Covalency in the f-element-chalcogen bond computational studies of [M(N(EPH2)2)3] (M = La, U, Pu; E = O, S, Se, Te)

The geometric and electronic structures of the title complexes have been studied using gradient corrected density functional theory. Excellent agreement is observed between computed r(M-E) and experimental values in analogous Pr-i complexes. Natural charge analysis indicates that the M-E bond becomes less ionic in the order O > S > S > Te, and that this decrease is largest for U and smallest for La. Natural and Mulliken overlap populations suggest increasing M-E covalency as group 16 is descended, and also in the order La < Pu < U for a given chalcogen. Increased covalency down group 16 arises from increased metal d (and s) participation in the bonding, while that from La to Pu and U stems from larger 5f orbital involvement compared with 4f. (c) 2007 Elsevier B.V. All rights reserved.