| 15540256 |
Zhang QF, Lam TC, Yi XY, Chan EY, Wong WY, Sung HH, Williams ID, Leung WH: Titanium (IV) and zirconium (IV) sulfato complexes containing the Klaui tripodal ligand: molecular models of sulfated metal oxide surfaces. Chemistry. 2004 Dec 17;11(1):101-11.
Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL (OEt) (L (OEt) (-)=[(eta (5)-C (5) H (5)) Co{P (O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L (OEt) Ti)(2)(mu-O)(2)(mu-SO (4))] (2). In more concentrated sulfuric acid (> 1 M), the same reaction yielded the di-mu-sulfato complex [(L (OEt) Ti)(2)(mu-O)(mu-SO (4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF (3) SO (3)) gave the tris (triflato) complex [L (OEt) Ti (OTf)(3)] (4), whereas treatment of 2 with Ag (OTf) in CH (2) Cl (2) afforded the sulfato-capped trinuclear complex [{(L (OEt))(3) Ti (3)(mu-O)(3)}(mu (3)-SO (4)){Ag (OTf)}][OTf] (5), in which the Ag (OTf) moiety binds to a mu-oxo group in the Ti (3)(mu-O)(3) core. Reaction of 2 in H (2) O with Ba (NO (3))(2) afforded the tetranuclear complex (L (OEt))(4) Ti (4)(mu-O)(6) (6). Treatment of 2 with [{Rh (cod) Cl}(2)] (cod=1,5-cyclooctadiene), [Re (CO)(5) Cl], and [Ru (tBu (2) bpy)(PPh (3))(2) Cl (2)] (tBu (2) bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag (OTf) afforded the heterometallic complexes [(L (OEt))(2) Ti (2)(O)(2)(SO (4)){Rh (cod)}(2)][OTf](2) (7), [(L (OEt))(2) Ti (O)(2)(SO (4)){Re (CO)(3)}][OTf] (8), and [{(L (OEt))(2) Ti (2)(mu-O)}(mu (3)-SO (4))(mu-O)(2){Ru (PPh (3))(tBu (2) bpy)}][OT f](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu (B). Treatment of zirconyl nitrate with NaL (OEt) in 3.5 M sulfuric acid afforded [(L (OEt))(2) Zr (NO (3))][L (OEt) Zr (SO (4))(NO (3))] (10). Reaction of ZrCl (4) in 1.8 M sulfuric acid with NaL (OEt) in the presence Na (2) SO (4) gave the mu-sulfato-bridged complex [L (OEt) Zr (SO (4))(H (2) O)](2)(mu-SO (4)) (11). Treatment of 11 with triflic acid afforded [(L (OEt))(2) Zr][OTf](2) (12), whereas reaction of 11 with Ag (OTf) afforded a mixture of 12 and trinuclear [{L (OEt) Zr (SO (4))(H (2) O)}(3)(mu (3)-SO (4))][OTf] (13). The Zr (IV) triflato complex [L (OEt) Zr (OTf)(3)] (14) was prepared by reaction of L (OEt) ZrF (3) with Me (3) SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography. |
2(0,0,0,2) |