A comparative study of the structure and bonding in heavier pnictinidene complexes [(ArE)M(CO)n] (E = As, Sb and Bi; M = Cr, Mo, W and Fe).

N,C,N-Chelated pnictinidenes ArE [where E = As (1), Sb (2) or Bi (3); Ar = C6H3-2,6-(CH[double bond, length as m-dash]Nt-Bu)2] were used as ligands for the coordination of transition metal carbonyls. Thus, the reaction of 1-3 with [M(CO)5THF] (where M = Cr, W) or [Mo(CO)5(Me3N)] gave complexes [(ArE)M(CO)5] [where E = As and M = Cr (1a), Mo (1b), W (1c); E = Sb and M = Cr (2a), Mo (2b), W (2c); E = Bi and M = Cr (3a), Mo (3b), W (3c)]. Analogously, the treatment of 1-3 with [Fe2(CO)9] resulted in the formation of the complexes [(ArE)Fe(CO)4] [where E = As (1d), Sb (2d) or Bi (3d)]. All compounds were characterized by 1H and 13C NMR spectroscopy, Raman, IR and UV-Vis spectroscopy. The molecular structures of the majority of the compounds (except 1b and 1c) were also determined by the single-crystal X-ray diffraction analysis. Furthermore, the structure and bonding of the title compounds have also been thoroughly investigated using a computational approach.