Cyanides dinuclear complexes

Before we obtained the X-ray structure determinations of both the knotted and unknotted dicopper(I) complexes, we could identify them after careful comparative H NMR and mass spectroscopy studies performed not only on the dinuclear complexes but also on their respective free ligands afforded by demetalation. Treatment of Cii2(m-43) + by a large excess of potassium cyanide led indeed quantitatively to a plain 43-membered macrocycle whereas an analogous treatment of Cii2(K-86r+ led to the free knot K-86 whose topological chirality could be demonstrated by NMR and mass spectroscopy (Figure 20). 

Other dinuclear cyanide-containing complexes with trivalent metal ions include the homodinuclear species A[(NS3)2V 2(CN)] A=TEA, TEA" NS3=[N(CH2CH2S)3] (54), (TBA)[(salen)2Cr 2(CN)3] (55), (PI14P)... 

The majority of cyanide-bridged dinuclear complexes described for the combination of metal ions belong to the biologically relevant class of Cu —Fe dimers. These compounds serve as models for the binuclear cyanide-inhibited site of cytochrome c oxidase, an enzyme that contains the heme-copper active site responsible for the O2 reduction chemistry (59). The lethal toxicity of cyanide was traced to its irreversible binding and inhibition of this active site in the enzyme (60). The biologically relevant aspects of these complexes were the subject of many reports (61,62). Our interest is in describing their crystal structure, which will be correlated to the magnetic properties in a later section. 

The second class of dinuclear Cu —Cu complexes is represented by several cascade complexes, in which a pair of cations is encapsulated within a cryptand host (XVII-XIX), with a bridging CN ligand spanning the space between the cations. In these cases, the dinuclear complex is stabilized due to the encapsulated cations rather than by the cyanide bridge. Lu et al., (78) reported a product of this type, [Cu°2(XVII)(CN)](C104)3 (Fig. 9), as a result of the unexpected C C bond cleavage of acetonitrile in the presence of [Cu 2(XVII)]( 104)4. These authors established that the reaction rate exhibits a first-order dependence... 

Cyanide, alkyl isocyanides and aryl isocyanides Phosphines and arsines Dinuclear Complexes Containing the Rely and Re 2 Cores... 

Reaction of Fe(CO)s with dialkyl sulfides in the presence of trimethylamine-A -oxide leads to simple, mono-substituted Fe(CO)4(SR2) complexes (Scheme 71), whereas this reaction performed with cyclic thioethers gave dinuclear complexes. Dinuclear complexes related to 51 with a variety of groups bridging between the two sulfur atoms have been derivatized with cyanide and organic isocyanides. 

The behavior of Hg(CN)2 toward the dinuclear gold(I) amidinate complexes requires comment. In the case of the dinuclear gold(I) ylide, oxidation of the Au(I) to Au(II) resulted in the formation of a reduced mercury(O) product. Figure 1.19(a) [36]. In the mercury(II) cyanide reaction with the dinuclear gold(I) dithiophosphinate. Figure 1.19(b), the stability of the gold(I)-carbon bond compared... 

Gold(I) ylides are oxidized in 0.1 M [Bu4N]BF4/THFat low potentials of +0.11 and + 0.23 V vs. Ag/AgCl (quasi-reversible). The dinuclear amidinate oxidizes under the same conditions at + 1.24 V vs. Ag/AgCl (reversible). These large differences in chemical character of the dinuclear gold(I) complexes appear to explain the widely different behavior of these compounds and especially toward the reaction with mercury cyanide. 

Mohamed, A.A., Abdou, H.E. and Fackler, J.P. Jr (2006) Mercury(ll) cyanide coordination polymer with dinuclear gold (1) amidinate. Structure of the 2-D [Au2(2,6-Me2-formamidinate)2]-2Hg (CN)2 2THF complex. Inorganic Chemistry, 45, 11-12. 

Nitroprusside forms both dinuclear and trinuclear complexes with aquacobalamin (Bj2a) [131]. Coordination involves a Fe-C=N-Co link, with linkage involving trans cyanides in the trinuclear complex. Such complexes are slower acting as hypotensive agents than nitroprusside itself [7]. 

If [Rh(diphos)2]Cl is allowed to react with an anion exchange resin in the cyanide form, the corresponding cyanide complex (rc N 2089 cm-1) is formed. Upon dissolution of the product in benzene a diphos ligand is lost and [Rh2(CN)2(diphos)3] is formed.119 The dinuclear product probably contains a bridging diphos ligand (c/. [Cu2(N3)2(diphos)3]251). These reactions and the anion exchange reactions of [Rh(diphos)2]Cl are shown in Scheme 10a. 

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