Crystal structures and luminescence spectra of transition metal complexes of rhodamine 6G:: R2[CuCl4]•3H2O and R2[MnCl4]•(EtCH)1/2 [R=9-(2-ethoxycarbonyl)phenyl-3,6-bis(ethylamino)-2,7-dimethylxanithylium]

Bis(9-(2-ethoxycarbonyl)phenyl-3,6-bis(ethylamino)-2,7-dimethylxanthylium) tetrachlorocopper(II) trihydrate solvate (1) was obtained by reaction of rhodamine 6G with CuCl(2)6H(2)O in the presence of hydrochloride under reflux for 1 h, the structure of which was determined by X-ray diffraction. The complex belongs to the monoclinic space group C2/c, with a = 28.271(7), b = 14.829(2), c = 15.892(3) Angstrom, beta = 117.29(1)degrees, V = 5921(2) Angstrom(3), Z = 4, R-1 = 0.0994, wR(2) = 0.2424. The copper ion is located on crystallographic two-fold a.xis and has a coordination geometry intermediate between tetrahedral and square planar. There are hydrogen-bonding interactions among tetrachloro cuprate(2-) ions and rhodamine 6G cations, and pi-pi stacking interactions between rhodamine 6G cations. Another transition metal complex of rhodamine 6G bis(9-(2-ethoxycarbonyl)phenyl-3,6-bis (ethylamino)-2,7-dimethylxanthylium) tetrachloro manganese(II) demiethanol solvate (2) was prepared by reflux of ethanol solution of rhodamine 6G and MnCl(2)6H(2)O for 1 h. This complex crystallizes in the triclinic space group P-1 with a = 11.677(2), b = 12.532(1), c = 20.683(1) Angstrom, alpha = 99.42(3), beta = 99.57(1), gamma = 96.46(2), V = 2913.8(5), Z = 2, R-1 = 0.0659, wR(2) = 0.1300. The anion MnCl42- exhibits a very slightly distorted tetrahedron with Mn-Cl bond distances 2.355(1)-2.375(1) Angstrom. All chlorine atoms in MnCl42- are hydrogen-bonded to the ethanol molecules and rhodamine 6G cations, and there are pi-pi stacking interactions between rhodamine 6G cations. Blue-shifts were observed in the solid state fluorescence of complex 1 and 2 with respect to rhodamine 6G. The larger blue-shift of complex 1 relative to that of complex 2 could be attributed to the packing effects. In addition, the IR-spectra of two compounds are discussed and related to their structures.