Synthesis, Characterization, Crystal Structures, Hirshfeld Surface Analysis and Theoretical Calculations of Some New Bisphosphoramidate Derivatives and Novel Binuclear Triorganotin(IV) Complexes with Diphosphoryl Ligand

Abstract

A series of new bisphosphoramidate and (thio)phosphoramidate derivatives with the general formula R<inf>1</inf>R<inf>2</inf>P(X)–Y–P(X)R<inf>1</inf>R<inf>2</inf> have been synthesized and characterized by IR and NMR spectroscopies (L<inf>1</inf>–L<inf>12</inf>). The crystal structure of compound 1,4-[(C<inf>2</inf>H<inf>5</inf>O)<inf>2</inf>P(S)(CH<inf>2</inf>)<inf>3</inf>NH]<inf>2</inf>C<inf>4</inf>H<inf>8</inf>N<inf>2</inf> (L<inf>4</inf>) is also investigated by X-ray diffraction analysis. Two novel organotin(IV) complexes μ-{1,4-[(C<inf>6</inf>H<inf>5</inf>)<inf>2</inf>P(O)(CH<inf>2</inf>)<inf>3</inf>NH]<inf>2</inf>C<inf>4</inf>H<inf>8</inf>N<inf>2</inf>}[SnR<inf>3</inf>Cl]<inf>2</inf>, R<inf>3</inf>SnCl (R = phenyl/butyl), C<inf>1</inf> and C<inf>2</inf>, respectively, are prepared by the reaction of new diphosphoryl ligand L<inf>1</inf> and R<inf>3</inf>SnCl under different conditions. C<inf>1</inf> and C<inf>2</inf> are characterized by IR and NMR spectroscopies and X-ray crystallography diffraction analysis. X-ray analysis illustrates that both complexes have similar structures containing binuclear triorganotin(IV) skeletons and ligand coordinates in a bridging mode through two phosphoryl groups. Sn(IV) coordination geometries are distorted trigonal bipyramidal (TBP) for C<inf>1</inf> and C<inf>2</inf> structures contained binuclear arrangement with two SnPh<inf>3</inf>Cl/SnBu<inf>3</inf>Cl groups linked via the bridging diphosphoryl ligand. The organization of the crystal structures and the intermolecular interactions are discussed. Hirshfeld surfaces and two-dimensional fingerprint plots are used to study short intermolecular contacts in C<inf>1</inf>, C<inf>2</inf> and L<inf>4</inf>. Finally, the influence of chain length and the effects of various substituents on P=O and P=S bond strength in synthesized ligands (L<inf>1</inf>–L<inf>12</inf>) and optimized ligands (L<inf>13</inf>–L<inf>17</inf>) are theoretically investigated by NBO analysis to survey the character of mentioned bonds in these ligands. The AIM analysis is also used to determine the nature of the P=O bond in L<inf>1</inf> and also P=O and O⋯Sn4+ bonds in C<inf>1</inf> and C<inf>2</inf>. Results show ionic character for O⋯Sn4+ interaction in both complexes and mostly electrostatic character for P=O bond in the free ligand, but with a little shift to the covalent character after the complexation. © 2018 Elsevier B.V.