Synthesis of heterometallic butterfly carbide clusters containing three different metals: (PPN)[Fe 2CoM(dmpm)(CO) 11C] (MMo or W)

Abstract

Cluster building reactions with the phosphine-substituted ketenylidene cluster (PPN)[Fe 2Co(dmpm)(CO) 7CCO] ( 1) provide a route to four-metal carbide clusters containing three different metals. The new clusters have the general formula (PPN)[Fe 2CoM(dmpm)(CO) 11C] (MMo ( 2a), W ( 2b)) and were characterized by IR spectroscopy, variable temperature NMR spectroscopy, FAB mass spectrometry, elemental analysis and, for MW, a single crystal X-ray structure. The structure of (PPN)[Fe 2CoW(dmpm)(CO) 11C] ( 2b) consists of a ‘butterfly’ arrangement of the four metals around the carbide. The tungsten atom is located on the hinge, the cobalt atom is at one wingtip, and the dmpm ligand spans the cobalt-tungsten bond. Mechanisms for the formation of these products are discussed. Crystal data for 2b: space group P 1 , a=9.458(4), b=15.408(6), c=19.472(9) Å, α=73.73(4), β=76.52(3), γ=83.56(3)°, V=2646(3) Å 3, Z=2.