Syntheses, Characterization, and Catalytic Ability in Alkane Oxygenation of Chloro(dimethyl sulfoxide)ruthenium(II) Complexes with Tris(2-pyridylmethyl)amine and Its Derivatives^1,2

Abstract

New ruthenium(II) complexes having a tetradentate ligand such as tris(2-pyridylmethyl)amine (TPA), tris[2-(5-methoxycarbonyl)pyridylmethyl]amine [5-(MeOCO)3-TPA], tris(2-quinolylmethyl)amine (TQA), or bis(2-pyridylmethyl)glycinate (BPG) have been prepared. The reaction of the ligand with [RuCl2(Me2SO)4] resulted in a mixture of trans and cis isomers of the chloro(dimethyl sulfoxide-kappaS)ruthenium(II) complexes containing a TPA or a BPG, whereas a trans(Cl,N(amino)) isomer was selectively obtained for 5-(MeOCO)3-TPA and TQA. The trans and cis isomers of the [RuCl(TPA)(Me2SO)]+ complex were easily separated by fractional recrystallization. The molecular structures of trans- and cis(Cl,N(amino))-[RuCl(TPA)(Me2SO)]+ complexes and the trans(Cl,N(amino))-[RuCl{5-(MeOCO)3-TPA}(Me2SO)]+ complex have been determined by X-ray structural analyses. The reaction of TPA with [RuCl2(PhCN)4] gave a single isomer of the chloro(benzonitrile)ruthenium(II) complex, whereas the bis(benzonitrile)ruthenium(II) complex was obtained with BPG. The cis(Cl,N(amino))-[RuCl(TPA)(Me2SO)]+ complex is thermodynamically much less stable than the trans isomer and isomerizes in dimethyl sulfoxide at 65-100 degrees C. Oxygenation of alkanes catalyzed by these ruthenium(II) complexes has been examined. The chloro(dimethyl sulfoxide-kappaS)ruthenium(II) complexes with TPA and its derivatives using m-chloroperbenzoic acid as a cooxidant showed high catalytic ability. Adamantane was efficiently and selectively oxidized to give 1-adamantanol up to 88%. The chloro(dimethyl sulfoxide-kappaS)ruthenium(II) complex with 5-(MeOCO)3-TPA was found to be the most active catalyst among the complexes examined.

Synthesis, Structure and Spectral, and Electrochemical Properties of New Mononuclear Ruthenium(III) Complexes of Tris[(benzimidazol‐2‐yl)methyl]amine: Role of Steric Hindrance in Tuning the Catalytic Oxidation Activity

“…Several ruthenium complexes of nitrogen-containing ligands have drawn much attention as oxidation catalysts and have shown high catalytic ability towards alkane oxygenation of both saturated and unsaturated hydrocarbons. [10][11][12][13][14][15][16][17] Thus the tripodal 4N ligand tris-(pyrid-2-ylmethyl)amine (tpa, Scheme 1) and its derivatives have attracted considerable interest and metal complexes of first-row transition metals and a few second-and third-row transition metal complexes have been explored. [12,13] The tpa ligand, which includes a σ-donating tertiary amine and three π-accepting pyridine nitrogens, confers on ruthenium interesting excited-state properties [12] and also catalytic properties.…”

“…These complementary reactivities of ruthenium complexes, regulated by substituents at the 6 position of the tpa-type ligand, may have both a steric effect and an electronic effect on the catalytic ability. Recently, Yamaguchi et al reported [17] the chloro(dimethyl sulfoxide)ruthenium(II) complexes of tpa and its derivatives 5-(MeOCO) 3 -tpa, tqa [tqa = tris(2-quinolylmethyl)amine], and bpg [bpg = bis-(pyrid-2-ylmethyl)glycinate]. The use of m-CPBA as a cooxidant showed efficient catalytic ability towards oxidation of adamantane to 1-adamantanol with a high selectively of up to 88 %.…”

Oxidations catalyzed by osmium compounds. Part 1: Efficient alkane oxidation with peroxides catalyzed by an olefin carbonyl osmium(0) complex

“…In last decades, new methods of alkane functionalization with participation of various transition metal complexes in solutions have been discovered and developed (see recent books and reviews [1][2][3][4][5][6][7][8][9][10]) and original publications [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Organometallic derivatives of transition metals very seldom exhibit high activity in alkane oxygenations [29,30].…”

Ligand Oxidation of a Deprotonated Bis(picolyl)amine IrI(cod) Complex

“…[6] Also these ligands are valuable in late transition metal (organometallic) chemistry, especially in alkane oxidation (Ru), [7] olefin oxidation (Rh, Ir), [8] and stabilisation of reactive organometallic radical complexes (Rh, Ir).…”