Synthesis and structural characterisation of coordination polymers designed using discrete phosphonodithioato NiII complexes and dipyridyl donor ligands

Square-planar phosphonodithioato complexes [Ni(ROdtp)2] [ROdtp = (4-MeOPh)(RO)PS22; R = Me (1), Et (2)] have been treated with four different dipyridyl donors, namely 1-pyridyl-4-(4’-pyridyl-ethynyl)-benzene (I), 4,4’-bipyridine (II), 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine (III), and 3,6-bis(3-pyridyl)-1,2,4,5-tetrazine (IV). The single crystal X-ray structures of the reaction products (1.I) (3), (1.III) (5), and (2.IV) (6), along with that of the previously reported compound (2.II) (4) prove the ability of dipyridyl donors to self-assemble with coordinatively unsaturated nickel-phosphonodithioates to give 1D coordination polymers whose topology, such as the shape and the separation between consecutive metal centres, can be tuned through structural modifications in the N-donor linkers. DFT calculations on the free ligands have been performed with the goal of elucidating the nature of the frontier orbitals of the ligands involved in the coordination of the nickel complexes.