On the nature of actinide- and lanthanide-metal bonds in heterobimetallic compounds

Eleven experimentally characterized complexes containing heterobimetallic bonds between elements of the f-block and other elements were examined by quantum chemical methods: [(η(5)-C(5)H(5))(2)(THF)LuRu(η(5)-C(5)H(5))(CO)(2)], [(η(5)-C(5)Me(5))(2)(I)ThRu(η(5)-C(5)H(5))(CO)(2)], [(η(5)-C(5)H(5))(2)YRe(η(5)-C(5)H(5))(2)], [{N(CH(2)CH(2)NSiMe(3))(3)}URe(η(5)-C(5)H(5))(2)], [Y{Ga(NArCh)(2)}{C(PPh(2)NSiH(3))(2)}(CH(3)OCH(3))(2)], [{N(CH(2)CH(2)NSiMe(3))(3)}U{Ga(NArCH)(2)}(THF)], [(η(5)-C(5)H(5))(3)UGa(η(5)-C(5)Me(5))], [Yb(η(5)-C(5)H(5)){Si(SiMe(3))(3)(THF)(2)}], [(η(5)-C(5)H(5))(3)U(SnPh(3))], [(η(5)-C(5)H(5))(3)U(SiPh(3))], and (Ph[Me]N)(3)USi(SiMe(3))(3). Geometries in good agreement with experiment were obtained at the density functional level of theory. The multiconfigurational complete active space self-consistent field method (CASSCF) and subsequent corrections with second order perturbation theory (CASPT2) were applied to further understand the electronic structure of the lanthanide/actinide-metal (or metal-metalloid) bonds. Fragment calculations and energy-decomposition analyses were also performed and indicate that charge transfer occurs from one supported metal fragment to the other, while the bonding itself is always dominated by ionic character.