SYNTHESIS OF DOUBLY-BRIDGED FE SE AND FE/TE COMPLEXES VIA REACTIONS OF THE [MGX](+) SALTS OF ANIONS [(MU-RE)(MU-CO)FE-2(CO)(6)](-) (E = SE,TE) - CRYSTAL-STRUCTURE OF (MU-P-MEC6H4TE)(MU-PHC=NPH)FE-2(CO)(6)/

The reactions of Grignard reagents RMgX with elemental Se or Te in THF , followed by treatment of the intermediates RSeMgX or RTeMgX with Fe- 3(CO)(12) at room temperature (r.t.), were found to give [MgX](+) salt s of anions [(mu-RSe)(mu-CO)Fe-2(CO)(6)](-) (2) and [(mu-RTe)(mu-CO)Fe -2(CO)(6)](-) (3), respectively. Furthermore, the [MgX](+) salts of an ions 2 (R = Et) reacted in situ with the electrophile Ph2AsCl to affor d (mu-EtSe)(mu-Ph2As)Fe-2(CO)(6) (4), whereas the [MgX](+) salts(R =p- MeC6H4) reacted with the electrophile PhNCS, followed by treatment wit h another electrophile Met to give (mu-p-MeC6H4Se)(mu-Ph-N(Me)C=S)Fe-2 (CO)(6) (5). Similarly, the [MgX](+) salts of anions 3 (R = Et, t-Bu, i-Bu) were found to react sequentially with the electrophiles PhC=CPh and CF3COOH to yield (mu-RTe)(mu-sigma,pi-PhC-CHPh)Fe-2(CO)(6) (6a, R = Et; 6b, R = t-Bu; 6c, R = i-Bu), whereas reactions of the [MgX](+) s alts of anions 3 (R = Et, Ph, p-MeC6H4) with the electrophiles Ph2AsCl or PhC(CI)NPh produced (mu-RTe)(mu-Ph2As)Fe-2(CO)(6) (7a, R = Et; 7b, R =p-MeC6H4) and (mu-RTe)(mu-PhC=NPh)Fe-2(CO)(6) (8a, R = a(axial)-Ph ; 8b, R = e(equatorial)-Ph; 9a, R = a-p-MeC6H4; 9b, R = e-p-MeC6H4), r espectively. The reaction courses for the formation of Fe/Se and Fe/Te complexes;4-9 were discussed briefly and the structures of there new complexes, along with two other new Fe/Te complexes (mu-RTe)(2)Fe-2(CO )(6) (R = Et, i-Bu), were characterized by elemental analysis and spec troscopy, as well as for complex 9b, whose structure was confirmed fur ther by X-ray diffraction analysis. (C) 1998 Elsevier Science S.A. All rights reserved.