Bidentate 1,3-diaminopropane

Although earlier attempts to isolate chromium(II) complexes of various bidentate amines from aqueous solutions produced chromium(III) complexes and hydrogen, the predominantly non-aqueous methods outlined in Scheme 10 provide complexes of ethylenediamine (en), 1,2-diaminopropane (pn), 1,3-diaminopropane (tmd), l,2-diamino-2-methylpropane (dmp), jVjA-dimethylethylenediamine (NNdmn) and N, N -dimethylethylenediamine (NN dmn) (Table 11). In general, ethanol is a suitable solvent but with some amines it is necessary to dehydrate the halide with 2,2-dimethoxypropane (DMP) and dry the ethanol carefully to prevent hydrolysis and oxidation. 

Both monodentate and bidentate amines form cationic complexes. Reactions of [MX(S2CNMe2)] (X = Cl, Br) with a wide range of amines has been carried out, the nature of the product being sensitive to the stoichiometry of the reaction. Neutral products, [MX(amine)(S2CNMe2)], are obtained when 1 equiv of amine is added, while cations, [M(amine)2(S2CNMe2)]X, result upon addition of 2-3 equiv. With the bidentate amines, ethylenediamine and 1,3-diaminopropane, cationic products [M(diamine)(S2CNMe2)]X always ensue (1609,1610). 

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