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Reactions of DNA Purines with Dirhodium Formamidinate Compounds That Display Antitumor Behavior

1999; American Chemical Society; Volume: 38; Issue: 17 Linguagem: Inglês

10.1021/ic990194n

1520-510X

K.V. Catalan, Jennifer S. Hess, Margaret Maloney, Daniel J. Mindiola, Donald L. Ward, Kim R. Dunbar,

Organometallic Complex Synthesis and Catalysis

The synthesis and characterization of products from reactions of Rh2(form)2(O2CCF3)2(CH3CN)2 (form = N,N'-p-ditolylformamidinate, N,N'-diphenylformamidinate) and the partially solvated [Rh2(DTolF)2(CH3CN)6][BF4]2 (DtolF = N,N'-p-ditolylformamidinate) with the DNA purine analogues, 9-ethylguanine, and 9-ethyladenine are described. X-ray crystallography was used to characterize Rh2(DTolF)2(O2CCF3)2(CH3CN)2 (1) which crystallizes in the space group P21/n with a = 10.849 (3) Å, b = 21.435 (6) Å, c = 18.677 (3) Å, V = 4340 Å3, Z = 4, R = 0.0451, and Rw = 0.0904. The two rhodium centers are bridged by four O2CCF3- ligands with a Rh−Rh distance of 2.24743(5) Å. Compound 1 reacts with 9-ethylguanine to form Rh2(DTolF)2(9-EtGH)2(O2CCF3)2 (3) which exists as two isomers, namely head-to-head and head-to-tail as confirmed by 1H NMR spectroscopy. [Rh2(DTolF)2(CH3CN)6][BF4]2 (5) crystallizes in the Pbca space group with a = 21.646 (3) Å, b = 31.272 (3) Å, c = 14.561(4) Å, V = 9857 Å3, Z = 8, R = 0.046, and Rw = 0.063. The Rh−Rh bond distance is 2.5594 (8) Å. The partially solvated compound 5 reacts with 9-ethyladenine and 9-ethylguanine to form [Rh2(DTolF)2(9-EtAH)2(CH3CN)][BF4]2 (6) and [Rh2(DTolF)2(9-EtGH)2(CH3CN)][BF4]2 (7), respectively. Compound 6 was characterized by X-ray crystallography as well as by variable temperature 1H NMR spectroscopy. [Rh2(DTolF)2(9-EtAH)2(CH3CN)][BF4]2 crystallizes in the P21/c space group with a = 15.648(8) Å, b = 16.575(5) Å, c = 20.026(8) Å, β = 105.17(4)°, V = 4994 Å3, Z = 4, R = 0.063, and Rw = 0.073. This compound contains two bridging DTolF- ligands as well as two 9-ethyladenine ligands bridging through the N7 and exocyclic N6 positions in a head-to-tail fashion. 1H NMR studies performed on 6 revealed that the N6 position is in the imino (NH-) form.