Preparation and interconversion of dimeric di-µ-hydroxo and tri-µ-hydroxo complexes of platinum(II) and palladium(II) with 2,2′-bipyridine and 1,10-phenanthroline

Specific Chelate Tuning of the Substitution Kinetics of Platinum(II) Complexes in Aqueous Solution

“…From this dependence an activation volume of Ϫ7.1±0.9 cm 3 mol Ϫ1 was obtained. These acti-where ЈN 2 Ј is an aromatic α-diimine, the central atom being platinum or palladium, has led to studies [36] [37] [38] [39] that vation parameters are in accord with those generally observed for associative substitution reactions of d 8 com-were criticized later by Wimmer and Castan [31] [40] , who showed that under the selected conditions reported for synplexes [4] [30] . The more negative entropy of activation for the second step might be due to the steric hindrance caused by thesis and reaction, the dimeric species is the main species present in solution.…”

“…The spectral changes do not show very characteristic features, since the bands observed are due to intraligand π-π * transitions of the phen ligand. These are known to show a relatively weak dependence on the nature of the coordination sphere of the metal centre [31] [40] [50] . The aim of the Global Analysis treatment was to confirm the two-step mechanism and to provide a spectrum of the intermediate 1:1-complex.…”

“…Therefore the abDuring the investigation of the hydrolysis behaviour of Cisplatin the property of complexes of the type sorbance change at 330 nm was used, which, however, did not allow the evaluation of the first substitution step, since [Pt(ЈN 2 Ј)(OH 2 ) 2 ] 2ϩ (ЈN 2 Ј ϭ am(m)ine 2 or bidentate amine) to form dimeric [26] [27] [28] [31] , trimeric [32] [33] [34] and (rarely) the absorbance changes for the two steps are too similar (see Figure 2) to allow separation. Following the arguments tetrameric [35] species of the general formula [{Pt(…”

“…Activation parameters are derived from the temperature deture [31] [40] . During our investigations we found that the di-pendence and summarized in Table 4.…”

A Dinitrato(diphenylphenanthroline)palladium(II) Complex

“…Crystals grew upon evaporation in a stream of dry nitrogen gas, and were sensitive light-brown rhombic prisms. A similar procedure, using Pd(NO3)2 in HNO3, reacting L = 1,10-phenanthroline or 2,2'-bipyridine with Pd or Pt, has been reported by Anderegg & Wanner (1986) and by Wimmer, Castan, Wimmer & Johnson (1989) Crystal data [Pd(NO312(C24H16N2) SHELXL92 (Sheldrick, 1992) Uiso for C and O atoms of DMSO, which was refined in two orientations.…”