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 R1R2P(X)-Y-P(X)R1R2 have been synthesized and characterized by IR and NMR spectroscopies (L-1-L-12). The crystal structure of compound 1,4-[(C2H5O)(2)P(S)(CH2)(3)NH](2)C4H8N2 (L-4) is also investigated by X-ray diffraction analysis. Two novel organotin(IV) complexes mu-{1,4-[(C6H5)(2)P(O)(CH2)(3)NH](2)C4H8N2}[SnR3Cl](2), R3SnCl (R = phenyl/butyl), C-1 and C-2, respectively, are prepared by the reaction of new diphosphoryl ligand L-1 and R3SnCl under different conditions. C-1 and C-2 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-1, and C-2 structures contained binuclear arrangement with two SnPh3Cl/SnBu3Cl 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-1, C-2, and L-4. Finally, the influence of chain length and the effects of various substituents on P=O and P=S bond strength in synthesized ligands (L-1-L-12) and optimized ligands (L-13-L-17) 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-1 and also P=O and O center dot center dot center dot Sn4+ bonds in C-1 and C-2. Results show ionic character for O center dot center dot center dot 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. (C) 2018 Elsevier B.V. All rights reserved.