6050-22-2Relevant academic research and scientific papers
Catalytic P-H activation by Ti and Zr catalysts
Masuda, Jason D.,Hoskin, Aaron J.,Graham, Todd W.,Beddie, Chad,Fermin, Maria C.,Etkin, Nola,Stephan, Douglas W.
, p. 8696 - 8707 (2006)
Catalytic dehydrocoupling of phosphines was investigated using the anionic zirconocene trihydride salts [Cp*2Zr(μ-H) 3Li]3 (1a) or [Cp*2Zr(μ H) 3K(thf)4] (1b), and the metallocycles [CpTi(NPtBu 3)(CH2)4] (6) and [Cp*M(NPtBu 3)(CH2)4] (M = Ti 20, Zr 21) as catalyst precursors. Dehydrocoupling of primary phosphines RPH2 (R = Ph, C6H2Me3, Cy, C10H7) gave both dehydrocoupled dimers RP(H)P(H)R or cyclic oligophosphines (RP)n (n = 4, 5) while reaction of tBu3C6H2PH 2 gave the phosphaindoline fBu2(Me2C-CH 2)C6H2PH (9). Stoichiometric reactions of these catalyst precursors withprimary phosphines afforded [Cp* 2Zr((PR)2)H][K(thf)4] (R = Ph 2, Cy 3, C 6H2Me3 4), [Cp*2Zr((PPh) 3)H] [K(thf)4] (5), [CpTi(NPtBu3)(PPh) 3] (7) and [CpTi(NPfBu3)(nrPHPh)]2 (8), while reaction of 6 with (C6H2tBu3)PH2 in the presence of PMe3 afforded [CpTi(NPtBu3)(PMe 3)(P(C6H2tBu3)] (10). The secondary phosphines Ph2PH and (PhHPCH2)2CH2 also undergo dehydrocoupling affording (Ph2P)2 and (PhPCH2)2CH2. The bisphosphines (CH 2PH2)2 and C6H4(PH 2)2 are dehydrocoupled to give (PCH2CH 2PH)v (12) and (C6H4P(PH)) 2 (13) while prolonged reaction of 13 gave (C6H 4P2)8 (14). The analogous bisphosphine Me 2C6H4(PH)2 (17) was prepared and dehydrocoupling catalysis afforded (Me2C6H 2P(PH))2 (18) and subsequently [(Me2C 6H2P2)2(μ-Me2C 6H2P2)]2 (19). Stoichiometric reactions with these bi-sphosphines gave [Cp*2Zr(H)(PH)2C 6H4][Li(thf)4] (22), [CpTi(NPtBu 3)(PH)2C6H4]2 (23) and [Cp*Ti(NPfBu3)(PH)2C6H4] (24). Mechanistic implications are discussed.
