1070-3632/03/7311-1821 $25.00 2003 MAIK Nauka/Interperiodica Russian Journal of General Chemistry, Vol. 73, No. 11, 2003, pp. 1821 1822. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 11, 2003, pp. 1922 1923. Original Russian Text Copyright 2003 by Ivanov, Puzyk, Balashev. LETTERS TO THE EDITOR Preparation and Spectral Properties of Au(III) Complexes with Heterocyclic Diimine Ligands M. A. Ivanov, M. V. Puzyk, and K. P. Balashev Herzen Russian State Pedagogical University, St. Petersburg, Russia Received December 24, 2002 Progress in the chemistry of electronically excited states of coordination compounds is associated with discovery of a new class of complexes exhibiting long-lived luminescence. These are coordination com- pounds of platinum group metals of nd 6 and nd 8 elec- tronic configurations with polypyridine and cyclomet- allating ligands [1 4]. This work continues the studies of complexes of Au(III) as an isoelectronic analog of Pt(II) [5, 6]. We prepared and characterized by NMR and electronic spectroscopy new Au(III) complexes of the type [Au(N^N)Cl 2 ], where N^N are diimine heterocyclic ligands: 2,2 -bipyridine (bpy), 1,10-phenanthroline (phen), and their dimethyl derivatives: 2,9-dimethyl- 1,10-phenanthroline (Me 2 -phen) and 4,4 -dimethyl- 2,2 -bipyridine (Me 2 -bpy). The complexes are stable both in the solid state and in various solvents (H 2 O, CH 3 CN, CH 3 OH, DMF). We found that the electronic absorption spectrum of the mixed-ligand diimine complexes of Au(III) is characterized by three types of spin-allowed bands in the UV range. The bands corresponding to the d* charge transfer from the heterocyclic ligand to metal are located at about 230 nm. The intraligand -type transitions involving orbitals localized mainly on the heterocyclic diimine ligands (275 310 nm) show a long-wave shift relative to the free ligand [2]. The third band ( 320 nm), absent in the spectrum of the free ligand, was assigned to metal-to-ligand (d * type) charge transfer. The luminescence at 77 K was detected only for Au(III) phenanthroline complexes. The luminescence spectra have a well-defined vibronic structure ( 1500 cm 1 ) originating from vibrations of the C=C(N) bonds in the phenanthroline ligand, with a slight long- wave shift relative to the spectrum of the free ligand. The spectral range is the same as for the previously studied cyclometallated Au(III) 2-phenylpyridinate complexes [5]. The luminescence lifetime lum is of the order of microseconds. These data show that the luminescence is due to the spin-forbidden intraligand 3 ( *) type transition with slightly admixed metal- localized states. Dichloro(2,2 -bipyridine)gold(III) perchlorate [AubpyCl 2 ]ClO 4 was prepared by a procedure modi- fied relative to that described in [7]. A 1-mmol portion of bpy was dissolved in 2 ml of hot (40 C) water to form a suspension. An aqueous solution of H[AuCl 4 ] (c 10 2 M) was added dropwise with stirring. A yel- low precipitate formed initially, which dissolved in the course of subsequent refluxing. To the resulting hot true solution of the Au(III) complex, a saturated NaClO 4 solution was added, and a light yellow pre- cipitate was obtained. The precipitate was collected on a paper filter, washed with cold water, and vacuum- dried; yield 77%. Electronic absorption spectrum (CH 3 CN), max , nm ( 10 3 , mol l 1 cm 1 ): 222 (44.00), 313 (13.9). 1 H NMR spectrum (CD 3 OD), , ppm (J, Hz): 9.57 d (H 3 , J HH 5.7), 8.84 d (H 6 , J HH 8.4), 8.68 t (H 5 , J HH 7.7), 8.14 t (H 4 , J HH 7.0). Dichloro(4,4 -dimethyl-2,2 -bipyridine)gold(III) chloride Au(Me 2 -bpy)Cl 2 ]Cl. A solution of H[AuCl 4 ] (c 10 2 M) was added dropwise with stirring to a hot (40 C) aqueous suspension of Me 2 -bpy (1 mmol in 2 ml of water). A yellow precipitate formed, which grew light in the course of subsequent refluxing for 1 h. The precipitate was collected on a filter, washed with cold water, and dried at 350 K; yield 68%. Elec- tronic absorption spectrum, max , nm ( 10 3 , mol l 1 cm 1 ): 230 (33.0), 312 (11.1). 1 H NMR spec- trum (CD 3 OD), , ppm (J, Hz): 9.34 d (H 3 , J HH 6.3), 8.69 d (H 6 , J HH 8.4), 7.93 d (H 5 , J HH 6.3). Dichloro(1,10-phenanthroline)gold(III) per- chlorate [AuphenCl 2 ]ClO 4 was prepared by the modified procedure (cf. [8]); yield 81%. Electronic absorption spectrum (CH 3 CN), max , nm ( 10 3 ,