Alkylidyne[pyrazol-1-yl)borato]tungsten complexes:metal–carbon triple bonds as four-electron donors

The tungsten Complexes [W(CR)(CO)2(R′Bpz3)](R = Me or C6H4Me-4,R′H; R = C6H4Me-4,R = pz = pyrazol-1-yl) have been prepared and used to synthesise heteronuclear di-and tri-metal compounds with bridging alkylidyne ligands;the structures of the species [WCC6H4Me-4)(CO)2(Bpz4)] and [FeW(µ-CC6H4Me-4)(CO)5(HBpz3)] have been established by X-ray diffraction.