title: p-Tolylimido rhenium(v) complexes with phenolate-based ligands: synthesis, X-ray studies and catalytic activity in oxidation with tert-butylhydroperoxide.
abstract: The reactions of mer-[Re(p-NTol)X3(PPh3)2] (X = Cl, Br) with chelating phenolate-based ligands (2-(2-hydroxy-5-methylphenyl)benzotriazole (HL(1)), 2-(2-hydroxyphenyl)benzothiazole (HL(2)) or 2-(2-hydroxyphenyl)benzoxazole (HL(3))) afforded a series of p-tolylimido rhenium(v) complexes cis- or trans-(X,X)-[Re(p-NTol)X2(L)(PPh3)]·yMeCN (where X = Cl, Br; L = L(1), L(2), L(3) and y = 0-2) and [Re(p-NTol)X(L)(PPh3)2]Z·pPPh3 (where X = Cl, Br; Z = ReO4, PF6; L = L(1), L(2), L(3) and p = 0 or 1). The reported compounds were characterized by elemental analysis, FT-IR, NMR ((1)H, (13)C and (31)P) and X-ray crystallography. Interestingly, the halide ions of [Re(p-NTol)Cl2(L(1))(PPh3)]·MeCN (1) and [Re(p-NTol)Cl2(L(2))(PPh3)]·2MeCN (3) are in cis relative dispositions, whereas the complexes [Re(p-NTol)Br2(L)(PPh3)] (L(1) for 2, L(2) for 4 and L(3) for 6) and [Re(p-NTol)Cl2(L(3))(PPh3)] (5) were found to be trans-(X,X) isomers. The compounds [Re(p-NTol)X(L)(PPh3)2](PF6) (X = Cl, Br; L = L(1) and L(2)) and [Re(p-NTol)X(L(3))(PPh3)2](PF6)·PPh3 (X = Cl, Br) have been tested in oxidative catalysis. A few compounds exhibited very good catalytic properties in oxidation of alcohols with tert-BuOOH (TBHP) in acetonitrile solution at moderate temperatures. Complex [Re(p-NTol)Cl(L(2))(PPh3)2]PF6 (13) is the catalyst of choice for oxidation of 1-phenylethanol to acetophenone (in 80% yield; turnover number attained 290 after 30 h) and cyclooctanol to cyclooctanone (in 88% yield). Notably lower activity has been found in the oxidation of alkanes with TBHP. Product distribution in the oxidation of methylcyclohexane indicates some steric hindrance around the reaction center.
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. basia@ich.us.edu.pl.
authors.forename: Izabela
authors.initials: I
authors.lastname: Gryca
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. basia@ich.us.edu.pl.
authors.forename: Barbara
authors.initials: B
authors.lastname: Machura
authors.affiliation: Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland. basia@ich.us.edu.pl.
authors.forename: Jan Grzegorz
authors.initials: JG
authors.lastname: Małecki
authors.affiliation: Institute of Physics, University of Silesia, 40-007 Katowice, Poland.
authors.forename: Joachim
authors.initials: J
authors.lastname: Kusz
authors.affiliation: Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ulitsa Vavilova, dom 28, Moscow 119991, Russia.
authors.forename: Lidia S
authors.initials: LS
authors.lastname: Shul'pina
authors.affiliation: Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, ulitsa Vavilova, dom 28, Moscow 119991, Russia.
authors.forename: Nikolay S
authors.initials: NS
authors.lastname: Ikonnikov
authors.affiliation: Semenov Institute of Chemical Physics, Russian Academy of Sciences, ulitsa Kosygina, dom 4, Moscow 119991, Russia. Shulpin@chph.ras.ru and Plekhanov Russian University of Economics, Stremyannyi pereulok, dom 36, Moscow 117997, Russia.
authors.forename: Georgiy B
authors.initials: GB
authors.lastname: Shul'pin