Ullrich Englert

Electron-transfer processes with substituted group 5 metal carbonyls. Synthesis, crystal and molecular structure of Ag3M3(CO)12(Me2PCH2CH2PMe2)3, M = Nb, Ta, the first structurally characterized carbonyl derivatives of niobium(0) and tantalum(0)

Some new tetracarbonyl derivatives of tantalum(I), TaI(CO)4LL (LL = tmeda, dppm, 2,2′-dipy), have been obtained by diiodine oxidation of [Ta(CO)6]− in the presence of the bidentate ligand. Dicyclopentadienylcobalt(II) does not react with the tetracarbonyl dppe derivatives of niobium(I) and tantalum(I), MI(CO)4dppe, whereas the corresponding pentamethyl substituted complex, CoCp2★, carries out the two-electron transfer to form [CoCp2★][M(CO)4dppe]. Finally, oxidation of the [M(CO)4dmpe]− anion, M = Nb, Ta, with the silver(I) salts AgNO2 and AgBF4 gave the hexanuclear mixed metal clusters Ag3M3(CO)12(dmpe)3, which were studied by X-ray diffraction methods. Crystals of Ag3Nb3(CO)12(dmpe)3 are rhombohedric, space group R3c, hexagonal setting, No. 167, a 14.323(1), c 44.772(4) A, V 7954.6 A3, Z = 6, Dcalc 1.739 g cm−3, μ(Cu-Kα) 162.93 cm−1, F(000) = 4068; R = 0.044. Crystals of the tantalum derivative are isotypic: a 14.274(5), c 44.55(3) A, V 7860.6 A3, Z = 6, Dcalc 2.095 g cm−3, μ(Mo-Kα) 78.82 cm−1, F(000) = 4644, R = 0.029. The coordination geometry around the group 5 metal may be described as a distorted square antiprism, the coordination sites being filled with the four carbonyl groups, the two silver atoms and the two phosphorous atoms of the bidentate ligand. The central core of the clusters is constituted by two almost regular interpenetrated equilateral triangles of silver and niobium (or tantalum) atoms. Both metal clusters react with dry hydrogen iodide giving silver metal and MI(CO)4(dmpe).

Synthesis and X-ray crystal structure of the first manganese(II) dialkylamido complex: {Mn3(µ-NEt2)6(µ-Cl)2[Li(THF)2]2}·(C7H16)(THF = tetrahydrofuran)

Reaction of MnCl2 with LiNEt2 in tetrahydrofuran(THF)/n-heptane afforded the pentanuclear title complex {Mn3(µ-NEt2)6(µ-Cl)2[Li(THF)]2}, whose molecular structure shows the presence of three tetrahedrally co-ordinated manganese atoms, joined by four bridging NEt2 groups [with Mn–N bond distances ranging from 2.089(4) to 2.203(4)A, the Mn ⋯ Mn distance being 2.917(1)A], and two Li(THF)2 moieties terminally bonded via diethylamido and chloride bridges.

Nitrosyl- und Nitrokomplexe des Cobalts, 1. Mitteilung Kristallstruktur von Co(acac)2(NO) und seinen Oxidationsprodukten Co(acac)2(NO2)(H2O) und Co5(acac)8(μ3-OH)2(μ-N ,O–NO2)2/ Nitrosyl and Nitro Complexes of Cobalt, Part 1 Crystal Structure of Co(acac)2(NO) and its Oxidation Products Co(acac)2(NO2)(H:O) and Co5(acac)8(μ3-OH)2Cu- N,O-NO2)2

Abstract The compound Co(acac)2(NO) (1) crystallizes in the triclinic space group P1̄ with lattice constants« - 806.4(2), b = 1095.3(7), c - 776.4(3) pm, α = 105.62(4), β = 113.18(2), γ = 75.14(3)°, Z - 2. The Co atom exhibits a square pyramidal coordination with the chelating acac ligands in the basis and the NO group at the apex, the angle Co - N - O being 120.4°. 1 is very sensitive to oxygen and, with air in aqueous acetone, yields Co(acac)2(NO2)(H2O) (2). 2 crystallizes in the monoclinic space group P21/n with lattice constants a = 704.9(9), b = 1314.2(7). c - 1451.3(7) pm. β = 97.93(2)°, Z = 4. The structure of 2 is built up by octahedral complexes with the aquo and the nitro ligand in trans positions. A CH2Cl2 solution containing 1 and Co(acac)2 reacts with O2, to form CO5(acac)8(μ-OH )2(μ - N, O -NO;)2 (3) which precipitates on cooling to - 30°C and addition of hexane. 3 crystallizes in the monoclinic space group P2/n with a = 2227(1), b = 1128.9(7), c = 2293(2) pm, β = 104.79(3)°, Z - 4. The structure consists of pentanuclear complexes with C2 symmetry. Two Cortriangles sharing one corner are each bridged by one μ3 - OH -group. The NO2 ligand functions as a N,O-bonded bridging group. The acac ligands complete the coordination of the Co-atoms to distorted octahedra.

Electron- and ligand-transfer reactions involving N,N-dialkylcarbamates. Synthesis and molecular structure of V2[η5-(C5H5)]2[O2CN(C2H5)2]4

Abstract Electron-and ligand-transfer reactions of low-valent organometallic compounds of titanium and vanadium with N,N-dialkylcarbamates of titanium(IV) are reported. The reaction of VCp2 (Cp = η5-cyclopentadienyl) with Ti(O2CNEt2)4 affords, inter alia, the dimeric vanadium(III) N ,N-diethylcarbamato derivative V2Cp2(O2CNEt2)4 which has been studied by X-ray diffraction methods. Crystal data; triclinic, space group P1̄ ; a = 10.802(2), b = 11.004(1), c = 8.960(1) Å; α = 112.879(9), β = 102.66(1), γ = 102.42(1)°; V = 902.3(6) Å3; Z = 1; F(000) = 368, ρcalc = 1.282 g cm-3; μ = 5.47 cm-1. It consists of a centrosymmetric dimer, the two vanadium atoms being surrounded by four oxygen atoms of the bridging N,N-diethylcar-bamato groups and by the cyclopentadienyl ligand. The metal atom exhibits a distorted square-pyramidal coordination geometry with the oxygen atoms occupying the basal plane. The reaction of TiCp2(CO)2 or Vmes2 (mes = η6-1,3 ,5 -Me3C6H3) with Ti(O2CNEt2)4 affords Ti(III) and V(III) N,N-diethylcarbamato derivatives by a simultaneous ligand-and electron-transfer reaction. Magnesium N ,N-diisopropylcarbamate, Mg(O2CNPri2)2, has been obtained by a ligand-transfer reaction between MgCp2 and Ti(O2CNPri2)3.