Metal-Ligand Multiple Bonding in Thorium Phosphorus and Thorium Arsenic Complexes

The complexes (C5Me5)(2)Th(EHTipp)(2), (E = P or As; Tipp = 2,4,6-triisopropylphenyl), provide a ligand framework that results in facile access to rare Th-E multiple bonds. The reaction of (C5Me5)(2)Th(EHTipp)(2) with KN(SiMe3)(2), proceeds cleanly to the desired bridging phosphinidiide or arsinidiide complex, [{(C5Me5)(2)Th(mu(2)-ETipp)(mu(2)-EHTipp)}K](2) under ambient conditions. In the absence of a chelating agent, the potassium cation of one monomeric unit interacts with the aryl ring of a second monomer to form a bridged dimer. In the presence of 2,2,2-cryptand, the terminal phosphinidene complex, [(C5Me5)(2)Th =PTipp(PHTipp)][K(2,2,2-cryptand)] is isolated. Using X-ray crystallographic analysis, we have determined these complexes display the shortest Th P and Th-As bond lengths reported.