Organo-f-element thermochemistry. Absolute metal-ligand bond disruption enthalpies in bis(pentamethylcyclopentadienyl)samarium hydrocarbyl, hydride, dialkylamide, alkoxide, halide, thiolate, and phosphide complexes. Implications for organolanthanide bonding and reactivity

Absolute samarium-ligand bond disruption enthalpies in the series Cp{prime}{sub 2}Sm-R/X (Cp{prime} = {eta}{sup 5}-(CH{sub 3}){sub 5}C{sub 5}) have been measured by iodinolytic and alcoholytic isoperibol titration calorimetry of Cp{prime}{sub 2}Sm/(Cp{prime}{sub 2}Sm-I){sub n}, (Cp{prime}{sub 2}Sm-O{sup t}Bu){sub 2}/Cp{prime}{sub 2}Sm-R/X ensembles in toluene. A variety of Sm-centered ligand transposition and oxidative addition/reductive elimination processes are analyzed in light of the present data. The formation of strong Sm-heteroelement bonds makes an important contribution to the driving force. Hydrocarbon functionalization via dinuclear Sm(II) {yields} Sm(III) oxidative addition processes is only expected to be exothermic in special cases.