Chemistry of di- and tri-metal complexes with bridging carbene or carbyne ligands. Part 42. Synthesis of the compounds [N(PPh3)2][Fe2W(µ-CO)(µ-NO)(µ3-CR)(CO)6(η-C5H5)](R = Me or C6H4Me-4) and the X-ray crystal structure of the tolylmethylidyne complex

Abstract

The compounds [Fe2W(µ3-CR)(µ-CO)(CO)8(η-C5H5)](R = Me or C6H4Me-4) and [N(PPh3)2][NO2] react in tetrahydrofuran at room temperature to afford the salts [N(PPh3)2][Fe2W(µ-CO)(µ-NO)(µ3-CR)(CO)6(η-C5H5)]. An X-ray diffraction study was carried out on the species with R= C6H4Me-4, which crystallises with a molecule of tetrahydrofuran. The anion contains an essentially isosceles triangle of metal atoms [Fe–W 2.702(2) and 2.71 6(2), Fe–Fe 2.607(3)Å], capped by the CC6H4Me-4 group [µ3-C–Fe 1.969(13) and 2.008(10), µ3-C–W 2.055(11)Å]. Each iron atom carries three terminally bound CO molecules. The tungsten atom is bonded by the cyclopentadienyl ligand, and in addition is attached to a CO and an NO group. These carbonyl and nitrosyl groups asymmetrically bridge the two Fe–W edges of the metal triangle [W–C–0160.0(9), W–N–O 157.0(10)°]. Protonation of the salt [N (PPh3)2][Fe2W(µ-CO)(µ-NO)(µ3-CC6H4Me-4)(CO)6(η-C5H5)] with HBF4·Et2O affords thedi-irontungsten complex [Fe2W(µ-CC6H4Me-4)(µ3-NOH)(CO)7(η-C5H5)]. A structurally related species [Fe2W(µ-CC6H4Me-4)(µ3-NC6H4Me-4)(CO)7(η-C5H5)] is obtained by heating a mixture of [Fe2W(µ3-CC6H4Me-4)(µ-CO)(CO)8(µ-C5H5)] with McC6H4N3–4 in tetrahydrofuran. Spectroscopic data (i.r. and n.m.r.) for the new complexes are reported and discussed.