Synthesis and structure of a triply-chloro-bridged dimer of a homobinuclear Rh I complex: [{Rh 2(CO)(HC(PPh 2) 3)} 2(μ-Cl) 3] +[Rh(CO) 2Cl 2] −

Abstract

The tripod ligand HC(PPh 2) 3 reacts with Mo(CO) 3(CH 3CN) 3 yielding Mo(CO) 3(CH 3CN)(HC(PPh 2) 3). Reaction of this Mo 0 complex with [Rh(CO) 2Cl] 2 gives unexpectedly the tetranuclear species [Rh 2(CO)(HC(PPh 2) 3)] 2(μ-Cl) + 3 ( 3) which crystallizes as the Rh(CO) 2Cl − 2 salt ( 3a). This complex crystallizes in the monoclinic space group P2 1/c with Z = 4, with all dimensions a = 19.685(3), b = 19.524(3), c = 22.657(4) Å, and β = 96.96(2)°. A direct route to the PF − 6 salt of 3 (3b) is also presented. The 31P NMR data show 3a and 3b to be identical and that the tetranuclear structure is retained in solution, i.e. two units of binuclear Rh I species bridged by three chlorine atoms. In each binuclear unit, the tripod ligand spans two Rh I which are linked directly by a metal-metal bond (RhRh = 2.696 Å).