Proton- and carbonyl-mediated electron transfer processes from the hexacarbonylvanadate(−I) anion

摘要: Abstract Hexacarbonylvanadate(−I) derivatives of several heterocyclic nitrogen bases, BH+[V(CO)6]−, have been synthesized. The deep red volatile pyridinium derivative [C5H5NH]+[V(CO)6]−, was studied by X-ray diffraction methods and found to be tetragonal, space group I41/amd, with a 10.384(3), c 12.373(3) A Z = 4. Solution the structure heavy-atom method followed full-matrix least-squares refinement gave final residuals (R 0.0450 Rw 0.0442) for 180 unique observed reflections. Coordination about vanadium atom, which lies at site local 4 2m symmetry, is octahedral due two independent carbonyl groups. pyridine moiety disordered. major feature molecular interaction proton oxygens [V(CO)6]− in equatorial plane octahedron. structural features are regarded as evidence favour carbyne-type C6HO6V precursor V(CO)6 (C6HO6V → 1/2 H2 + V(CO)6). Several substitution redox processes involving protonated base observed, namely: (a) exchange; (b) dihydrogen evolution upon treatment sodium metal; (c) electron-transfer from nitrogen-bonded proton, evolution; (d) cation carbon-carbon coupling case acridinium derivative. All compounds reported deeply coloured (the quinolinium black), suggesting existence multicentre CO-mediated charge transfer base.