REACTIONS OF HETERONUCLEAR DIMETALLATED OLEFIN COMPLEXES - REACTIONS OF CPFE(CO)(2)[MU-(Z)-(MEO(2)C)C=C(CO(2)ME)]RE(CO)(4) WITH CO AND P-TOLYL ISOTHIOCYANATE

Addition of CO to the dimetalated olefin complex CpFe(CO)(2)[mu-(Z)-(MeO(2)C)C=C(CO(2)Me)]Re(CO)(4), 1, at 25 degrees C/700 psi of CO resulted in the formation of the adduct CpFe(CO)(2)[mu-(E)(MeO(2)C)C=C(CO(2)Me)]Re(CO)(5), 2, in 52% yield by cleavage of the Re-O bond to the coordinated carboxylate group. In contrast the reaction of 1 with CO at 70 degrees C/900 psi of CO provided the new compound CpFe(CO)(2)[mu-(Z)-C=O(MeO(2)C)C=C(CO(2)Me)]Re(Co)(4) 3, in 77% yield. Compounds 2 and 3 were characterized by single-crystal X-ray diffraction analyses. Compound 2 is a Z-dimetalated olefin formed by addition of CO to the Re(CO)4 group in 1, C-C = 1.35(1) Angstrom. Compound 3 is an isomer of 2 in which a CO was added to 1 and inserted into the iron-carbon bond to the alkyne. The oxygen atom of the inserted CO grouping is coordinated to the rhenium atom, C-C = 1.349(7) and Re-O = 2.154(4) Angstrom. Compound 2 loses CO spontaneously but slowly at room temperature to return to 1, but compound 3 does not even under forcing conditions. When treated with EtNH(2), the CpFe(CO)(2) group in 3 was replaced by a EtNH grouping to yield the trisubstituted vinyl ligand in the complex (EtNHC=O)(MeO(2)C)C=C(CO(2)Me)]Re(CO)(4), 5, in which carbonyl oxygen atom of the amido grouping is coordinated to the rhenium atom. Compound 1 reacts with EtNH(2) or H2O to yield the new compound CpFe(CO)(2)[(MeO(2)C)C=C(CO(2)Me)(H)], 6, by the cleavage of the rhenium grouping from the molecule. The reaction with H2O is catalyzed by silica gel. The reaction of 1 with p-tolyl isothiocyanate provided the iron-rhenium complex CpFe(CO)(mu-CO)[mu-CC(CO(2)Me)(2)C=SN(p-MeC(6)H(4))C=O]Re(CO)(3), 7 (17% yield), that was shown crystallographically to contain heterocycle CC(CO(2)Me)(2)C=SN(p-MeC(6)H(4))C=O formed by the coupling of the isothiocyanate molecule to a CO ligand and a rearranged form of the alkyne group. Crystal data for-a: space group = P2(1)/c, a = 15.386(3) Angstrom, b = 7.520(2) Angstrom, c = 18.862(2) Angstrom, beta = 107.66(1)degrees, Z = 4. 1750 reflections, R = 0.024. For 3: space group E P2(1)/c, a = 14.285(2) Angstrom, b = 7.335(1) Angstrom, c = 20.943(4) Angstrom, beta = 104.60(1)degrees, Z = 4, 2214 reflections, R = 0.022. For 7: space group = P ($) over bar 1, a = 10.655(2) Angstrom, b = 13.828(2) Angstrom, c = 9.626(1) Angstrom, alpha = 109.53(1)degrees, beta = 98.23(1)degrees, gamma = 91.83(1)degrees, Z = 2, 3311 reflections, R = 0.020.