Judith L. Kerschner

The dinuclear manganese complex Mn2O(OAc)2(TPTN) as a catalyst for epoxidations with hydrogen peroxide

In acetone and at ambient temperature, the dinuclear manganese complex of TPTN is able to catalyse the oxidation of several alkenes to the corresponding epoxides with high turnovers numbers (up to 900) using H2O2 as oxidant.

Synthesis and structure of some asymmetric aryloxide derivatives of zirconium(IV): X-ray crystal structures of Cp2Zr(OAr-2,4Me2,6cyMe)(CH2Ph) and Cp2Zr(OAr-2Me,6But)(η2-ButNCCH2Ph), where OAr-2,4Me2,6cyMe = 2,4-dimethyl,6-(α-methylcyclohexyl)phenoxide and OAr-2Me,6But = 2-methyl,6-tert-butylphenoxide

Abstract Reaction of all asymmetric phenols 2-methyl,6-tert-butylphenol (HOAr-2Me,6But) and 2,4-dimethyl,6-(α-methylcyclohexyl)phenol (HOAr-2,4Me2,6cyMe) with Cp2Zr(CH2Ph)2 at 120°C in toluene leads to the slow formation of the mono-substituted derivatives Cp2Zr(OAr-2Me,6But)(CH2Ph) (1) and Cp2Zr(OAr-2,4Me2,6cyMe)(CH2Ph) (2) along with one equivalent of toluene. A single crystal X-ray diffraction analysis of 2 confirmed the stoichiometry and shows the carbon and oxygen atoms of the benzyl and aryloxide ligands occupying positions about the zirconium atom typical of Cp2Zr(X)(Y) type compounds. The large ZrOAr angle of 165.3(5)° results in the aryloxide occupying a “wedge-like” space within the coordination sphere. This wedge is oriented within the plane which bisects the metallocene unit, i.e. almost coplanar with the ZrCO plane, and is oriented so that the bulky α-methylcyclohexyl group lies next to the benzyl ligand. The reaction of 1 with ButNC also takes place very slowly leading to the η2-iminoacyl compound Cp2Zr(OAr-2Me,6But)(η2-ButNCCH2Ph) (3). Despite the steric demands of the bulky aryloxide ligand, the spectroscopic and structural data on 3 show the iminoacyl to be η2-bonded to zirconium, ZrN = 2.244(4) A, ZrC = 2.208(5) A. In the solid state the 18-electron compound 3 has the η2-iminoacyl group lying along the plane bisecting the metallocene unit. Crystal data at 20°C for ZrOC34H42 (2): a = 10.201(1), b = 14.372(3), c = 20.365(3) A, β = 95.210(9)°, Z = 4, dcalc = 1.287 g cm−3 in space group P21/n; for ZrONC33H41 (3): a = 9.708(1), b = 10.698(1), c = 27.829(3) A, Z = 4, dcalc = 1.284 g cm−3 in space group P212121.

Synthesis, structure and spectroscopic properties of some 2-phenylphenoxide derivatives of molybdenum

Abstract Treatment of the molybdenum dimethylamido compounds, Mo(NMe2)4 and Mo2(NMe2)6 (MoMo), with 2-phenylphenol (HOAr-2Ph), leads to formation of the aryloxide compounds, Mo(OAr-2Ph)4(HNMe2)2 (1) and Mo2(OAr-2Ph)6(HNMe2)2 (2), respectively. A single crystal X-ray diffraction analysis of 1 shows a trans arrangement of dimethylamine ligands about the octahedral MoO4N2 core, while in 2 an unbridged O3NMoMoNO3 central coordination environment is present. Spectroscopic studies on 2 indicate a significant barrier to rotation about the unbridged molybdenum-molybdenum triple bond, presumably due to the steric demands of the OAr-2Ph ligands. Crystal data for MoO4N2C52H50 (1) at 21°C: a = 9.617(6), b = 10.199(1), c = 12.315(7) A, α = 107.04(2), β = 106.29(5), γ = 95.46(2)δ, Z = 1, dcalc = 1.317 g cm−3 in space group P1 ; for Mo2O6N2C83H70 (2) at 19°C: a = 22.890(2), b = 13.854(4), c = 24.337(2) A, β = 113.969(8)°, Z = 4, dcalc = 1.303 g cm−3 in space group P21/c.