Thomas Greiser

Über metallalkyl- und -arylverbindungen : XXV. Die kristallstruktur von dimethyl(N,N,N′,N′-tetramethylethylendiamin)magnesium

Abstract Dimethyl(N,N,N′,N′-tetramethylethylenediamine)magnesium is prepared from Me2Mg and N,N,N′,N′-tetramethylethylenediamine (TMEDA), it has been investigated by X-ray diffraction methods (orthorhombic space group Cmca, Z = 8, 879 reflections, R = 0.076). Similarly to Ph2Mg · TMEDA the Mg atom is fourfold coordinated by two methyl groups and the chelate ligand. MgC and MgN distances are very similar in both compounds. Compared to polymeric Me2Mg and Et2Mg the MgC distances in Me2Mg · TMEDA are significantly shorter.

Darstellung und eigenschaften von acetonyl-, phenacyl- und acetomethoxy-mangancarbonyl verbindungen. Die kristallstruktur von acetonyltetracarbonyltriphenylphosphinmangan

Abstract Several oxoalkylpentacarbonylmanganese compounds RC(O)CH 2 Mn(CO) 5 (R = Me, Ph, MeO) have been synthesized and investigated (IR, 1 H NMR, mass spectra). They are thermo- and photo-labile and can be stabilized by triphenylphosphine substitution. Thus acetonyltetracarbonyltriphenylphosphine-manganese is formed by treatment of Na[Mn(CO) 4 P(C 6 H 5 ) 3 ] with chloro-acetone. Its structure has been determined by X-ray analysis (space group P 2 1 / n , Z = 4) and refined to R = 0.036. The manganese atom is octahedrally coordinated, the acetonyl group and the triphenylphosphine ligand are in cis position. Significant deviations in the oxoalkyl ligand (e.g. shortening of the C α C β bond distance) are explained by electronic interaction between d -electrons of Mn and an empty π ★ orbital of the oxoalkyl carbonyl group. This appears to be generally valid for compounds of that type and may explain facts called the “β-effect”. The crystal data of phenacylpentacarbonylmanganese are also given.

The molecular structure of tetracarbonylhydrido(1,1,4,4-tetraphenyl-1,4-diphosphabutane)vanadium(+I), HV(CO)4(Ph2PCH2CH2PPh2)

SummaryThe crystal and molecular structures of the title compound have been determined. The compound crystallizes in the orthorhombic space group Pcab witha = 1463.3(30),b = 1663.1(36),c = 2250.1(47) pm and Z = 8. The molecular structure is best described as a distorted pentagonal bipyramid, the hydride ligand lying in a plane formed by vanadium, the two phosphorus atoms and two carbon monoxide groups. The V-H bond length is 155.2(93) pm, and the distance between H− and the nearest phosphorus atom is 157.9(118) pm. In solution, HV(CO)4Ph2P(CH2)2PPh2 appears to be fluxional.