CRYSTAL-STRUCTURES OF [(ETA(5)-C5H4COOH)W(CO)(3)R] (R=ME, I)

The crystal structures of [(eta(5)-C5H4COOH)W(CO)(3)R] (R = Me, I) hav e been determined. They crystallize in two different monoclinic space groups. R = Me is P2(1)/c, a = 10.4833(6), b = 8.0144(7), c = 13.0731( 6) Angstrom, beta = 93.147(4)degrees, and D(calc) = 2.374 g-cm(-3) for Z = 4. R = I is P2(1)/n, a = 7.814(2), b = 13.075(4), c = 11.097(4) A ngstrom, beta = 91.75(2)degrees, and D(calc) = 2.953 g-cm(-3) for Z = 4. Both possess a ''four-legged piano stool'' geometry. The methyl lig and in the R = Me complex is disordered between two positions in syn o r anti relative to the substituted carbon of the cyclopentadienyl liga nd. The iodo ligand in the R = I complex is, however, exclusively in s yn-position.