New N-pyrazole, P-phosphine hybrid ligands and their reactivity towards Pd(II): X-ray crystal structures of complexes with [PdCl2(N,P)] core

Abstract

Two new N-pyrazole, P-phosphine hybrids ligands: 1-[2-(diphenylphosphanyl)methyl]-3,5-dimethylpyrazole (LP1) and 1-[2-(diphenylphosphanyl)propyl]-3,5-dimethylpyrazole (LP3) are presented. The reaction of these two ligands and two other ligands reported in the literature: 1-[2-(diphenylphosphanyl)ethyl]-3,5-dimethylpyrazole (LP2) and 1-[2-(diphenylphosphanyl)ethyl]-3,5-diphenylpyrazole (LP4) with [PdCl2(CH3CN)2] yield [PdCl2(LP)] (LP = LP1 (1), LP2 (2), LP3 (3) and LP4 (4)) complexes. All complexes are fully characterised by analytical and spectroscopic methods and the resolution of the crystal structure of complexes 2 and 3 by single crystal X-ray diffraction is also presented. In these complexes the ligands are coordinated to Pd(II) via κ2(N,P) forming metallocycles of six (2) and seven (3) members and finish their coordination with two cis-chlorine atoms. Finally, complex 2 is studied in the palladium-catalysed C-C coupling reaction, being active even for aryl chlorides substrates.