The double halide-bridged
pi.gif" BORDER=0 >-allyl com
plexes {(
3-C
3H
5)M(
-X)}
2 (M = Ni, Pd; X = Cl, Br)resist halide abstraction by thallium salts of weakly coordinating anions Y = PF
6, B(C
6F
5)
4,and B{C
6H
3(CF
3)
2}
4 in noncoordinating CH
2Cl
2. In the
presence of a bulky
phos
phine(P
iPr
3, P
tBu
3) or when 2 equiv of (
3-C
3H
5)M(PR
3)X is reacted with TlY, one of the halideions is re
placed to afford the ionic dinuclear, single halide-bridged com
plexes [{(
3-C
3H
5)M(PR
3)}
2(
-X)]Y (M = Ni, X = Br (
6,
7); M = Pd, X = Cl (
8,
9) and Br (
10,
11)), which do notreact with further TlY. The corres
ponding com
plexes with Y = Al{OC(CF
3)
3}
4 have also been
pre
pared. In addition, it has been found that the dinuclear
palladium com
plexes, but notthe nickel derivatives, are also stable for Y = OTf. According to NMR the com
plexes re
presenta mixture of diastereomers in solution. For [{(
3-C
3H
5)Ni(P
iPr
3)}
2(
-Br)][Al{OC(CF
3)
3}
4] (
6c)and [{(
3-C
3H
5)Pd(P
tBu
3)}
2(
-Br)][B(C
6F
5)
4] (
11b) the crystal structures have been determined. The reaction of (
3-C
3H
5)M(PMe
3)X with TlY affords a mixture of [(
3-C
3H
5)M(PMe
3)
2]Y (described for M = Ni, Y = PF
6 (
12) and M = Pd, Y = PF
6 (
13)) and the starting
phos
phine-free {(
3-C
3H
5)M(
-X)}
2.