Ruthenium complexes diimines

There are more examples of a second type in which the chirality of the metal center is the result of the coordination of polydentate ligands. The easiest case is that of octahedral complexes with at least two achiral bidentate ligands coordinated to the metal ion. The prototype complex with chirality exclusively at the metal site is the octahedral tris-diimine ruthenium complex [Ru(diimine)3 with diimine = bipyridine or phenanthroline. As shown in Fig. 2 such a complex can exist in two enantiomeric forms named A and A [6,7]. The bidentate ligands are achiral and the stereoisomery results from the hehcal chirality of the coordination and the propeller shape of the complex. The absolute configuration is related to the handness of the hehx formed by the hgands when rotated... 

Tris(diimine)ruthenium(III) complexes are significantly more oxidizing than the analogous complexes of both iron(III) and osmium(III). This correlates well with the observation that rates of reduction in base are also faster for the tris(diimine)ruthenium(III) complexes. The tris(l,10-phenanthroline)ruthenium(III) reduction is significantly faster than the tris(2,2 -bipyridine)ruthenium(III) reduction, and this may be the reason why it is only the latter reaction that has been investigated in detail (1, 2). This system is particularly complex, and the rate law given by Eq. (1) holds only for very small concentrations of ruthenium complex. In contrast to the irondll) systems, simple kinetics... 

A series of ruthenium (II) diimine complexes containing oxa-thiacrown derived from 1,10-phenanthroline have been synthesized and characterized <2007IC720>. The crystal stmctures of [Ru(bpy)2200](PF6)2, [Ru(bpy)2201](ClC>4)2, [Ru(bpy)2202](C104)2 have been determined. The luminescence properties of [Ru(bpy)2200](C104)2 were found to be sensitive and selective toward the presence of Hgz+ ions in an acetonitrile solution. 

In order to clarify the mechanism of cyclopropanation, several carbene-complexes of ruthenium have been isolated by reaction with diazocompounds. In the case of Pybox, the corresponding ruthenium-carbene complexes 38 were isolated and characterized using either NMR or X-ray analysis [32]. Similar ruthenium-carbene complexes, such as porphyrin-ruthenium carbene complex 39 [33] and pyridine-diimine-ruthenium complex 40 [34] were isolated and characterized (Chart 7.6). 

These eight-coordinate d and d chelates are analogous to the octahedral d and d ruthenium diimine species that are currently a focus of coordination compound energy transfer. The tungsten species offer both metal and ligand components which are appreciably less expensive than the ruthenium complexes. 

The preparation of ruthenium bis(diimine)sulfoxide complexes by reaction of cis-[Ru(bipyridine)2(Cl)2] (165) with enantiomerically pure chiral sulfoxides 166 was described by Ait-Haddou [94] as a new concept in the preparation of optically active octahedral ruthenium complexes (Scheme 5.47). The reaction produces two dia-stereomeric complexes 167 and 168 and the microwave-irradiated reactions resulted in excellent yields and high reaction rates with a notable increase in the observed diastereomeric excess. 

Although it is not surprising that Ru-tris(diimine) complexes can easily be differentiated and/or resolved using A-TRISPHAT as chiral auxiliary, (see Section 4.1.2), yet the resolution of the dinuclear ruthenium complex fran5-[bis(Cp Ru)carbazolyl][PFg]... 

Applications have appeared, among several others, on the following transition metal compounds Mn04, Ni(CO)4, Mn2(CO)io, M(CO)e (M = Cr, Mo, W), ruthenium diimine and other ruthenium complexes, CpMn(CO)3, MFg (M = Cr, Mo, W), and several other metal complexes. ... 

Arakawa, R., Jian, L., Yoshimura, A., Nozaki, K., Ohno, T., Doe, H Matsuo, T. (1995) On-Line Mass Analysis of Reaction Products by Electrospray Ionization. Photosubstitution of Ruthenium(II) Diimine Complexes. Inorg. Chem. 34 3874-3878. 

Figure 11.9 Photochemicai reaction monitoring by ESi-MS. (a) Schematic representation of ESI-MS for on-iine anaiysis of photochemical reaction products. The drawing is not to scale, (b, c) ESi mass spectra of Ru(bpy) Cl2 (bpy = 2,2 -bipyridine) in acetonitrile (0.1 mM) (b) without and (c) with photoirradiation (A > 290 nm). L, bpy AN, acetonitrile X, C1 [6]. Reproduced with permission from Arakawa, R., jian, L., Yoshimura, A., Nozaki, K., Ohno, T, Doe, H., Matsuo, T. (1995) On-line Mass Analysis of Reaction Products by Electrospray Ionization. Photosubstitution of Ruthenium(ll) Diimine Complexes. Inorg. Chem. 34 3874-3878. Copyright (1995) American Chemical Society...

The cylindrical helical binuclear complex [Fe2L3]4+, where L is the bis-diimine Schiff base 1, exists as two enantiomers, whose interactions with DNA differ markedly. The more strongly interacting enantiomer targets the major groove (cf. ruthenium(II) complexes, Section II.E.l below) and induces dramatic tightening of the DNA coil (118). 

Ru(CN)jNO reactions with OH , SH and SOj" resemble those of the nitroprusside ion, with attack at the coordinated nitrosyl to give analogous transients and similar second-order rate constants. Ruthenium(II) complexes of the general type Ru(N2), Nj = biden-tate hgands, are important reactants. The relative inertness of Ru(NH3) + and Ru(diimine)f+ towards substitution makes these complexes definite, although weak, outer-sphere reductants (Tables 5.4, 5.5, 5.6 and 5.1). Ruthenium(ll) complexes of the general type Ru(diimine)f +, and particularly the complex Ru(bpy)j+, have unique excited state properties. They can be used as photosensitizers in the photochemical conversion of solar energy. Scheme 8.1 ... 

Iron(III) complexes are generally more labile than analogous complexes of both ruthenium(III) and osmium(III), and this also holds for the diimine complexes discussed here. In acidic and neutral solution,... 

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