摘要 : para-Nitrobenzaldehyde semicarbazone undergoes an unusual chemical transformation upon reaction with [Rh(PPh3)(3)Cl] in the presence of trialkyl and dialkylamines (NR2R'; R = Et, Pr-i, Bu-n; R' = H or R' = R) via dissociation of t... 展开 para-Nitrobenzaldehyde semicarbazone undergoes an unusual chemical transformation upon reaction with [Rh(PPh3)(3)Cl] in the presence of trialkyl and dialkylamines (NR2R'; R = Et, Pr-i, Bu-n; R' = H or R' = R) via dissociation of the C-NH2 bond and formation of a new C-NR2 bond (where the NR2 fragment is provided by the amine). The transformed semicarbazone ligand binds to rhodium as a dianionic C,N,O-donor to afford complexes of type [Rh(PPh3)(2)(CNO-NR2)Cl] (CNO-NR2 = the coordinated semicarbazone ligand). Another group of semicarbazones (viz. salicylaldehyde semicarbazone, 2-hydroxyacetophenone semicarbazone, and 2-hydroxynaphthaldehyde semicarbazone) has also been observed to undergo a similar chemical transformation upon reaction with [Rh(PPh3)(3)Cl] under similar experimental conditions as before, and these transformed semicarbazones bind to rhodium as dianionic O,N,O-donors affording complexes of the type [Rh(PPh3)(2)(ONOn-NR2)Cl] (ONOn-NR2 = the coordinated sernicarbazone ligand; n = 1-3). The structure of the [Rh(PPh3)(2)(CNO-NEt2)Cl] and [Rh(PPh3)(2)-(ONO2-NR2)Cl] complexes has been determined. All the complexes show characteristic H-1 NMR signals. They also show intense absorptions in the visible and ultraviolet region. Cyclic voltammetry on the complexes shows an oxidative response within 0.52-0.97 V versus SCE and a reductive response within -1.00 to -1.27 V versus SCE, where both the responses are believed to be centered on the semicarbazone ligand. [References: 43] 收起