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

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 [MCl₂L] (M = Cu, Co, Ni, Zn, Pt), [ML₂](NO₃)₂ (M = Cu, Co, Ni, Zn), [AgL]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 [CoCl₂L]₂, [ZnCl₂L] 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).