Mo(IV) and W(IV) cyanido complexes with Schiff bases. Synthesis, X-ray single crystal structures, physicochemical properties and quantum chemical calculations

Abstract

In the reaction of salicylaldehyde derivatives and aminoethanol with Mo(IV) or W(IV) cyanido complexes, six new salts were isolated and characterized by physicochemical measurements. The single crystal X-ray analysis of four salts of the formula (PPh4)2[M(CN)3O(LL)]·nH2O, (where LL=Schiff bases formed in situ in the reaction of aminoethanol and 5-bromo-, 5-chloro-, 5-methoxy-, 3,5-dichloro- or 5-bromo-3-methoxy-substituted salicylaldehyde, M=Mo or W, n=1, 1.5, 2 or 5 water molecules) reveals a distorted octahedral geometry of the anions. All the complexes were characterized by elemental analysis, IR and UV–Vis spectroscopy and by cyclic voltammetry measurements. The role of the salicylaldehyde substituents on the structures and physicochemical properties is discussed. The results are compared with quantum chemical calculations, indicating that, contrary to literature data, even strong hydrogen bonds do not influence the anion structure.