PREPARATION OF SOME PLATINUM-LINKED ACRIDINES AND CRYSTAL-STRUCTURE OF (N,N,N',N'-TETRAMETHYLETHYLENEDIAMINE)PLATINUM(II) PERCHLORATE

The cationic platinum complex [Pt(eta2-C2H4)Cl(tmen)]+1 (tmen=N,N,N',N '-tetramethylethylenediamine) reacted with acridines {3,6-diaminoacrid ine [proflavine, NC13H7(NH2)2] and 3,6-bis(dimethylamino)acridine (acr idine orange, NC13H7(NMe2)2]} to give platinum species in which the me tal is linked to the polycyclic molecule by an ethylene chain. In the case of acridine orange the attack occurs at the endocyclic nitrogen g iving the complex [Pt{CH2CH2N13H7(NMe2)2}Cl(tmen)]+ 2 which is in equi librium with the starting species. On the contrary, in the case of pro flavine the attack occurs preferentially at the exocyclic aminic group s leading to the formation of [{PtCl(tmen)}2{HNC13H7(NHCH2CH2)2}]+3, w hich does not dissociate into its constituents. In 3 each NH2 group of the incorporated proflavine molecule has lost a proton, one of them h as been taken up by the endocylic nitrogen, the other by an extra mole cule of proflavine. Crystals of 2, obtained from a dichloromethane sol ution, were characterized by X-ray crystallography: space group P2(1)/ n, a = 7.700(4), b = 25.446(3), c = 14.858(6) angstrom, beta = 99.08(2 )-degrees and Z = 4. The refinement converged to R = 0.0572. The co-or dination around platinum is essentially square planar and the co-ordin ation plane makes an angle of 29.2(4)-degrees with the plane of the ac ridine moiety. The acridine rings are infinitely stacked in a head-to- tail fashion. The plane-to-plane distance is about 3.5 angstrom and th e closest Pt ... Pt distance is 5.178(2) angstrom.