The reaction of N, N′-bis[o-(diphenylphosphino)benzylidene]-1,2-diaminoethane (L2) with one equivalent of RuCl2(PPh3)3 in dichloromethane at room temperature gave trans-RuCl2(PPh3)(κ3-L2) 2 in high yield. When refluxed in toluene in air, 2 was converted quantitatively to trans-RuCl2(κ4-L2) 3. When treated with one equivalent of hydrogen peroxide in chloroform, 2 was oxidized to trans-RuCl2(PPh3)(κ3-L 3) 4, in which the pendant phosphine has been oxidized to a phosphine oxide. Complex 4 can be further oxidized with another equivalent of hydrogen peroxide to trans-RuCl2(PPh3)(κ3-L4) 5, in which the amino group trans to PPh3 has been oxidized to an imino group. When treated with excess hydrogen peroxide in ethanol, 3 was oxidized to trans-RuCl2(κ4-L5) 6, in which the diamino moiety [-N(H)CH2CH2N(H)-] has been oxidized to a conjugated diimino moiety (-N=CHCH=N-). The solid-state structures of 2, 4, 5 and 6 were ascertained by X-ray crystallography. Catalytic studies show that 2 is an effective catalyst for the oxidation of alkanes, alkenes and alcohols with air or tert-butyl hydroperoxide. Experimental evidence suggests that free radicals are probably involved in the catalytic oxidation processes.
|Number of pages||8|
|Journal||Journal of the Chemical Society. Dalton Transactions|
|Publication status||Published - 2002|
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