Platinum -II

The paucity of complexes with O-donors arises because Pd(II) and Pt(II) are soft metal centres (see Table 7.9). We noted above the instability of the tetraaqua ions. Reaction of [PtCl4] with KOH and excess Hacac gives monomeric [Pt(acac)2]. PaUadium(II) and platinum(II) acetates are trimeric and tetrameric respectively. The Pd atoms in [Pd(02CMe)2]3 are arranged in a triangle with each Pd—Pd (non-bonded, 310-317 pm) bridged by two 

Zeise s salt, K[PtCl3(Tl -C2H4)], is a well-known organo-metalUc Pt(II) complex and is discussed in Section 24.10. 

Explain why 4-coordinate Pt(II) complexes are usually diamagnetic. Comment on factors that might lead to a 4-coordinate Pt(II) complex being param netic. 

Each of the mononuclear complexes A and B has the molecular formula C 2H3oCl2P2Pt. The P spectrum of each complex shows a singlet ( -11.8 ppm for A, —3.1 ppm for B) superimposed on a doublet. For A, Jp,p = 2400Hz, and for B, Jptp = 3640Hz. Suggest structures for A and B, and explain how the spectra and the different coupling constants arise. 

Friesner and S.J. Lippard (2003) Journal of the American Chemical Society, vol. 125, p. 14082 - Theoretical study of cisplatin binding to purine bases why does cisplatin prefer guanine over adenine  

The reactions under consideration in this section are summarized in Table 

Palmer and Kelm and coworkers have carried out comprehensive investigations into several substitution reactions of Pt(II) complexes by measuring the activation parameters (A//, A5, and AV and solvent effects. In the first group 

Acetone, nitromethane, MeOH, EtOH, CH2CI2 MeOH MeOH 

Temperature, ionic strength, solvent (water unless otherwise specified). 

Another group of reactions [Table 4.1(d)] involves the sterically hindered 

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Ethene can add on to certain metal salts it is believed that the extra electrons of the double bond can be donated to some extent an example is the compound PtCl2-C2H4 formed with platinum(II) chloride which has the structure... 

Ac-Imidazole, PtCl2(C2H4), 23°, 0.5-144 h, 51-87% yield. Platinum(II) acts as a template to catalyze the acetylation of the pyridinyl alcohol, C5H4N(CH2) CH20H. Normally acylimidazoles are not very reactive acy-lating agents with alcohols. 

Differences are also observed in the reactivity of platinum(II) complexes of [82X2] and [802X2] towards halogens. In the former case oxidative addition to give platinum(IV) complexes occurs, with retention... 

In 1974, Hegedus and coworkers reported the pa]ladium(II)-promoted addition of secondary amines to a-olefins by analogy to the Wacker oxidation of terminal olefins and the platinum(II) promoted variant described earlier. This transformation provided an early example of (formally) alkene hydroamination and a remarkably direct route to tertiary amines without the usual problems associated with the use of alkyl halide electrophiles. 

Several N-(chloromethyl)pyridinium platinum complexes have been described in the literature [89JOM255 92JCR(S)296 92JOM155]. Interestingly, 2-pyridyl platinum(II) complexes 11 and 12, having been dissolved in dichloromethane, are slowly N-alkylated by the solvent, yielding the N-(chloromethyl)pyridinium compounds 13 (76%) and 14 (77%) (Scheme 3). 

Oxidative addition reactions of platinum(II) complexes with N-heterocyclic ligands 97CRV1735. 

Guanine derivatives, the effects of N(7)-coordinated ci.s-diammine-platinum(II) on the acid-base properties of 98PAC845. 

Platino-. platinous, platino-, platinum (II). -chlorid, n. platinous chloride, platinum(II) chloride, -chlorwasserstoff, m., -chlorwasserstoffsaure, /. chloroplatinous acid, chloroplatinic (II) acid. -cyanwasserstoff, m., -cyanwasserstoffsaure, /. cyanoplatinous acid, cyanoplatinic (II) acid, platinocyanic acid, -rhodanwasserstoffsaure, /. thiocya-noplatinous acid, thiocyanoplatinic(II) acid. 

Platin-oxyd, n. platinum oxide, specif, platinic oxide, platinum(IV) oxide. -oxydul, n. platinous oxide, platinum(II) oxide, -oxy-dulverbindung, /. platinous compoimd, platinum (II) compound, -oxydverbindung, /. platinic compound, specif, platinum (IV) compound. 

The application of this principle is shown in Table 15.1, where we list the formulas of several complexes formed by platinum(II), which shows a coordination number of 4. Notice that one of the species, Pt(NH3)2Cl2, is a neutral complex rather than a complex ion the charges of the two Cl- ions just cancel that of the central Pt2+ ion. 

WEB Platinum(II) forms many complexes, among them those with the following ligands. Give the formula and charge of each complex. 

As is the case of tetrasubstituted phthalocyanines, a mixture of four structural isomers is obtained if the 5,6-substituents of isoindolinediimine are different. For example, 5-ethoxy-6-octyl-oxyisoindolinediimine, when treated with platinum(II) chloride in refluxing 2-(dimethylamino)-ethanol under nitrogen for 12 hours, yields a mixture of the corresponding isomeric piatinum(II) phthalocyanines in a yield of 28 %.117... 

However, it seems that these are best viewed as platinum(II) species too, so that two-electron metal-to-ligand transfer has been effected. The structures of Pt(PPh3)2Z (Z = r]2-02, t 2-C3H4, t]2-CS2) (Figure 3.16) all involve square planar coordination as expected for platinum(II) rather than the tetrahedral 4-coordination anticipated for platinum(O). 

The adoption of a planar structure in these adducts, rather than the sterically more favourable tetrahedral one, is in keeping with a platinum(II) oxidation state. The side-on bonding of the 02 molecule is believed to involve two components, as in Zeise s salt (Figure 3.18). 

Several m-platinum(II) dihydrides lose H2 reversibly in solution, forming dinuclear platinum(I) hydrides [(diphosphine)PtH]2 [62],... 

Although the bisammine complexes of platinum(II) are the most important because of the medical applications of the m-isomer (section 3.10), the synthesis of the others [69] is also important ... 

With their preference for square planar coordination, palladium(II) and platinum(II) are well suited to binding to porphyrins and related N4 donor macrocycles. Therefore, Pd(octaethylporphyrin) is readily synthesized starting from the labile PhCN complex (like the platinum analogue) [92]... 

Detailed kinetic studies of the decomposition of platinum(II) dineophyls show (Figure 3.60) the exclusive formation of t-butylbenzene and an internally metallated platinum complex (3,3-dimethylplatininadan). 

Platinum (II) carbenes should be mentioned as <7-bonded organometallics. An important general synthesis by cleavage of an electron-rich alkene affords a pair of isomers, the trans-form isomerizing to the thermodynamically more stable cw-form on heating (Figure 3.61). 

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