Cationic rhenium allyl complex [Cp*Re(eta(3)-C3H5)(CO)(2)][BF4] and its acetonitrile derivatives [Cp*Re(eta(3)-C3H5)(CO)(NCMe)][BF4] and [Cp*Re(eta(3)-C3H5)(NCMe)(2)][BF4]. Products of reactions with borohydride, methoxide and trimethylphosphine, and the X-ray crystal structure of the bis-ethylamine complex [endo-Cp*Re(eta(3)-C3H5)(NH(2)Et)(2)][ReO4].solv

By replacing one or both of the CO groups in [Cp*Re(eta(3)-C3H5)(CO)(2)][BF4] (1) by MeCN to give [Cp*Re(eta(3)-C3H5)(CO)(NCMe)][BF4] (3) or [Cp*Re(eta(3)-C3H5)(NCMe)(2)][BF4] (4), it was anticipated that the MeCN groups would be labile and would promote ligand substitution reactions, leading to a variety of new rhenium eta(3)-allyl half-sandwich derivatives. Instead, MeCN is found to be difficult to substitute, and nucleophiles often result in products that arise from attack at either the MeCN or allyl ligands. Complex 1 reacted with NaBH4 to give the propene complex Cp*Re(eta(2)-CH2CHCH3)(CO)(2) (2), with NaOMe to give the methoxycarbonyl complex Cp*Re(eta 3-C3H5)(CO)(COOMe) (6) and the 3-methoxypropene complex Cp*Re(eta(2)-CH(2)CHCH(2)OMe)(CO)(2) (5), and with PMe(3) to give [Cp*Re(eta(2)-CH(2)CHCH(2)PMe(3))(CO)(2)][BF4] (7). Complex 3 gave the ethylamine complex [Cp*Re(eta(3)-C3H5)(CO)(NH(2)Et)][BF4] (8) when reacted with NaBH4, [Cp*Re(eta(2)-CH(2)CHCH(2)PMe(3))(CO)(NCMe)][BF4] (9) with PMe(3), and Cp*Re(eta(3)-C3H5)(CO)(NHCOMe) (10) with NaOH. Complex 4 similarly yielded the bis-ethylamine complex [Cp*Re(eta(3)-C3H5)(NH(2)Et)(2)][BF4] (11) when reacted with NaBH4, but with PMe(3) ligand substitution occurred, resulting in [Cp*Re(eta(3)-C3H5)(NCMe)(PMe(3))][BF4] (12). Treating 12 with NaBH4, or 11 with PMe(3), yielded the ethylamine complex [Cp*Re(eta(3)-C3H5)(PMe(3))(NH(2)Et)][BF4] (13). The X-ray crystal structure of [endo-Cp*Re(eta(3)-C3H5)(NH(2)Et)(2)][ReO4].solv has been determined This compound crystallizes in the space group Pnma with a = 8.6554(8) Angstrom, b = 11.729(2) Angstrom, c = 26.928(3) Angstrom, V = 2733.7 Angstrom(3), and Z = 4. The structure was refined to R(F) = 0.028 for 1444 data (I-o greater than or equal to 2.5 sigma(I-o), 2 theta(max) = 46 degrees) and 158 variables. The cation has a crystallographic mirror plane that relates the two EtNH(2) ligands and bisects the endo-eta(3)-allyl and Cp* ligands. Selected distances and angles are Re-N = 2.228(7) Angstrom, Re-C(6) = 2.177(9) Angstrom (allyl terminal carbon), Re-C(7) = 2.090(13) Angstrom (allyl central carbon), N-C(4) = 1.470(10) Angstrom, Re-N-C(4) = 125.2(6) Angstrom, and C(6)-C(7)-C(6) = 114.1(13) Angstrom.