Phosphato, Chromato, and Perrhenato Complexes of Titanium(IV) and Zirconium(IV) Containing Kla 1 ui’s Tripodal Ligand Xiao-Yi Yi, Qian-Feng Zhang, Tony C. H. Lam, Eddie Y. Y. Chan, Ian D. Williams, and Wa-Hung Leung* Department of Chemistry, The Hong Kong UniVersity of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P. R. China Received August 4, 2005 Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL OEt (L OEt - ) [(η 5 -C 5 H 5 )Co{P(O)(OEt) 2 } 3 ] - ) in the presence of Na 3 PO 4 and Na 4 P 2 O 7 led to isolation of [(L OEt Ti) 3 (µ-O) 3 (µ 3- PO 4 )] (1) and [(L OEt Ti) 2 (µ-O)(µ-P 2 O 7 )] (2), respectively. The structure of 1 consists of a Ti 3 O 3 core capped by a µ 3 -phosphato group. In 2, the [P 2 O 7 ] 4- ligands binds to the two Ti’s in a µ:η 2 ,η 2 fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL OEt and 1.5 equiv of Na 2 Cr 2 O 7 gave [(L OEt Ti) 2 (µ-CrO 4 ) 3 ](3) that contains two L OEt Ti 3+ fragments bridged by three µ-CrO 4 2- -O,O′ ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L OEt Ti(OTf) 3 ] (OTf - ) triflate) with [n-Bu 4 N][ReO 4 ] afforded [{L OEt Ti(ReO 4 ) 2 } 2 (µ-O)] (4). Treatment of [L OEt MF 3 ] (M ) Ti and Zr) with 3 equiv of [ReO 3 (OSiMe 3 )] afforded [L OEt Ti(ReO 4 ) 3 ](5) and [L OEt Zr(ReO 4 ) 3 (H 2 O)] (6), respectively. Treatment of [L OEt MF 3 ] with 2 equiv of [ReO 3 (OSiMe 3 )] afforded [L OEt Ti- (ReO 4 ) 2 F] (7) and [{L OEt Zr(ReO 4 ) 2 } 2 (µ-F) 2 ](8), respectively, which reacted with Me 3 SiOTf to give [L OEt M(ReO 4 ) 2 - (OTf)] (M ) Ti (9), Zr (10)). Hydrolysis of [L OEt Zr(OTf) 3 ](11) with Na 2 WO 4 ‚xH 2 O and wet CH 2 Cl 2 afforded the hydroxo-bridged complexes [{L OEt Zr(H 2 O)} 3 (µ-OH) 3 (µ 3 -O)][OTf] 4 (12) and [{L OEt Zr(H 2 O) 2 } 2 (µ-OH) 2 ][OTf] 4 (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L OEt Ti IV complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates. Introduction Metal ions in oxygen-rich coordination environments have attracted much attention because of their relevance to metal oxo surfaces in heterogeneous catalysts. 1 In this connection, a lot of efforts have been made to synthesize mononuclear and polynuclear metal complexes containing O-donor ligands as molecular models for metal oxide catalysts. Of importance are oxygen-rich titanium complexes due to the significance of titanium-containing silicates and zeolites in catalytic organic oxidation. Thus, Ti(IV) complexes with polydentate oxygen ligands such as calixarenes, 2-5 trialkoxides, 6 and bis- (phenolates) 7 have been synthesized and their catalytic activities have been studied extensively. We have a long-standing interest in the organometallic chemistry of Kla ¨ui’s tripodal ligand L OEt - ([CpCo{P(O)- (OEt) 2 } 3 ] - , where Cp ) η 5 -C 5 H 5 ) (Chart 1) that has been * To whom correspondence should be addressed. E-mail: chleung@ust.hk. 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