作者:Jochen Krause、Richard Goddard、Richard Mynott、Klaus-Richard Pörschke
DOI:10.1021/om000765f
日期:2001.5.1
The reaction of Pd(eta (3)-C3H5)(2) with (PPr3)-Pr-i at -30 degreesC affords yellow crystals of the Pd-II complex ((Pr3P)-Pr-i)Pd(eta (3)-C3H5)(eta (3)-C3H5) (1). At 20 degreesC 1 transforms into the dinuclear Pd-I complex ((Pr3P)-Pr-i)Pd)(2)(mu -C3H5)(2) (2) due to oxidative C-C coupling of two allyl groups with elimination of 1,5-hexadiene. Heating 1 or 2 in 1,6-heptadiene to 80 degreesC produces the Pd-0 complex ((Pr3P)-Pr-i)Pd(eta (2),eta (2)-C7H12) (3) (eta (3)-C3H5)PdCl}(2) reacts with (Pr3P)-Pr-i to give ((Pr3P)-Pr-i)Pd(eta (3)-C3H5)Cl (4b), from which further derivatives ((Pr3P)-Pr-i)Pd(eta (3)-C3H5)X (X = OSO2CF3 (4a), C drop CH (5a), CH3 (5b)) are obtained by replacement reactions. The mononuclear Pd-II-acetylide Sa and complex 3 combine to give the dinuclear Pd-I derivative ((Pr3P)-Pr-i)Pd}(2)(mu -C3H5)(mu (2)-eta (2)-C2H) (6). The Pd-Pd bond in 6 is unsymmetrically bridged by a pi -allyl and a sigma-pi -ethynyl group, as determined by X-ray structure analysis. The structures of 1, 4a,b, and 6 are dynamic in solution, with 1 undergoing an exchange of the binding modes of the pi- and sigma -coordinated allyl groups and 4a,b displaying a pi/sigma -allyl group rearrangement, and in 6 the C drop CH substituent oscillates in its pi -coordination from one Pd-I atom to the other.