SYNTHESIS AND STRUCTURE OF FE-4(CO)(10)(MU(2)-CO)(MU(4)-TE)(2) AND FE-57 - MOSSBAUER-SPECTRA OF FE-3(CO)(9)(MU(3)-TE)(2) AND FE-4(CO)(10)(MU(2)-CO)(MU(4)-TE)(2)

The compound Fe-4(CO)(10)(mu(2)-CO)(mu(4)-Te)(2) (1) has been prepared by the reaction of Fe-3(CO)(9)Te-2 (2) and Fe-2(CO)(9) in toluene. Co mpound 1 is also formed by UV light irradiation of 2 and Fe(CO), in TH F. The structure of 1 was established by single-crystal analysis. Crys tal data: orthorhombic, Pccn, a = 6.843(1), b = 15.814(1), c = 17.436( 1) Angstrom; V = 1887 Angstrom(3); Z = 4; T = 293 K, R-1 = 0.040. 1 co nsists of a planar array of four iron atoms with a quadruply bridging telluro ligand on each side of the plane. The shortest metal-metal bon d contains a bridging carbonyl ligand, semi-bridging carbonyl ligands bridge the two adjacent metal-metal bonds. Te-125-NMR investigations s how a conversion from 1 to 2 within several hours. Fe-57 Mossbauer spe ctra show two doublets for 1 and only one broadened doublet for 2. The ratio of the intensities of the doublets of 1 is found close to unity and confirms the existence of two equipopulated crystallographic site s of iron. On the contrary, in the case of 2, the analysis of the spec tra does not allow the expected correlation with the results of the cr ystal structure determination. The same difficulty was previously enco untered in the case of the isostructural selenide Fe-3(CO)(9)Se-2. (C) 1998 Elsevier Science S.A. All rights reserved.