Pentacyanopropenide group as ligand in organometallic chemistry. Crystal structure and electrochemical studies of (Et4N)[W(CO)(5){(C(CN)(2)C(CN)C(CN)(2)}]

The title complex has been obtained by reaction of the tetraethylammonium p entacyanopropenide with tungsten hexacarbonyl in acetone. Its crystal struc ture involves discrete [W(CO)(5){C-3(CN)(5)}](-) anions in which the organi c fragment is N-coordinated via one of the nitrogen atoms of a cyano group borne by one of the terminal carbon atoms of the allylic skeleton. The anio n presents a distorted octahedral coordination with a W-N bond length [2.16 8(5) Angstrom] considerably longer than the W-C bond lengths [cis-W-C in th e range 1998(7)-2.068(4) Angstrom; trans-W-C 1.962(7) Angstrom]. Cyclic vol tammograms of this complex, recorded in CH2Cl2 and CH3CN (Bu4NPF6 0.1 M), d isplay a quasi-reversible reduction and irreversible oxidation waves. (C) 1 999 Elsevier Science Ltd. All rights reserved.