Synthesen und Reaktionen von Aluminiumalkoxid‐Verbindungen

Syntheses and Reactions of Aluminium Alkoxide Compounds Al(O^cHex)₃ ( 1 ) can be synthesized by the reaction of Al with cyclohexanol under evolving of H₂ in boiling xylene. [Li{Al(OCH₂Ph)₄}] ( 2 ) was obtained by treatment of PhCH₂OH with a 1 M solution of LiAlH₄ in THF. [{(THF)Li}₂{Al(O^tBu)₄}Cl] ( 3 ) is the result of the reaction of four equivalents of LiO^tBu on AlCl₃ in THF. 3 is the educt for the reactions with the Lewis‐acids InCl₃ and FeCl₃ in THF leading to the metalates [{(THF)₂Li}₂{Al(O^tBu)₄}] · [MCl₄] [M = In ( 4 ), Fe ( 5 )]. The attempt to react InCl₃ with four equivalents of LiO^tBu leads to only one isolated and characterized product, the complex [Li₄(O^tBu)₃(THF)₃Cl]₂ · THF ( 6 · THF), which can also be synthesized by the treatment of LiCl with three equivalents of LiO^tBu in THF. 1–6 · THF were characterized by NMR, IR and MS techniques as well as by X‐ray structure determinations. According to them, 1 , which is tetrameric in solution, is the first structurally characterized example of the proposed trimer form of aluminium alkoxides [ROAl{Al(OR)₄}₂] with a central trigonal bipyramidal coordinated Al atom. 2 forms a coordination polymer with a distorted tetrahedral coordination sphere of Li and Al, running along [100]. The trinuclear structure skeleton [{(THF)₂Li}₂{Al(O^tBu)₄}]⁺ is still present in the isotypical metalates 4 and 5 . The counter ions [MCl₄]^– possess nearly T_d symmetry. The remarkable structural motif of 6 · THF are two heterocubanes [Li₄(O^tBu)₃(THF)₃Cl] dimerized by Li–Cl bonds.     

Mesityl‐phenolato‐vanadium(III)‐Komplexe: Synthese,Struktur und Verhalten

Mesityl‐vanadium(III)‐phenolate Complexes: Synthesis, Structure, and Reactivity Protolysis reactions of [VMes₃(THF)] with ortho‐substituted phenols (2‐iso‐propyl‐(H–IPP), 2‐tert‐butyl(H–TBP), 2,4,6‐trimethylphenol (HOMes) and 2,2′biphenol (H₂–Biphen) yield the partially and fully phenolate substituted complexes [VMes(OAr)₂(THF)₂] (OAr = IPP ( 1 ), TBP ( 2 )), [VMes₂(OMes)(THF)] ( 4 ), [V(OAr)₃(THF)₂] (OAr = TBP ( 3 ), OMes ( 5 )), and [V₂(Biphen)₃(THF)₄] ( 6 ). Treatment of 6 with Li₂Biphen(Et₂O)₄ results in formation of [{Li(OEt₂)}₃V(Biphen)₃] ( 7 ) and with MesLi complexes [{Li(THF)₂}₂VMes(Biphen)₂] · THF ( 8 ) and [{Li(DME)}VMes₂(Biphen)] ( 9 ) are formed. Reacting [VCl₃(THF)₃] with LiOMes in 1 : 1 to 1 : 4 ratios yields the componds [VCl_3–n(OMes)_n(THF)₂] (n = 1 ( 5 b ), 2 ( 5 a ), 3 ( 5 )) and [{Li(DME)₂}V(OMes)₄] ( 5 c ), the latter showing thermochromism due to a complexation/decomplexation equilibrium of the solvated cation. The mixed ligand mesityl phenolate complexes [{Li(DME)_n}{VMes₂(OAr)₂}] (OAr = IPP ( 10 ), TBP ( 11 ), OMes ( 12 ) (n = 2 or 3) and [{Li(DME)₂}{VMes(OMes)₃}] ( 15 ) are obtained by reaction of 1 , 2 , 5 a and 5 with MesLi. With [{Li(DME)₂(THF)}{VMes₃(IPP)}] ( 13 ) a ligand exchange product of 10 was isolated. Addition of LiOMes to [VMes₃(THF)] forming [Li(THF)₄][VMes₃(OMes)] ( 14 ) completes the series of [Li(solv.)_x][VMes_4–n(OMes)_n] (n = 1 to 4) complexes which have been oxidised to their corresponding neutral [VMes_4–n(OMes)_n] derivatives 16 to 19 by reaction with p‐chloranile. They were investigated by epr spectroscopy. The molecular structures of 1 , 3 , 5 , 5 a , 5 a – Br , 7 , 10 and 13 have been determined by X‐ray analysis. In 1 (monoclinic, C2/c, a = 29.566(3) Å, b = 14.562(2) Å, c = 15.313(1) Å, β = 100.21(1)°, Z = 8), 3 (orthorhombic, Pbcn, a = 28.119(5) Å, b = 14.549(3) Å, c = 17.784(4) Å, β = 90.00°, Z = 8), ( 5 ) (triclinic, P1, a = 8.868(1) Å, b = 14.520(3) Å, c = 14.664(3) Å, α = 111.44(1)°, β = 96.33(1)°, γ = 102.86(1)°, Z = 2), 5 a (monoclinic, P2₁/c, a = 20.451(2) Å, b = 8.198(1) Å, c = 15.790(2) Å, β = 103.38(1)°, Z = 4) and 5 a – Br (monoclinic, P2₁/c, a = 21.264(3) Å, b = 8.242(4) Å, c = 15.950(2) Å, β = 109.14(1)°, Z = 4) the vanadium atoms are coordinated trigonal bipyramidal with the THF molecules in the axial positions. The central atom in 7 (trigonal, P3c1, a = 20.500(3) Å, b = 20.500(3) Å, c = 18.658(4) Å, Z = 6) has an octahedral environment. The three Li(OEt₂)⁺ fragments are bound bridging the biphenolate ligands. The structures of 10 (monoclinic, P2₁/c, a = 16.894(3) Å, b = 12.181(2) Å, c = 25.180(3) Å, β = 91.52(1)°, Z = 4) and 13 (orthorhombic, Pna2₁, a = 16.152(4) Å, b = 17.293(6) Å, c = 16.530(7) Å, Z = 4) are characterised by separated ions with tetrahedrally coordinated vanadate(III) anions and the lithium cations being the centres of octahedral and trigonal bipyramidal solvent environments, respectively.     

Synthesis and Chloride Affinity of Sterically Demanding Ditopic Lithium Bis(pyrazol‐1‐yl)borates

The synthesis and full characterization of the sterically demanding ditopic lithium bis(pyrazol‐1‐yl)borates Li₂[p‐C₆H₄(B(Ph)pz^R₂)₂] is reported (pz^R = 3‐phenylpyrazol‐1‐yl ( 3 ^Ph), 3‐t‐butylpyrazol‐1‐yl ( 3 ^tBu)). Compound 3 ^Ph crystallizes from THF as THF‐adduct 3 ^Ph(THF)₄ which features a straight conformation with a long Li···Li distance of 12.68(1) Å. Compound 3 ^tBu was found to function as efficient and selective scavenger of chloride ions. In the presence of LiCl it forms anionic complexes [ 3 ^tBuCl]⁻ with a central Li‐Cl‐Li core (Li···Li = 3.75(1) Å).     

Electroneutral coordination frameworks based on octahedral [Re<Subscript>6</Subscript>(μ<Subscript>3</Subscript>-Q)<Subscript>8</Subscript>(CN)<Subscript>6</Subscript>]<Superscript>4−</Superscript> complexes (Q = S,Se, Te) and the Mn<Superscript>2+</Superscript> cations

The novel coordination polymers, [{Mn(DMF)₃}₂{Re₆S₈(CN)₆}] (I), [{Mn(DMF)₂(H₂O)}₂{Re₆S₈(CN)₆}] · 2DMF (II), [{Mn(DMF)₃}₂{Re₆Se₈(CN)₆}] (III), [{Mn(DMF)₂(H₂O)}₂{Re₆Se₈(CN)₆}] · 2DMF (IV), and [{Mn(DMF)₂(H₂O)}₂{Re₆Te₈(CN)₆}] · 2DMF (V), were synthesized by interaction of the octahedral cluster complexes [Re₆(μ₃-Q)₈(CN)₆]^4? (Q = S, Se, Te) with the Mn²⁺ cations in the H₂O-DMF mixture. The crystal structures of compounds I, II, IV, and V were determined by X-ray diffraction analysis. The structural analogies between mononuclear cyanometallates and the obtained cluster coordination polymers were discussed.     

Metallat‐Ionen [Al(OR)4]— als Chelatliganden für Übergangsmetall‐Kationen

Metalat Ions [Al(OR)₄]^— as Chelating Ligands for Transition Metal Cations Waterfree CoCl₂ can be reacted with [{Li(Diglyme)}{Al(O^tBu)₄}] in THF to the complex [Li(THF)₄][{CoCl₂}{Al(O^tBu)₄}]. Addition of diglyme to the reaction mixtures gives the blue compound [Li(diglyme)₂][{CoCl₂}{Al(O^tBu)₄}] ( 1 ). According to this procedure the Fe^II complex [Li(Diglyme)₂][{FeCl₂}₂{Al(O^tBu)₄}] ( 2 ) was formed by treatment of FeCl₂ with Li[Al(O^tBu)₄]. [{Li(diglyme)}{Al(O^tBu)₄}] in THF/diglyme can be used as alkoxide transfer reagent on TiCl₄ to give the neutral complex [TiCl₂(O^tBu)₂(diglyme)] ( 3 ). The sky‐blue salt [Li(THF)₄]₂[{CoCl₂}₃{Al(OCH₂Ph)₄}₂] ( 4 ) was obtained by reaction of Li[Al(OCH₂Ph)₄] with CoCl₂ in THF. By treatment of 4 with diglyme ligand redistribution was observed giving the sky‐blue compound [Li(Diglyme)₂]₂[{CoCl₂}₃{Al(OCH₂Ph)₄}₂] ( 5 ) and the violet salt [Li(Diglyme)₂]₂[Co₂Cl₅(OCH₂Ph)] ( 6 ). A similar salt can be synthesized also directly from Li[Al(O^tBu)₄] and CoCl₂ in diglyme to give [Li(Diglyme)₂]₂[Co₂Cl₅(O^tBu)] ( 7 ). 1 — 7 were characterized by IR spectroscopy, partly by mass spectrometry and X‐ray analyses. UV‐VIS spectra were recorded from 1 and 5 . According to the X‐ray analyses the M^II ions as well as the Al^III ions are coordinated distorted tedrahedrally. In 1 , 2 , 4 und 5 the unit [Al(OR)₄]^— acts a chelating ligand as desired.     

[{(CH3)3Si}3C–Li–C{Si(CH3)3}3][Li · 3(OC4H8)] und {(CH3)3Si}3C–Li · O=C(Si(CH3)3)2, zwei neue Addukte des Lithium‐trisylmethanids

[{(CH₃)₃Si}₃C–Li–C{Si(CH₃)₃}₃][Li · 3(OC₄H₈)] and {(CH₃)₃Si}₃C–Li · O=C(Si(CH₃)₃)₂, two New Adducts of Lithium Trisylmethanide Sublimation of (Tsi–Li) · 2 THF (Tsi = –C(Si(CH₃)₃)₃) at 180 °C and 10^–4 hPa gives (Tsi–Li) · 1.5 THF in very low yield. The X‐ray structure determination shows an almost linear [Tsi–Li–Tsi]^– anion connected by short agostic Li…C contacts with the threefold THF‐coordinated Li‐cation. Base‐free Tsi–Li, solved in toluene is decomposed by oxygen, forming the strawberry‐colored ketone O=C(SiMe₃)₂, which forms an 1 : 1 adduct with undecomposed Tsi–Li. The X‐ray structure elucidation of this compound is also discussed.     

Gemischte Sandwichkomplexe der 4 f‐Elemente: Enantiomerenreine Cyclooctatetraenyl‐Cyclopentadienyl‐Komplexe des Samariums und Lutetiums mit donorfunktionalisierten Cyclopentadienylliganden

Organometallic Compounds of the Lanthanides. 139 Mixed Sandwich Complexes of the 4 f Elements: Enantiomerically Pure Cyclooctatetraenyl Cyclopentadienyl Complexes of Samarium and Lutetium with Donor‐Functionalized Cyclopentadienyl Ligands The reactions of [K{(S)‐C₅H₄CH₂CH(Me)OMe}], [K{(S)‐C₅H₄CH₂CH(Me)NMe₂}] and [K{(S)‐C₅H₄CH(Ph)CH₂NMe₂}] with the cyclooctatetraenyl lanthanide chlorides [(η⁸‐C₈H₈)Ln(μ‐Cl)(THF)]₂ (Ln = Sm, Lu) yield the mixed cyclooctatetraenyl cyclopentadienyl lanthanide complexes [(η⁸‐C₈H₈)Sm{(S)‐η⁵ : η¹‐C₅H₄CH₂CH(Me)OMe}] ( 1 a ), [(η⁸‐C₈H₈)Ln{(S)‐η⁵ : η¹‐C₅H₄CH₂CH(Me)NMe₂}] (Ln = Sm ( 2 a ), Lu ( 2 b )) and [(η⁸‐C₈H₈)Ln{(S)‐η⁵ : η¹‐C₅H₄CH(Ph)CH₂NMe₂}] (Ln = Sm ( 3 a ), Lu ( 3 b )). For comparison, the achiral compounds [(η⁸‐C₈H₈)Ln{η⁵ : η¹‐C₅H₄CH₂CH₂NMe₂}] (Ln = Sm ( 4 a ), Lu ( 4 b )) are synthesized in an analogous manner. ¹H‐, ¹³C‐NMR‐, and mass spectra of all new compounds as well as the X‐ray crystal structures of 3 b and 4 b are discussed.     

Lithium‐ und Caesium‐Alkoxometallate

Lithium and Cesium Alkoxometalates The aluminium alkoxide, Al(OCH₂Ph)₃ ( 1 ), can be obtained from a direct synthesis of Al and PhCH₂OH under HgCl₂ catalysis. The formation of the metalate [{(Diglyme)Li}{Al(O^tBu)₄}] ( 2 ) from LiAlH₄ and ^tBuOH in THF under evolution of hydrogen takes place, if the reaction product is heated under reflux with additional ^tBuOH in diglyme. The nucleophilic attack of F^– ions leads during the treatment of CsF on a THF solution of Al(O^cHex)₃ after ligand redistribution to the coordination polymer [{Cs(THF)₂}{Cs(THF)}{Al(O^cHex)₄}₂]_n ([3]_n). 1 , 2 , and 3 were characterized by NMR, IR and MS techniques as well as by crystal structure analyses. According to them 1 is present as tetramer in solution and the solid state. The central structural motif of the metalate 2 is a heteronuclear and planar LiO₂Al four‐membered ring with a penta‐coordinated Li⁺ ion. In the chainlike coordination polymer [ 3 ]_n Cs⁺ ions with coordination number five and six occupy alternating positions.     

Reaktionen von tBuPLi2 mit Carbodiimiden

Reaction of ^tBuPLi₂ with Carbodiimides The reaction of bis(cyclohexyl)carbodiimide with ^tBuPLi₂ in THF at 20 °C leads to the tetranuclear Li‐complex [Li₄(THF)₂{^tBuP([^cHexN]₂C)₂}₂] ( 1 ). No addition on the carbodiimide but a silyl transfer was observed under similar conditions during the treatment of bis(trimethylsilyl)carbodiimide with ^tBuPLi₂ to give the lithium salts ^tBuP(SiMe₃)Li and [Li(THF)(Me₃SiN‐C≡N)]_n ( 2 ). 1 was characterized by NMR, IR and RE spectroscopy, mass spectrometry and X‐ray analyses. Theoretical calculations were performed for 1 . According to the structural investigations 1 consists ofa central centrosymmetrical twelve‐membered Li₂N₄C₄P₂ ring adjacent by two six‐membered LiN₂C₂P rings. The peripheric Li⁺ cations posssess coordination number (cn) 3 buildt‐up by two N atoms and a THF ligand, while the two central Li⁺ cations possess only cn 2. However, the theoretical calculations have shown no relevant bonding Li···Li or Li···P interaction.     

Synthese und Struktur gemischt‐substituierter Dialane Al2X2{Si(SiMe3)3}2 · 2 THF (X = Cl,Br)

Synthesis and Structure of two Mixed Substituted Dialanes Al₂X₂{Si(SiMe₃)₃}₂ · 2 THF (X = Cl, Br) The syntheses of tris(trimethylsilyl)silyl (hypersilyl) and halide substituted dialanes Al₂X₂{Si(SiMe₃)₃}₂ · 2 THF (X = Cl, Br) are presented. The results of the X‐ray diffraction experiments are presented and discussed in comparison to the Al^III compounds AlBr₂Si(SiMe₃)₃ · THF and AlBr₃ · OPh₂.     

The first compound with an unusual type of anion, [Li(SR)2]–: bis­(μ2‐aqua‐d2)tetra­kis(aqua‐d2)dilithium(I) bis­[bis­(tri‐tert‐butoxy­silanethiol­ato‐κ2O,S)lithate(I)] dihydrate‐d2

The title complex, [Li₂(D₂O)₆][Li(C₉H₂₇SSiO₃)₂]₂·2D₂O, is the first compound with an S—M bond (M = alkali metal) within an unusual type of lithate anion, [Li(SR)₂]⁻ {where R is Si[OC(CH₃)₃]₃}. There is a centre of symmetry located in the middle of the Li₂O₂ ring of the cation. All Li atoms are four‐coordinate, with LiO₄ (cations) and LiO₂S₂ (anions) cores. The singly charged [Li(SR)₂]⁻ anions are well separated from the doubly charged [Li₂(D₂O)₆]²⁺ cations; the distance between Li atoms from differently charged ions is greater than 5 Å. Both ion types are held within an extended network of O—D⋯O and O—D⋯S hydrogen bonds.     

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.     

Kristallstruktur des Lithium‐Trimethylsilanolats [Li7(OSiMe3)7(THF)]

The lithium silanolate LiOSiMe₃ is accessible from the reaction of Me₃SiOSiMe₃ with LiMe in tetrahydrofuran. Single crystals of [Li₇(OSiMe₃)₇(THF)] were obtained from toluene at 25 °C. The structure of [Li₇(OSiMe₃)₇(THF)] (C2/c) features a capped trigonal antiprismatic arrangement of seven Li atoms. The Li atoms in [Li₇(OSiMe₃)₇(THF)] are μ₃‐bridged by seven O atoms of the silanolate ligand.     

Kristallstrukturelle,Festkörper‐31P‐CP/MAS‐NMR,TOSS, 31P‐COSY‐NMR und mechanistische Beiträge zur Koordinationschemie des Octacarbonyldicobalts mit den Liganden Bis(diphenylphosphanyl)amin,Bis(diphenylphosphanyl)methan und 1,1,1‐Tris(diphenylphosphanyl)ethan

Chemistry of Polyfunctional Molecules. 133. X‐Ray Crystal Structural, Solid‐state ³¹P CP/MAS NMR, TOSS, ³¹P COSY NMR, and Mechanistic Contributions to the Co‐ordination Chemistry of Octacarbonyldicobalt with the Ligands Bis(diphenylphosphanyl)amine, Bis(diphenylphosphanyl)methane, and 1,1,1‐Tris(diphenylphosphanyl)ethane Co₂(CO)₈ reacts with bis(diphenylphosphanyl)amine, HN(PPh₂)₂ (Hdppa, 1 ), in two steps to afford the known compound [Co(CO)(Hdppa‐κ²P)₂][Co(CO)₄] · 2 THF ( 6 a · 2 THF). The intermediate [Co(CO)₂(Hdppa‐κ²P) · (Hdppa‐κP)][Co(CO)₄] · dioxane · n‐pentane ( 5 · dioxane · n‐pentane) was isolated for the first time and was characterized by X‐ray analysis. The cation 5 ⁺ exhibits a slightly distorted trigonal‐bipyramidal geometry. Detailed ³¹P‐NMR investigations (solid‐state CP/MAS NMR, TOSS, ³¹P‐COSY, ³¹P‐EXSY) showed that the additional tautomer [Co(CO)₂(Hdppa‐κ²P)(Ph₂P–N=P(H)Ph₂‐κP)]⁺ ( 5 ′⁺) is present in solution. The tautomer equilibrium is slow in the NMR time scale. In contrast to the solid state only tetragonal pyramidal species of 5 are found in solution. At –90 °C there is slow exchange between the three diastereomeric species 5 a ⁺– 5 c ⁺. Compound 5 forms [Co(CO) · (Hdppa‐κ²P)₂]BPh₄ · THF ( 6 b · THF) in THF with NaBPh₄ under CO‐Elimination. A X‐ray diffraction investigation shows that the cation 6 ⁺ consists of a slightly distorted trigonal‐bipyramidal co‐ordination polyeder. However, a distorted tetragonal‐pyramidal structure has been found for the cation 7 ⁺ of the related compound [Co(CO)(dppm)₂][Co(CO)₄] · 2 THF ( 7 · 2 THF; dppm = bis(diphenylphosphanyl)methane, Ph₂PCH₂PPh₂). A comparison with the known [8] trigonal‐bipyramidal stereoisomer, ascertained for 7 ⁺ of the solvent‐free 7 , is described. In solutions of 6 a · 2 THF and 7 · 2 THF ¹³C{¹H}‐ and ³¹P{¹H}‐NMR spectra indicate an exchange of all CO and organophosphane molecules between cobalt(I) cation and cobalt(–I) anion. A concerted mechanism for the exchange process is discussed. CO elimination leads to discontinuance of the cyclic mechanism by forming binuclear substitution products such as the isolated Co₂(CO)₂ · (μ‐CO)₂(μ‐dppm)₂ · 0.83 THF ( 8 · 0.83 THF), which was characterized by spectroscopy and X‐ray analysis. For the dissolved [Co(CO)₂CH₃C(CH₂PPh₂)₃][Co(CO)₄] · 0.83 n‐pentane ( 9 a · 0.83 n‐pentane) no CO and triphos exchange processes between the cation and the anion are observed. Metathesis of 9 a · 0.83 n‐pentane with NaBPh₄ yields [Co(CO)₂CH₃C(CH₂PPh₂)₃]BPh₄ ( 9 b ) which has been characterized by single‐crystal X‐ray analysis. The cation shows a small distorted tetragonal‐pyramidal structure.     

Trapping Dimethyltin Cations by Bipyridine‐N,N′‐Dioxide Ligands

N,N′‐dioxide ligands such as 2, 2′‐bipyridine‐N,N‐dioxide (BPDO‐I) and 4, 4′‐bipyridine‐N,N‐dioxide (BPDO‐II) were used to trap the hydrated dimethyltin cations under controlled hydrolysis. The use of the chelating ligand BPDO‐I leads to the isolation of the discrete monocation [Me₂Sn(BPDO‐I)(OH₂)(NO₃)]⁺[NO₃]^– ( 2 ), whereas the linear ligand BPDO‐II directs the construction of cationic polymers, [{Me₂Sn(OH₂)₂(μ‐BPDO‐II)}²⁺{NO₃^–}₂ · 2H₂O]_n ( 3· 2H₂O) and [{Me₂Sn(μ‐OH)(BPDO‐II)}₂²⁺{NO₃^–}₂ · H₂O]_n ( 4· H₂O) under different reaction conditions.     

Dilithium Hexaorganostannate(IV) Compounds

Hypercoordination of main‐group elements such as the heavier Group 14 elements (silicon, germanium, tin, and lead) usually requires strong electron‐withdrawing ligands and/or donating groups. Herein, we present the synthesis and characterization of two hexaaryltin(IV) dianions in form of their dilithium salts [Li₂(thf)₂{Sn(2‐py^Me)₆}] (py^Me=C₅H₃N‐5‐Me) ( 2 ) and [Li₂{Sn(2‐py^OtBu)₆}] (py^OtBu=C₅H₃N‐6‐OtBu) ( 3 ). Both complexes are stable in the solid state and solution under inert conditions. Theoretical investigations of compound 2 reveal a significant valence 5s‐orbital contribution of the tin atom forming six strongly polarized tin–carbon bonds.     

Synthese und Kristallstrukturen der Nitrido‐Chloro‐Molybdate [Mg(THF)4{NMoCl4(THF)}2] · 4 CH2Cl2 und [Li(12‐Krone‐4)(NMoCl4)]2 · 2 CH2Cl2

Syntheses and Crystal Structures of the Nitrido‐chloro‐molybdates [Mg(THF)₄{NMoCl₄(THF)}₂] · 4 CH₂Cl₂ and [Li(12‐Crown‐4)(NMoCl₄)]₂ · 2 CH₂Cl₂ Both the title compounds as well as [Li(12‐crown‐4)₂]⁺MoNCl₄^– were made from MoNCl₃ and the chlorides MgCl₂ and LiCl, respectively, in dichloromethane suspensions in the presence of tetrahydrofuran and 12‐crown‐4, respectively. They form orange‐red moisture‐sensitive crystals, which were characterized by their IR spectra and partly by crystal structure analyses. [Mg(THF)₄{NMoCl₄(THF)}₂] · 4 CH₂Cl₂ ( 1 ): space group C2/m, Z = 2, lattice dimensions at –50 °C: a = 1736.6(1), b = 1194.8(1), c = 1293.5(2) pm; β = 90.87(1)°; R₁ = 0.037. In 1 the magnesium ion is coordinated octahedrally by the oxygen atoms of the four THF molecules and in trans‐position by the nitrogen atoms of the two [N≡MoCl₄(THF)]^– ions. [Li(12‐crown‐4)(NMoCl₄)]₂ · 2 CH₂Cl₂ ( 2 ): space group P 1, Z = 1, lattice dimensions at –70 °C: a = 930.4(1), b = 957.9(1), c = 1264.6(1) pm; α = 68.91(1)°, β = 81.38(1)°, γ = 63.84(1)°; R₁ = 0.0643. 2 forms a centrosymmetric ion ensemble in the dimeric cation of which, i. e. [Li(12‐crown‐4)]₂²⁺, the lithium ions on the one hand are connected to the four oxygen atoms each of the crown ether molecules in a way not yet known; and in addition, each of the lithium ions enters into a intermolecular Li–O bond with neighboring crown ether molecules under formation of a Li₂O₂ four‐membered ring. The two N≡MoCl₄^– counterions are loosely coordinated to one oxygen atom each of the crown ether molecules with Mo–O distances of 320.2 pm.     

Halogenid‐Ionen als Katalysator: Metallzentrierte C–C‐Bindungsknüpfung ausgehend von Acetontril

Halide Ions as Catalyst: Metalcentered C–C Bond Formation Proceeded from Acetonitril AlMe₃ reacts at 20 ?C in acetonitrile to the complex [Me₃Al(NCMe)] ( 1 ). By addition of cesium halides (X^– = F^–, Cl^–, Br^–) a trimerisation to the heterocycle [Me₂Al{HNC(Me)}₂C(CN)] ( 2 ) has been observed. The reaction might be carried out under catalytic conditions (1–2 mol% CsX). The gallium complex [Me₂Ga{HNC(Me)}₂ · C(CN)] ( 3 ), generated under similar reaction conditions, can be converted to the silylated compound [Me₂Ga{Me₃SiNC(Me)}₂C(CN)] ( 4 ) by successive treatment with two equivalents n‐butyllithium and Me₃SiCl. 3 reacts under hydrolysis conditions (1 M hydrochloric acid) to the iminium salt [{H₂NC(Me)}₂C(CN)]Cl ( 5 ). A mixture of H₂O, Ph₂PCl and 3 in THF/toluene leads in a unusual conversion to the diphospane derivative [Ph₂P–P(O)(Me₂GaCl)] ( 6 ). 1 , 2 , 4 , 5 and 6 have been characterized by NMR, IR and MS techniques. X‐ray structure analyses were performed with 1 , 2 , 4 and 6 · 0.5 toluene. According this 1 possesses an almost linear axis AlNCC [Al1–N1–C3: 179,5(2)?; N1–C3–C4: 179,7(4)?]. 2 is an AlN₂C₃ six‐membered heterocycle with two iminium fuctions. One N–H group is responsible for a intermolecular chain‐formation through hydrogen bridges to an adjacent nitrile group along the direction [010]. The basic structural motif of the heterocycle 3 has been maintained after silylation to 4 . In 6 · 0.5 toluene an unit Me₂GaCl, originated from 3 , is coordinated to the oxygen atom of the diphosphane oxide Ph₂P–P(O)Ph₂.     

Diborylated Magnesium Anthracene as Precursor for B2H5−‐Bridged 9,10‐Dihydroanthracene

9,10‐(Bpin)₂‐anthracene ( 3 , HBpin=pinacolborane) was synthesized from 9,10‐dibromoanthracene in a stepwise lithiation/borylation sequence. The reaction of 3 with highly activated magnesium furnished the diborylated magnesium anthracene 4 , which was quenched in situ with ethereal HCl to yield cis‐9,10‐(Bpin)₂‐DHA (cis‐ 5 , DHA=9,10‐dihydroanthracene). Compound cis‐ 5 , in turn, can be reduced with Li[AlH₄] in THF to give its diborate Li₂[cis‐9,10‐(BH₃)₂‐DHA] (Li₂[cis‐ 6 ]). In the crystal lattice, the THF solvate Li₂[cis‐ 6 ] ? 3 THF establishes a dimeric structure with Li‐(μ‐H)‐B coordination modes. Hydride abstraction from Li₂[cis‐ 6 ] with Me₃SiCl yields the B?H?B‐bridged DHA Li[ 7 ]. This product can also be viewed as a unique cyclic B₂H₇^? derivative with a hydrocarbon backbone. Treatment of Li₂[cis‐ 6 ] with the stronger hydride abstracting agent Me₃SiOTf (HOTf=trifluoromethanesulfonic acid) in THF affords the THF diadduct of cis‐9,10‐(BH(OTf))₂‐DHA.     

Tellurium‐Halogen Secondary Bonding in the Crystal Structures of [Q]+[PhTeCl4]— (Q = C5NH6, 2‐Br‐C5NH5, {2‐Br‐C5NH5}{Co(NH3)4Cl2})

The reaction of diphenylditelluride with pyridine, 2‐bromopyridine or 2‐bromopyridine/tetraamminedichlorocobalt(III) chloride in 12 M hydrochloric acid afforded the tetrachlorophenyltellurate(IV) compounds [C₅NH₆][PhTeCl₄] ( 1 ), [2‐Br‐C₅NH₅] [PhTeCl₄] ( 2 ), and [{2‐Br‐C₅NH₅}{Co(NH₃)₄Cl₂}] [PhTeCl₄]₂ ( 3 ). They were all characterized structurally by single crystal X‐ray diffraction. In all structures, the arrangement about the tellurium atoms is square pyramidal. The [PhTeCl₄]^— anions in 1 and 2 form trimeric and dimeric units, respectively, through Te···Cl secondary bonding. Compound 3 shows an unusual face‐to‐face packing of the [PhTeCl₄]^—anions with hydrogen bonding to the bromopyridium cation.