Late transition-metal multiple bonding: Platinum phosphinidenes and ruthenium alkylidenes

Transition-metal (TM)-main-group multiply bonded complexes have been heavily studied, due to their usefulness in a variety of applications, e.g., catalysis. The large majority of multiply bonded complexes are early TM systems, but late metal complexes are becoming more common and have been shown to be potent catalysts. An investigation of ligand and substituent effects for representative late TM multiply bonded complexes with heavy (Pt-phosphinidenes) and light (Ru-alkylidenes) elements is presented. Fundamental differences in the response of the metal-ligand multiple bond are observed for light vs. heavy main-group elements for these late TM systems. The results are, in many respects, diametrically opposed to those seen for their early TM congeners.