Synthesis and coordination chemistry of an alkyne functionalised bis(pyrazolyl)methane ligand

Abstract

The alkyne functionalised bidentate N-donor ligand (2-propargyloxyphenyl)bis(pyrazolyl)methane ( L) was prepared in high yield from the reaction of (2-hydroxyphenyl)bis(pyrazolyl)methane with propargyl bromide in the presence of base. A series of transition-metal complexes including [MCl2 L] (M = Cu, Co, Ni, Zn, Pt), [M L2](NO3)2 (M = Cu, Co, Ni, Zn), [Ag L]NO3 and [Pd( L)(dppe)](OTf)2 were prepared and characterised by spectroscopic techniques. In addition, ligand L as well as the Co(II) and Zn(II) complexes [CoCl2 L]2, [ZnCl2 L] were structurally characterized by single-crystal X-ray diffraction. The organometallic gold(I) and platinum(II) acetylide complexes [Pz2CH(C6H4-2-OCH2CCAuPPh3)] and trans-[{Pz2CHC6H4-2-OCH2CC}2Pt(PPh3)2] were prepared from L and [AuCl(PPh3)] and trans-[PtCl2(PPh3)2], respectively. Treatment of these complexes with [Pd(OTf)2(dppe)] or [Cu(MeCN)4]PF6 results in formation of the cationic, mixed-metal complexes, which were isolated (Pt/Pd, Au/Pt) or detected by electrospray mass spectrometry (Au/Cu, Pt/Cu).