Mixtures of two scorpionate/cyclopentadiene regioisomers
bpzcpH (1-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene (
1a) and 2-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1,1-diphenylethyl]-1,3-cyclopentadiene (
1b)) and bpztcpH (1-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1-
tert-butylethyl]-1,3-cyclopentadiene (
2a) and 2-[2,2-bis(3,5-dimethylpyrazol-1-yl)-1-
tert-butylethyl]-1,3-cyclopentadiene (
2b))
were prepared by deprotonation of bis(3,5-dimethylpyrazol-1-yl)methane with Bu
nLi followed by reaction with 6,6-diphenylfulvene or 6-
tert-butylfulvene and subsequent treatment with saturated aqueous ammonium chloride. Reactions of hybrid scorpionate/cyclopentadiene compounds with [M(CH
2SiMe
3)
3(THF)
3] (M = Sc, Y) afford the dialkyl complexes [M(CH
2SiMe
3)
2(bpzcp)] (M = Sc (
3), Y (
4)) and [M(CH
2SiMe
3)
2(bpztcp)] (M = Sc (
5), Y (
6)). The cationic alkyl complexes [M(CH
2SiMe
3)(bpzcp)]
+ (M = Sc (
7), Y (
8)) were also prepared by the reaction of complexes
3 and
4 with [CPh
3][B(C
6F
5)
4] in THF. The structures of these compounds were determined by spectroscopic methods, and the X-ray crystal structures of
2 and
3 were also established. The bis(alkyl) complexes
3 and
4 were found to be active initiators for the ring-opening polymerization of ε-caprolactone (up to 75% conversion of 200 equiv in 10 min) and yielded polymers with narrow molecular weight distributions.