Synthesis and structure of cyclic hexanuclear oxo-alkoxo–carboxylatoniobium(IV) complexes
摘要:
The synthesis and crystal structure of novel oxo-alkoxo-carboxylato Nb(IV) complexes, Nb-6(mu(2)-O)(3)(mu(2)-O2CCX3)(6)(mu(2)-OC2H5)(6)(OC2H5)(6) (X = Cl, F) are described. The single-crystal X-ray structure determination carried out, revealed a closed ring of six Nb(IV) ions linked alternately by two carboxylato groups and an oxo group, and two ethoxo groups. The hexanuclear molecule can essentially be described as a trimer of Nb-2(mu(2)-OC2H5)(2)(OC2H5)(2), each linked by an mu(2)-oxo group and two mu(2)-carboxylato groups. The ethoxo-bridged Nb-Nb distances are 2.735(5) Angstrom, which is consistent with a single metal-metal bond, while the oxo- and carboxylato-bridged non-bonding Nb-Nb distances are 3.635(2) Angstrom. (C) 2003 Published by Elsevier B.V.