97749-48-9Relevant academic research and scientific papers
Tantalum organometallics containing bulky oxy donors: Utilization of tri-tert-butylsiloxide and 9-oxytriptycene
LaPointe, Robert E.,Wolczanski, Peter T.,Van Duyne, Gregory D.
, p. 1810 - 1818 (2008/10/08)
Procedures entailing the preparation of alkyl- and chlorotantalum complexes containing 9-oxytriptycene (TpO) and (t-Bu)3SiO- (silox) are described. Addition of 2 equiv of TpOSiMe3 to TaCl5 yielded (TpO)2TaCl3 (2); alcoholysis of Np3Ta=C(H)CMe3 (Np = neopentyl) with TpOH produced (TpO)2TaNp3 (3). An X-ray structure determination of 3 indicated that the axially disposed TpO units are nearly eclipsed in this pseudo-tbp complex. Crystal data: orthorhombic, Pn21a, a = 16.024 (2) A?, b = 13.607 (4) A?, c = 21.377 (1) A?, Z = 4, and T = 25 °C. From 2651 data were |F0| ≥ 3σ (\Fo|), an R factor of 0.054 was obtained via standard refinement methods. Short Ta-O bonds (1.869 (16) A? average) concomitant with near linear Ta-O-C angles (170.3 (19) and 163.9 (16)°) suggest that strong π-bonding is evident. Treatment of TaCl5 and R3TaCl2 (R = Me, CH2Ph, Np) with stoichiometric amounts of Na(silox) gave (silox)2TaCl3 (4), (silox)2TaR3 (R = Me (5), CH2 Ph (6)), (silox)2NpTa=C(H)CMe3 (11), and (silox)TaNp3Cl (9), respectively. From Np2TaCl3 and 2Na(silox), (silox)2TaNp2Cl (10) was obtained. Either 9 and Na(silox) or 10 and NpLi also afforded 11. Thermolysis of 6 provided (silox)2Ta=C(H)Ph(CH2Ph) (7), and the addition of PhCH2MgCl to 4 in Et2O resulted in (silox)2TaCl2(CH2Ph) (8). Np3Ta=C(H)CMe3 reacted with (silox)H to form (silox)Np2Ta=C(H)CMe3 (12), but further silanolysis was not observed. Discussions pertaining to the effective size of the oxygen donor ligands, the stability of the complexes, and their relationship to analogous Cp species are presented.
