Silver complexes biguanides

The oxidation of silver(i) biguanide complexes 3delds the corresponding cationic silver(iii) species (H), where X represents a univalent anion. The... 

Trivalent complexes of biguanide and periodate are also prepared commercially for water sanitation. The trivalent silver periodate, for example, is prepared by the action of potassium periodate and potassium hydroxide on Ag O ... 

The longest established silver(III) complexes are the red to brown bi-guanides, like the ethylene bis(biguanide) shown in Figure 4.14 persulphate oxidation of Ag+ in the presence of this ligand gives a silver(III) complex with essentially square planar coordination. 

A number of well-defined crystalline complexes of silver(III) have been described.496 In particular, biguanides, substituted biguanides, ethylenebis(biguanide) and piperazine dibiguan-ide have been found to complex and stabilize silver(lll). 

The bivalent metals, as usual, combine with two molecules of biguanide to form 4-coordinated planar complexes, while the trivalent cobalt and chromium combine with three molecules of the ligand to produce a 6-coordinated octahedral configuration. The only exception is the trivalent silver which yields, however, a 4-coordinated planar complex. The preparation of the free tris(biguanidato) chromium, Cr(C2N5H6)s, in the anhydrous state,6 as well as of the corresponding anhydrous cobalt(III),8 copper(II), cobalt(II), palladium(II), and nickel(II) compounds, provides indisputable evidence for the structure proposed. Similar anhydrous metallic complexes with numerous substituted biguanides also have been included in the above-mentioned studies. 

The new Reinecke-salt-like compounds K[Cr(NCS)4L ] (n = 1 or 2 L = o- or m-phenylenediamine, respectively) have been prepared by the reaction of K3[Cr-(NCS)6] with L and their thermal stabilities investigated.179 Diquinolino- and di-iodoquinolino-silver(i) iodide salts of the anions [Cr(NCS)6]3- and [Cr(NCS)4L2] (L = aniline, o- or p-toluidine) have been prepared and characterized.180 Chro-mium(m) thiocyanato-complexes with biguanide derivatives, K[Cr(NCS)4L] [L = phenyl-, p-chlorophenyl-, tolyl-, or 1-(p-chlorophenyl-5-isopropyl)biguanide], have been prepared by the reaction of K3[Cr(NCS)6] with L in anhydrous EtOH and their i.r. and electronic spectra reported.181 cis- and trans-[Cr(en)2(NH3XNCS)]2 + have been prepared and both shown to have a Amax value at 476 nm, but with the expected relative magnitudes of s values, cis > trans, as 120 to 80.182 The thermal decompositions of the salts [Cr(NH3)6 x(NCS)x](NCS)3 x (x = 0. 1. or 2) have been characterized. Under d.t.a. conditions [Cr(NH3)6](NCS)3 changes stepwise to [Cr(NH3)5(NCS)](NCS)2, trans-[Cr(NH3)4(NCS)2](NCS), and finally to merfac-[Cr(NH3)3(NCS)3].183... 

Photoelectron spectroscopy of a sample of [Ag OEP]Q04 mhed with a small amount of Ag OEP showed marked shifts of 3 eV in the binding energies of the silver and 3dsa electrons for the Ag complex. These occurred at 377.1 and 371.0 eV for the A complex. Comparable shifts have also been reported for Ag biguanides. ... 

Silver(n) complexes, 839-850 amino adds, 846 aqua,844,850 biguanides, 849 2,2 -bipyridyl, 843 carboxylates, 844 cinchomeronic acid, 842 dipicolinic acid, 842 dithiocarbamates, 845 isodnchomcronic add, 842 isonicotinates, 840 lutidinic acid, 842 N-heterocyclic ligands, 839 nicotinates, 840 1,10-phenanthroline, 843 phthalocyanines, 848 picolinates, 840... 

---