Cyanide bridge

The stmcture of Pmssian Blue and its analogues consists of a three-dimensional polymeric network of Fe —CN—Fe linkages. Single-crystal x-ray and neutron diffraction studies of insoluble Pmssian Blue estabUsh that the stmcture is based on a rock salt-like face-centered cubic (fee) arrangement with Fe centers occupying one type of site and [Fe(CN)3] units randomly occupying three-quarters of the complementary sites (5). The cyanides bridge the two types of sites. The vacant [Fe(CN)3] sites are occupied by some of the water molecules. Other waters are zeoHtic, ie, interstitial, and occupy the centers of octants of the unit cell. The stmcture contains three different iron coordination environments, Fe C, Fe N, and Fe N4(H20), in a 3 1 3 ratio. 

The affinity of cyanide groups for lanthanide ions has motivated the use of [M(CN)6]3 tectons (with M = Cr3+, Mn3+, Fe2+, Fe3+, Co3+) that can give rise to a wide variety of one-dimensional cyanide-bridged structures ((E) topologic mode in Scheme 4.2) [90]. Some noticeable compounds are [Ln(DMF)4(H20)2Mn(CN)6]-H20 K chains (DMF, dimethylformamide), where antiferromagnetic coupling was observed between Mn3+ tecton and Sm3+, Tb3+,... 

Chemical Reviews paper. We can only discuss a small number of these here, but some important categories are (1) synthetic Fe(II)-Cu(I) complexes and their reactions with O2, (2) oxidized heme-copper models (Fe(III)-X-Cu(II) complexes, where X equals 0x0- and hydroxo-bridged complexes, cyanide-bridged complexes, or other X-bridged complexes), (3) crosslinked histidine-tyrosine residues at the heme-copper center, and (4) Cua site synthetic models. 

Cyanide-bridged complexes involving iron-diimine-cyanide complexes are discussed in Section 5.4.3.5.8. 

PHOSPfflNE LIGAND DERIVATIVES OF DIAMOND-SHAPED, CYANIDE-BRIDGED IRON(II)-COPPER(I) COMPLEXES... 

J8. Cyanide-Bridged Iron(II)-M(II) Molecular Squares LgFe--------C=N-------ML2.1... 

Figure 1. Structure of a cyanide-bridged Fe(II)-M(II) molecular square (L = bpy M = Fe,Co,Cu).

A large number of polymeric complexes is known containing ambidentate cyanide bridging groups. These are related to Prussian blue, which is formed by the addition of ferric salts to ferrocyanides ... 

It is of interest to note that the adduct Fe(phen)2(CN)2(BH3)2 (phen = 1,10-phenanthroline) has been prepared 87>. Cyanide bridges exist between the transition metal and BH3 groups. 

Based on their easily tunable photophysical and redox properties, transition metal complexes are versatile components to be used in the construction of photochemical molecular devices. The studies presented in this article show that the combination of the Ru(bpy)22+ photosensitizer and cyanide bridging units allows the synthesis of a variety of polynuclear systems that exhibit interesting photochemical properties. Depending on the nature of the attached metal-containing units, supramolecular systems can be obtained that undergo efficient photoinduced intramolecular energy or electron transfer processes. 

While bifunctionality is known for the halogens and many pseudohalogens, it is most pronounced for cyanide and influences the structures, properties and chemistry of many of its derivatives. Cyanide bridges were present in the first recorded synthetic inorganic complex, Prussian blue (ca. 1700), and cyanide linkage isomers were often proposed in the old literature but reasonable evidence for the existence of linkage isomers and the structure of Prussian blue is very recent. 

It is probable that polymer formation through cyanide bridges serves as a driving force and accounts for the generality of this type of reaction (equations 1—5). 

Sodium cyanide and diborane react in the presence of ether to give NaH3BCNBH3 2R20. The cyanide bridged structure is assigned on the basis of two quadruplets of equal intensity in the B11 n. m. r. spectrum [Aftandilian, Miller and Mutterties, 1961). 

Rupp, J. J. and D. F. Shriver Cyanide Bridge Compounds with Group Four Metal Tetrafluorides. Abstract of Papers Presented at ACS Meeting (151st) (1966). 

Considerable controversy over the nature of the blue solids existed for many years. It now appears that the solids have the same composition, Fc4[Fc(CN)6] i 16 H20, in which there are cyanide bridges between the Fe2+ and Fe3+ ions (see Chapter 19). This situation may be similar to the case of Sb2Clg (or SbCl3 SbCls), in which there is rapid electron exchange that results in the antimony atoms being equivalent rather than existing as Sb(III) and Sb(V) (see Chapter 13). 

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