Carbonyl and Isocyanide Complexes of Copper and Silver Supported by Fluorinated Poly(pyridyl)borates

The pyridine-based poly(pyridyl)borates are a recent addition to the scorpionate family. Furthermore, pyridyl ring substituted analogues are also rare. The synthesis of a bis(pyridyl)borate featuring trifluoromethyl substituted pyridyl donor arms and its utility in isocyanide and carbonyl chemistry of copper(I) and silver(I) have been described together with related molecules supported by a fluorinated tris(pyridyl)borate, and a comparison to the better-known poly(pyrazolyl)borate relatives. X-ray crystal structures of copper and silver complexes show that the B-arylated, bis- and tris(pyridyl)borate ligands use only two pyridyl moieties for metal ion coordination. Flanking B-aryl groups close to metal sites are also a common feature in copper and silver complexes supported by [Ph2B(6-(CF3)Py)2]−and [t-BuC6H4B(6-(CF3)Py)3]−. The CN stretching frequencies of the t-BuNC complexes of Cu(I) and Ag(I) are notably higher than that of the free t-BuNC. The CO stretch of the analogous fluorinated poly(pyridyl)borate ligand supported metal carbonyls lies closer to that of the free CO, indicating the presence of fairly Lewis acidic metal sites. Metal bound carbonyl stretching frequencies of comparable poly(pyridyl)borate and poly(pyrazolyl)borate have been utilized to gauge the relative donor properties of the two ligand families.