Amidino-O-alkylureas

The structures of 16 copper(II) complexes of bidentate amidino-O-alkylureas ([CuL jyXj) have been determined by single crystal methods [59-61,63-66]. The range of ligands and of copper(II) salts studied is summarised in Table 2. Although the N-alkylamidino-O-alkylurea derivatives form part of the systematic study by Suksangpanya et al. [59-61] [Cu(LHm)2]Cl2 [66], [Cu(LHm)2]Br2 [63], [Cu(LHe)2] Cl2 [64] and [Cu(LHe)2]Br2 [65] were prepared in independent studies. 

The potential triple A D D D A A interaction between cytosine and bis(amidino-0-methylurea)ethane, when co-ordinated to copper(II), is shown in Scheme 12 (l.h.s.). Alternative complementary interactions between amidino-O-alkylureas and DNA pyrimidine bases include the double D A A-D interaction with thymine shown in Scheme 12 (r.h.s.). 

Donor properties of 1-amidino-O-alkylureas. R. L, Dutta and A. Syamal, Coord. Chem. Rev., 1967,2,441-459(65). 

In a recent series of experiments, Suksangpanya et al. [67] have investigated the interactions between pyrimidine bases and [Cu(Lkl)]2+ cations. Amidino-O-alky-lureas contain an A-D-D sequence, similar to that of guanine. The only difference lies in the oxygen acceptor, which is part of an ether linkage in the amidino-0-alkylurea but part of a carbonyl functionality in guanine. Despite this difference, the formation of a triple complementary interaction between amidino-O-alky-lurea and cytosine, which has a D-A-A sequence was thought to be feasible. 

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