Darstellung,Eigenschaften und Reaktionsverhalten von 2-(Dimethylaminomethyl)phenyl- und 8-(Dimethylamino)naphthylsubstituierten Lithiumhydridosilylamiden – Bildung von Silaniminen durch Lithiumhydrideliminierung

Preparation, Properties, and Reaction Behaviour of 2-(Dimethylaminomethyl)phenyl- and 8-(Dimethylamino)naphthylsubstituted Lithium Hydridosilylamides – Formation of Silanimines by Elimination of Lithium Hydride The hydridosilylamines Ar(R)Si(H)–NHR′ ( 2 a : Ar = 2-Me₂NCH₂C₆H₄, R = Me, R′ = CMe₃; 2 b : Ar = 2-Me₂NCH₂C₆H₄, R = Ph, R′ = CMe₃; 2 c : Ar = 2-Me₂NCH₂C₆H₄, R = Me, R′ = SiMe₃; 2 d : Ar = 8-Me₂NC₁₀H₆, R = Me, R′ = CMe₃; 2 e : Ar = 8-Me₂NC₁₀H₆, R = Ph, R′ = CMe₃; 2 f : Ar = 8-Me₂NC₁₀H₆, R = Me, R′ = SiMe₃) have been synthesized from the appropriate chlorosilanes Ar(R)SiHCl either by reaction with the stoichiometric amount of Me₃CNHLi ( 2 a , 2 b , 2 d , 2 e ) or by coammonolysis in liquid NH₃ with chlorotrimethylsilane in molar ratio 1 : 3 ( 2 c , 2 f ). Treatment of 2 a–2 f with n-butyllithium in equimolar ratio in n-hexane resulted in the lithiumhydridosilylamides Ar(R)Si(H)–N(Li)R′ 3 a–3 f . The frequencies of the Si–H stretching vibration and ²⁹Si–¹H coupling constants in the amides are smaller than in the analogous amines indicating a higher hydride character for the hydrogen atom of the Si–H group in the amides compared to the amines. Results of NMR spectroscopic studies point to the existence of a (Me₂)N → Si coordination bond in the 8-(dimethylamino)naphthyl-substituted amines and amides. The amides 3 a–3 c are stable under refluxing in m-xylene. At the same conditions 3 d and 3 e eliminate LiH and the silanimines 8-Me₂NC₁₀H₆(R)Si=NCMe₃ ( 4 d : R = Me, 4 e : R = Ph) are formed. The amides 3 a–3 d und 3 f react with chlorotrimethylsilane in THF to give the corresponding N-substitution products Ar(R)Si(H)–N(SiMe₃)R′ 6 a–6 d and 6 f in good yields. 4 d is formed as a byproduct in the reaction of 3 d with chlorotrimethylsilane. In n-hexane and m-xylene these amides are little reactive opposite to chlorotrimethylsilane. 6 a–6 d and 6 f are obtained in very small amounts. In the case of 3 d besides the N-substitution product 6 d the silanimine 4 d is obtained. In contrast to chlorotrimethylsilane the amides 3 a and 3 f react well with chlorodimethylsilane in m-xylene producing 2-Me₂NCH₂C₆H₄(H) SiMe–N(SiHMe₂)CMe₃ ( 7 a ) and 8-Me₂NC₁₀H₆(H)SiMe–N(SiHMe₂)SiMe₃ ( 7 f ).     

Lithiumhydridosilylamide R2(H)SiN(Li)R′ – Darstellung,Eigenschaften und Kristallstrukturen

Lithium Hydridosilylamides R₂(H)SiN(Li)R′ – Preparation, Properties, and Crystal Structures The hydridosilylamines R₂(H)SiNHR′ ( 1 a : R = CHMe₂, R′ = SiMe₃; 1 b : R = Ph, R′ = SiMe₃; 1 c : R = CMe₃, R′ = SiMe₃; 1 d : R = R′ = CMe₃) were prepared by coammonolysis of chlorosilanes R₂(H)SiCl with Me₃SiCl ( 1 a , 1 b ) as well as by reaction of (Me₃C)₂(H)SiNHLi with Me₃SiCl ( 1 c ) and Me₃CNHLi with (Me₃C)₂(H)SiCl ( 1 d ). Treatment of 1 a–1 d with n-butyllithium in equimolar ratio in n-hexane resulted in the corresponding lithiumhydridosilylamides R₂(H)SiN(Li)R′ 2 a–2 d , stable in boiling m-xylene. The amines and amides were characterized spectroscopically, and the crystal structures of 2 b–2 d were determined. The comparison of the Si–H stretching vibrations and ²⁹Si–¹H coupling constants indicates that the hydrogen atom of the Si–H group in the amides has a high hydride character. The amides are dimeric in the solid state, forming a planar four-membered Li₂N₂ ring. Strong (Si)H … Li interactions exist in 2 c and 2 d , may be considered as quasi tricyclic dimers. The ‘‘NSiHLi rings”︁”︁ are located on the same side of the central Li₂N₂ ring. In 2 b significant interactions occurs between one lithium atom and the phenyl substituents. Furthermore all three amides show CH₃ … Li contacts.     

1‐Azaallyl Complexes of NiII,PdII, and TiIII

The metal complexes [Ni{N(Ar)C(R)C(H)Ph}₂) ( 2 ) (Ar = 2,6‐Me₂C₆H₃, R = SiMe₃), [Ti(Cp₂){N(R)C(Bu^t)C(H)R}] ( 3 ), M{N(R)C(Bu^t)C(H)R}I [M = Ni ( 4 a ) or Pd ( 4 b )] and [M{N(R)C(Bu^t)C(H)R}I(PPh₃)] [M = Ni ( 5 a ) or Pd ( 5 b )] have been prepared from a suitable metal halide and lithium precursor of ( 2 ) or ( 3 ) or, alternatively from [M(LL)₂] (M = Ni, LL = cod; M = Pd, LL = dba) and the ketimine RN = C(Bu^t)CH(I)R ( 1 ). All compounds, except 4 were fully characterised, including the provision of X‐ray crystallographic data for complex 5 a .     

Darstellung und Kristallstrukturen von neutralen und kationischen Kupfer(I)-Gemischtligandkomplexen mit Derivaten des Biimidazols und Triphenylphosphan

Preparation and Crystal Structures of Neutral and Cationic Copper(I) Mixed Ligand Complexes with Triphenylphosphane and Derivatives of Biimidazole Eight triphenylphosphanecopper(I) complexes with bibenzimidazole, tetramethylbiimidazole or tetrahydrobiimidazole were prepared and characterized so far as possible by elemental analysis, IR, ¹H-NMR and ³¹P-NMR spectra. The crystal structures of two complexes with bibenzimidazole were determined. [Cu(bbimH₂)(PPh₃)₂]Cl · CH₂Cl₂: Reaction of CuCl with bibenzimidazole in fused triphenylphosphane or [CuCl(PPh₃)₃] with bibenzimidazole in CH₂Cl₂. Space group P 1, Z = 2, 6440 observed independent reflections, R = 0.064 for refletions with I > 2σ(I). Lattice parameters at 203 K: a = 983.6; b = 1348.9; c = 1805.5 pm; α = 77.24; β = 80.90; γ = 85.81°. The crystal structure is built up by monomeric molecules with distorted tetrahedral coordination of the copper atom (CuN₂P₂) and bibenzimidazole as bidentate ligand. The chloride ion is linked by H-bonds with the NH groups of the bibenzimidazole. [{Cu(PPh₃)₂}₂(μ-bbim)] · 2 CH₂Cl₂: Reaction of [CuCl(PPh₃)₃] with the dipotassium salt of bibenzimidazole in CH₃OH/CH₂Cl₂. Space group P 1, Z = 1, 7192 observed independent reflections, R = 0.057 for reflections with I > 2σ(I). Lattice parameters at 203 K: a = 1334.1; b = 1386.8; c = 1443.7 pm; α = 107.51; β = 103.35; γ = 113.74°. The crystal structure is built up by centrosymmetric molecules with distorted tetrahedral coordination of the copper atoms (CuN₂P₂) and bibenzimidazolate(2–) as tetradentate bridging ligand.     

Homoleptische Amide von Zink,Cadmium und Quecksilber

Homoleptic Amides of Zinc, Cadmium, and Mercury ZnCl₂, CdCl₂ and HgCl₂ react with the lithium salts ( 1 a–5 a ) of the sterically demanding secundary amines HN(SiMe₃)Ph ( 1 ), HN(SiMe₃)C₆H₃Me₂‐2,6 ( 2 ), HN(SiMe₃)C₆H₃ⁱPr₂‐2,6 ( 3 ), HN(SiMe₃)C₆H₃^tBu₂‐2,5 ( 4 ), and HN(SiMe₂NMe₂)C₆H₃ⁱPr₂‐2,6 ( 5 ) yielding the corresponding homoleptic metal amides Zn[N(SiMe₂R′)R]₂ ( 1 b–5 b ), Cd[N(SiMe₂R′)R]₂ ( 1 c , 5 c ), and Hg[N(SiMe₂R′)R]₂ ( 1 d–5 d ), respectively. Except the dimeric {Zn[N(SiMe₃)Ph]₂}₂ ( 1 b ), all complexes are monomeric. The compounds were characterized by elemental analyses, molecular weight determinations, NMR and mass spectra. Furthermore, the zinc amides ( 1 b–5 b ) and the mercury amides 1 d–3 d and 5 d were characterized by single crystal X‐ray structure analysis. Except 1 b and 5 b , they show a linear N–M–N arrangement.     

Beryllium Halide Complexes Incorporating Neutral or Anionic Ligands: Potential Precursors for Beryllium Chemistry

Reactions of the beryllium dihalide complexes [BeX₂(OEt₂)₂] (X=Br or I) with N,N,N′,N′‐tetramethylethylenediamine (TMEDA), a series of diazabutadienes, or bis(diphenylphosphino)methylene (DPPM) have yielded the chelated complexes, [BeX₂(TMEDA)], [BeX₂{(RN=CH)₂}] (R=tBu, mesityl (Mes), 2,6‐diethylphenyl (Dep) or 2,6‐diisopropylphenyl (Dip)), and the non‐chelated system, [BeI₂(κ¹‐P‐DPPM)₂]. Reactions of lithium or potassium salts of a variety of β‐diketiminates have given both three‐coordinate complexes, [{HC(RCNAr)₂}BeX] (R=H or Me; Ar=Mes, Dep or Dip; X=Br or I); and four‐coordinate systems, [{HC(MeCNPh)₂}BeBr(OEt₂)] and [{HC(MeCNDip)(MeCNC₂H₄NMe₂}BeI]. Alkali metal salts of ketiminate, guanidinate, boryl/phosphinosilyl amide, or terphenyl ligands, lead to dimeric [{BeI{μ‐[(OCMe)(DipNCMe)]CH}}₂], and monomeric [{iPr₂NC(NMes)₂}BeI(OEt₂)], [κ²‐N,P‐{(HCNDip)₂B}(PPh₂SiMe₂)NBeI(OEt₂)] and [{C₆H₃Ph₂‐2,6}BeBr(OEt₂)], respectively. Compound [{HC(MeCNPh)₂}BeBr(OEt₂)] undergoes a Schlenk redistribution reaction in solution, affording the homoleptic complex, [{HC(MeCNPh)₂}₂Be]. The majority of the prepared complexes have been characterized by X‐ray crystallography and multi‐nuclear NMR spectroscopy. The structures and stability of the complexes are discussed, as is their potential for use as precursors in poorly developed low oxidation state beryllium chemistry.     

Ligand Effects on the Electronic Structure of Heteroleptic Antimony‐Centered Radicals

We report on the structures of three unprecedented heteroleptic Sb‐centered radicals [L(Cl)Ga](R)Sb^. ( 2‐R , R=B[N(Dip)CH]₂ 2‐B , 2,6‐Mes₂C₆H₃ 2‐C , N(SiMe₃)Dip 2‐N ) stabilized by one electropositive metal fragment [L(Cl)Ga] (L=HC[C(Me)N(Dip)]₂, Dip=2,6‐i‐Pr₂C₆H₃) and one bulky B‐ ( 2‐B ), C‐ ( 2‐C ), or N‐based ( 2‐N ) substituent. Compounds 2‐R are predominantly metal‐centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R, and significant delocalization of unpaired‐spin density onto the ligands was observed in 2‐B and 2‐N . Cyclic voltammetry (CV) studies showed that 2‐B undergoes a quasi‐reversible one‐electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]₂] ([K([2.2.2]crypt)][ 2‐B ]) containing the stibanyl anion [ 2‐B ]^?, which was shown to possess significant Sb?B multiple‐bonding character.     

Ligand Effects on the Electronic Structure of Heteroleptic Antimony-Centered Radicals

We report on the structures of three unprecedented heteroleptic Sb-centered radicals [L(Cl)Ga](R)Sb^. ( 2-R , R=B[N(Dip)CH]₂ 2-B , 2,6-Mes₂C₆H₃ 2-C , N(SiMe₃)Dip 2-N ) stabilized by one electropositive metal fragment [L(Cl)Ga] (L=HC[C(Me)N(Dip)]₂, Dip=2,6-i-Pr₂C₆H₃) and one bulky B- ( 2-B ), C- ( 2-C ), or N-based ( 2-N ) substituent. Compounds 2-R are predominantly metal-centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R, and significant delocalization of unpaired-spin density onto the ligands was observed in 2-B and 2-N . Cyclic voltammetry (CV) studies showed that 2-B undergoes a quasi-reversible one-electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]₂] ([K([2.2.2]crypt)][ 2-B ]) containing the stibanyl anion [ 2-B ]⁻, which was shown to possess significant Sb−B multiple-bonding character.     

Cyclische Diazastannylene. XXXII. Zur Synthese und Reaktivität difunktionalisierter Cyclosilagermadiazane—Bildung von Digermanen

Cyclic Diazastannylenes. XXXII. On the Synthesis and Reactivity of Difunctional Cyclosilagermadiazanes—Formation of Digermanes The cyclic bisaminostannylene Me₂Si(t-BuN)₂Sn 1 reacts with tetrahalides of germanium GeX₄(X = Cl, Br, I) forming the bisaminodihalogengermanes 2a, 2b and 2c. The halogen atoms of the compounds 2 may be substituted by alkyl-, amino- and pseudohalide groups: Me₂Si(t-BuN)₂GeXY (X = Y = N₃ 3 ; X = Br, Y = Me 4 , Y = t-Bu 6 , Y = N(SiMe₃)₂ 8a , Y = NEt₂ 9 ; X = Me, Y = N₃ 5a , Y = CN 5b ; X = N₃, Y = t-Bu 7 , Y = N(SiMe₃)₂ 10 ; X = I, Y = N(SiMe₃)₂ 8b ). Reduction of the compounds 2b and 4 with sodium naphthalide generates the digermanes (Me₂Si(t-BuN)₂GeR)₂ (with R = Br 11 , R = Me 12 ) Compound 8b crystallizes in the monoclinic space group P2₁/c with Z = 8 and lattice constants a = 16.205(8), b = 19.854(9), c = 17.537(9) Å, β = 107.50(9)°. Compound 11 crystallizes in the triclinic space group P1 with Z = 2 and lattice constants a = 8.921(4), b = 11.091(5), c = 17.590(8) Å, α = 80.5(1), β = 89.2(1), γ = 71.4(1)°.     

Reaktionen von Lithiumhydridosilylamiden RR′(H)Si–N(Li)R″ mit Chlortrimethylsilan in Tetrahydrofuran und unpolaren Lösungsmitteln: N‐Silylierung und/oder Cyclodisilazanbildung

Reactions of Lithium Hydridosilylamides RR′(H)Si–N(Li)R″ with Chlorotrimethylsilane in Tetrahydrofuran and Nonpolar Solvents: N‐Silylation and/or Formation of Cyclodisilazanes The lithiumhydridosilylamides RR′(H)Si–N(Li)R″ ( 2 a : R = R′ = CHMe₂, R″ = SiMe₃; 2 b : R = R′ = Ph, R″ = SiMe₃; 2 c : R = R′ = CMe₃, R″ = SiMe₃; 2 d : R = R′ = R″ = CMe₃; 2 e : R = Me, R′ = Si(SiMe₃)₃, R″ = CMe₃; 2 f – 2 h : R = R′ = Me, f : R″ = 2,4,6‐Me₃C₆H₂, g : R″ = SiH(CHMe₂)₂, h : R″ = SiH(CMe₃)₂; 2 i : R = R′ = CMe₃, R″ = SiH(CMe₃)₂) were prepared by reaction of the corresponding hydridosilylamines RR′(H)Si–NHR″ 2 a – 2 i with n‐butyllithium in equimolar ratio in n‐hexane. The unknown amines 1 e – 1 i and amides 2 f – 2 i have been characterized spectroscopically. The wave numbers of the Si–H stretching vibrations and ²⁹Si–¹H coupling constants of the amides are less than of the analogous amines. This indicates a higher hydride character for the hydrogen atom of the Si–H group in the amide in comparison to the amines. The ²⁹Si‐NMR chemical shifts lie in the amides at higher field than in the amines. The amides 2 a – 2 c and 2 e – 2 g react with chlorotrimethylsilane in THF to give the corresponding N‐silylation products RR′(H)Si–N(SiMe₃)R″ ( 3 a – 3 c , 3 e – 3 g ) in good yields. In the reaction of 2 i with chlorotrimethylsilane in molar ratio 1 : 2,33 in THF hydrogen‐chlorine exchange takes place and after hydrolytic work up of the reaction mixture [(Me₃C)₂(Cl)Si]₂NH ( 5 a ) is obtained. The reaction of the amides 2 a – 2 c , 2 f and 2 g with chlorotrimethylsilane in m(p)‐xylene and/or n‐hexane affords mixtures of N‐substitution products RR′(H)Si–N(SiMe₃)R″ ( 3 a – 3 c , 3 f , 3 g ) and cyclodisilazanes [RR′Si–NR″]₂ ( 6 a – 6 c , 6 f , 6 g ) as the main products. In case of the reaction of 2 h the cyclodisilazane 6 h was obtained only. 2 c – 2 e show a very low reactivity toward chlorotrimetyhlsilane in m‐xylene and toluene resp.. In contrast to Me₃SiCl the reactivity of 2 d toward Me₃SiOSO₂CF₃ and Me₂(H)SiCl is significant higher. 2 d react with Me₃SiOSO₂CF₃ and Me₂(H)SiCl in n‐hexane under N‐silylation to give RR′(H)Si–N(SiMe₃)R″ ( 3 d ) and RR′(H)Si–N(SiHMe₂)R″ ( 3 d ′) resp. The crystal structures of [Me₂Si–NSiMe₃]₂ ( I ) ( 6 f , 6 g and 6 h ) have been determined.     

Manganese(II) Silylamides

Mn[N(SiMe₃)₂]₂(THF) ( I ) (Me = methyl, THF = tetrahydrofuran) was obtained on large scale from “active” MnCl₂ and LiN(SiMe₃)₂ in THE in 85–93% yield. The novel, theoretically interesting tetra-coordinated Mn[N(SiMe₃)₂]₂L₂ series was derived from I , where L = THF, pyridine and t-butyleyanide. All these species are quite stable thermally and exhibit exteme oxygen sensitivity. Preparation, properties, and reactions of unsymmetrically substituted (“hemi”) X? Mn? Y type compounds are presented also, where X = ? Cl, ? NO₃ and n = butyl, and Y = ? N(SiMe₃)₂ and ? OR. From Cl? Mn? N(SiMe₃)₂, with or without coordinated THF being present, the unusual (Mn{SiMe₃)₂, was isolated as yellow crystals. The “hemi” Mn(II)-system exhibits only moderate thermal stability and tends to disproportionate. Many derivatives are photosensitive, especially with UV light.     

Synthesis and Reactivity of Low‐Valent Group 14 Element Compounds

The tetravalent germanium and tin compounds of the general formulae Ph*EX₃ (Ph* = C₆H₃Trip‐2,6, Trip = C₆H₂iPr₃‐2,4,6; E = Sn, X = Cl ( 1a ), Br ( 1b ); E = Ge, X = Cl ( 2 )) are synthesized by reaction of Ph*Li·OEt₂ with EX₄. The subsequent reaction of 1a , b with LiP(SiMe₃)₂ leads to Ph*EP(SiMe₃)₂ (E = Sn ( 3 ), Ge ( 4 )) and the diphosphane (Me₃Si)₂PP(SiMe₃)₂ by a redox reaction. In an alternative approach 3 and 4 are synthesized by using the corresponding divalent compounds Ph*ECl (E = Ge, Sn) in the reaction with LiP(SiMe₃)₂. The reactivity of Ph*SnCl is extensively investigated to give with LiP(H)Trip a tin(II)‐phosphane derivative Ph*SnP(H)Trip ( 6 ) and with Li₂PTrip a proposed product [Ph*SnPTrip]^– ( 7 ) with multiple bonding between tin and phosphorus. The latter feature is confirmed by DFT calculations on a model compound [PhSnPPh]^–. The reaction with Li[H₂PW(CO)₅] gives the oxo‐bridged tin compound [Ph*Sn{W(CO)₅}(μ‐O)₂SnPh*] ( 8 ) as the only isolable product. However, the existence of 8 as the bis‐hydroxo derivative [Ph*Sn{W(CO)₅}(μ‐OH)₂SnPh*] ( 8a ) is also possible. The Sn^IV derivatives Ph*Sn(OSiMe₃)₂Cl ( 9 ) and [Ph*Sn(μ‐O)Cl]₂ ( 10 ) are obtained by the oxidation of Ph*SnCl with bis(trimethylsilyl)peroxide and with Me₃NO, respectively. Besides the spectroscopic characterization of the isolated products compounds 1a , 2 , 3 , 4 , 8 , and 10 are additionally characterized by X‐ray diffraction analysis.     

Übergangsmetallphosphidokomplexe. XII. Diphosphenkomplexe (DRPE)Ni[η2-(PR′)2] und die Struktur von (DCPE)NiP(SiMe3)2

Transition Metal Phosphido Complexes. XII. Diphosphene Complexes (DRPE)Ni[η²-(PR′)₂] and the Structure of (DCPE) NiP (SiMe₃)₂ LiP(SiMe₃)₂ reacts with the complexes (DRPE)NiCl₂ 1 (DRPE = R₂PCH₂CH₂PR₂; R = Et: DEPE a ; R = Cy: DCPE b ; R = Ph: DPPE c ) to form the diphosphene complexes (DRPE)Ni[η²-(PSiMe₃)₂] 5a–c . Using low temperature nmr measurements the monosubstitution products (DRPE)Ni[P(SiMe₃)₂]Cl 2a–c and the disubstitution products (DRPE)Ni[P(SiMe₃)₂]₂ 3a, 3c can be detected as intermediates. From the reaction of 1b the paramagnetic nickel(I) complex (DCPE)NiP(SiMe₃)₂ 4b can be isolated. Reacting 1a, 1b with LiP(SiMe₃)CMe₃ the complexes (DRPE)Ni[P(SiMe₃)CMe₃]Cl 8a, 8b , which are analogous to 2 , and the nickel(0) diphosphine complex (DEPE)Ni[η¹-P(SiMe₃)CMe₃P(SiMe₃)CMe₃] 9a can be detected n.m.r. spectroscopically, but no diphosphene complexes can finally be isolated. The diphosphene complexes (DRPE)Ni[η²(PPh)₂] 10a-c are available from reactions of PhP(SiMe₃)₂with l a - c. MeP(SiMe,), reacts only with 1b to give a diphosphene complex (DCPE)Ni[η²(PMe)₂] 11 b. Reacting [P(SiMe₃)CMe₃]₂ with 1a-c the diphosphene complexes (DRPE)Ni[η²(PCMe₃)₂] 12a-c can be obtained. 4b crystallizes monoclinic in the space group P2Jc with a = 1228.6 pm, b = 2387.1 pm, c = 2621.8 pm, β = 92.16°, and Z = 8 formula units. The nickel atom is nearly planar coordinated by three phosphorus- atoms, the phosphorus atom of the terminal P(SiMe₃)₂ group is pyramidally coordinated. The Ni? P bond distances of the two four-coordinated phosphorus atoms are with 219.2 pm and 220.2 pm only slightly shorter than the corresponding distance of the P-atom of the P(SiMe₃)₂ group with 223.5 pm. N.m.r. and mass spectral data are reported.     

Eine neue Methode zur Darstellung von Silaheterocyclen durch Cycloaddition im System Heterobutadien/HSiCl3/NR3

A New Method for the Generation of Silaheterocycles via [4 + 1]-Cycloaddition Reaction in the System Heterobutadiene/HSiCl₃/NR₃ The reaction of trichlorosilane with tert. amines provides the anion SiCl₃^– (Benkeser type system). This system can be used as a simple accessible SiCl₂ synthon in certain cases. Thus [4 + 1]-cycloadditions of diazabutadienes in the system HSiCl₃/NR₃ lead to silacyclopentene derivatives. The reaction of 1,3-diaza-1,3-dienes with equimolar amounts of DBU and HSiCl₃ in THF gives the 1,4-diazasila-cyclopentene (CF₃)₂C–N=C(Ph)–N(^tBu)–SiCl₂ ( 2 a ) derivative only in one case [6], whereas in other cases hydrosilylation products are obtained. In (CF₃)₂CH–N=C(Ph)–N(^tBu)–SiCl₂F ( 3 a ), which is obtained from ( 2 a ) with wet toluene, the amidinate is bidentate and thus coordinating in a chelating fashion to the five-coordinate silicon atom. 1,4-diaza-1,3-dienes (DAD) give the [4 + 1]-cycloaddition products in all cases. Product distribution and yield are strongly influenced by the substituents, the nature of the solvent and the reaction conditions. All compounds have been characterized by NMR and mass spectroscopy. In five cases, the results of crystal structure determinations by X- ray diffraction are reported.     

Darstellung und Kristallstrukturen von Silber(I)-Gemischtligandkomplexen mit Bibenzimidazol und Triphenylphosphan: [Ag(PPh3)2(bbimH2)](COOCH3) · 2 CH2Cl2 und [{Ag(PPh3)2}2(μ-bbim)] · 4 CH2Cl2

Preparation and Crystal Structures of Silver(I) Mixed Ligand Complexes with Bibenzimidazole and Triphenylphosphane: [Ag(PPh₃)₂(bbimH₂)](COOCH₃) · 2 CH₂Cl₂ and [{Ag(PPh₃)₂}₂(μ-bbim)] · 4 CH₂Cl₂ The title compounds are obtained from silver acetate, 2,2′-bibenzimidazole and PPh₃. They are characterized by their IR, ¹H-NMR, ³¹P-NMR spectra and crystal structure determinations. [Ag(PPh₃)₂(bbimH₂)](COOCH₃) · 2 CH₂Cl₂: Reaction in CH₂Cl₂. Space group C2/c, Z = 4, 3129 observed unique reflections, R = 0.033. Lattice parameters at 203 K: a = 1450.8; b = 1556.2; c = 2316.4 pm; β = 99.69°. The crystal structure is built up by monomeric molecules with distorted tetrahedral coordination of the silver atom (AgP₂N₂) and bibenzimidazole as a bidentate ligand. The acetate ion is linked to the NH-groups of the bibenzimidazole by hydrogen bonds. [{Ag(PPh₃)₂}₂(μ-bbim)] · 4 CH₂Cl₂: Reaction in fused PPh₃ at 180 °C. Space group P 1, Z = 1. 9227 observed unique reflections, R = 0.051. Lattice parameters at 203 K: a = 1276.5; b = 1352.1; c = 1408.1 pm; α = 96.97; β = 115.87; γ = 96.84°. The crystal structure is built up by centrosymmetric molecules with distorted tetrahedral coordination of the silver atoms (AgN₂P₂) and bibenzimidazolate(2–) as tetradentate bridging ligand.     

Die Kristallstrukturen einer Serie von Verbindungen mit Kationen des Typs [R3PNH2]+, [R3PN(H)SiMe3]+ und [R3PN(SiMe3)2]+

Crystal Structures of a Series of Compounds with Cations of the Type [R₃PNH₂]⁺, [R₃PN(H)SiMe₃]⁺, and [R₃PN(SiMe₃)₂]⁺ The crystal structures of a series of compounds with cations of the type [R₃PNH₂]⁺, [R₃PN(H)SiMe₃]⁺, and [R₃PN(SiMe₃)₂]⁺, in which R represents various organic residues, are determined by means of X‐ray structure analyses at single crystals. The disilylated compounds [Me₃PN(SiMe₃)₂]⁺I^–, [Et₃PN(SiMe₃)₂]⁺I^–, and [Ph₃PN(SiMe₃)₂]⁺I₃^– are prepared from the corresponding silylated phosphaneimines R₃PNSiMe₃ with Me₃SiI. [Me₃PNH₂]Cl (1): Space group P2₁/n, Z = 4, lattice dimensions at –71 °C: a = 686.6(1), b = 938.8(1), c = 1124.3(1) pm; β = 103.31(1)°; R = 0.0239. [Et₃PNH₂]Cl (2): Space group Pbca, Z = 8, lattice dimensions at –50 °C: a = 1272.0(2), b = 1147.2(2), c = 1302.0(3) pm; R = 0.0419. [Et₃PNH₂]I (3): Space group P2₁2₁2₁, Z = 4, lattice dimensions at –50 °C: a = 712.1(1), b = 1233.3(2), c = 1257.1(2) pm; R = 0.0576. [Et₃PNH₂]₂[B₁₀H₁₀] (4): Space group P2₁/n, Z = 4, lattice dimensions at –50 °C: a = 809.3(1), b = 1703.6(1), c = 1800.1(1) pm; β = 96.34(1)°; R = 0.0533. [Ph₃PNH₂]ICl₂ (5): Space group P1, Z = 2, lattice dimensions at –60 °C: a = 825.3(3), b = 1086.4(3), c = 1241.2(4) pm; α = 114.12(2)°, β = 104.50(2)°, γ = 93.21(2)°; R = 0.0644. In the compounds 1–5 the cations are connected with their anions via hydrogen bonds of the NH₂ groups with 1–3 forming zigzag chains. [Me₃PN(H)SiMe₃][O₃S–CF₃] (6): Space group P2₁/c, Z = 8, lattice dimensions at –83 °C: a = 1777.1(1), b = 1173.6(1), c = 1611.4(1) pm; β = 115.389(6)°; R = 0.0332. [Et₃PN(H)SiMe₃]I (7): Space group P2₁/n, Z = 4, lattice dimensions at –70 °C: a = 1360.2(1), b = 874.2(1), c = 1462.1(1) pm; β = 115.19(1)°; R = 0.066. In 6 and 7 the cations form ion pairs with their anions via NH … X hydrogen bonds. [Me₃PN(SiMe₃)₂]I (8): Space group P2₁/c, Z = 8, lattice dimensions at –60 °C: a = 1925.4(9), b = 1269.1(1), c = 1507.3(4); β = 111.79(3)°; R = 0.0581. [Et₃PN(SiMe₃)₂]I (9): Space group Pbcn, Z = 8, lattice dimensions at –50 °C: a = 2554.0(2), b = 1322.3(1), c = 1165.3(2) pm; R = 0.037. [Ph₃PN(SiMe₃)₂]I₃ (10): Space group P2₁, Z = 2, lattice dimensions at –50 °C: a = 947.7(1), b = 1047.6(1), c = 1601.6(4) pm; β = 105.96(1)°; R = 0.0334. 8 to 10 are built up from separated ions.     

Synthesis and characterization of aluminum(III) and tin(II) complexes supported by diiminophosphinate ligands and their application in ring‐opening polymerization catalysis of ε‐caprolactone

A series of Al(III) and Sn(II) diiminophosphinate complexes have been synthesized. Reaction of Ph(ArCH₂)P(?NBu^t)NHBu^t (Ar = Ph, 3 ; Ar = 8‐quinolyl, 4 ) with AlR₃ (R = Me, Et) gave aluminum complexes [R₂Al{(NBu^t)₂P(Ph)(CH₂Ar)}] (R = Me, Ar = Ph, 5 ; R = Me, Ar = 8‐quinolyl, 6 ; R = Et, Ar = Ph, 7 ; R = Et, Ar = quinolyl, 8 ). Lithiated 3 and 4 were treated with SnCl₂ to afford tin(II) complexes [ClSn{(NBu^t)₂P(Ph)(CH₂Ar)}] (Ar = Ph, 9 ; Ar = 8‐quinolyl, 10 ). Complex 9 was converted to [(Me₃Si)₂NSn{(NBu^t)₂P(Ph)(CH₂Ph)}] ( 11 ) by treatment with LiN(SiMe₃)₂. Complex 11 was also obtained by reaction of 3 with [Sn{N(SiMe₃)₂}₂]. Complex 9 reacted with [LiOC₆H₄Bu^t‐4] to yield [4‐Bu^tC₆H₄OSn{(NBu^t)₂P(Ph)(CH₂Ph)}] ( 12 ). Compounds 3–12 were characterized by NMR spectroscopy and elemental analysis. The structures of complexes 6 , 10 , and 11 were further characterized by single crystal X‐ray diffraction techniques. The catalytic activity of complexes 5–8 , 11 , and 12 toward the ring‐opening polymerization of ε‐caprolactone (CL) was studied. In the presence of BzOH, the complexes catalyzed the ring‐opening polymerization of ε‐CL in the activity order of 5 > 7 ≈ 8 > 6 ? 11 > 12 , giving polymers with narrow molecular weight distributions. The kinetic studies showed a first‐order dependency on the monomer concentration in each case. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4621–4631, 2006     

Synthese und Struktur C,N‐difunktionalisierter Sulfinimidamide

Synthesis and Structure of C,N‐difunctionalized Sulfinimideamides Sulfurdiimides RN=S=NR ( 1 a , b ) react in diethyl ether with two equivalents of lithiummethyl to give dimeric C,N‐dilithiummethylenesulfinimideamide ether adducts {Li₂[H₂C–S(NR)₂ · Et₂O]}₂ ( 2 a , b ) ( a : R = ^tBu, b : R = SiMe₃). Metathesis of 2 b with four equivalents of Me₃SiCl, Me₃SnCl or Ph₃SnCl yields the corresponding C,N‐bis‐substituted sulfinimideamides R₃EH₂C–S[N(SiMe₃)₂]NER₃ ( 3 – 5 ) ( 3 : R = Me, E = Sn; 4 : R = Ph, E = Sn; 5 : R = Me, E = Si). The crystal structures of 2 a and 2 b were determined by X‐ray structure analysis. Both compounds form centrosymmetric cage structures consisting of two distorted face sharing cubes ( 2 a : space group P1 (No. 2); Z = 2 (4 · 0,5); 2 b : space group C2/c (No. 15), Z = 4).     

Intramolecular intermetallic interactions in bi- and tetrametallic organometallic complexes as demonstrated with cyclic voltammetry

With bis(alkynyl) titanocene ligands acting as chelating moieties for low-valent transition-metal heterobimetallic Ti(IV)---M(I) (M=Cu, Ag), complexes of the type {[Ti](CCSiMe₃)}MX ([Ti]=(η⁵-C₅H₄SiMe₃)₂Ti; X=Cl; Br; I) were prepared. On reacting such complexes with {[Ti](CCSiMe₃)₂}MX′ (X′=OClO₃) tetrametallic species of the type [{[Ti](CCSiMe₃)₂}M---X---M{(Me₃SiCC)₂[Ti]}]⁺ are formed. Their redox electrochemistry was studied with cyclic voltammetry (CV); for comparison, data of related bimetallic complexes were obtained. Results indicate a strong intramolecular interaction between the Group 11 metal held in place by the organometallic {[Ti](CCSiMe₃)₂} π-tweezers.     

Trialkylhydridoalanate RxR′3-xAlH⊖ [R = CMe3; R′ = CH(SiMe3)2]

Trialkylhydridoalanates R_xR′_3?xAlH^? [R = CMe₃; R′ = CH(SiMe₃)₂] The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe₃)₂]₂CMe₃ 1 and Al[CH(SiMe₃)₂](CMe₃)₂ 2 not under proton abstraction from the C? H acidic elementorganic substituent, but under β-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates — [Hal{CH(SiMe₃)₂}₂CMe₃]^? 3 and [HAl{CH(SiMe₃)₂}(CMe₃)₂]^? 4 each with Li(TMEDA)₂^⊕ as counterion — were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3 . In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.