Ru IV Complexes

Ru(0)Cl(ding)2 (dmg=dimethylglyoximato mono-anion). This is prepared from K[Ru Clj(dmg)2] and PhIO IR (v(Ru=0) 835 cm ), electronic spectra and cyclic voltammetric data were recorded. The magnetic moment is 3.9 B.M. It may be involved as an intermediate in the catalytic epoxidation of cyclohexene by RuClj(dmg)2/PhIO/water [640], 

7 s-[Ru(0)2(R-TMC)](C10 ) These are complexes of the macrocychc tertiary amines listed under franx-[Ru(0)2(R-TMC)](C10 )j (Pig. 1.29). The 14-TMC complex is yellow the 15-TMC and 16-TMC complexes were not isolated, but were made by electro reduction of franx-[Ru (0)2(R-TMC)]. Their oxidative properties were not studied [576], 

Of the Ru(IV) complexes recorded here most are mono-oxo species which, despite the strong axial distortion brought about by the terminal oxo ligand, are probably all paramagnetic. Semi-empirical molecular orbital calculations (INDO/1) for epoxidations effected by oxo-Ru(IV) complexes have been reported (a non-concerted [1 h- 2] pathway was preferred) [642], [643] and for alcohol oxidations by octahedral species containing an Ru (0) unit [644]. The reactivity of high oxidation-state polypyridyl complexes of osmium and Ru, with particular emphasis on Ru(IV) and Os(IV) oxo species, has been reviewed [43]. 

The structural, spectroscopic and electrochemical properties of oxoruthenate (IV) complexes have been summarised, and a representative compilation of kinetic parameters for their oxidation reactions with alcohols, alkanes and alkenes presented [20], 

This account starts with the most important of Ru(lV) compounds, ruthenium dioxide. 

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Scheme 48 Allylic oxidation of alkene with Ru(IV)-complexes.

The Ru(iv) complex Ru(SiMe3)2(H)2(PMe3)3 is a model for dehydrogenative C-Si bond formation chemistry. Berry and coworkers have shown that, at low temperature, this complex undergoes fast reversible SiH reductive elimination on the NMR time scale (Eq. (3)), and slow H2 reductive elimination as a minor process [154]. 

Water-soluble bisallyl Ru(IV) complexes 3 and 4 also initiate the emulsion polymerization of norbornene [31]. The lack of preformed alkylidenes in these complexes limits initiation efficiency, although the onset of initiation is not subject to lengthy initiation periods. Speculation on the active species in polymerizations initiated by these bisallyl complexes has not been reported. 

The d oxidative addition may seem unfamiliar because there are many more examples 47) of d d and d d processes. However, ruthenocene, which is sl (P ruthenium (II) complex with a delocalized electronic structure, undergoes two-electron oxidative addition by I2 and Br2 to give the Ru(IV) complexes Ru(cp)2r and Ru(cp)2Br (48). X-ray studies of Ru(cp)2r show that it is eflFectively a seven-co-ordinate complex (48). 

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