∑-Alkenyl and halogeno complexes of vanadium (I and II). The crystal structures of (C1V(CO)2(Ph2PCH2CH2PEt2)2 · benzene, Br2V(Me2PCH2CH2PMe2)2 and I2V(Me2PCH2CH2PMe2)2 · toluene
摘要:
Various sigma-alkenyl complexes of the general composition (alkenyl)V(CO6-npm (where n = 2, 3 and p(m) is a potentially m-dentate phosphine coordinated through n of its donor centres, n less-than-or-equal-to m) have been prepared by photo-induced hydrovanadation of the alkynes 2-butyne, 1-hexyne, 3-hexyne and 3,3-dimethyl-1-butyne. In each case the Z isomer is formed exclusively or as the predominant product. Reaction of hexacarbonylvanadate with pyridinium bromide and p(m) leads to the bromo complexes BrV(CO)6-npm (n = 2-4). In the case of p(m) = Me2PCH2CH2PMe2 (dmpe), the complex Br2V(dmpe) is also formed. The complex I2V(dmpe)2 . toluene was obtained as a by-product from the reaction between [Et4N][V(CO)4dmpe] and perfluoro-isopropyl iodide. The face-capped, trigonal-prismatic complex ClV(CO)2(pepe)2 . benzene (pepe = Ph2PCH2CH2PEt2) was obtained from the photo-reaction between HV(CO)4pepe and [Et4N]Cl. Single-crystal X-ray diffraction studies were carried out on all three complexes. The V-50 NMR chemical shifts for the seven-coordinate complexes XV(CO)npm have been used to arrange the ligands X in a magnetochemical series of ligand strengths (alkenyl congruent-to alkyl < SiMe3 < H congruent-to Br congruent-to I < O2CR < Cl congruent-to N3 < CN).
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.
Synthesis of hexacarbonyl derivatives of Group 5 metals and electron-transfer processes. Crystal and molecular structure of tetracarbonyl[1,2-bis(diphenylphosphino)ethane]iodotantalum