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The known (tetraphenyl-η4-cyclobutadiene)-η5-cyclopentadienylcobalt (1) and a series of its new substituted derivatives have been prepared. The electronic states of a few representatives have been characterized by absorption and magnetic circular dichroism. Time-dependent density functional theory has been used to arrive at spectral assignments for several prominent low-energy bands. The absorption spectra of the radical ions of 1 have also been recorded.

The trinuclear [{Ru(NH3)4(py-COOH)}(μ-CN){Ru(bpy)2}(μ-CN){Ru(NH3)4(py-COOH)}]6+ (py-COOH = isonicotinic acid, bpy = 2,2'-bipyridine) (1) and dinuclear [{Ru(dcb)2}2L]7- (dcb = 2,2'-bipyridine-4,4'-dicarboxylic acid, H3L = 9-phenyl-2,3,7-trihydroxy-6-fluorone) (2) complexes were prepared and their spectroelectrochemical behaviour characterised in solution and on conductive glass electrodes layered with Sb-doped nanocrystalline SnO2. The systems display a reversible redox response in a narrow potential range (-0.5 to +0.5 V vs SCE) and offer the possibility of controlling colour changes of electrochromic devices through variations of the coordinated and bridging ligands at the metal centres. SnO2(Sb) electrodes loaded with these dyes show switching times of the order of ms.

A synthetic approach to a two-dimensional grid polymer is proposed and the execution of initial steps is described. Pd-catalyzed coupling of (1,12-dicarba-closo-dodecaboran-1-yl)copper (10) with iodobenzene, m-diiodobenzene, and 1,3,5-triiodobenzene yielded the known 1,12-dicarba-closo-dodecaboran-1-ylbenzene (3) and the new m-bis(1,12-dicarba-closo-dodecaboran-1-yl)benzene (4) and 1,3,5-tris(1,12-dicarba-closo-dodecaboran-1-yl)benzene (1), respectively. Each arm of the trigonal connector 1 was provided with one or two sticky tentacles by conversion to 1,3,5-tris[12-((3-(ethylthio)propyl)dimethylsilyl)-1,12-dicarba-closo-dodecaboran-1-yl]benzene (7) and 1,3,5-tris[12-(bis(3-(ethylthio)propyl)methylsilyl)-1,12-dicarba-closo-dodecaboran-1-yl]benzene (8). Linear coupling of carboranyl CH terminals through a mercury atom produced very stable dimeric structures from 3 and 4. The carborane 3, its mercury-linked dimer 13, the 1:1 complex of 13 with 2,2‘-bipyridyl, and the 2:1 complex of 13 with 2,2‘-bipyrimidyl ...

The first example of a binuclear ruthenium complex involving the p-carborane framework in the bridging ligand is reported. The bridging ligand is a symmetric linear array comprising a central p-carborane unit, two p-phenylene spacers, and two 5-yl-2,2'-bipyridine coordinating units. A homobinuclear Ru(II) complex, with 2,2'-bipyridine as peripheral ligands, was synthesized and characterized. The Ru(II)-Ru(III) mixed-valence species, obtained by partial oxidation, has been investigated with steady-state and time-resolved techniques in CH3CN. The rate of photoinduced electron transfer is 2.3 x 10(8) s(-1).

A series of cyano-bridged binuclear mixed valence complexes of the general formula M-Ru(III)(NH(3))(4)pyCOOH [pyCOOH = isonicotinic acid; M = cis-Ru(bpy)(2)(CN)(2), 1 (bpy = 2,2' bipyridine); trans-Ru(py)(4)(CN)(2), 2 (py = pyridine); [Ru(CN)(6)](4)(-), 3; [Fe(CN)(6)](4)(-), 4] have been prepared and anchored through the carboxylic function to nanocrystalline TiO(2) or SnO(2) electrodes. The complexes display a reversible electrochromic behavior in the range of applied potential from -0.5 to +0.5 V, versus SCE. Tuning of the electronic transitions in the visible and near-infrared spectral regions is achieved through changes of the solvent and of the cyano-bridged metal moiety M.