Functionalizing Titanium−Phosphinimide Complexes

The reaction of the titanacycle CpTi(NPt-Bu3)(C4H8) (1) with benzyl halides, 4-bromo-1-butene, and
allyl chloride proceeds with loss of ethylene to give CpTiX(NPt-Bu3)(CH2Ph) (X = Cl, 3; Br, 4), CpTiBr(NPt-Bu3)(CH2CH2CHCH2) (5), and CpTiCl(NPt-Bu3)(CH2CHCH2) (6), respectively. Complexes 4 and
6 were readily alkylated to CpTiMe(NPt-Bu3)(CH2Ph) (7) and CpTiMe(NPt-Bu3)(CH2CHCH2) (8),
respectively. Loss of ethylene also occurs on reaction of 1 with bipyridine to give CpTi(NPt-Bu3)(bipy)
(9). In contrast, reaction of 1 with ClSiMePh2 in the presence of PMe3 gave CpTiCl(NPt-Bu3)(CH2CH2SiPh2Me) (10). In a similar fashion, the two-carbon derivatives CpTiCl(NPt-Bu3)(CH2CH2SiMe3) (11),
CpTiCl(NPt-Bu3)(CH2CH2Si(SiMe3)3) (12), CpTi(NPt-Bu3)(CH2CH2SiMe3)(OSO2CF3) (13), CpTiCl(NPt-Bu3)(CH2CH2Snn-Bu3) (14), CpTiCl(NPt-Bu3)(CH2CH2SiCl3) (15), and [CpTiCl(NPt-Bu3)(CH2CH2)]2SiCl2 (16) were produced. In the absence of PMe3, reaction of 1 with SiCl4 and ClSnMe3 gave the four-carbon derivatives CpTiCl(NPt-Bu3)(CH2CH2CH2CH2SiCl3) (17) and CpTiCl(NPt-Bu3)(CH2CH2CH2CH2SnMe3) (18), while reaction of 1 with ClSnPh3 gave only the two-carbon chain derivative CpTiCl(NPt-Bu3)(CH2CH2SnPh3) (19). Nonetheless, in the presence and absence of PMe3 reaction of 1 with ClBcat
or ClPPh2 gave the analogous two- and four-carbon derivatives CpTiCl(NPt-Bu3)(CH2CH2Bcat) (20),
CpTiCl(NPt-Bu3)(CH2CH2CH2CH2Bcat) (21), CpTiCl(NPt-Bu3)(CH2CH2PPh2)(22), and CpTiCl(NPt-Bu3)(CH2CH2CH2CH2PPh2) (23), respectively. The corresponding species CpTiCl(NPt-Bu3)(CH2CH(CH3)CH(CH3)CH2PPh2) (24) was prepared from CpTi(NPt-Bu3)(CH2CHMe)2 (2), while complexation
of 23 and 24 afforded CpTiCl(NPt-Bu3)(CH2CH2CH2CH2PPh2)RhCl(cod) (25) and CpTiCl(NPt-Bu3)(CH2CH(CH3)CH(CH3)CH2PPh2)RhCl(cod) (26). The mechanisms affording the functionalized two- and four-carbon derivatives above are discussed and the implications considered.