Ga2Br2R2 und Ga3I2R3 [R = C(SiMe3)3] — zwei neue elementorganische Galliumsubhalogenide mit einer bzw. zwei Ga‐Ga‐Bindungen

Ga₂Br₂R₂ and Ga₃I₂R₃ [R = C(SiMe₃)₃] — Two New Organoelement Subhalides of Gallium Containing One or Two Ga‐Ga Single Bonds The oxidation of the tetrahedral tetragallium cluster Ga₄[C(SiMe₃)₃]₄ ( 1 ) with elemental bromine in the presence of AlBr₃ yielded the corresponding gallium subhalide Ga₂Br₂R₂ [ 4 , R = C(SiMe₃)₃], which remains monomer even in the solid state and in which the Ga^II atoms are connected by a short Ga‐Ga single bond [243.2(2) pm]. The analogous diiodide Ga₂I₂R₂ ( 3 ), which was obtained on a similar route by our group only recently, did not react with lithium tert‐butanolate by substitution as originally expected. Instead, partial disproportionation occurred with the formation of the trigallium diiodide Ga₃I₂R₃ ( 6 ), in which three Ga atoms are connected by two Ga‐Ga single bonds (255.1 pm on average). Both terminal Ga atoms have a coordination number of four owing to the bridging function of both iodine atoms, while the inner one which has an oxidation number of +1 remains coordinatively unsaturated. An average oxidation state of 1.66 resulted for all atoms of the chain. The Ga^III compound {[GaI(R)(OCMe₃)(OH)]Li}₂ ( 7 ) was isolated as the second product of the disproportionation. It is a dimer in the solid state via Li‐O bridges and shows a hindered rotation of its tert‐butyl group.     

1,4‐Di(isopropyl)‐1,4‐diazabutadien als Abfangreagenz für monomere Bruchstücke des Tetragalliumclusters Ga4[C(SiMe3)3]4 – Bildung eines ungesättigten GaN2C2‐Heterocyclus und eines Oxidationsprodukts mit Ga‐O‐O‐Ga‐Gruppe

1,4‐Di(isopropyl)‐1,4‐diazabutadiene as a Reagent for the Trapping of Monomeric Fragments of the Tetragalliumcluster Ga₄[C(SiMe₃)₃]₄ – Formation of an Unsaturated GaN₂C₂ Heterocycle and an Oxidation Product Containing a Ga‐O‐O‐Ga Group The tetrahedral tetragallium cluster Ga₄[C(SiMe₃)₃]₄ ( 1 ) dissociates upon dissolution to yield the monomeric fragments Ga‐R [R = C(SiMe₃)₃]. These monomers could be trapped now by the treatment of their solutions with 1,4‐di(isopropyl)‐1,4‐diazabutadiene. The product of the cycloaddition reaction ( 2 ) possesses a five‐membered GaN₂C₂ heterocycle with a coordinatively unsaturated gallium atom and an endocyclic C=C double bond. 2 is rather sensitive towards oxidation by traces of air. The contact with oxygen yielded a digallium peroxide [(C₂N₂iPr₂)RGa‐O‐O‐GaR(C₂N₂iPr₂)] ( 3 ) which was isolated in a very low yield only and which has a gallium atom attached to each oxygen atom of the inner peroxo group. Both chelating ligands of 3 possess an unpaired electron.     

New Ga/N‐based Active Lewis Pairs,Trifunctional Ga–Ga Compounds,Reactions with Cyanamide and Dual Insertion of Isocyanate

Hydrogallation of Me₃Si–C≡C–NR'₂ with R₂Ga–H (R = tBu, CH₂tBu, iBu) yielded Ga/N‐based active Lewis pairs, R₂Ga–C(SiMe₃)=C(H)–NR'₂ ( 7 ). The Ga and N atoms adopt cis‐positions at the C=C bonds and show weak Ga–N interactions. tBu₂GaH and Me₃Si–C≡C–N(C₂H₄)₂NMe afforded under exposure of daylight the trifunctional digallium(II) compound [MeN(C₂H₄)₂N](H)C=C(SiMe₃)Ga(tBu)–Ga(tBu)C(SiMe₃)=C(H)[N(C₂H₄)₂NMe] ( 8 ), which results from elimination of isobutene and H₂ and Ga–Ga bond formation. 8 was selectively obtained from the ynamine and [tBu(H)Ga–Ga(H)tBu]₂[HGatBu₂]₂. 7a (R = tBu; NR'₂ = 2,6‐Me₂NC₅H₈) and H₈C₄N–C≡N afforded the adduct tBu₂Ga‐C(SiMe₃)=C(H)(2,6‐Me₂NC₅H₈) · N≡C–NC₄H₈ ( 11 ) with the nitrile bound to gallium. The analogous ALP with harder Al atoms yielded an adduct of the nitrile dimer or oligomers of the nitrile at room temperature. The reaction of 7a with Ph–N=C=O led to the insertion of two NCO groups into the Ga–C_vinyl bond to yield a GaOCNCN heterocycle with Ga bound to O and N atoms ( 12 ).     

Reaktionen der Digalliumverbindung R2Ga–GaR2 [R = CH(SiMe3)2] mit Wasser und Carbonsäuren – Synthese von μ‐Hydroxo‐μ‐carboxylatodigallium‐Verbindungen unter Erhalt der Ga–Ga‐Bindungen

Treatment of the digallium compound R₂Ga–GaR₂ [ 1 , R = CH(SiMe₃)₂] with a broad variety of functionalized carboxylic acids in the presence of water yielded μ‐hydroxo‐μ‐carboxylatodigallium compounds ( 2 – 10 ) containing intact Ga–Ga bonds in high to moderate yields. The compounds form dimeric formula units in which the unsupported Ga–Ga bonds are bridged by two hydroxo and two carboxylato ligands. Each gallium atom is terminally coordinated by a bulky alkyl group. NMR spectroscopy revealed mixtures of two isomeric compounds in solution in all cases. The second component may show a different bridging mode with each Ga–Ga bond bridged by a bidentate carboxylato ligand to form Ga₂O₂C five‐membered heterocycles.     

Die Insertion von Sauerstoffatomen in Ga–Ga- und In–In-Bindungen – Bildung von monomeren Verbindungen R2E–O–ER2 [R = CH(SiMe3)2] mit stark aufgeweiteten E–O–E-Winkeln

The Insertion of Oxygen Atoms into Ga–Ga and In–In Bonds – Formation of the Monomeric Compounds R₂E–O–ER₂ [R = CH(SiMe₃)₂] with Strongly Enlarged Angles E–O–E The tetraalkyldielement compounds R₂Ga–GaR₂ ( 1 ) und R₂In–InR₂ ( 2 ) [R = CH(SiMe₃)₂] reacted with trimethylamine N-oxide by the insertion of oxygen atoms in their element-element single bonds. The products R₂E–O–ER₂ are monomeric in the solid state due to the high steric shielding by the voluminous bis(trimethylsilyl)methyl groups. As shown by crystal structure determinations, the E–O–E bridges have large angles of 142.7 (E = Ga, 3 ) and 138.6° (E = In, 4 ) and short separations between the oxygen and the coordinatively unsaturated Ga and In atoms. Both products are extremely hygroscopic.     

Einfluß der Ringatome auf die Struktur von Triel‐Pentel‐Heterozyklen – Synthese und Molekülstrukturen von [Me2InAs(SiMe3)2]2 und [Me2InSb(SiMe3)2]3

Influence of the Ring Atoms on the Structure of Triel‐Pentel Heterocycles – Synthesis and X‐Ray Crystal Structures of [Me₂InAs(SiMe₃)₂]₂ and [Me₂InSb(SiMe₃)₂]₃ Triel‐pentel heterocycles [Me₂InE(SiMe₃)₂]_x have been prepared by dehalosilylation reactions from Me₂InCl and E(SiMe₃)₃ (E = As, x = 2; E = Sb, x = 3) and characterised by NMR spectroscopy and by X‐ray crystal structure analyses. In addition the X‐ray crystal structures of [Me₂GaAs(SiMe₃)₂]₂ and [Me₂InP(SiMe₃)₂]₂ are reported. The compounds complete a family of 13 identically substituted heterocycles [Me₂ME(SiMe₃)₂]_x (M = Al, Ga, In; E = N, P, As, Sb, Bi; x = 2, 3), whose structures were investigated depending on the ring atoms M and E. The tendencies that have been observed concerning the ring sizes can be explained by the interplay of the atomic radii of the central atoms and the sterical demand of the ligands. After a formal separation of the M–E bonds in σ bonds and dative bonds the characteristic differences and trends in the endocyclic and exocyclic bond angles of both centres M and E can be interpreted on the basis of a simple Lewis acid/base adduct model.     

Synthese,NMR‐Spektren und Molekülstruktur von [(CH3)2Ga{μ‐P(H)Si(CH3)3}2Ga(CH3)2{μ‐P(Si(CH3)3)2}Ga(CH3)2]

Synthesis, NMR Spectra and Structure of [(CH₃)₂Ga{μ‐P(H)Si(CH₃)₃}₂Ga(CH₃)₂{μ‐P(Si(CH₃)₃)₂}Ga(CH₃)₂] The title compound has been prepared in good yield by the reaction of [Me₂GaOMe]₃ (Me = CH₃) with HP(SiMe₃)₂ in toluene (ratio 1 : 1,1) and purified by crystallization from pentane or toluene, respectively. This organogallium compound forms (Ga–P)₃ ring skeletons with one Ga–P(SiMe₃)₂–Ga and two Ga–P(H)SiMe₃–Ga bridges and crystallizes in the monoclinic space group C2/c. The known homologous Al‐compound is isotypic, both (M^III–P)₃ heterocycles have twist‐conformations, the ligands of the monophosphane bridges have trans arrangements.     

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.     

Hydrogallierungsreaktionen mit den Monoalkinen H5C6‐C≡C‐SiMe3 und H5C6‐C≡C‐CMe3 – cis/trans‐Isomerie und Substituentenaustausch

Hydrogallation Reactions Involving the Monoalkynes H₅C₆‐C≡C‐SiMe₃ and H₅C₆‐C≡C‐CMe₃ – cis/trans Isomerisation and Substituent Exchange Phenyl‐trimethylsilylethyne, H₅C₆‐C≡C‐SiMe₃, reacted with different dialkylgallium hydrides, R₂Ga‐H (R = Me, Et, nPr, iPr, tBu), by the addition of one Ga‐H bond to its C≡C triple bond (hydrogallation). The gallium atoms attacked selectively those carbon atoms, which were also attached to trimethylsilyl groups. The cis arrangement of Ga and H across the resulting C=C double bonds resulted only for the sterically most shielded di(tert‐butyl)gallium derivative, while in all other cases spontaneous cis/trans rearrangement occurred with the quantitative formation of the trans addition products. The diethyl compound Et₂Ga‐C(SiMe₃)=C(H)‐C₆H₅ ( 2 ) gave by substituent exchange the secondary products EtGa[C(SiMe₃)=C(H)‐C₆H₅]₂ ( 7 , Z,Z) and Ga[C(SiMe₃)=C(H)‐C₆H₅]₃ ( 8 ). Interestingly, compound 8 has two alkenyl groups with a Z configuration, while the third C=C double bond has the cis arrangement of Ga and H (E configuration). The reversibility of the cis/trans isomerisation of hydrogallation products was observed for the first time. tert‐Butyl‐phenylethyne gave the simple addition product, R₂Ga(C₆H₅)=C(H)‐CMe₃ ( 9 ), only with di(n‐propyl)gallium hydride.     

Umsetzungen der Dielementverbindungen R2E–ER2 [E = Ga,In; R = CH(SiMe3)2] mit Lithium‐phenylethinid – Bildung von Addukten unter Erhalt der E–E‐Bindungen

Reactions of the Dielement Compounds R₂E–ER₂ [E = Ga, In; R = CH(SiMe₃)₂] with Lithium Phenylethynide – Formation of Adducts by Retention of the E–E Bonds Lithium phenylethynide reacted with the dielement compounds tetrakis[bis(trimethylsilyl)methyl]digallane(4) ( 2 ) and diindane(4) ( 3 ) as a Lewis‐base and gave by the addition of one ethynido ligand to one of the Lewis‐acidic central atoms the anionic adducts 4 and 5 with intact Ga–Ga and In–In single bonds. Thus, compounds were formed, in which tricoordinated, coordinatively unsaturated Ga or In atoms are neighbored to tetracoordinated, coordinatively saturated ones. The E–E bonds [255.83 pm in 4 (Ga–Ga) and 285.24 pm in 5 (In–In)] are only slightly lengthened compared to those of the starting compounds 2 and 3 . A dynamic behavior with a fast change of the position of the ethynido ligand was observed for both compounds in solution at room temperature.     

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.     

Darstellung,Charakterisierung und Reaktionsverhalten von Natrium‐ und Kaliumhydridosilylamiden R2(H)Si—N(M)R′ (M = Na,K) — Kristallstruktur von [(Me3C)2(H)Si—N(K)SiMe3]2·THF

Preparation, Characterization and Reaction Behaviour of Sodium and Potassium Hydridosilylamides R₂(H)Si—N(M)R′ (M = Na, K) — Crystal Structure of [(Me₃C)₂(H)Si—N(K)SiMe₃]₂ · THF The alkali metal hydridosilylamides R₂(H)Si—N(M)R′ 1a‐Na — 1d—Na and 1a‐K — 1d‐K ( a : R = Me, R′ = CMe₃; b : R = Me, R′ = SiMe₃; c : R = Me, R′ = Si(H)Me₂; d : R = CMe₃, R′= SiMe₃) have been prepared by reaction of the corresponding hydridosilylamines 1a — 1d with alkali metal M (M = Na, K) in presence of styrene or with alkali metal hydrides MH (M = Na, K). With NaNH₂ in toluene Me₂(H)Si—NHCMe₃ ( 1a ) reacted not under metalation but under nucleophilic substitution of the H(Si) atom to give Me₂(NaNH)Si—NHCMe₃ ( 5 ). In the reaction of Me₂(H)Si—NHSiMe₃ ( 1b ) with NaNH₂ intoluene a mixture of Me₂(NaNH)Si—NHSiMe₃ and Me₂(H)Si—N(Na)SiMe₃ ( 1b‐Na ) was obtained. The hydridosilylamides have been characterized spectroscopically. The spectroscopic data of these amides and of the corresponding lithium derivatives are discussed. The ²⁹Si‐NMR‐chemical shifts and the ²⁹Si—¹H coupling constants of homologous alkali metal hydridosilylamides R₂(H)Si—N(M)R′ (M = Li, Na, K) are depending on the alkali metal. With increasing of the ionic character of the M—N bond M = K > Na > Li the ²⁹Si‐NMR‐signals are shifted upfield and the ²⁹Si—¹H coupling constants except for compounds (Me₃C)(H)Si—N(M)SiMe₃ are decreased. The reaction behaviour of the amides 1a‐Na — 1c‐Na and 1a‐K — 1c‐K was investigated toward chlorotrimethylsilane in tetrahydrofuran (THF) and in n‐pentane. In THF the amides produced just like the analogous lithium amides the corresponding N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2a — 2c ) in high yields. The reaction of the sodium amides with chlorotrimethylsilane in nonpolar solvent n‐pentane produced from 1a‐Na the cyclodisilazane [Me₂Si—NCMe₃]₂ ( 8a ), from 1b‐Na and 1‐Na mixtures of cyclodisilazane [Me₂Si—NR′]₂ ( 8b , 8c ) and N‐silylation product 2b , 2c . In contrast to 1b‐Na and 1c‐Na and to the analogous lithium amides the reaction of 1b‐K and 1c‐K with chlorotrimethylsilane afforded the N‐silylation products Me₂(H)Si—N(SiMe₃)R′ ( 2b , 2c ) in high yields. The amide [(Me₃C)₂(H)Si—N(K)SiMe₃]₂·THF ( 9 ) crystallizes in the space group C2/c with Z = 4. The central part of the molecule is a planar four‐membered K₂N₂ ring. One potassium atom is coordinated by two nitrogen atoms and the other one by two nitrogen atoms and one oxygen atom. Furthermore K···H(Si) and K···CH₃ contacts exist in 9 . The K—N distances in the K₂N₂ ring differ marginally.     

Two‐Coordinate Iron(I) Complex [Fe{N(SiMe3)2}2]−: Synthesis,Properties, and Redox Activity

First‐row two‐coordinate complexes are attracting much interest. Herein, we report the high‐yield isolation of the linear two‐coordinate iron(I) complex salt [K(L)][Fe{N(SiMe₃)₂}₂] (L=18‐crown‐6 or crypt‐222) through the reduction of either [Fe{N(SiMe₃)₂}₂] or its three‐coordinate phosphine adduct [Fe{N(SiMe₃)₂}₂(PCy₃)]. Detailed characterization is gained through X‐ray diffraction, variable‐temperature NMR spectroscopy, and magnetic susceptibility studies. One‐ and two‐electron oxidation through reaction with I₂ is further found to afford the corresponding iodo iron(II) and diiodo iron(III) complexes.     

Studien zur Reaktion von [Me2AlP(SiMe3)2]2 mit basenstabilisierten Organogalliumchloriden und ‐hydriden

Investigations on the Reactivity of [Me₂AlP(SiMe₃)₂]₂ with Base‐stabilized Organogalliumhalides and ‐hydrides [Me₂AlP(SiMe₃)₂]₂ ( 1 ) reacts with dmap?Ga(Cl)Me₂, dmap?Ga(Me)Cl₂, dmap?GaCl₃ and dmap?Ga(H)Me₂ with Al‐P bond cleavage and subsequent formation of heterocyclic [Me₂GaP(SiMe₃)₂]₂ ( 2 ) as well as dmap?AlMe_xCl_3?x (x = 3 8 ; 2 3 ; 1 4 ; 0 5 ). The reaction between equimolar amounts of dmap?Al(Me₂)P(SiMe₃)₂ and dmap?Ga(t‐Bu₂)Cl yield dmap?Ga(t‐Bu₂)P(SiMe₃)₂ ( 6 ) and dmap?AlMe₂Cl ( 3 ). 2 – 8 were characterized by NMR spectroscopy, 2 and 6 also by single crystal X‐ray diffraction.     

Synthese eines funktionalen Aluminiumalkinids,Me3C‐C≡C‐AlBr2, und dessen Reaktionen mit der sperrigen Lithiumverbindung LiCH(SiMe3)2

Synthesis of a Functional Aluminium Alkynide, Me₃C‐C≡C‐AlBr₂, and its Reactions with the Bulky Lithium Compound LiCH(SiMe₃)₂ Treatment of aluminium tribromide with the lithium alkynide (Li)C≡C‐CMe₃ afforded the aluminium alkynide Me₃C‐C≡C‐AlBr₂ ( 1 ) in an almost quantitative yield. 1 crystallizes with trimeric formula units possessing Al₃C₃ heterocycles and the anionic carbon atoms of the alkynido groups in the bridging positions. A dynamic equilibrium was determined in solution which probably comprises trimeric and dimeric formula units. Reaction of 1 with one equivalent of LiCH(SiMe₃)₂ yielded the compound [Me₃C‐C≡C‐Al(Br)‐CH(SiMe₃)₂]₂ ( 2 ), which is a dimer via Al‐C‐Al bridges. Two equivalents of the lithium compound gave a mixture of four main‐products, which could be identified as 2 , Li[Me₃C‐C≡C‐Al{CH(SiMe₃)₂}₃] ( 3 ), Me₃C‐C≡C‐Al[CH(SiMe₃)₂]₂ ( 4 ), and Al[CH(SiMe₃)₂]₃. The lithium atom of 3 is coordinated by the C≡C triple bond and an inner carbon atom of one bis(trimethylsilyl)methyl group. Further interactions were observed to C‐H bonds of methyl groups.     

Two‐Coordinate Iron(I) Complex [Fe{N(SiMe3)2}2]−: Synthesis,Properties, and Redox Activity

First‐row two‐coordinate complexes are attracting much interest. Herein, we report the high‐yield isolation of the linear two‐coordinate iron(I) complex salt [K(L)][Fe{N(SiMe₃)₂}₂] (L=18‐crown‐6 or crypt‐222) through the reduction of either [Fe{N(SiMe₃)₂}₂] or its three‐coordinate phosphine adduct [Fe{N(SiMe₃)₂}₂(PCy₃)]. Detailed characterization is gained through X‐ray diffraction, variable‐temperature NMR spectroscopy, and magnetic susceptibility studies. One‐ and two‐electron oxidation through reaction with I₂ is further found to afford the corresponding iodo iron(II) and diiodo iron(III) complexes.     

Die Reaktionen von Europium und Yttrium mit N‐Iod‐triphenylphosphanimin. Kristallstrukturen von [EuI2(DME)3], [Eu2I(NPPh3)5(DME)] und [Y2I(NPPh3)4(THF)4]+I3–

The Reactions of Europium and Yttrium with N‐Iodinetriphenylphosphoraneimine. Crystal Structures of [EuI₂(DME)₃], [Eu₂I(NPPh₃)₅(DME)] and [Y₂I(NPPh₃)₄(THF)₄]⁺I₃^– When treated with ultrasound, the reaction of europium metal with INPPh₃ in 1,2‐dimethoxyethane (DME) leads to the complexes [EuI₂(DME)₃] ( 1 ) and [Eu₂I(NPPh₃)₅(DME)] ( 2 ) which are separated from each other by fractional crystallization. On the other hand, the reaction of yttrium metal with INPPh₃ under similar conditions in THF gives the ionic phosphoraneiminato complex [Y₂I(NPPh₃)₄(THF)₄]⁺I₃^– ( 3 ). All complexes are characterized by crystal structure determinations. 1 : Space group P2₁, Z = 2, lattice dimensions at 188 K: a = 848.9(1); b = 1059.4(1); c = 1227.9(1) pm; β = 93.793(6)°; R = 0.0246. In the molecular structure of 1 the europium atom is eightfold coordinated with a bond angle I–Eu–I of 158.51°. 2 · 2 DME: Space group P1, Z = 2, lattice dimensions at 193 K: a = 1405.5(1); b = 1652.2(2); c = 2203.7(2) pm; α = 89.404(11)°; β = 72.958(11)°; γ = 78.657(11)°; R = 0.0391. In 2 the europium atoms are linked by the μ‐N‐atoms of two (NPPh₃^–) groups to form a planar Eu₂N₂ four‐membered ring. One of the Eu atoms is terminally coordinated by the N atoms of two (NPPh₃^–) groups, thus achieving a distorted tetrahedral surrounding. The second Eu atom is coordinated by the N atom of one (NPPh₃^–) group, by the terminally bounded iodine atom and by the oxygen atoms of the DME chelate, thus achieving a distorted octahedral surrounding. 3 · 6¹/₂ THF: Space group P1, Z = 2, lattice dimensions at 103 K: a = 1739.7(2); b = 1770.1(2); c = 2153.8(3) pm; α = 74.929(15)°; β = 84.223(14)°; γ = 64.612(12)°; R = 0.0638. In the cation [Y₂I(NPPh₃)₄(THF)₄]⁺ of 3 the yttrium atoms are linked by the μ‐N atoms of two (NPPh₃^–) groups as well as by the μ‐I atom. One (NPPh₃^–) ligand and two THF molecules complete the distorted octahedral coordination at each yttrium atom.     

Terminale und verbrückende Koordination von Indium‐Indium‐Bindungen – bemerkenswerte Polymorphie an der Verbindung In2R2[(OCC6H5)2CH]2 [R = C(SiMe3)3]

Terminal and Bridging Coordination of Indium‐Indium Bonds – Remarkable Polymorphism with the Compound In₂R₂[(OCC₆H₅)₂CH]₂ [R = C(SiMe₃)₃] Treatment of the dimeric indium(II) subhalide (In₂R₂Cl₂)₂ ( 1 ) [R = C(SiMe₃)₃] with four equivalents of lithium dipivaloylmethanide or lithium dibenzoylmethanide afforded by the release of lithium chloride the corresponding diindium diacetylacetonates ( 2 and 3 ). The In‐In single bonds of the products were terminally coordinated by chelating acectylacetonato ligands and the bulky alkyl groups. Three different crystal structures were determined for the dibenzoylmethanide derivative 3 which in the solid state adopted trans and gauche conformations across the In‐In bonds. In contrast to the terminally arranged acetylacetonato ligands of compounds 2 and 3 alkylbenzoato ligands R‐COO^? (3,5‐dimethylbenzoate and p‐tert‐butylbenzoate) gave the bridging coordination of the In‐In bonds by two chelating carboxylato groups ( 4 and 5 ). This particular coordination caused a strong shortening of the In‐In bond length in 4 compared to the unsupported bonds in 2 and 3 (264.6 versus 274.7 to 279.3 pm).     

Die Reaktion von Ytterbium mit N‐Iod‐triphenylphosphanimin. Kristallstrukturen von [Yb2I(THF)2(NPPh3)4] · 2 THF, [YbI2(HNPPh3)(DME)2] und [{YbI2(DME)2}2(μ‐DME)]

The Reaction of Ytterbium with N‐iodo‐triphenylphosphaneimine. Crystal Structures of [Yb₂I(THF)₂(NPPh₃)₄] · 2 THF, [YbI₂(HNPPh₃)(DME)₂], and [{YbI₂(DME)₂}₂(μ‐DME)] When treated with ultrasound, the reaction of ytterbium powder with INPPh₃ in tetrahydrofuran leads to [YbI₂(THF)₄] and to the mixed‐valence phosphoraneiminato complex [Yb₂I(THF)₂(NPPh₃)₄] · 2 THF ( 1 ), which forms red single‐crystals. In the analogous reaction in 1,2‐dimethoxyethane (DME) only the ytterbium(II) iodide solvates [YbI₂(HNPPh₃)(DME)₂] ( 2 ) and [{YbI₂(DME)₂}₂ · (μ‐DME)] ( 3 ) can be isolated, which form yellow single crystals. All compounds were characterized by crystal structure analyses. 1 : Space group P1, Z = 2, lattice dimensions at –80 °C: a = 1337.6(5), b = 1389.6(5), c = 2244.2(17) pm; α = 86.11(7)°, β = 88.06(7)°, γ = 88.63(4)°; R = 0.0759. In 1 the two ytterbium atoms are connected via the N atoms of two phosphoraneiminato groups (NPPh₃^–) to form a planar Yb₂N₂ four‐membered ring. The structure can also be described as an ion pair consisting of [YbI(THF)₂]⁺ and [Yb(NPPh₃)₄]^–. 2 : Space group P2₁, Z = 2, lattice dimensions at –80 °C: a = 811.9(1), b = 1114.0(1), c = 1741.3(1) pm; β = 95.458(5)°; R = 0.0246. 2 forms molecules in which the ytterbium atom is coordinated in a pentagonal‐bipyramidal fashion with the iodine atoms in the axial positions. The O atoms of the two DME‐chelates and the N atom of the phosphaneimine ligand HNPPh₃ are in the equatorial positions. 3 : Space group P1, Z = 2, lattice dimensions at –70 °C: a = 817.5(1), b = 1047.7(1), c = 1115.5(2) pm; α = 90.179(10)°, β = 97.543(15)°, γ = 91.087(12)°; R = 0.0317. 3 has a dimeric molecular structure, in which the two fragments {YbI₂(DME)₂} are connected centrosymmetrically via a μ‐DME bridge. As in 2 , the ytterbium atoms are coordinated in a pentagonal‐bipyramidal fashion with the iodine atoms in the axial positions, as well as with the two DME chelates and with one O atom each of the μ‐DME ligand in the equatorial positions.     

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.