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

The complexes (C 5 Me 5 ) 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 (C 5 Me 5 ) 2 Th(EHTipp) 2 with KN(SiMe 3 ) 2 , proceeds cleanly to the desired bridging phosphinidiide or arsinidiide complex, [{(C 5 Me 5 ) 2 Th(μ 2 ‐ETipp)(μ 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, [(C 5 Me 5 ) 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.