Synthese und Charakterisierung heterobimetallischer Bis(trimethylsilyl)phosphanide von Barium und Zinn

Synthesis and Characterization of Hetero-bimetallic Bis(trimethylsilyl)phosphanides of Barium and Tin The reaction of barium bis[bis(trimethylsilyl)amide] with one equivalent of bis(trimethylsilyl)phosphane in 1,2-dimethoxyethane (dme) yields the heteroleptic dimeric (dme)barium bis(trimethylsilyl)amide bis(trimethylsilyl)phosphanide. This colorless compound crystallizes in the monoclinic space group P2₁/n with a = 1 259.1(3), b = 1 822.7(4), c = 1 516.1(3) pm, β = 110.54(3)° and Z = 4. The central moiety of the centrosymmetric molecule is the planar Ba₂P₂-cycle with Ba? P-bond lengths of 329 and 334 pm. In the presence of bis[bis(trimethylsilyl)amino]stannylene hetero-bimetallic bis(trimethylsilyl)phosphanides of tin(II) and barium are isolated. If the reaction of Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂ in the molar ratio of 1:2 with six equivalents of HP(SiMe₃)₂ is performed in toluene, barium bis{tin(II)-tris[bis(trimethylsilyl)phosphanide]} can be isolated. This compound crystallizes in the orthorhombic space group P2₁2₁2₁ with a = 1 265.1(1), b = 2 290.1(3), c = 2 731.9(3) pm and Z = 4. The anions {Sn[P(SiMe₃)₂]₃}^? bind as two-dentate ligands to the barium atom which shows the extraordinary low coordination number of four. The addition of tetrahydrofuran (thf) to the above mentioned reaction solution leads to the elimination of tris(trimethylsilyl)phosphane and the formation of thf complexes of barium bis{tin(II)-bis(trimethylsilyl)phosphanide-trimethylsilylphosphandiide}. The derivative crystallizes from toluene in the monoclinic space group P2₁/c with a = 1 301.9(2), b = 2 316.3(3), c = 3 968.7(5) pm, β = 99.29(1)° and Z = 8.     

Aufbau von Trimethylsilyl-substituierten Polyedern aus Calcium,Zinn(II) und Phosphor

Synthesis of Trimethylsilyl Substituted Polyhedra of Calcium, Tin(II), and Phosphorus The reaction of calcium-bis[bis(trimethylsilyl)amide] with bis(trimethylsilyl)phosphane in thf yields the heteroleptic, dimeric (tetrahydrofuran-O)calcium-bis(trimethylsilyl)amidebis(trimethylsilyl)phosphanide 1 (triclinic, P 1 , a = 1066,6(2), b = 1141,3(2), c = 1226,6(2)pm, α = 97,78(3)°, β = 107,47(3)°, γ = 101,12(3)°, Z = 1 dimer). The bridging phosphanide-substituent displays with Ca? P bond lengths of 292,6 and 300,5 pm a distortion of the four-membered Ca₂P₂-cycle. The reaction with another equivalent of HP(SiMe₃)₂ in thf leads to the formation of tetrakis(tetrahydrofuran-O)calcium-bis[bis(trimethylsilyl)phosphanide] 2 mit Ca? P distances of 292 pm (monoclinic, P2₁/c, a = 1626,0(3), b = 1295,3(4), c = 2039,5(5) pm, β = 102,60(2)°, Z = 4). The performance of the reaction in the presence of bis[bis(trimethylsilyl)amino]stannylene yields heterobimetallic compounds with a central polyhedron of Ca-, Sn- and P-atoms. Dependent on the Sn/Ca ratio the isolation of tris(trimethylsilyl)phosphane as well as bis[tris(tetrahydrofuran-O)calcium]-ditin(II)-tetrakis(μ₃-trimethylsilylphosphandiide) 3 with a central dicalcia-distanna-tetraphosphacubane-fragment or (thf)₂CaSn₂[μ-P(SiMe₃)₂]₂[μ₃-PSiMe₃]₂ 4 (orthorhombic, Pnma, a = 2247,7(2), b = 1868,9(1), c = 1168,0(1) pm, Z = 4), respectively, succeeds. The Ca? P distances lie at 291 pm.     

Alkyne Addition and Insertion Reactions of [(Me3Si)3Si]2Ge⋅PMe3

Silylated germylene–PMe₃ adducts exchange their phosphane moiety smoothly for an N‐heterocyclic carbene or isocyanide species to form their respective base adducts. Reaction of the silylated germylene–PMe₃ adducts with monosubstituted alkynes produce germylene adducts with the alkyne inserted into a Ge?Si bond. A computational study of this process provides evidence for the initial formation of a germirene, which rearranges to a vinylgermylene species. The thermodynamic driving force for this reaction is provided by subsequent adduct formation with PMe₃. Reaction of the PMe₃ adduct of bis[(trimethylsilyl)silyl]germylene with disubstituted alkynes leads to the formation of stable germirenes, which can be isomerized further to silagermetes.     

Niederkoordinierte Phosphorverbindungen. 60 [1]. Reaktionen von Iminomethylidenphosphanen mit Trimethylsilylphosphanen

Low-Coordinated Phosphorus Compounds. 60. Reactions of Iminomethylidenphosphanes with Trimethylsilylphosphanes The preparation of the new, monomer stable N-n-propyl-P-(2,4,6-tri-tertbutylphenyl)iminomethylidenphosphane 1 c is presented. The reactions of this compound and those of the already known iminomethylidenphosphanes 1a, b with trimethylsilylphosphanes are described. In non-polar solvents, 1,3-diphosphapropenes 4a—h respectively 1,3,4-triphospha-1-butenes 6a—d are obtained. In polar solvents, the reaction of 1b, c with phenyl-bis(trimethylsilyl) phosphane 3d results in the formation of 1,3,5-triphospha-1,4-pentadienes 7a, b and 8a, b through double addition. While tempering the new phosphacumulene 1c in solution, dimerisation occurs and yields the 1,3-diphosphetane 2c . The reaction of the 1,2-bis(trimethylsilyl)diphosphane 5b with 1c in acetonitrile produces the new 1,3,4,6-tetraphospha-1,5-hexadiene 9 . In contrast to analogous compounds with sterically less pretentious substituents at the double-bonded phosphorous, 9 shows no Cope-rearrangement.     

Heteroleptische Diorganylzink-Verbindungen mit einem Bis(trimethylsilyl)phosphanido-Substituenten

Heteroleptic Diorganylzinc Compounds with a Bis(trimethylsilyl)phosphido Substituent Dialkylzinc ZnR₂ (Me, Et, iso-Pr, nBu, tBu, CH₂SiMe₃) reacts with one equivalent of bis(trimethylsilyl)-phosphine in carbohydrates to the heteroleptic compounds RZnP(SiMe₃)₂; dependent from the steric demand of the alkyl group R the derivatives are dimeric or trimeric in solution as well as in the solid state. Monomeric bis(trimethylsilyl)phosphido-tris(trimethylsilyl)methylzinc yields from the reaction of lithium tris(trimethylsilyl)methanide and lithium bis(trimethylsilyl)phosphide with zinc(II) chloride. Bis(trimethylsilyl)phosphido-methylzinc crystallizes in the orthorhombic space group P2₁2₁2₁ with {a = 1 007.6(1); b = 1 872.3(3); c = 2 231.0(4) pm; Z = 4} as a trimeric molecule with a central cyclic Zn₃P₃ moiety in the twist-boat conformation. Bis(trimethylsilyl)phosphido-n-butylzinc, that crystallizes in the orthorombic space group Pben with {a = 1 261.7(2); b = 2 253.0(4); c = 1 798.9(2) pm; Z = 4}, shows a simular central Zn₃P₃ fragment. The sterically more demanding trimethylsilylmethyl substituent leads to the formation of a dimeric molecule of bis(trimethylsilyl)phosphido-trimethylsilylmethylzinc {monoklin, P2₁/c; a = 907.2(4); b = 2 079.8(8), c = 1 070,2(3) pm; β = 103,48(1)°; Z = 2}. Bis(trimethylsilyl)phosphido-iso-propylzinc shows in solution a temperature-dependent equilibrium of the dimeric and trimeric species; the crystalline state contains a 1:1 mixture of these two oligomers {orthorhombisch; Pbca; a = 1 859.0(3); b = 2 470.9(2); c = 3 450.7(3) pm; Z = 8}. The Zn? P bond lengths vary in a narrow range around 239 pm, the Zn? C distances were found between 196 and 203 pm.     

A Germylene Supported by Two 2-Pyrrolylphosphane Groups as Precursor to PGeP Pincer Square-Planar Group 10 Metal(II) and T-Shaped Gold(I) Complexes

An efficient synthesis of 2-di-tert-butylphosphanylmethylpyrrole (HpyrmPtBu₂), by treating 2-dimethylaminomethylpyrrole (HpyrmNMe₂) with tBu₂PH at 135 °C in the absence of any solvent, has allowed the preparation of the new PGeP germylene Ge(pyrmPtBu₂)₂ ( 1 ), by treating [GeCl₂(dioxane)] with LipyrmPtBu₂, in which the Ge atom is stabilized by intramolecular interactions with one (solid state) or both (solution) of its phosphane groups. Reactions of germylene 1 with Group 10 metal dichlorido complexes containing easily displaceable ligands have led to [MCl{κ³P,Ge,P-GeCl(pyrmPtBu₂)₂}] [M=Ni ( 2 ), Pd ( 3 ), Pt ( 4 )], which have an unflawed square-planar metal environment. Treatment of germylene 1 with [AuCl(tht)] (tht=tetrahydrothiophene) rendered [Au{κ³P,Ge,P-GeCl(pyrmPtBu₂)₂}] ( 5 ), which is a rare case of a T-shaped gold(I) complex. The hydrolysis of 5 gave the linear gold(I) derivative [Au(κP-HpyrmPtBu₂)₂]Cl ( 6 ). Complexes 2 – 5 contain a PGeP pincer chloridogermyl ligand that arises from the insertion of the Ge atom of germylene 1 into a M−Cl bond of the corresponding metal reagent. The bonding in these molecules has been studied by DFT/NBO/QTAIM calculations. These results demonstrate that the great flexibility of germylene 1 makes it a better precursor to PGeP pincer complexes than the previously known germylenes of this type.     

Kristallstrukturen und spektroskopische Eigenschaften von 2λ3‐Phospha‐1, 3‐dionaten und 1, 3‐Dionaten des Calciums ‐ ein Vergleich am Beispiel der 1, 3‐Diphenyl‐ und 1, 3‐Di(tert‐butyl)‐Derivate

Crystal Structures and Spectroscopic Properties of 2λ³‐Phospha‐1, 3‐dionates and 1, 3‐Dionates of Calcium ‐ Comparative Studies on the 1, 3‐Diphenyl and 1, 3‐Di(tert‐butyl) Derivatives A hydrogen‐metal exchange between dibenzoylphosphane and calcium carbide in tetrahydrofuran (THF) followed by addition of the ligand 1, 3, 5‐trimethyl‐1, 3, 5‐triazinane (TMTA) furnishes the binuclear complex bis[(tmta‐N, N′, N″)calcium bis(dibenzoylphosphanide)] ( 1a ) co‐crystallizing with benzene. Similarly, reaction of bis(2, 2‐dimethylpropionyl)phosphane with bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in 1, 2‐dimethoxyethane (DME) gives bis(dme‐O, O′)calcium bis[bis(2, 2‐dimethylpropionyl)phosphanide] ( 1b ) in high yield. The carbon analogues 1, 3‐diphenylpropane‐1, 3‐dione (dibenzoylmethane) or 2, 2, 6, 6‐tetramethylheptane‐3, 5‐dione (dipivaloylmethane) and bis(thf‐O)calcium bis[tris(trimethylsilylmethyl)zincate] in DME afford bis(dme‐O, O′)calcium bis(dibenzoylmethanide) ( 2a ) and the binuclear complex (μ‐dme‐O, O′)bis[(dme‐O, O′)calcium bis(dipivaloylmethanide)] ( 2b ), respectively. Dialkylzinc formed during the metalation reaction shows no reactivity towards the 1, 3‐dionates 2a and 2b . Finally, from the reaction of the unsymmetrically substituted ligand 2‐(methoxycarbonyl)cyclopentanone and bis(thf‐O)calcium bis[bis(trimethylsilyl)amide] in toluene, the trinuclear complex 3 is obtained, co‐crystallizing with THF. The β‐ketoester anion bridges solely via the cyclopentanone unit.     

Bis[N-(trimethylsilyl)iminobenzoyl]phosphanide des Lithiums und Zinks – Synthese sowie NMR-spektroskopische,strukturelle und quantenchemische Untersuchungen

Acyl- and Alkylidenephosphanes. XXXV. Bis[ N -(trimethylsilyl)iminobenzoyl]phosphanides of Lithium and Zinc – Syntheses as well as NMR Spectroscopic, Structural, and Quantumchemical Studies From the reaction of bis(tetrahydrofuran)lithium bis(trimethylsilyl)phosphanide with two equivalents of benzonitrile in 1,2-dimethoxyethane, the yellow dme complex ( 2 a ) of lithium bis[N-(trimethylsilyl)iminobenzoyl]phosphanide ( 2 ) was obtained in 69% yield. However, the intermediate {1-[N-lithium-N-(trimethylsilyl)amido]benzylidene}trimethylsilylphosphane ( 1 ), formed by an analogous 1 : 1 addition in diethyl ether, turned out to be unstable and as a consequence could be characterized by nmr spectroscopic methods only; attempts to isolate the compound failed, but small amounts of the neutral complex 2 b , with the ligands benzonitrile and tetrahydrofuran coordinated to lithium, precipitated. The reaction of compound 2 with zinc(II) chloride in diethyl ether gives the orange-red spiro-complex zinc bis{bis[N-(trimethylsilyl)iminobenzoyl]phosphanide} ( 3 ); this complex is also formed from bis[N-(trimethylsilyl)iminobenzoyl]phosphane ( 4 ), easily amenable by a lithium hydrogen exchange of 2 a with trifluoroacetic acid [18], and zinc bis[bis(trimethylsilyl)amide]. As derived from nmr spectroscopic studies and x-ray structure determinations, compounds 2 a {δ³¹P +63.3 ppm; P2₁/n; Z = 4; R₁ = 0.067}, 2 b {δ³¹P +63.3 ppm; P2₁/c; Z = 4; R₁ = 0.063}, 3 {δ³¹P +58.2 ppm; C2/c; Z = 4; R₁ = 0.037} and 4 {δ³¹P +58.1 ppm [18]} exist as cyclic 3-imino-2λ³σ²-phosphapropenylamides and -propenylamine, respectively, in solution as well as in the solid state. Unlike hydrogen derivative 4 the bis[N-(trimethylsilyl)iminobenzoyl]phosphanide fragments N,N′-coordinating either a lithium or a zinc cation are characterized by almost completely equalized bond lengths; typical mean distances and angles are: PC 180.3 and 178.7; CN 130.5 and 131.8; N–Si 175.3 and 179.3; N–Li 202.3; N–Zn 203.5 pm; CPC 108.8° and 110.5°; PCN 130.9° and 132.9°; CN–Li 113.0°, CN–Zn 117.4°; N–Li–N 104.6°; N–Zn–N 108.8°. Alterations in the shape of the six membered chelate rings, caused by an exchange of the 3-imino-2λ³σ²-phosphapropenylamide or related 2λ³σ²-phospha-1,3-dionate units for the corresponding phosphorus free ligands, are discussed in detail. The results of quantumchemical DFT-B3LYP calculations coincide very well with the experimentally obtained findings.     

Trimethylsilylated allyl complexes of nickel. The stabilized bis(pi-allyl)nickel complex [eta3-1,3-(SiMe3)2C3H3]2Ni and its mono(pi-allyl)NiX (X=Br, I) derivatives

Reaction of 2 equiv of K[1,3-(SiMe3)2C3H3] with NiBr2(dme) in THF at -78 degrees C produces the orange pi-allyl complex [1,3-(SiMe3)2C3H3]2Ni (1). Unlike the pyrophoric (C3H5)2Ni, the trimethylsilylated derivative only slowly decomposes in air (from hours to days). Both eclipsed (1a) and staggered (1b) conformations are found in solution; the eclipsed form irreversibly converts to the thermodynamically more stable staggered conformation when heated above 85 degrees C. Single-crystal X-ray structures obtained for both 1a and 1b confirm that the allyl ligands are bound in a trihapto manner to the metals and that trimethylsilyl substituents are in syn, anti arrangements. Density functional theory calculations performed on the bis(allyl)nickel complexes indicate that the substituents exert little effect on the basic metal-ligand geometries. Trimethylphosphine is converted to tetramethyltetraphosphane, (MeP)4, on reaction with 1. In toluene, 3-bromo-1,3-bis(trimethylsilyl)propene reacts with (COD)2Ni to produce the dimeric purple complex {[1,3-(SiMe3)2C3H3]NiBr}2 (2a). Both NMR and X-ray crystallographic data establish that the allyl ligands are staggered and that the trimethylsilyl substituents are in a syn, syn conformation. NMR data indicate that the reaction of one equivalent of 1 with Br2 in benzene produces an analogous complex (2b) with the allyl ligand substituents in a syn, anti configuration. When 1 equiv of 1 is treated with I2 in hexanes, the dark red dimeric complex {[1,3-(SiMe3)2C3H3]NiI}2 (3) is formed. Its X-ray crystal structure demonstrates that both eclipsed (3a) and staggered (3b) allyl conformation are present. The trimethylsilyl groups on the allyl ligands are in syn, anti arrangements in the two forms.     

Synthese,spektroskopische Charakterisierung und Molekülstrukturen ausgewählter Lewis‐Basen‐Addukte der Alkalimetall‐tri(tert‐butyl)silylphosphanide

Synthesis, Spectroscopic Characterization, and Molecular Structures of Selected Lewis‐Base Adducts of the Alkali Metal Tri(tert‐butyl)silylphosphanides The metalation of tri(tert‐butyl)silylphosphane with butyllithium and the bis(trimethylsilyl)amides of sodium, potassium, and rubidium yields quantitatively the corresponding alkali metal tri(tert‐butyl)silylphosphanides, which crystallize after addition of appropriate Lewis‐bases as dimeric (DME)LiP(H)SitBu₃ ( 1 ), chain‐like (DME)NaP(H)SitBu₃ ( 2 ), monomeric ([18]Krone‐6)KP(H)SitBu₃ ( 3 ), and dimeric (TMEDA)_1.5RbP(H)SitBu₃ ( 4 ). The reaction of H₂PSitBu₃ with cesium bis(trimethylsilyl)amide at room temperature gives monocyclic and tetrameric cesium tri(tert‐butyl)silylphosphanide ( 5 ) with two additional coordinated CsN(SiMe₃)₂ molecules. At 80 °C this complex reacts with excess of phosphane to the tetrameric toluene adduct (η⁶‐Toluol)CsP(H)SitBu₃ ( 6 ) which contains a central Cs₄P₄‐heterocubane fragment. The constitution of these compounds was verified by X‐ray structure determinations.     

Metallderivate von Molekülverbindungen. VI. Lithium- und (Tetrahydrofuran)lithium-cyantrimethylsilylamid — Synthese und Struktur

Metal Derivatives of Molecular Compounds. VI. Lithium and (Tetrahydrofuran)lithium Cyanotrimethylsilylamide — Syntheses and Structures At different temperatures N,N′-bis(trimethylsilyl)carbodiimide ( 1 ) and lithium methanide react either under addition or substitution. When compound 1 , however, is treated at ?40°C with an equimolar amount of (1,2-dimethoxyethane-O,O′)lithium phosphanide ( 2 ) in 1,2-dimethoxyethane, only exchange of one trimethylsilyl group versus lithium is observed and in addition to phosphane and tris(trimethylsilyl)phosphane a very pure lithium derivative insoluble in n-pentane can be isolated. The vibrational spectra prove the compound to be lithium cyanotrimethylsilylamide ( 3 ). Recrystallization from tetrahydrofuran (+40/+20°C) yields (tetrahydrofuran)lithium cyanotrimethylsilylamide ( 3 ′). As shown by an X-ray structure analysis {C2/c; a = 2 261.1(5); b = 1 106.4(2); c = 1 045.9(2) pm; β = 113.63(1)°; Z = 8 formula units}, compound 3 ′ is polymeric in the solid state. Coordinative Li? N2′ bonds allow a head-to-tail addition of two monomeric units each to give an eight-membered heterocycle with two linear N1? C2≡N2 fragments (N1? C2 126.1; C2≡N2 117.5; N1? Si 171.4; Li? N1 203.2; Li? N2′ 206.1 pm; C2? N1? Li 109.0; N1? Li? N2′ 115.9; N2≡C2? N1 177.2°). Forming planar four-membered Li? N2? Li? N2 rings (Li? N2″″ 198.3 pm; Li′? N2? Li″ 80.3; N2′? Li? N2″″ 99.5°) these heterocycles polymerize to slightly folded tapes.     

Dimethylgallium-bis(trimethylsilyl)phosphan Schwingungsspektrum,Kraftkonstanten und Struktur

Dimethylgallium-bis(trimethylsilyl)phosphane, Vibrational Spectrum, Force Constants, and X-Ray Structure Dimeric dimethylgallium-bis(trimethylsilyl)phosphane, [Me₂Ga? P(SiMe₃)₂]₂, (Me = CH₃) is synthesized from Me₂GaCl and P(SiMe₃)₃ in hot toluene. The compound crystallizes in the triclinic space group P1 with the cell parameters a = 909.8(2), b = 960.5(2), c = 971.6(2) pm; α = 76.75(1)°, β = 80.35(1)°, γ = 63.94(1)° and Z = 1 (dimer). The Ga? P distances are 244.8 and 245.2 pm, the ring angles are 91.8° (Ga? P? Ga) and 88.2° (P? Ga? P), respectively. The vibrational spectrum (IR and Raman for the solid) has been measured and assigned; force constants calculations are carried out for the skeleton [C₂Ga? P(SiC₃)₂]₂ using Fleischhauers [26] PC-program.     

Bildung und Eigenschaften von Acylphosphanen. IX. Reaktion von Phenylbis(trimethylsilyl)phosphan mit Formaldehyd und Dimethylformamid

Syntheses and Properties of Acylphosphanes. IX. Reaction of Phenylbis(trimethylsilyl)-phosphane with Formaldehyde and Dimethylformamide Trimethylsilylphosphanes add to carbonyl compounds. Therefore phenyl-bis(tri-methylsiloxymethyl)phosphane 3 can be prepared by reacting phenylbis(trimethylsilyl)phosphane 1 with formaldehyde 2 . With dimethylformamide 4 , however, an addition-elimination-reaction yields hexamethyldisiloxane 6 and N,N-dimethylaminomethyliden-phenylphosphane 5 . NMR-spectroscopic studies show the rotation of the dimethylamino group to be hindered. The dimer 2,4-bis(N,N-dimethylamino)-l,3-diphenyl-l,3-diphosphetane 11 is isolated as a by-product.     

Reactions of palladium germylene complexes: formation of sulfide bridges

Reactivity of three novel Pd germylene species is presented. (Et(3)P)(2)PdGe[N(SiMe(3))(2)](2) (1) and (dppe)PdGe[N(SiMe(3))(2)](2) (6) react with COS to give the sulfide bridged species (Et3P)2Pd(mu S)Ge[N(SiMe3)2]2 (2) and (dppe)Pd(mu S)Ge-[N(SiMe3)2]2 (7) (dppe = (diphenylphosphino)ethane). (Ph(3)P)(2)PdGe[N(SiMe(3))(2)](2) (4) reacts with COS to give the disulfide bridged complex (Ph(3)P)(2)Pd(muS)(2)Ge[N(SiMe(3))(2)](2) (5) resulting in Pd-Ge bond cleavage. This phosphine dependent reactivity is explored. Crystal structures of 2, 5, 7, and the dimeric form of complex 2, (8), are reported. In the presence of excess germylene, complexes 2 and 5 are shown to partially regenerate their parent palladium germylene complexes, 1 and 4, respectively, via photolysis or heating.     

Amidinato Germylene‐Zinc Complexes: Synthesis,Bonding, and Reactivity

Despite the explosive growth of germylene compounds as ligands in transition metal complexes, there is a modicum of precedence for the germylene zinc complexes. In this work, the synthesis and characterization of new germylene zinc complexes [PhC(NtBu)₂Ge{N(SiMe₃)₂}→ZnX₂]₂ (X= Br ( 2 ) and I ( 3 )) supported by (benz)‐amidinato germylene ligands are reported. The solid‐state structures of 2 and 3 have been validated by single‐crystal X‐ray diffraction studies, which revealed the dimeric nature of the complexes, with distorted tetrahedral geometries around the Ge and Zn center. DFT calculations reveal that the Ge–Zn bonds in 2 and 3 are dative in nature. The reaction of 2 with elemental sulfur resulted in the first structurally characterized germathione stabilized ZnBr₂ complexes PhC(NtBu)₂Ge(=S){N(SiMe₃)₂}→ZnBr₂ ( 5 ). Therefore, the Ge=S in 5 is in‐between Ge–S single and Ge=S double bond length, owing to the coordination of a sulfur lone pair of electrons to ZnBr₂.     

A Silylene–Germylene Molecule Containing a SiI−GeI Single Bond

The first isolable silylene–germylene complex 5 was assembled by a salt metathesis reaction between the germylene anion 3 and the N-heterocyclic chlorosilylene 4 , and structurally characterized. The central structure of 5 demonstrates a remarkable gauche-bent geometry with the silylene and germylene units, which are interconnected by a Si−Ge bond with a length of 2.4498(9) Å. This value is not only perceptibly longer than the distances known in doubly bonded germasilenes, and also slightly longer than those in germylsilanes. The DFT calculations on 5 confirmed a nearly nonpolar Si^I−Ge^I single-bond nature and its bonding orbital, as well as the aromaticity of the C₃NGe-rings in 3 and 5 . The latter increases the molecular stability of 3 and 5 , and makes the preparation of silylene–germylene complex 5 a reality.     

Synthesis and structural characterization of two-coordinate low-valent 14-group metal complexes bearing bulky bis(amido)silane ligands

A series of germylene, stannylene and plumbylene complexes [η(2)(N,N)-Me(2)Si(DippN)(2)Ge:] (3a), [η(2)(N,N)-Ph(2)Si(DippN)(2)Ge:] (3b), [η(2)(N,N)-Me(2)Si(DippN)(2)Sn:] (4), [η(2)(N,N)-Me(2)Si(DippN)(2)Pb:](2) (5a), and [η(2)(N,N)-Ph(2)Si(DippN)(2)Pb:] (5b) (Dipp = 2,6-iPr(2)C(6)H(3)) bearing bulky bis(amido)silane ligands were readily prepared either by the transamination of M[N(SiMe(3))(2)](2) (M = Sn, Pb) and [Me(2)Si(DippNH)(2)] or by the metathesis reaction of bislithium bis(amido)silane [η(1)(N),η(1)(N)-R(2)Si(DippNLi)(2)] (R = Me, Ph) with the corresponding metal halides GeCl(2)(dioxane), SnCl(2), and PbCl(2), respectively. Preliminary atom-transfer chemistry involving [η(2)(N,N)-Me(2)Si(DippN)(2)Ge:] (3a) with oxygen yielded a dimeric oxo-bridged germanium complex [η(2)(N,N)-Me(2)Si(DippN)(2)Ge(μ-O)](2) (6). All complexes were characterized by (1)H, (13)C, (119)Sn NMR, IR, and elemental analysis. X-ray single crystal diffraction analysis revealed that the metal centres in 3b, 4, and 5b are sterically protected to prevent interaction between the metal centre and the nitrogen donors of adjacent molecules while complex 5a shows a dimeric feature with a strong intermolecular Pb···N interaction.     

Metallderivate von Molekülverbindungen. IV. Synthese,Struktur und Reaktivität des Lithium-[tris-(trimethylsilyl)silyl]tellanids · DME

Metal Derivatives of Molecular Compounds. IV Synthesis, Structure, and Reactivity of Lithium [Tris(trimethylsilyl)silyl]tellanide · DME Lithium tris(trimethylsilyl)silanide · 1,5 DME [3] and tellurium react in 1,2-dimethoxyethane to give colourless lithium [tris(trimethylsilyl)silyl]tellanide · DME ( 1 ). An X-ray structure determination {-150 · 3·C; P2₁/c; a = 1346.6(4); b = 1497.0(4); c = 1274.5(3) pm; β = 99.22(2)·; Z = 2 dimers; R = 0.030} shows the compound to be dimeric forming a planar Li? Te? Li? Te ring with two tris(trimethylsilyl)silyl substituents in a trans position. Three-coordinate tellurium is bound to the central silicon of the tris(trimethylsilyl)silyl group and to two lithium atoms; the two remaining sites of each four-coordinate lithium are occupied by the chelate ligand DME {Li? Te 278 and 284; Si? Te 250; Li? O 200 pm (2X); Te? Li? Te 105°; Li? Te? Li 75°; O? Li? O 84°}. The covalent radius of 154 pm as determined for the DME-complexed lithium in tellanide 1 is within the range of 155 ± 3 pm, also characteristic for similar compounds. In typical reactions of the tellanide 1 [tris(trimethylsilyl)silyl]tellane ( 2 ), methyl-[tris(trimethylsilyl)silyl]tellane ( 4 ) and bis[tris(trimethylsilyl)silyl]ditellane ( 5 ) are formed.     

Synthesis and characterization of rhodium complexes with phosphine-stabilized germylenes

The reaction of phosphine-stabilized germylenes (1a,b) with dimer complex [Rh(2)(μ-Cl)(2)(COD)(2)] leads to the corresponding phosphine-germylene-Rh(I) complexes (2a,b). Interestingly, the stability of these complexes depends strongly on the nature of the substituent of the germylene fragment. Indeed, the complex (2a) with the chloro-germylene ligand isomerizes into a metallacycle rhodium complex (3a) via germylene insertion into the Rh-Cl bond, while the complex with the phenyl-substituted germylene (2b) was isolated and represents the first stable Rh(I)-germylene complex with a Rh-Cl bond.     

Niederkoordinierte Phosphorverbindungen. 58. Synthese und Reaktivität der 2, 4, 6-Tri-tert-butylphenyl (halogenmethylen)phosphane

The synthesis of the 2,4,6-tri-tert-butylphenyl(halogenmethylene)phosphanes 4a—d from the tri-tert-butylphenylphosphane 1 and trihalogenomethanes 2a—d is described. Tri-tert-butylphenyl(difluoromethylene)phosphane 8a and the analogous (diiodomethylene)-phosphane 8d are obtained by dehalogenation of the chloro(trifluoromethyl)phosphane 7 and dehydrohalogenation of the triiodomethylphosphane 10 . The first different halogeno-substituted (bromochloromethylene)phosphane 8e leads after metallation with lithiumbis (trimethylsilyl)phosphide 13 and elimination of lithiumchloride to the phosphaalkyne 16 . Direct addition of chlorotrimethylsilane to the metallated 8e yields the 2,4,6-tri-tert-butylphenyl(chloro(trimethylsilyl)-methylene)phosphane 17 .