Transition metal cyanides

Polynuclear transition metal cyanides such as the well-known Prussian blue and its analogues with osmium and ruthenium have been intensely studied Prussian blue films on electrodes are formed as microcrystalline materials by the electrochemical reduction of FeFe(CN)g in aqueous solutionThey show two reversible redox reactions, and due to the intense color of the single oxidation states, they appear to be candidates for electrochromic displays Ion exchange properties in the reduced state are limited to certain ions having similar ionic radii. Thus, the reversible... 

Ludi A, Gudel HU (1973) Structural Chemistry of Polynuclear Transition Metal Cyanides. 14 1-21... 

Investigations of cyanides and cyano complexes of Cd and Hg have augmented tremendously since about 1990, after detection of inclusion compounds of Cd(CN)2. A thorough review on transition-metal cyanides especially emphasizes the chemistry of inclusion compounds of both the Hofmann type (frameworks dominated by planar Ni(CN)4 building blocks) and the cyanocad-mate type (frameworks with tetrahedral Cd(CN)4 units).87 The structures of these inclusion compounds, but also of cyanides themselves, often topologically resemble the structures of minerals this aspect ( mineralomimetic chemistry ) is dealt with in a simultaneous survey.88 A more generic review of framework structures, with a section on cyanide inclusion compounds, is also to be mentioned.90... 

Dunbar, K. R. Heintz, R. A. Chemistry of Transition Metal Cyanide Compounds Modern Perspectives. In Progress in Inorganic Chemistry, Karlin, K. D., Ed. J. Wiley New York, 1997, Vol. 45, pp 283-391. 

K. Itaya, I. Uchida, and V.D. Neff, Electrochemistry of polynuclear transition metal cyanides Prussian blue and its analogues. Aco. Chem. Res. 19, 162—168 (1986). 

Dunbar, Kim R. and Heintz, Robert A., Chemistry of Transition Metal Cyanide... 

Transition Metal Cyanides and Their Complexes B. M. Chadwick and A. 0. Sharpe... 

Discovery. These catalysts were discovered during a study of the use of transition metal cyanides in combination with metal alkyl and hydride reducing agents in polymerizations. The combination of nickel cyanide and lithium aluminum hydride complexed very strongly with tetrahydrofuran. A similar complexing action occurred with propylene oxide and nickel hexacyanoferrate(II)-lithium aluminum hydride. This led to speculation as to the role of the double-metal cyanide itself. 

Dyes such as erythrosin B [172], eosin [173-177], rose bengal [178,179], rhodamines [180-185], cresyl violet [186-191], thionine [192], chlorophyll a and b [193-198], chlorophyllin [197,199], anthracene-9-carboxylate [200,201], perylene [202,203] 8-hydroxyquinoline [204], porphyrins [205], phthalocyanines [206,207], transition metal cyanides [208,209], Ru(bpy)32+ and its analogs [83,170,210-218], cyanines [169,219-226], squaraines [55,227-230], and phe-nylfluorone [231] which have high extinction coefficients in the visible, are often employed to extend the photoresponse of the semiconductor in photoelectro-chemical systems. Visible light sensitization of platinized Ti02 photocatalyst by surface-coated polymers derivatized with ruthenium tris(bipyridyl) complex has also been attempted [232,233]. Because the singlet excited state of these dyes is short lived it becomes essential to adsorb them on the semiconductor surface with... 

Vrachnou, E. Graetzel, M. McEvoy, A. J. Efficient visible light photoresponse following surface complexation of titanium dioxide with transition metal cyanides, J. Electroanal. Chem. Interfacial Electrochem. 1989, 258, 193. 

Here we report the efficient spectral sensitization of Ti02 by surface derivatization with a series of transition metal cyanides. The sensitization of Ti02 when treated with a ferrocyanide solution is described in a recent publication from this laboratory (Vrachnou E., Vlachopoulos N., and Gratzel M., 1987). There is evidence that the active species formed on the surface is a titanium analogue of Prussian blue. 

As can be seen from the action spectra in Figures 7-9, of all the transition metal cyanides tested to date, the ferrocyanide derivatization of Ti02 gives the most effective sensitization at the peak of the photocurrent action spectrum at a wavelength of 420 nm, corresponding to the absorption maximum of this complex, the quantum efficiency for electron transfer is 37% (monochromatic incident light intensity 0.84 W.nT2, photo- current 10.4 pA.crn 2). 

Ludi, A. and Gtidel, H.L. 1973. Structural chemistry of polynuclear transition metal cyanides. Structure and Bonding, 14, 1-21. 

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