Ruthenium

Abstract

GENERAL CHEMISTRY 1189 GENERAL CHEMICAL TRENDSMendeléeff's placing of three elements of each period in Group VIII has over-emphasized their similarity to one another; this resemblance is not much closer than between any three consecutive transition elements. Sidgwick 46 has suggested that it would be more accurate to divide the group vertically into three triads which would be called Groups VIIIA, IXA and XA, since the elements of each triad have respectively 8, 9 and 10 electrons more than the preceding rare gas. However, the convention of placing the nine elements in one group is too well established to be changed 46 .The Group VIII elements have the smallest atomic volumes in each of the three long periods. Consequently these elements display a pronounced tendency to form covalent bonds, the effect being more marked for the second and third transition series. Whereas iron, cobalt and nickel readily form the hydrated ions [M(H 2 0) 6 ] 2+ , the six platinum metals show little tendency to do so. Aqua ions of Ru(II), Rh(III) and Pd(II) are known to exist in solution but only in the absence of anions which are capable of forming complex ions. Aqua ions do not appear to be formed by the heavier metals, osmium, iridium and platinum. Apart from binary compounds, such as oxides, halides, sulphides, etc., the compounds formed by the platinum metals are complex.Because of this difference between iron, cobalt and nickel, on the one hand, and the platinum metals on the other, it must not be overlooked that the relationships within Group VIII are vertical. Correlations can be found; a few examples are listed below. Iron, ruthenium and osmium form the monomeric carbonyls M(CO)s, the very stable complexes [M(CN) 6 ] 4 -, [M(phen) 3 ]2+ a nd [M(bipy) 3 ] 2+ (M = Fe, Ru, Os); alkali metal salts of the anion [M0 4 ] 2_ can be prepared, although the iron compound is easily reduced. Cobalt, rhodium and iridium form the complex anions [M(CN) 6 ] 3~, [M(N0 2 )6] 3_ and [M(C204)3] 3~, and the dimeric carbonyls M 2 (CO)s (M = Co, Rh, Ir). Nickel, palladium and platinum form the very stable [M(CN)4p" (M = Ni, Pd, Pt) and neutral complexes with a large number of oximes, the best known being dimethylglyoxime which is used for the quantitative estimation of nickel and palladium.The stability of the higher oxidation states increases down each triad : Fe < Ru < Os ; Co < Rh < Ir; Ni < Pd < Pt, and decreases across each period: Ru > Rh > Pd and Os > Ir > Pt. The maximum oxidation state is 8 for ruthenium and osmium, 6 for rhodium, iridium and platinum, and 4 for palladium. The lowest oxidation states yet reported are: -2 for ruthenium, -1 for rhodium and iridium, and 0 for osmium, palladium and platinum.

Iodide n,π-chelate complexes of platinum(II) based on N-allyl substituted thioureas and their effect on the activity of hepatobiliary system enzymes in comparison with chloride analogs

“…chemistry. n,π-Chelate complexes [Pt(HL 1,2 )I 2 ] have been obtained for the first time according to Scheme 1 by the reactions of K 2 [PtCl 4 ] with N-allylmorpholine-4-carbothioamide (HL 1 ) or 3-allyl-1,1-diethylthiourea (HL 2 ) in the presence of HCl (to avoid hydrolysis of platinum and stabilize the surrounding metal with chloride ions [36,37]) and a significant excess of KI to ensure anion exchange.…”

Environmental biotechnologies can make water pollutants part of the path to mitigating climate change

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