Theoretical study of a series of N-(N-propyl)-N′-(para-R-benzoyl)-thioureas with trans[pt(py)2cl2] through chemistry reactivity descriptors based on density functional theory

R-empty set-C(O)-NH-C(S)-N'-HR' ligands, classified as N-alkyl-N'-(R-para)-benzoylthioureas (H2Ln), in general present a type of monodentated coordination, predominantly orientated on the thiouric sulfur atom; this makes the species in mention very regioselective toward this type of coordination. Within the electronic effects that directly generate the presented regioselectivity, there is not only the participation of the hydrogen bridge formed between the oxygen atom of the carbonyl group and the hydrogen atom of the adjacent nitrogen, that simultaneously closes a ring of six members, but also the participation of the resonance of the (O)C-NH and (S)C-N bonds, which do not allow the optimal conformation in these structures to be adopted so they can be coordinated in a bidentated form. In fact, the location of the molecular orbital responsible of this reactivity, the highest occupied molecular orbital (HOMO) is occupying its major space on the sulfur atom, with nonbonding sigma or nonbonding character, which corroborates the nucleophilic affinity of this atom. (C) 2008 Elsevier B.V. All rights reserved.