Mer Isomer

Where X is phenyl, the result of irradiation (sunlight, mercury lamp) is the formation of Ru(NO)X3(PPh3)(OPPh3) (X = Cl, Br) in the case of the diethyl-phenylphosphine complex, irradiation causes isomerization to the cis,mer-isomer. The frans,mer-isomer is the usual synthetic product, but in the case of dimethylphenylphosphine the/ac-isomer was obtained using short reaction times it isomerized to the usual mer,trans-isomer on heating [123],... 

Distinguishing between the fac- and mer-isomers is theoretically possible with far-IR spectra, as the mer-isomer (C2v symmetry in the coordination sphere) should give rise to three u(Os—X) stretching bands, while the C3v... 

Figure 2.2 103Rh NMR spectrum of mixtures of [RhCl Br6 ]3 species (n = 0-6 a denotes cis,/ac-isomer, b denotes trans,mer-isomer), (a-d) are varying Cl Br ratios in the starting material. (Reproduced with permission from Z. Naturforsch., Teil B, 1989, 44, 1402.)...

Other halides can be introduced by metathesis. Figure 2.55 summarizes some of the complexes isolable with dimethylphenylphosphine, similar in general to the corresponding iridium complexes (section 2.13.3), including the photochemical isomerization of the mer-isomer. 

NMR spectra of tertiary phosphine complexes are often helpful in assigning stereochemistries [114] and two examples of mer-isomers are illustrated here. 

Figure 2.86 The 1H NMR spectrum in the hydride region of the isomers of [IrH3(PEt2Ph)j] top, /ac-isomer bottom, mer-isomer. (Reproduced with permission from E.L. Muetterties (ed.), Transition Metal Hydrides, published by Marcel Dekker, 1971, p. 80.)...

C20-0089. Draw a ball-and-stick model of the mer isomer of [NiCl3 F3, oriented so that the fluoride ions are in the top, bottom, and left forward positions. 

Reaction of dien, dien = diethylene-triamine, with IrCl3-1.51120 yielded [Ir(dien)2]Cl3.157 Separation of the mer-isomer was effected by chromatography on SP-Sephadex, with an X-ray structure... 

Crystal structures have been determined (Figure 2.56) for RhCl3(PEt2Ph)3 and RhBr3(PMe2Ph)3 (in both cases mer-isomer) - in each case, the Rh-X bond length shows the tram-influence of a tertiary phosphine [110]. 

The /uc-isomers are conveniently made by a general reaction involving irradiation (fluorescent tube) of a solution of the mer-isomer [155]... 

The fac- and mer-isomers can be distinguished by physical methods (IR, NMR spectra, dipole moments) they also differ in reactivity ... 

In the/flc isomer, the three chloride ions are located on the corners of one of the triangular faces of the octahedron. In the mer isomer, the three chloride ions are located around an edge (meridian) of the octahedron. The IUPAC system of nomenclature does not use this approach. A summary of the IUPAC procedures is presented in the book by Huheey, Keiter, and Keiter that is cited in the references listed at the end of this chapter. 

Fac and mer isomers of IrH3(CO)(Ph3P)2 were characterized by H and P nmr spectra. Their rates of interconversion in CH2CI2 at 25 °C... 

In addition the fac and mer isomers undergo reaction with PhjP. Using excess PhjP to prevent any back reaction, the rates of reaction were followed at the 330 nm band of the product. With the same conditions. 

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