THE REACTIONS OF IRON-CARBONYL AND ALKYNE-CARBONYL COMPLEXES WITH NICKELOCENE, 2 AND (η-C5H5)2Ni2(RC2R'). CRYSTAL STRUCTURES OF TWO HETEROMETALLIC TETRANUCLEAR CLUSTERS

Article abstract of DOI:10.1016/S0022-328X(00)83857-7

The reaction of nickelocene, <(η-C5H5)Ni(CO)>2 and its alkyne-substituted derivatives with Fe(CO)5, Fe3(CO)12 and alkyne-cluster derivatives of iron are reported and discussed.A considerable number of new heterometallic complexes has been obtained: the structures of the two tetranuclear complexes (η-C5H5)2Ni2Fe2(CO)7 (I) and (η-C5H5)2Ni2Fe2(CO)6(C2Et2) (IIa) have been determined by X-ray diffraction methods.Crystals of I are triclinic, a 8.028(8), b 14.561(12), c 7.961(8) Angstroem; α 94.58(7), β 97.26(11), γ 92.23(9)^o; space group P<*>.Crystals of IIa are triclinic, a 10.124(10), b 14.676(12), c 8.396(8) Angstroem; α 95.80(8), β 111.20(10), γ 72.89(9)^o, space group P<*>.Both structures have been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R=0.039 for I and 0.045 for IIa.The structure of I is characterized by a tetrahedral metal atom core, bound to two cyclopentadienyl ligands (through the Ni atoms) and to six terminal CO's (through the Fe atoms).The seventh carbonyl is triply bridging between two Fe and one Ni atoms in an asymmetric way.The structure of IIa consists of a tetrahedrally distorted square arrangement of two Fe and two Ni atoms.The alkyne is ?-bonded to the Ni atoms and ?-bonded to the Fe atoms.The formation of heterometallic complexes in the above reactions is not selective, although the stability of the cluster reactants, and the nature of the bonding and the substituents in the alkynes can influence the nature and the yields of the products.