Oxidative Addition of Small Molecules to a Dinuclear Au(I) Amidinate Complex, Au2[(2,6-Me2Ph)2N2CH]2. Syntheses and Characterization of Au(II) Amidinate Complexes Including One Which Possesses Au(II)-Oxygen Bonds

摘要

The dinuclear Au(I) amidinate complex Au2(2,6-Me2Ph-form)2 (1) is isolated in quantitative yield by the reaction of (THT)AuCI and the potassium salt of 2,6-Me2Ph-form in a 1:1 stoichiometric ratio. Various reagents such as Cl2, Br2, I2, CH3I, and benzoyl peroxide add to the dinuclear Au(I)amidinate complex Au2(2,6-Me2Ph-form)2 to form oxidative-addition Au(II) metal-metal-bonded complexes 2, 3, 4, 5, and 6. The Au(II) amidinate complexes are stable as solids at room temperature. The structures of the dinuclear Au2(2,6-Me2Ph-form)2 and the Au(II) oxidative-addition products Au2(2,6-Me2Ph-form)2X2, X = Cl, Br, I, are reported. Crystalline products with an equal amount of oxidized and unoxidized complexes in the same unit cell, [Au2(2,6-Me2Ph-form)2X2][Au2(2,6-Me2Ph-form)2], X = Cl, 2m, or Br, 3m, are isolated and their structures are presented. The structure of [Au2(2,6-Me2Ph-form)2X2][Au2(2,6-Me2Ph-form)2], X = Cl has a Au(II)—Au(II) distance slightly longer, 0.05A, than that observed in the fully oxidized product Au2(2,6-Me2-form)2Cl2,2. The gold-gold distance in the dinuclear complex decreases upon oxidative addition with halogens from 2.7 to 2.5 A, similar to observations made with the Au(I) dithiolates and ylides. The oxidative addition of benzoyl peroxide leads to the isolation of the first stable dinuclear Au(II) nitrogen complex possessing Au-O bonds, Au2(2,6-Me2Ph-form)2(PhCOO)2, 6, with the shortest Au-Au distance known for Au(II) amidinate complexes, 2.48 A. The structure consists of unidentate benzoate units linked through oxygen to the Au(II) centers. The replacement of the bromide in 3 by chloride, and the benzoate groups in 6 by chloride or bromide also occurs readily. The unit cell dimensions are, for 1, a = 7.354(6) A, b = 9.661(7) A, c = 11.421(10) A, alpha = 81.74(5)°, beta = 71.23(5)°, and gamma = 86.07(9)° (space group P1, Z = 1), for 2centre dot 1.5C6H12, a = 11.012(2) A, b = 18.464(4) A, c = 19.467(4) A, alpha = 90°, beta = 94.86(3)°, and gamma = 90° (space group P2_1/c, Z = 4), for 2m centre dot CICH2CH2CI, a = 16.597(3) A, b = 10.606(2) A, c = 19.809(3) A, alpha = 90°, beta = 94.155(6)°, and gamma = 90° (space group P2_1, Z = 2), for 3m, a = 16.967(3) A, b = 10.783(2) A, c = 20.060(4) A, alpha = 90°, beta = 93.77(3)°, and gamma = 90° (space group P2_1, Z = 2), for 4 centre dot THF, a = 8.0611(12) A, b = 10.956(16) A, c = 11.352(17) A, alpha = 84.815(2)°, beta = 78.352(2)°, and gamma = 88.577(2)° (space group P1, Z= 1), for 5, a = 16.688 A, b = 10.672(4) A, c = 19.953(7) A, alpha = 90.00 (6) °, beta = 94.565(7)°, and gamma = 90.00° (space group P2_1, Z= 4), for 6 centre dot 0.5C7H8, a = 11.160(3) A,b= 12.112(3) A, c = 12.364(3) A, alpha = 115.168(4)°, beta = 161.112(4)°, and gamma = 106.253(5)° (space group P1, Z=1).