Synthesis and molecular structure of the all-trans- and the trans–cis-isomers of dichlorodimethyltin complexes of phosphoric triamides

Four new phosphoramidates with formula 4-RC6H4C(O)NHP(O)(NH(CH(CH3)2)2, R = H (1), OCH3 (2), CH3 (3), Cl (4) and their diorganotin(IV) complexes with formula SnCl2(CH3)2(X)2, X = 1 (5), 2 (6), 3 (7) and 4 (8) were synthesized and characterized by NMR, IR spectroscopy and elemental analysis. The spectroscopic properties of complexes were compared with those corresponding ligands. The molecular structures for 5, 5·CH3CN, 6·CH3CN, 7 and 8 were established by X-ray diffraction analysis and shown that the tin atoms have a distorted octahedral coordination with trans-methyl groups. Two different all-trans and cis–trans isomers were obtained by changing the crystallization solvent system. The existence of CH3CN in molecular packing of trans–cis isomers might be a packing factor governing the orientation of the ligands. Due to the presence of several hydrogen bond donors and acceptors on compounds, extended hydrogen-bonded networks were observed. The structure of 2 was also determined and possesses two crystallographically independent molecules in asymmetric unit. On forming complex 6·CH3CN, the ligand 2 shows shortening of CO and P–N bond distances and increasing of PO bond length. Pseudopolymorphism of diorganotins in 5 and 5·CH3CN is reported for the first time.