H. Bürger

Darstellung und schwinkungsspektren von silylamiden der elemente zink, cadmium und quecksilber☆

Zusammenfassung Durch Reaktion von Natrium-bis(trimethylsilyl)amid mit ZnCl 2 , CdI 2 bzw. HgBr 2 bilden sich in hohen Ausbeuten die monomeren, leicht fluchtigen Silylamide [(CH 3 ) 3 Si] 2 NMN[Si(CH 3 ) 3 ] 2 (M = Zn, Cd, Hg). Ihie physikalischen und chemischen Eigenschaften werden mitgeteilt. Die aus den IR- und Raman-Spektren berechneten Kraftkonstanten sprechen in allen Verbindungen fur eine kovalente MN-Einfachbindung, hingegen im Einklang mit den 1 H-KMR-Spektren fur einen erhohten SiN-Bindungsgrad.

Syntheses and crystal structures of the dimers of a bis(lithioamino)- and a tris(lithioamino)-silane containing electron-deficient Li4N4 and Li6N6 clusters

Abstract The syntheses of [t-BuN(H)]3SiPh and {[t-BuN(Li)]3SiPh}2 (IV) are described, and their 1H NMR, infrared and Raman spectra are reported. Crystals of {[t-BuN(Li)]2SiMe2}2 (III) belong to the space group C2/c with a 18.799(5), b 8.963(3), c 18.672(5) A, β 112.19(2)°, Z = 4 and R = 0.084. There is a Li4 bisphenoid at the core of the dimers, the two pairs of Li3 faces being linked by the two NSiN bridges. The molecular symmetry is roughly 4 2m (D2d) although only two-fold crystallographic symmetry is required. The dimers IV are centered on 1 symmetry sites of the space group P 1 with a 10.234(2), b 10.406(2), c 11.476(3) A, α 61.43(1), β 82.16(1), γ 73.28(1)°, Z = 1 and R = 0.057. Each nitrogen atom is bonded to a Li3 face of a Li6 trigonal antiprism with the Si atoms over the remaining two unbridged faces. The overall symmetry approaches 3 m (D3d). Factors determining the shapes of the Li4N4 and Li6N6 clusters of III and IV, respectively, are discussed.

Silylamido-Verbindungen von Chrom, Mangan, Nickel und Kupfer

Natrium-bis-(trimethylsilyl)-amid reagiert mit CrCl3, MnJ2, NiJ2 und CuJ in Tetrahydrofuran zu fluchtigen, sehr hydrolyse-und sauerstoffempfindlichen Disilylamiden des Cr(III), Mn(II), Ni(II) und Cu(I).

Beiträgezur chemie der silicium-stickstoff-verbindungen: CVII. Darstellung, schwingungsspektren und normalkoordinatenanalyse von disilylamiden der 3. Gruppe: M[N(SiMe3)2]3 mit M = Al, Ga und In

Abstract The formerly unknown silylamides Ga[N(SiMe 3 ) 2 ] 3 (II) and In[N(SiMe 3 ) 2 ] 3 (III) as well as Al[N(SiMe 3 ) 2 ] 3 (I) were prepared in excellent yields from LiN(SiMe 3 ) 2 and the appropriate chlorides. Their thermal behaviour was investigated by thermal analysis. All compounds are monomeric, the central metal atoms possessing a trigonal environment. (II) is isostructural with (I) and the corresponding Fe and Cr compounds. The infrared and Raman spectra are almost identical for all compounds. A normal coordinate treatment suggests a close vibrational relationship of the MN(SiMe 3 ) 2 fragment with trisilylamines X 3 Si-N(SiMe 3 ) 2 . Good agreement of calculated and observed frequencies was achieved with the following MN stretching force constants: AlN 2.09, GaN 1.95, and InN 1.77 mdyn/A.

Tris(trimethylsilylamino)silanes RSi(NHSiMe3)3. Synthesis, crystal and molecular structure of three dimeric trilithio derivatives

Abstract MeSi(NHSiMe 3 ) 3 (I) and t-BuSi(NHSiMe 3 ) 3 (II) have been prepared and their 1 H NMR, infrared and Raman spectra determined. Reaction of I, II and PhSi(NHSiMe 3 ) 3 with n-butyllithium yielded the respective trilithio derivatives VI, VII and VIII, for which 1 H and 7 Li NMR, infrared and Raman spectra are reported. Each trilithio derivative has been shown by X-ray diffraction to form dimers in the solid state. Ignoring the phenyl groups in VIII, the symmetry of the dimers approaches 3 m ( D 3 d ). The dimers may be described as a trigonal antiprismatic core of six lithium atoms to which two RSi(NSiMe 3 ) 3 fragments are attached. Each nitrogen and lithium atom forms three LiN bonds, so that the bonding in the Li 6 N 6 clusters is electron deficient. The relationship between these clusters and an undistorted icosahedron is discussed.

Die hydrolytische spaltung von tris(trimethylsilyl)derivaten der elemente phosphor, arsen und antimon

Abstract The cleavage of [(CH 3 ) 3 Si] 3 M (M = P, As) by H 2 O, D 2 O, and CH 3 OH is a convenient method for the preparation of [(CH 3 ) 3 Si] n MD(D) 3− n compounds. The 1 H NMR and the vibrational spectra suggest a pyramidal structure of all P, As, and Sb derivatives and do not support the presence of π interactions in the SiM bond.

Spektroskopische untersuchungen an tris(trimethylsilyl)silan und -silan-d1

Abstract An improved synthesis of (Me 3 Si) 3 SiH and the preparation of (Me 3 Si) 3 SiD are described. 1 H-NMR-, infrared and Raman spectra and a normal coordinate analysis of these compounds are reported and analyzed with regard to the inductive properties of the Me 3 Si group.

Titan-Stickstoff-Verbindungen : XVII. σ-(Ferrocenyl)-titan-dialkylamide

Abstract Mono- and dilithioferrocene react with dialkylamidotitanium bromides to yield h 1 -ferrocenyltitanium dialkylamides. 1 H- and 13 C-NMR and IR spectra establish that in these compounds C 5 H 4 groups are π-linked to Fe and σ-bonded to Ti; the structures are rigid in the NMR time scale. Dependent on the NR 2 substituent the TiC σ-bond is stable to ∼60° for short periods.

Darstellung, eigenschaften, kmr-spektren, schwingungs-spektren und normalkoordinatenanalyse von tris(tri-methylsilyl) halogensilanen

Abstract Preparation and properties of the (Me 3 Si) 3 SiX compounds (X = F, Cl, Br, I) are described and their NMR, IR and Raman spectra reported. A complete assignement of the vibrational spectra is given on the basis of a normal coordinate analysis. Si  Si and Si  X bonds are markedly weakened by the inductive effect of the Me 3 Si groups, compared with other SiSi and SiX compounds.

Alkali metal derivatives of octamethyltrisiladiazane. Unusually short NaC contacts in the molecular structure of the disodium salt

Abstract Alkali metal derivatives (Me3SiNM)2SiMe2 of octamethyldisilatriazane (I) have been obtained by the reaction of I with mNH2 (M  Na, K, Cs), or with M in the presence of styrene (M  K, Rb) or with elemental Cs. A monosodium derivative has also been prepared. The dilithium derivative II and the disodium analogue III from stable complexes with ethers. In contrast to the dimeric molecular weights of II and III in benzene solution, an X-ray study of III has revealed trimeric association in the solid state. The crystals belong to the monoclinic space group C2/c with a 21.725(2), b 18.5012(9), c 12.7867(7) A, β 103.347(4)°, Z  4 and dc 1.11 g/cm3. Refinement yielded a conventional R value of 0.045 for 2909 counter-measured observed reflections. The trimers possess a cluster of six Na+ which are bridged by the N atoms of the anions. If only nSi and NNa bonds are considered, the N atoms have coordination numbers of 4 and 5 while coordination numbers of 2, 3 and 4 are found for the cations. The NNa distances (2.304(3)-2.601(3) A) reflect the coordination numbers of both N and Na. Surprisingly, the shortest NaC contact, 2.656(6) A, is comparable to the longest NNa bond, and the possible chemical consequences of such metal-alkyl interactions are discussed. The SiNSi bond angles vary over a substantial range 122.6(2)–140.0(2)°.