Polymerization Isomerism in [MFe(CO) 4 n ] n- (M = Cu, Ag, Au; N = 3, 4) Molecular Clusters Supported by Metallophilic Interactions

Triangular clusters [MFe(CO) 4 3 ] 3- (M = Cu, 4; Ag, 5; Au, 6) were selectively obtained by heating Fe(CO) 4 (MIMes) 2 (M = Cu, 1; Ag, 2; Au, 3; IMes = C 3 N 2 H 2 (C 6 H 2 Me 3 ) 2 ). 1-3 were synthesized by reacting Na 2 [Fe(CO) 4 ]·2thf with 2 equiv of M(IMes)Cl. As previously described, the direct reactions of Na 2 [Fe(CO) 4 ]·2thf with one equivalent of M(I) salts resulted in the triangular cluster [CuFe(CO) 4 3 ] 3- for Cu, whereas the square clusters [MFe(CO) 4 4 ] 4- were formed for Ag and Au. Thus, depending on the synthetic protocol adopted, both the triangular [MFe(CO) 4 3 ] 3- and square [MFe(CO) 4 4 ] 4- polymerization isomers can be selectively obtained, at least for Ag and Au. Polymerization isomerism, that is two compounds having the same elemental compositions but different molecular weights, was investigated in [MFe(CO) 4 n ] n- (n = 3, 4; M = Cu, Ag, Au) by means of structural and theoretical methods and the role of metallophilic interactions was computationally studied by means of the atoms-in-molecules (AIM) approach.