Intramolecular apical Metal–H–Csp3 interaction in molybdenum and silver complexes

Abstract

The reaction of HTIMP3 (HTIMP3 = tris[1-diphenylphosphino)-3-methyl-1H-indol-2-yl]methane) with AgBF₄ and Mo(CO)₃(NCCH₃)₃ leads to Ag(HTIMP3)BF₄ and Mo(CO)₃(HTIMP3), respectively. The metal centre is coordinated to the three phosphorus atoms of the HTIMP3 ligand, which adopts a facial coordination mode, placing a H-Csp³hydrogen atom at the apical position close to the metal centre. The solid-state structure of Mo(CO)₃(HTIMP3) has been determined by X-ray crystallography, and the data have been used as input parameters for obtaining the optimised geometry of the complex using the B3PW91 functional. The silver structure has been modelled from the X-ray parameters of the molybdenum structure. In addition, theoretical calculations on the H–Csp³ downfield shift upon metal coordination has also been performed. They reproduce the experimental H–Csp³ chemical shifts well and supports that proton deshielding is mainly due to the presence of the metal, since the hydrogen is already located in the cone created by the aromatic-phosphino arms in the free ligand.