Synthesis and crystal structure of nickel(II) and zinc(II) complexes with 2,4-bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine

Abstract

2,4-Bis(3,5-dimethylpyrazol-1-yl)-6-methoxyl-1,3,5-triazine(bpt) has been synthesized by using a new, simple and general method with high yields. Reactions of bpt with Ni(ClO 4) 2 · 6H 20 and Zn(ClO 4) 2 · 6H 2O in methanol gave mononuclear complex [Ni(bpt) 2] · (ClO 4) 2 · H 2O and ternary complex [Zn(mpt) 2(dmp)](ClO 4) 2 respectively, where mpt (2,4-dimethoxy-6-(3,5-dimethyl-pyrazol-1-yl)-1,3,5-triazine) and dmp(3,5-dimethylpyrazole) are the alcoholysis products of bpt in the presence of Zn 2+ ion. A possible mechanism for this catalytic reaction was proposed. X-ray crystal structure for ligand bpt, Ni and Zn complexes are reported. The protonated form of the ligand bpt crystallizes as its perchlorate salt including one molecule of water, [Hbpt · H 2O · ClO 4]. The proton is located on one pyrazole N-atom. [Hbpt · H 2O · ClO 4], in which [Hbpt] + is in cis-cis conformation, are packed in slipped stacks of approximately parallel layers. The π-π overlap interactions between the non-protonized pyrazoles of the adjacent layers give a zigzag arrangement of the planar aromatic [Hbpt] + molecules. In [Ni(bpt) 2](ClO 4) 2 · H 2O, bpt are meridionally three-coordinated with Ni 2+. The coordination sphere around Ni 2+ is a slightly distorted square bipyramid, where four pyrazole nitrogen atoms occupy the basal positions and two triazine nitrogen atoms the apical one. In [Zn(mpt) 2(dmp)](ClO 4) 2, the Zn atom is coordinated with a pair of bidentate mpt ligands and one monodentate dmp ligand, forming a distorted trigonal bipyramid, where the two triazine nitrogen atoms of mpt and one nitrogen atom of dmp occupy the basal positions, and the two pyrazole nitrogen atoms of mpt the apical one.