Pd(II) and Pt(II) Coordination Chemistry with Hybrid Pyridine-Pyrazole Ligands: from 3D-Frameworks Structures in Molecular Complexes

Abstract

In this paper we studied the reaction of ligands 2-[5-phenyl-1-(3,6,9-trioxodecane)-1H-pyrazol-3-yl]pyridine (L1) and 3,5-bis(2-pyridyl)-1-(3,6,9-trioxodecane)-1H-pyrazole (L2) with [MCl2(CH3CN)2] (M = Pd(ii), Pt(ii)), to obtain monomeric complexes [MCl2(L)] (M = Pd(ii): L = L1 (1), L = L2 (2); M = Pt(ii): L = L1 (3), L = L2 (4)). Additionally, the reaction of [Pd(CH3COO)2] with L1 (5) and L2 (6) was also studied pointing out dimeric structures with bridged acetates between the Pd(ii) atoms. All complexes were characterised by elemental analyses, conductivity measurements, infrared spectroscopy (IR), 1H, 13C{1H}, and 195Pt{1H} NMR spectroscopies, and electrospray ionisation mass spectrometry (MS-ESI(+)). The crystal structure of complex [PtCl2(L1)] (3) was determined by X-ray diffraction methods; it consists of a mononuclear complex where L1 acts as a bidentate chelate ligand. Moreover, we also studied the extended structure observing that the ether, present in the alkyl chain of the ligand, chlorine, and platinum moieties play a fundamental role in the final disposition of the supramolecular structure. All these results show how the design of an appropriate hybrid ligand can strongly influence the structural control of the molecular packing.