Synthesis, characterization and complexation properties of N-phosphorylated thioureas RNHC(S)NHP(O)(OiPr)2 (R = 2-Py, 3-Py) towards Ni(II)

Reaction of O,O′-diisopropylphosphoric acid isothiocyanate (iPrO)2P(O)NCS with 2- or 3-aminopyridine leads to the new N-phosphorylated thioureas RNHC(S)NHP(O)(OiPr)2 (R = 2-Py, HLI; 3-Py, HLII). Reaction of the potassium salt KLI with Ni(II) in aqueous EtOH leads to the new complex Ni[2-PyNHC(S)NP(O)(OiPr)2-N(Py),N(P),O]2, where the metal cation is coordinated by two deprotonated ligands LI through the pyridine and phosphorylamide nitrogen atoms, and the PO oxygen atoms. Using KLII leads to an oligomeric (or polymeric) structure, where the Ni(II) cation is coordinated by two anionic ligands LII through the CS sulfur atoms and the P–N nitrogen atoms, and the pyridine nitrogen atoms of neighboring molecules. The new compounds were investigated by 1H and 31P{1H} NMR spectroscopy, and microanalysis. Single crystal X-ray diffraction studies showed HLI forms both intra- and intermolecular hydrogen bonds, which in turn lead to the formation of a polymeric chain. Moreover, π⋯π stacking interactions were observed between molecules of two neighboring chains.