Kr. Porschke et al., BIS(DI-TERT-BUTYLPHOSPHINO)ETHANE-NICKEL(O) COMPLEXES, Zeitschrift fur Naturforschung. B, A journal of chemical sciences, 48(5), 1993, pp. 608-626
Ni(cdt) reacts with tBu2PC2H4PtBu2 in pentane at 20-degrees-C to yield
brownish crystals of (tBu2PC2H4PtBu2)Ni(eta2-C12H18) (1). The molecul
ar structure of 1, as established by X-ray crystallography, exhibits a
trigonal-planar coordination geometry of the nickel center with a eta
2-bonded cdt ligand. In the crystal 1 exists as two enantiomers, which
are determined by the left- or right-handed screw axis of the cdt lig
and. The cdt ligand in 1 resists most typical displacement reactions b
ut 1 reacts with CO at -78-degrees-C to afford the colorless 18e compl
ex (tBu2PC2H4PtBu2)Ni(CO)2 (2). From the reaction of Ni(cod)2 with tBu
2PC2H4PtBu2 yellow needles of (tBu2PC2H4PtBu2)Ni(eta2-cod) (3) are obt
ained. Low temperature NMR spectroscopy established that only one dien
e C=C bond is coordinated to nickel(0). At higher temperatures a rapid
exchange of the coordinated and unbound C=C bonds is induced. When so
lutions of 3 are kept at 20-degrees-C for several days the dinuclear,
almost insoluble yellow complex {(tBu2PC2H4PtBu2)Ni} 2(mu-eta2,eta2-co
d) (4) precipitates. The reaction of Ni(C2H4)3 and tBu2PC2H4PtBu2 affo
rds orange (tBu2PC2H4PtBu2)Ni(C2H4) (5). From Ni(1,5-hexadiene)2 and t
Bu2PC2H4PtBu2 in 1,5-hexadiene the yellow-greenish complex (tBu2PC2H4P
tBu2)Ni(eta2-C6H10) (6) is obtained. As for 3, only one diene C=C bond
is coordinated to nickel(0), but the structure is fluxional with exch
ange of the coordinated and unbound C=C bonds (NMR at 20-degrees-C). F
rom a solution of 6 in pentane the dinuclear, diastereomeric compounds
rac/meso-{(tBu2PC2H4PtBu2)Ni}2(mu-eta2,eta2-C6H10) (7 a, b) separate
in large yellow crystals. In similar reactions the 1,6-heptadiene comp
lexes (tBu2PC2H4PtBu2)Ni(eta2-C7H12) (8) and rac/meso-{(tBu2PC2H4PtBu2
)Ni}2(mu-eta2,eta2-C7H12) (9a,b) are also obtained. In 6, 7a,b, 8, and
9a,b the open-chain diene ligands can easily be displaced, e.g., by e
thene to afford 5. Thus, complexes 6, 7a,b, 8, 9a,b are the most react
ive. These complexes react readily (the ethene derivative 5 also react
s but very slowly) with butadiene to yield large yellow cubes of (tBu2
PC2H4PtBu2)Ni(eta2-C4H6) (10), which is also fluxional. The alkene com
plexes 5, 6, 7a, b, 8, 9a,b, 10 react with ethyne to yield yellow-brow
nish crystalline (tBu2PC2H4PtBu2)Ni(C2H2) (11).