A novel Zn(II) complex of N-nicotinyl phosphoramide: Combined experimental and computational studies

• Synthesis and characterization of a novel Zn(II) complex of N-nicotinyl phosphoramide.
• O- and N-coordination led to a 1D coordination polymer.
• Solid and gas phase structures have been compared.
• Electronic properties have been studied by NBO and QTAIM analyses.

A novel Zn(II) coordination polymer of N-nicotinyl phosphoric triamide ligand, {[Zn(L)2(H2O)2]⋅(NO3)2}nC1 (L = 3-NC5H4C(O)NHP(O)(NC6H12)2), has been synthesized and characterized by IR and 1H, 13C, 31P NMR spectroscopy. Crystal structure analysis of C1 demonstrates a distorted octahedral geometry for Zn(II) ions. The oxygen atom of phosphoryl group (Ophosphoryl) and the nitrogen atom of pyridine ring (Npyridine) of ligand take part in coordination to Zn(II) centers in a bidentate bridging mode. This coordination pattern results in infinite 1D polymeric chains along c axis, which are composed of metal shared 16-membered puckered rings. Structural data show that despite binding through Ophosphoryl, the PO bond distance unexpectedly shortens in C1 when compared to that of the ligand, conceivably due to the steric factors in the solid state. This is confirmed by comparing the structural and electronic properties of C1 and L in the gas phase by using density functional theory (DFT) calculations. Natural bond orbital (NBO) analysis reveals the metal–ligand interaction for C1 as donor–acceptor type delocalizations (charge transfer). Besides, on the basis of the quantum theory of atoms in molecules (QTAIM) analysis, the nature of ZnO and ZnN bondings is found to be mainly electrostatic with a small amount of covalent character.