Triphenyltin(iv) adducts of diphosphoryl ligands: structural, electronic and energy aspects from X-ray crystallography and theoretical calculations

Abstract

Some triphenyltin(IV) adducts with a family of diphosphoryl ligands, RR′P(O)–X–P(O)RR′ (R = OPh, Ph, R′ = R, An (aniline)) and X = 1,4-OC₆H₄O, 1,4-OC₆H₄NH, 1,4-NHC₆H₄NH 1,4-(NHCH₂)₂C₆H₄, 1,3-(NHCH₂)₂C₆H₄ and piperazine have been synthesized and characterized by IR and NMR spectroscopy. X-Ray crystallography reveals that the structure of these complexes comprises a binuclear arrangement with two SnPh₃Cl moieties linked via the bridging P(O)–X–P(O) ligands. The influence of the ligand structures on the organization of the crystal structures and the coordination interactions are discussed. Studies of the crystal packing reveal NH⋯Cl, CH⋯Cl or CH⋯O hydrogen bonding interactions, as a function of the X or R groups, to be the main factor controlling the supramolecular architecture in this series of complexes. Based on the results from quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses, Sn–ligand interactions are found to be mainly electrostatic (donor–acceptor-like with charge transfer from the phosphoryl donors to the tin atoms). The stronger coordination bonds are found in the complexes containing Ph substituents with aliphatic spacers, in agreement with the experimental evidence. Binuclear arrangements instead of polymeric or chelating systems may be attributed to the steric demands of SnPh₃Cl, regardless of the ligand structures.