DIALKYLDICARBONYL RHENIUM COMPLEXES (ETA(5)-C(5)ME(5))RE(CO)(2)R(2), R=ME AND ET - X-RAY STRUCTURE OF TRANS-(ETA(5)-C(5)ME(5))RE(CO)(2)ET(2)

The compounds cis-(eta(5)-C(5)Me(5))Re(CO)(2)Me(2) and trans-(eta(5)-C (5)Me(5))Re(CO)(2)Et(2) were prepared by alkylation of cis-(eta(5)- C( 5)Me(5))Re(CO)(2)Cl-2 using the corresponding organocopper (RCu). Phot olysis of cis-(eta(5)-C(5)Me(5))Re(CO)(2)Me(2) in frozen toluene-d(8) readily produces the trans-(eta(5)-C(5)Me(5))Re(CO)(2)Me(2). All the c ompounds were characterized by spectroscopy and analyses, and the ster eochemistry assigned from examination of nu(CO) IR intensities; additi onally trans-(eta(5)-C(5)Me(5))Re(CO)(2)Et(2) was studied by X-ray cry stallography. Crystal data: monoclinic P2(1)/m, a = 8.034(8) Angstrom, b = 11.991(8) Angstrom, c = 8.69(2) Angstrom, beta = 91.38 degrees, V = 837(2) Angstrom(3), Z = 4, lambda(Mo K alpha) = 0.7107 Angstrom, R( F) = 0.0285 and wR(I) = 0.071 for 1670 measured reflections with 5 < 2 theta < 50 degrees.