The molecular structures of Au(2,2′-bpy)Cl3·2.25H2O and its 1-methyluracil adduct [Au(2,2′-bpy)( 1-MeU)2] ClO4·4H2O
1989; Elsevier BV; Volume: 165; Issue: 1 Linguagem: Inglês
10.1016/s0020-1693(00)83401-5
ISSN1873-3255
AutoresWolfgang Micklitz, Bernhard Lippert, Gerhard Müller, Patrizia Mikulcik, Jürgen Riede,
Tópico(s)Organometallic Complex Synthesis and Catalysis
ResumoThe molecular structures and spectroscopic data (IR, 1H NMR) of two Au(III) complexes are reported, Au(2,2′-bpy)Cl3·2.25H2O (1) and [Au(2,2′-bpy)- (1-MeU)2]ClO4·4H2O (2b) (1-MeU = 1-methyluracil anion, C5H5N2O2). 1 crystallizes in the space group C2/c with a = 35.452(3), b = 7.701(1), c = 22.115(2) Å, β = 90.67(1)°, V = 6037.3 Å3, Z = 16.2b crystallizes in the space group P1 with a = 7.930(1), b = 12.606(1), c = 13.768(1) Å, α = 93.46(1)°, β = 102.62(1)°, γ = 96.74(1)°, V = 1328.5 Å3, Z = 2. 1 is best described as consisting of dinuclear units, built up from two planar (2,2′-bpy)AuCl2 entities that are connected via a long AuClAu bridge of 3.218(3) Å (AuCl, av.). The 2,2′-bpy rings are almost parallel and within the dinuclear unit c. 6.26 Å (av.) apart. 1 reacts with AgX and excess 1-MeU to give [Au(2,2′-bpy)(1-MeU)2]X·nH2O (2). In 2b (X = ClO4−, n = 4), the arrangement of the two 1-MeU ligands in the solid state is head-to tail, but 1H NMR suggests that in aqueous solution this rotamer coexists with the head-to-head species. Comparison of 2b with the corresponding Pt(II) and Pd(II) complexes reveals that, in its effect on the 1-MeU ring (internal ring angle at N3, IR spectrum, basicity of exocyclic oxygen, donor properties toward heterometals), the Au(III) electrophile behaves very much different and in this respect is close to the effect of a H+. Both in strongly acidic and strongly alkaline solution, 1-MeU is displaced from 2 to give [(2,2′-bpy)Au(1-MeU)(H2O)]2+ (5) and [(2,2′-bpy)Au(1-MeU)(OH)]+ (5′), respectively.
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