A TRICARBONYL, TETRANUCLEAR TUNGSTEN CLUSTER SUPPORTED BY ALKOXIDE LIGANDS - W4(OCH2PRI)12(ETA-2,MU-4-CO)(CO)2

Hydrocarbon solutions of W4(OCH2Pri)12 react with carbon monoxide (3-6 equiv.) to give a green, air and moisture sensitive compound W4(CO)3(OCH2Pri)12, which has been characterized by infrared and NMR spectroscopy in solution and by a single crystal X-ray analysis in the solid state. The latter revealed a "spiked triangle" of tungsten atoms with WW bonding distances ranging from 2.658(2) Å to 2.806(3) Å, all supported by bridging alkoxides. Two carbonyl ligands are cis to one another on a tungsten atom contained in the basal W3 triangle. The η2,μ4-CO ligand is C bonded to each of the three tungsten atoms in the basal triangle and O bonded to the "spiked" W atom. The η2,μ4-CO ligand contains a highly reduced carbon monoxide moiety that may be viewed as a μ3-oxyalkylidyne ligand and provides a model for partial reduction of CO on a metal surface in the steps preceding reductive cleavage to carbide and oxide. The solution NMR data are consistent with expectations based on the solid-state structure. Crystal data for W4(CO)3(OCH2Pri)12 at -141°C: a 13.361(5) Å, b 22.703(11) Å, c 11.627(5) Å, α 94.46(3)°, β 107.30(2)°, γ 102.79(3)°, Z = 2, dcalcd 1.737 g cm-3, space group P1. © 1990.