Potential multifunctional anti-cancer metal complexes II. Synthesis of some rhodium(II) and platinum(II) complexes of diamine-substituted acridine-4-carboxamides, and the X-ray structure of [Rh(CH 3CO 2) 2L] 2 (L= N-[2-(dimethylamino)hexyl]acridine-4-carboxamide)

Abstract

The preparations are reported of [Rh(RCO 2) 2L] 2 (where R=CH 3, C 2H 5, and CH 3OCH 2; L is one of a series of N-[2-(dimethylamino)alkyl]acridine-4-carboxamide ligands in which the alkyl group is ethyl, n-butyl, or n-hexyl) and also the compounds (LH) 2PtCl 4. X-ray structural studies have been carried out on {Rh(CH 3CO 2) 2[ N-(2-dimethylamino)hexyl]acridine-4-carboxamide} 2 ( 1). Compound 1 is triclinic, space group P 1 , with a=8.149(1), b=8.494(2), c=37.647(10) Å, α=92.49(2), β=95.45(2), γ=91.26(2)°, V=2591 Å 3, Z=4 (two crystallographically independent molecules). The acridine-4-carboxamide binds to the dinuclear rhodium(II) acetate unit via the N(CH 3) 2 nitrogen atom with RhN bond distances of 2.339(6) and 2.349(5) Å, respectively for the two crystallographically independent molecules. In common with the analogous complex formed by 6-chloro-9-(2-dimethylaminoethyl)amino-2-methoxyacridine (D M.L. Goodgame, C.J. Page and D.J. Williams, Inorg. Chim. Acta, 153 (1988) 219), the acridine units form a continuous stack in the crystal, though with different overlapping orientations. In 1 the significantly longer diamine side chain distances the acridine nitrogen atom N(10) c. 11 Å from the nearest rhodium atom.