Nickel‐Molybdenum and Nickel‐Tungsten Dithiolates: Hybrid Models for Hydrogenases and Hydrodesulfurization

The heterobimetallic complexes [(dppe)Ni(pdt)Mo(CO) 4 ], [(dcpe)Ni(pdt)Mo(CO) 4 ], [(dppe)Ni(pdt)W(CO) 4 ] and [(dcpe)Ni(pdt)W(CO) 4 ] {dppe = Ph 2 P(CH 2 ) 2 PPh 2 ; dcpe = Cy 2 P(CH 2 ) 2 PCy 2 ; pdt 2– = – S(CH 2 ) 3 S – } have been prepared and structurally characterized. The internuclear separation in these Ni II M 0 species is highly sensitive to diphosphine basicity and is smallest in the dppe complexes wherein the planar Ni centres are electron‐poor and require interaction with the group 6 metal. The Ni II W 0 species [(dppe)Ni(pdt)W(CO) 4 ] was converted into its stable conjugate acid [(dppe)Ni(pdt)HW(CO) 4 ] + , a rare example of a nickel–tungsten hydride. This Ni II HW II complex is an electrocatalyst for H + reduction and is relevant to both biological and synthetic H 2 ‐processing catalysts.