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The mixed chloro-bromo complexes [PtClnBr6-n]2-, n = 1-5, are separated by ion exchange chromatography on diethylaminoethylcellulose. The separation of corresponding stereoisomers for n = 2, 3, 4 is not possible. Due to the stronger trans-effect of Br compared with Cl, on treatment of [PtBrß]2- with Cl- in the presence of Br2 nearly pure cis-isomers, and by reaction of [PtClsBr]2- and cis-fPtC^Bro]2- with Br~/Br2 completely pure transisomers are formed. The stereoselectivity of the successive ligand exchange reactions is better than in corresponding series of Re, Os and Ir. The highly resolved vibrational spectra allow the distinction of the mixed ligand complexes as well as the estimation of purity of the isomers. All allowed stretching frequencies are observed and assigned according to point groups D4h, C4V, C3Vand C2V. Especially in the ν(Pt-Br) region it is possible to distinguish bands arising either from symmetric Br-Pt-Br or asymmetric Cl-Pt-Br axes. The UV/VIS spectra exhibit systematic hypsochromic shifts on the successive exchange of Br-ligands by Cl. A critical discussion of the literature concerning chloro-bromo-platinates- (IV) shows the importance of effective separation processes for the isolation of pure mixed ligand complexes

The oxidative addition of Br2to [PtCl4]2-in HBr yields almost pure trans-[PtCl4Br2]2-, in HCl nearly pure [PtCl5Br]2-, and in CH2Cl2by a quantitative and stereospecific reaction completely pure trans-[PtCl4Br2]2-. This is confirmed by ion exchange chromatography on diethylaminoethyl cellulose and by analysis of the vibrational spectra in comparison with the IR and Raman spectra of the well-known species of the series [PtClnBr6-n]2-, n = 0-6. The literature concerning trans-[PtCl4Br2]2-and other mixed ligand complexes is critically discussed.

195Pt NMR spectra for the pure anionic complexes [PtClnBr6-n]2-have been measured in acetone solution. The isomerization reactions cis-[PtClnBr6-n]2-→ trans-[PtClnBr6-n]2-, n = 2, 4 and fac-[PtCl3Br3]2-→ mer-[PtCl3Br3]2-are slow on the NMR time scale and these slow kinet ics allow an unambiguous assignment of the 195Pt signals. The cis and fac complexes are found at slightly lower field (12-15 ppm) than their trails and mer counter­parts. There is a linear correlation of δ 195Pt with the sum of the Allred-Rochow electronegatives of the halogen atoms.

Synthetic musks (nitro and polycyclic musks) are a group of chemicals offering a wide range of important properties for environmental monitoring programs. They are produced as odorous chemicals and added to a wide variety of perfumes, toiletry products and other household products. As such, they are directly applied in cosmetic products or in washed textiles to the human body in considerable concentrations and accumulate owing to dermal resorption. In addition, synthetic musks also enter the environment via waste water treatment. Several polycyclic musks are chiral. By using chiral gas chromatographic methods, it is possible to determine the enantiomeric ratio and assess their bioavailability. Although an comprehensive quality assurance program must be followed during the analysis of synthetic musks in environmental samples, the determination of these compounds is not very demanding and can be carried out by a standard analytical laboratory specialising in trace analysis of organic pollutants. Owing to the pheromone-like behavior of some synthetic musks, the induction of receptors in olfactory systems should be investigated. For HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[ g]-2-benzopyran, e.g., Galaxolide® ), three-dimensional structural similarities with androstenone (5α-androst-16-en-3-one), a mammalian steroid pheromone, were found, which support the hypothesis of HHCB as an artificial pheromone. Owing to their environmental abundance, their relation to human activities and their potential for pheromone-like environmental behavior, synthetic musks are especially valuable as future indicator chemicals for environmental monitoring.