Synthesis and Reactivity of Group 6 Metal Carbonyl Complexes Containing bis(Pyrazol‐1‐yl)methane with Bulky Substituents on the 3‐ and 5‐Positions of Pyrazole Rings

Abstract

Two new bis(pyrazol‐1‐yl)methane ligands, bis(3,5‐diisopropylpyrazo‐1‐yl)‐methane and bis(3,5‐diisobutylpyrazol‐1‐yl)methane, were synthesized by the reaction of 3,5‐diisopropylpyrazole or 3,5‐diisobutylpyrazole with CH₂Br₂ under phase transfer catalysis. These ligands can react with M(CO)₆ (M=Cr, Mo or W) under UV irradiation at room temperature to yield bis(pyrazo‐1‐yl)methane tetracarbonylchromium, molybdenum or tungsten complexes. Treatment of the molybdenum or tungsten complexes with SnCl₄ gives Mo–Sn or W–Sn heterobimetallic complexes, one of which has been characterized by X‐ray analysis. All new compounds have also been characterized by elemental analyses and spectroscopic (¹H NMR and IR) studies.

Acknowledgment

The authors are thankful to the National Natural Science Foundation of China for financial support (No. 20172029).