ 31 and also the disilacyclobutanes cis- and trans-(Cl₃Si)HC(SiCl₂)₂CH(SiCl₃) 41 and (Cl₃Si)₂C(SiCl₂)₂CH(SiCl₃) 45 the 1,3,5-trisilacyclohexane [Cl₃Si(H)C? SiCl₂]₃ 44 as well as [(Cl₃Si)₂CH]₂SiCl₂, and (Cl₃Si)₂CClMe 39 mainly yields (Cl₃Si)₂C?CH₂and (Cl₃Si)₂besides of HC(SiCl₃)₃, MeC(SiCl₃)₃and (Cl₃Si)₃C? SiCl₂Me.,. Me₂CCl₂ 59 mainly yields Me(Cl)C?CH₂, Me₂CHCl and HCl₂Si? CMe₂? SiCl₃, besides of Me₂C(SiCl₃)₂ and Me₂C(SiCl₂H)₂ Compound 3 crystallizes triclinically in the space group P1 (Nr. 2) mit a = 900,3, b = 914,0, c = 855,3 pm, α = 116,45°, β = 101,44°, γ = 95,86° and one molecule per unit cell. Compound 4 crystallizes monoclinically in thc space group C2/c (no. 15) with a = 3158.3,b = I 103.7, c = 2037.4 pm, β = 1 16.62° and 8 molecules pcr unit cell. The disilacyclobutane ring of compound 3 is plane, showing a mean distance of d (Si-C) =19 1.8 pm and the usual deformations of endocyclic angles: α_Si = 94,2°> 85,8° = α_C.The spiro-linked disilacyclobutane rings of compound 4 are slightly folded by a mean angle of (19.0°). Their mean distances were found to be d (Si? C) = 190.4 pm relating to the central carbon atom and 192.0 pm to the outer ones, respectively. The deformations of endocyclic angles: α_Si = 93,9°> 84,4° = α_C are comparable to those of compound 3.     

Beiträge zur Chemie der Silicium-Schwefel-Verbindungen. XXXIII. Die Struktur des Bis(triphenylsilyl)sulfids

Contributions to the Chemistry of Silicon Sulphur Compounds. XXXIII. Structure of Bis (triphenylsilyl)sulphide The condensation of triphenylsilanethiol yielded bis(triphenylsilyl)sulphide ( 1 ). The compound is remarkable resistent to hydrolysis. 1 crystallizes monoclinically [P2₁/n (No. 14): a = 1707.8 pm; b = 1454.6 pm; c = 1225.0 pm; β = 97.27°; Z = 4; 4470 h k l; R = 0.053]. The molecule is bent with a bond angle Si? S? Si = 112.0°. The mean bond distances Si? S and Si? C are 215.2 pm and 187.4 pm, respectively. Some structural details are discussed.     

Metallderivate von Molekülverbindungen. VII. Bis[1,2-bis(dimethylamino)ethan-N,N′]lithium-disilylphosphanid — Synthese und Struktur

Metal Derivatives of Molecular Compounds. VII. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium Disilylphosphanide — Synthesis and Structure Crystalline lithium phosphanides studied so far show a remarkably high diversity of structure types dependent on the ligands at lithium and the substituents at phosphorus. Bis[1,2-bis(dimethylamino)ethane-N,N′]lithium disilylphosphanide ( 1 ) discussed here, belongs to the up to now small group of compounds which are ionic in the solid state. It is best prepared from silylphosphane by twofold lithiation with lithium dimethylphosphanide first and subsequent monosilylation with silyl trifluoromethanesulfonate, followed by complexation. As found by X-ray structure determination (wR = 0.038) on crystals obtained from diethyl ether {monoclinic; space group P2₁/c; a = 897.8(1); b = 1 673.6(2); c = 1 466.8(1) pm; β = 90.73(1)° at ?100 ± 3°C; Z = 4 formula units}, the lithium cation is tetrahedrally coordinated by four nitrogen atoms of two 1,2-bis(dimethylamino)ethane molecules. Characteristic parameters of the disilylphosphanide anion are a shortened average P? Si bond length of 217 pm (standard value 225 pm) and a Si? P? Si angle of 92.3°.     

Synthese,Charakterisierung und Struktur von P7(t-Bu3Si)3 („Tris(supersilyl)heptaphosphan(3)”︁)

Synthesis, Characterization, and Structure of P₇(t-Bu₃Si)₃ (?Tris(supersilyl)heptaphosphane(3)”? Tris(tri-tert-butylsilyl)heptaphosphanortricyclane P₇(t-Bu₃Si)₃ 1 is obtained from the reaction of (t-Bu)₃Si? Si(t-Bu)₃ with white phosphorus and forms colorless to pale yellow thermostable crystals. 1 is identified by the complete analysis of its ³¹P{¹H} NMR spectrum (A[MX]₃ spin system) as well as by a single crystal structure determination (space group Pca2₁, a = 170.76(2)pm, b = 131.14(3)pm, c = 426.61(5)pm, α = β = γ= 90°, Z = 8 formula units in the elementary cell). The steric demand of the (t-Bu)₃Si-Groups causes an increase of the exocyclic bond angles at the equatorial phosphorus atoms P^e, while it does not particularly influence the P₇-skeleton. Chlorine (r.t.) and bromine (70°C) degrade the P₇-cage of 1 with formation of PX₃ and (t-Bu)₃SiX (X = Cl, Br).     

Bildung siliciumorganischer Verbindungen. 94. Die Kristallstruktur des Hexaphenyltrisilacyclohexans Si3C39H36

Formation of Organosilicon Compounds. 94. Crystal Structure of Hexaphenyltrisilacyclohexane Si₃C₃₉H₃₆ 1.1.3.3.5.5-Hexaphenyl-1.3.5-trisilacyclohexane crystallizes monoclinically in the space group P2₁/n (No. 14) with a = 1718.3 pm, b = 1769.2 pm, c = 1091.4 pm, β = 90.72° and Z = 4 molecules per unit cell. The trisilacyclohexane sceleton is present in a flattened twist boat conformation with mean bond angles of 110.0° at the Si atoms and 117.9° at the C atoms, respectively. The mean bond lengths are d(Si? C) = 187.1 pm in the six membered ring and 187.9 pm to the substituents.     

Moleküle mit ungewöhnlich langen N(sp2)–Si(sp3)-Bindungen: Synthese und Kristallstrukturen von 1,2-Benzoldisulfonylaminosilanen

Polysulfonylamines. XCIV. Molecules with Unusually Long N(sp²)–Si(sp³) Bonds: Synthesis and Crystal Structures of 1,2-Benzenedisulfonylaminosilanes The following compounds were obtained by metathesis of silver 1,2-benzenedisulfonimide (AgZ) with the appropriate chlorosilanes: ZSiMe₃ ( 4 ), ZSiⁿPr₃, ZSiMe₂ⁿBu, ZSiMe₂(CMe₂–CHMe₂) ( 7 ), (Z)₂SiMe₂ ( 8 ). In the crystal structures of 4 (monoclinic, space group P2₁/n), 7 (monoclinic, P2₁/c) and 8 (monoclinic, P2₁/n), which were determined by low-temperature X-ray diffraction, the molecules adopt the N-silyl form and display unusually long bonds between the trigonal-planar N and the tetrahedrally coordinated Si atoms ( 4 : 182.6, 7 : 184.1, 8 : 177.8 and 180.5 pm). For 7 in CDCl₃ solution, ¹H and ¹³C NMR data indicate N,O-silylotropy. The solid state structures of molecules 4 and 7 strongly suggest that the N–Si bond lengthening in N,N-disulfonylated aminosilanes is mainly induced by the π-acceptor character of the SO₂ groups and not by the occasionally observed coordination expansion of the Si atom through short intramolecular O…Si contacts.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 7. Die Kristall- und Molekülstruktur des Diphosphagermetans (t-BuP)2(GePh2)2

Structural Chemistry of Phosphorus Containing Chains and Rings. 7. Molecular and Crystal Structure of the Diphosphagermetane (t-BuP)₂(GePh₂)₂ The compound 1,2-di-tert-butyl-3,3,4,4-tetraphenyl-diphospha-3,4-digerma-cyclobutan, (t-BuP)₂(GePh₂)₂, crystallizes monoclinically in the space group P2₁/c with a = 996.8 pm, b = 1337.3 pm, c = 2403.4 pm, β = 92.66° and Z = 4 formula units. The main structural feature is a non-planar four-membered ring. The (average) bond lengths are d(Ge? Ge) = 242.1 pm, d(Ge? P) = 234.0 pm, d(P? P) = 221.6 pm, d(Ge? C) = 194.9 pm, d(P? C) = 188.tyl4 pm, d(C? C)_Ph = 136.l5 pm, d(C? C)_t-Bu = 151.8 pm, d(C? H)_Ph = 91 pm, d(C? H)_t-Bu ? 95 pm. The geometry of the substituents phenyl and tert-butyl is quite normal.     

Polysulfonylamine. LVII. Zwei Silber(I)-di(organosulfonyl)-amide mit einer Silber-η2-Aryl- beziehungsweise einer Silber-Silber-Wechselwirkung: Kristallstrukturen von Silberdi(benzolsulfonyl)-amid-Wasser (1/0,5) und von wasserfreiem Silberdi(4-toluolsulfonyl)-amid

Polysulfonyl Amines. LVII. Two Silver(I) Di(organosulfonyl)-amides with Silver-η²-Aryl or Silver-Silver Interactions: Crystal Structures of Silver Di(benzenesulfonyl)amide-Water (1/0.5) and of Anhydrous Silver Di(4-toluenesulfonyl)-amide Crystals of [(PhSO₂)₂NAg(μ-H₂O)AgN(SO₂Ph)₂]_n ( 5 ) and [(4-Me? C₆H₄SO₂)₂NAgAgN(SO₂C₆H₄-4-Me)₂]_n ( 6 ) were obtained from aqueous solutions. The crystallographic data are for 5 (at ?95°C): monoclinic, space group C2/c, a = 2 743.8(5), b = 600.49(12), c = 1 664.5(3) pm, β = 101.143(15)°, V = 2.6908 nm³, Z = 8, D_x = 2.040 Mg m^?3; for 6 (at ?130°C): monoclinic, space group P2₁/n, a = 1 099.8(5), b = 563.7(3), c = 2 487.7(13) pm, β = 99.68(4)°, V = 1.5203 nm³, Z = 4, D_x = 1.888 Mg m^?3. In both crystals, the silver atom has a fivefold coordination. The structure of 5 displays [(RSO₂)₂N? Ag(μ-H₂O)Ag′? N(SO₂R)₂] units with Ag? N 226.9 pm, Ag? O 236.7 pm and Ag? O? Ag′ 95.3°; the water oxygen lies on a crystallographic twofold axis. These units are extended to two fused six-membered rings by intramolecular dative bonds (S)O → Ag′ and S(O)′ → Ag (249.3 pm). One phenyl group from each (PhSO₂)₂N moiety is η²-coordinated with its p-C and one m-C atom to a silver atom of a neighbouring bicyclic unit related by a glide plane to form infinite parallel strands (p-C? Ag 252.2, m-C? Ag 263.9 pm). The strands are interconnected into parallel layers through hydrogen bonds between H₂O and sulfonyl oxygens [O …? O(S) 276.1 pm]. These layers consist of a hydrophilic inner region containing metal ions, N(SO₂)₂ fragments and water molecules, and hydrophobic surfaces formed by phenyl groups. The structure of 6 features centrosymmetric [(RSO₂)₂N? Ag? Ag′? N(SO₂R)₂] units with two intramolecular dative bonds (S)O → Ag′ and (S)O′ → Ag (Ag? Ag′ 295.4, Ag? N 226.0, Ag? O 229.4 pm). These bi-pentacyclic units are associated by translation parallel to y into infinite strands by two dative (S)O → Ag bonds per silver atom (Ag? O 243.2 and 253.3 pm).     

Komplexchemie P-reicher Phosphane und Silylphosphane. VII [1]. Bildung und Struktur von [Li(DME)3]2{(SiMe3)[Cr(CO)5]2 P?PP?P[Cr(CO)5]2(SiMe3)}

Transition Metal Complexes of P-rich Phosphanes and Silylphosphanes. VII. Formation and Structure of [Li(DME)₃]₂{(SiMe₃)[Cr(CO)₅]₂ P-P ? P-P[Cr(CO)₅]₂(SiMe₃)} Deep red crystals of the title compound 1 are produced in the reaction of LiP(Me₃Si)₂[Cr(CO)₅] with 1, 2-dibromoethane in DME. The structure of 1 was derived from the investigation of the ³¹P-NMR spectra and confirmed by a single crystal structure determination. 1 crystallizes in the space group P1 (no. 2); a = 1307.8(5)pm, b = 1373.1(5)pm, c = 1236.1(4)pm, α = 106.22(4)°, β = 88.00(3)°, γ = 115.52(4)° and Z = 1. 1 forms a salt composed of a dianion R₂R₄′P₄^2? (R ? SiMe₃, R′ ? Cr(CO)₅) and solvated Li⁺ cations. The zigzag shaped dianion possesses the symmetry 1 -C_i. The distances d(P? P) = 202.5(1)pm and d(P? P) = 221.9(1)pm correspond to a double bond and single bonds, respectively. The distances d(Cr? P) = 251.1(1) pm and 255.3(1) pm are larger than those observed so far which might be caused by the charge distribution in the dianion.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 1. Die KristallStruktur des Diphosphasilirans (t-BuP)2SiPh2

Structural Chemistry of Phosphorus-containing Chains and Rings. 1. Crystal Structure of the Diphosphasilirane (t-BuP)₂SiPh₂ The three-membered P₂Si-heterocycle 1, 2-di-tert-butyl-3, 3-diphenyl-1, 2, 3-diphosphasilirane (t-BuP)₂SiPh₂ crystallizes monoclinic in the space group P2₁ with a = 1041.2 pm, b = 882.3 pm, c = 1158.1 pm, β = 91.33° and Z = 2 formula units. A special structural feature is the regular triangle built up by two P and one Si. Therefore the endocyclic bond angle at Si is as low as 60°. The average bond lengths are P? P = 222.6 pm, P? Si = 222.5 pm, P? C = 190.8 pm, Si? C = 186.6 pm, (C? C )ph = 139.0 pm, ( C? C )_t-Bu = 151.7 pm. The geometry of the substituents phenyl and tert-butyl is quite normal, the last ones are slightly disordered.     

[VCl3(NPPh3)(OPPh3)], ein Phosphaniminato-Komplex von Vanadium(IV)

[VCl₃(NPPh₃)(OPPh₃)], a Phosphorane Iminato Complex of Vanadium(IV) The title compound has been prepared from vanadium tetrachloride and Me₃SiNPPh₃ in the presence of OPPh₃ in CCl₄ solution, forming orange-red, moisture sensitive crystals, which were characterized by an X-ray structure determination. Space group Cc, Z = 4, 2 560 observed unique reflections, R = 0.049. Lattice dimensions at 0°C: a = 1 018(1), b = 1 826(2), c = 1 859(2) pm, β = 93.65(9)° [VCl₃(NPPh₃)(OPPh₃)] forms monomeric molecules, in which the vanadium atom is coordinated in a distorted square pyramidal fashion with the (NPPh₃)^? ligand in apical position. The three chlorine atoms and the oxygen atom of the OPPh₃ molecule occupy the basal positions. The phosphorane iminato group V?N?PPh₃ is nearly linear (bond angle VNP 161.4°), the bond lengths VN (169 pm) and PN (162 pm) correspond with double bonds.     

Bildung siliciumorganischer Verbindungen. 95. Die Kristallstruktur eines Hexadecamethyl-octasila-dispiro-[5.1.5.1]-tetradecans,Si8C22H65

Formation of Organosilicon Compounds. 95. Crystal Structure of a Hexadecamethyloctasila-dispiro [5.1.5.1]tetradecane, Si₈C₂₂H₅₆ 1,1,3,3,5,5,7,7,9,9,11,11,13,13,14,14-Hexadecamethyl-1,3,5,7,9,11,13,14-octasila-dispiro[5.1.5.1]tetradecane crystallizes monoclinically in the space group P2₁/n (No. 14) with a = 1352.4 pm, b = 1215.5 pm, c = 1001.2 pm, β = 92.11° and Z = 2 molecules per unit cell. The dispiro system is formed by a central disilacyclobutane and two C-spiro connected trisilacyclohexane rings. The symmetry of the molecule is 2/m, with flattened six membered rings in chair conformation. The Si? C bonds are enlarged (192 pm) at the strained spiro region whereas the Si? C bonds are distinctly shortened (186 pm) at the opposite Si atoms in the six membered rings.     

Bildung Siliciumorganischer Verbindungen. 103. Bildung und Struktur von cis- und trans-2,4-Dichloro-2,4-bis(trimethyl-silyl)-1,1,3,3-tetramethyl-1,3-disilacyclobutan

Formation of Organosilicon Compounds. 103. Formation and Structure of cis and trans 2,4-Dichloro-2,4-bis(trimethylsilyl)-1,1,3,3-tetramethyl-1,3-disilacyclobutane The reaction of Me₃Si? CCl₂? SiMe₂Cl with LiBu in THF yields 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl) 1,3-disilabicyclo[1.1.0]butane. The product of the first reaction stage is Me₃Si? CCl(Li)-SiMe₂Cl. The 1,3-Disilacyclobutane 2 and 3 were isolated, when Me₃Si? CCl₂? SiMe₂Cl was treated with LiBu in Et₂O. This way the proof is given that 2 and 3 are intermediates of the formation of product 1 . The further products are 4 and 5 (CCl in 2 and 3 substituted by CH) and Me₃Si? CH₂? C(SiMeCl)₂SiMe₃. 2 crystallizes orthorhombically in the space group Fdd 2 (no. 43) with a = 2149.1 pm, b = 2229.2 pm, c = 1763.6 pm and Z = 16 molecules per cell. The central ring of disilacyclobutane is slightly folded (17.9°). The configuration of the C-Atoms in this four membered ring gets closer to a sp² configuration built up by three Si? C bonds. The Cl-atoms approximately have orthogonal positions to these CSi₃ arrangements. The extension of the C? Cl bonds (184.6 pm) and the mutual approximations of the Cl-atoms in the cis-position indicate a high reactivity of the molecule.     

Die Kristallstruktur des Tetrakis(di-tert.-butylphosphino)diphosphans. [(tBu)2P]2P?P[P(tBu)2]2

The Crystal Structure of Tetrakis(di-tert.-butylphosphino)diphosphane [(tBu)₂P]₂P? P[P(tBu)₂]₂ [(tBu)₂P]₂P? P[P(tBu)₂]₂ 1 obtained at ?20°C from a solution of (tBu)₂P? P=P(Br)tBu₂ forms yellow crystals (regular hexagons). 1 crystallizes monoclinic in the space group C2/c with a = 2145.6pm, b = 1137pm, c = 1696.1pm, β = 110.075° and Z = 4 formula units in the elementary cell. Due to high steric load the bond angles at the tertiary P atoms with δ = 115.7° are significantly larger than those at the primary P atoms with δ = 108.6°.     

Zur Bildung und Struktur der Phosphinophosphiniden-phosphorane tBu2P?PP(Me)tBu2 1, tBu(Me3Si)P?PP(Me)tBu2 2 und tBu2P?PP(Br)tBu2 3

Synthesis and Structure of Phosphinophosphinidene-phosphoranes tBu₂P? P?P(Me)tBu₂ 1, tBu(Me₃Si)P? P?P(Me)tBu₂ 2, and tBu₂P? P?P(Br)tBu₂ 3 A new method for the synthesis of 1 and 2 (Formulae see ?Inhaltsübersicht”?) is reported based on the reaction of 5 with substitution reagents (Me₂SO₄ or CH₃Cl). The results of the X-ray structure determination of 1 and 2 are given and compared with those of 3 . While in 3 one P? P distance corresponds to a double bond and the other P? P distance to a single bond (difference 12.5 pm) the differences of the P? P distances in 1 and 2 are much smaller: 5.28 pm in 1 , 4.68 pm in 2 . Both 1 and 2 crystallize monoclinic in the space group P2₁/n (Z = 4). 2 additionally contains two disordered molecules of the solvent pentane in the unit cell. Parameters of 1 : a = 884.32(8) pm, b = 1 924.67(25) pm, c = 1 277.07(13) pm, β = 100.816(8)°, and of 2 : a = 1 101.93(12) pm, b = 1 712.46(18) pm, c = 1 395.81(12) pm, β = 111.159(7)°, all data collected at 143 K. The skeleton of the three P atoms is bent (PPP angle 100.95° for 1 , 100.29° for 2 and 105.77° for 3 ). Ab initio SCF calculations are used to discuss the bonding situation in the molecular skeleton of the three P atoms of 1 and 3 . The results show a significant contribution of the ionic structure R₂P? P(^?)? P(⁺)(X)R₂. The structure with (partially) charged P atoms is stabilized by bulky polarizable groups R (as tBu) as compared to the fully covalent structure R₂P? P(X)? PR₂.     

Bildung siliciumorganischer Verbindungen. 96. Bildung und Struktur von P-Yliden des 1,3,5-Trisilacyclohexans (Einfluß der Substituenten)

Formation of Organosilicon Compounds. 96. Preparation and Structure of P-Ylides of the 1,3,5-Trisilahexanes (Influence of the Substituents) The influence of the substituents at the silicon atoms on formation and structure of ylides of 1,3,5-trisilacyclohexanesis investigated. The reactions of 1 , 2 , 3 with Me₃Si? PMe₂ lead via cleavage of the Si? P bond and subsequent rearrangement to the ylides 4 , 5 and 6 . The x-ray structure determination reveals, that the atoms of the ylid part of 4 are in a plane with the shortened bond distances d(C? P) = 168.6 pm and d(Si? C) = 180.1 pm, whereas the other endocyclic Si? C distances remain nearly unaffected by the ylid formation. Only the endocyclic bond angles C? Si? C of the Si atoms of the ylid are enlarged (116°). In the molecule 6 d(C? P) = 164.6 pm is much shorter, but d(P? Br) = 236.6 pm is enlarged. This enlargement is coupled with a deviation of 17 pm for the ylidic C atom from the ylid plane. Distances and angles are normal in the methylated trisilnhexane. The ring in 6 has boat conformation, in 4 a flat chair conformation.     

Hydrido-Silyl-Komplexe. V. Strukturelle Änderungen in Hydrido-Silyl-Komplexen infolge Si?H-Wechselwirkung; Strukturvergleich zwischen (π-CH3C5H4)(CO)2Mn(H)SiR3- und analogen (π-C5H5)(CO)2FeSiR3-Komplexen

Hydrido Silyl Complexes. V. Structural Changes in Hydrido Silyl Complexes Due to Si? H Interaction; Comparison between the Structures of (π-CH₃C₅H₄)(CO)₂Mn(H)SiR₃ and Analogous (π-C₅H₅)(CO)₂FeSiR₃ Complexes The structures of the complexes Cp(CO)₂FeSiFPh₂ ( 2a ) and Cp(CO)₂FeSiCl₃ ( 2b ), containing ?normal”? metal-silicon bonds, are compared with the known structures of the complexes MeCp(CO)₂Mn(H)SiFPh₂ ( 1a ) and MeCp(CO)₂Mn(H)SiCl₃ ( 1b ), containing Mn? H? Si three-center bonds. 2a crystallizes in space group P2₁/c, a = 805.8(3), b = 1417.5(6), c = 1498.2(4) pm, β = 90.99(3)°, 2b in space group P2₁/n, a = 817(1), b = 1244(1), c = 1142(1)pm, β = 99.9(1)°. In 2a gauche conformation in respect to the Fe? Si bond is found; in 2b the silylligand is rotated 12° around the Fe? Si axis out of a staggered conformation. Possible reasons for the unsymmetrical conformations are discussed. Lengthening of the Fe? Si distance from 221.6(1)pm in 2b to 227.8(1) pm in 2a corresponds to the expected increase in the bond radius of silicon due to exchange of the substituents at silicon. Additional lengthening of the Mn? Si distance by about 3.5 pm in 1a compared with 1b is attributed to the increased delocalization of the Mn? H? Si bond in 1a .     

Chelatkomplexe von Rheniumtetrachlorid. Die Kristallstrukturen von ReCl4(DME) und ReCl4(DPPE) · Tolan

Chelate Complexes of Rhenium Tetrachloride. The Crystal Structures of ReCl₄(DME) and ReCl₄(DPPE) · Tolan Bright green crystals of ReCl₄(DME) have been prepared by the reaction of rhenium pentachloride with dimethoxyethane (DME) in dichloromethane. ReCl₄(DPPE) · tolan was obtained in form of red crystals by the reaction of the alkyne complex [ReCl₄(Ph? C?C? Ph)(POCl₃)] with bis(diphenylphosphino)ethane (DPPE) in dichloromethane. The complexes were characterized by X-ray structure determinations. ReCl₄(DME): Space group I4 2d, Z = 8, 829 observed unique reflexions, R = 0.022. Lattice dimensions at 19.5°C: a = b = 960.60(6), c = 2337.2(6) pm. The complex forms monomeric molecules with DME as chelating ligand; the Re? O bond lengths are 213.1 pm. The chlorine atoms, arranged in trans position to the chelating ligand, have slightly shorter Re? Cl bonds than the chlorine atoms in cis position (232,1 pm). ReCl₄(DPPE) · tolan: Space group P2₁/n, Z = 4,4313 observed unique reflexions, R = 0.040. Lattice dimensions at ?80°C: a = 1095.7(1), b = 1764.2(2), c = 1898.0(2) pm, β = 99.229(8)°. The compound consists in form of monomeric molecules [ReCl₄(DPPE)] and diphenylacetylene molecules, which are incorporated in the lattice. The two phenyl rings of the tolan molecules are twisted towards each other along the C? C axis with a dihedral angle of 21°. The DPPE molecules are bonded to the rhenium atom in a chelating fashion with medium Re? P lengths of 250.4 pm. The chlorine atoms, arranged in trans position to this ligand, with Re? Cl bond lengths of 234.5 pm are slightly longer than the Re? Cl bonds in cis position with 232.3 pm.     

Zur Kenntnis der Struktur von Sr3(BN2)2

On the Structure of Sr₃(BN₂)₂ The structure of Sr₃(BN₂)₂ was determined on single-crystal X-ray data collected with a four-circle diffractometer. Sr₃(BN₂)₂ crystallizes in the cubic space group Im3 m (no. 229) with a = 764.56(3) pm and Z = 3. The structure contains linear BN^3?₂ ions with a B? N bond length of 135.8(6) pm. The straight forward synthesis employing metal nitrides plus boron nitride yielded crystalline powders of M₃(BN₂)₂ (M = Ca, Sr) at 1100°C (5 days). Cubic indexing of guinier patterns gave a = 765.8(1) pm for M = Sr and a = 734.7(2) pm for M = Ca. The structure refinement on a single crystal of Sr₃(BN₂)₂ revealed that one strontium site (2a; 0, 0, 0) is occupied by only about 50%. It has been tried to fully occupy this site with an alkali metal (A) to obtain ASr₄(BN₂)₃ (Z = 2). Reactions with A = Na yielded crystalline powders. Cubic indexing of the guinier pattern analogous to that of Sr₃(BN₂)₂ gave a = 754.2(1) pm.     

Die Struktur des Tetraphenyldisiloxans

Structure of Tetraphenyldisiloxane Tetraphenyldisiloxane 1 crystallizes at 298 K monoclinically (P2₁/n; a = 1407.6; b = 610.7; c = 1262.7 pm; β = 95.87° Z = 2) and undergoes a second order phase transition at 200 K, in an almost unchanged structure of triclinic symmetry. At 298 K the molecules are already bent (Si? O? Si = 160°) with static or dynamical disorder of the bridging atom. Both Si? O distances are different (156 or 169 pm), because the shift of the bridging O atom is not perpendicular to the Si? to? Si vector. The reason for this remarkable behavior is not yet clear. According to the vibrational spectra, the Si? O? Si bridge is bent in the crystal but, in CCl₄ solution a dynamical oscillation through the linear configuration may occur.