Synthesis of Type B Tetrazolylidene–Palladium Complexes and Comparative Analysis with a Type A Analog

Type
B mesoionic carbenes (BMICs) have rarely been studied
experimentally, despite their strong donor potential. The tetrazolylidene
scaffold allows for the investigation of substituent effects on nitrogen
atoms without altering the heterocyclic structure. However, previous
reports on tetrazolo-BMIC have been limited to labile lithium
complexes, detectable only by 13C NMR at –100 °C,
which decompose at room temperature. Herein, we present the synthesis
of stable 2,3-diaryltetrazolylidene–Pd complexes as BMICs complexes, which are compared with known NHC–Pd complexes
using 13C NMR, 31P NMR, single-crystal X-ray
diffraction, catalytic activity analyses, and computational analysis.