INTERACTION OF IRON ETHYNYL AND ETHYNEDIYL COMPLEXES WITH CP2NI2(CO)2 - FORMATION OF TRINUCLEAR AND TETRANUCLEAR ADDUCTS WITH A MULTIPLY BRIDGING C2H LIGAND

Reaction of ethynyliron complexes Fp-C=C-H [FP = Fp (1), Fp * (1*)] with Cp2Ni2(CO)2 (5) affords the expected adducts Cp2Ni2(mu-eta2:eta2-FP-C=C-H) [FP = Fp (6), Fp* (6*)] with a tetrahedral C2Ni2 core together with tetranuclear adducts (CPFe)(CpNi)2Ni(CO)2(mu-CO)(mu4-C2H) [CP = CP (7), Cp* (7*)] with a quadruply bridging C2H ligand. 7 (7*) is formed by a formal capping reaction of 6 (6*) with a Ni(CO) fragment. On the other hand, reaction of an ethynediyldiiron complex Fp*-C=C-Fp* (2) with 5 affords a dinuclear complex, Cp*FeCpNi(mu-CO)2(CO) (10), without the C2 ligand, the fate of which is not known. The molecular structures of 6, 7, and 10 have been determined by X-ray crystallography.