Ru and Co Complexes

The oxalate complex K3[ri(C204)3(H20)] was prepared by the addition of excess K2[C204] to a solution of [Ti ((112N)2CO)6]Cl 3. The crystal structure revealed a seven-coordinate pentagonal bipyramidal geometry about the Ti center.989 The kinetics of electron transfer reactions between Ti oxalate complexes with Ru and Co complexes have been studied in detail.969,990,991... 

Besides the metal complexes based on Ni and Pd that were previously proved suitable for the asymmetric hydrovinylation reactions, Ru and Co complexes have also been employed in this type of transformation. The one sole example of Ru-catalyzed enantioselective hydrovinylation was reported by the List group in 2012. In their initial studies, they envisioned that Ni complexes with chiral counteranions might enable the desired reaction. However, it was found that these species either were unreactive or did not furnish enantioselective control in the hydrovinylation reactions. In this context, Jiang and List focused their attention on Ru catalysis (Table 9.6). Systematic evaluation on the effects of Ru complexes ligated by different phosphine ligands as well as various chiral phosphate anions introduced by the corresponding silver salts demonstrated that the combination of Ru complex Ru-3 and additive Ag-1 was the optimal catalyst, leading to acceptable results (entry 8). 

Dinuclear Ru and Os complexes containirm halo bridges include a number of fluoro carbonyl complexes, described in the last section. The reactions between anhydrous HF and [MH2(CO)2(PPh3)2] (M = Ru, Os) produce cix,cA,tra i-[MF2(CO)2(PPh3)2], but when the precursor is [MH2(CO)(PPh3)3], the dinuclear complexes [M2(CO)2(PPh3)4(/u-F)3]" result. Initially, these form as the [Hp2] salts, but are better isolated as the air-stable [BPh4] salts. " ... 

Another modification of the double silylation process reported by Tanaka and co-workers involves the use of a bis(hydrosilane) instead of a disilane as the reactant molecule.61 This reaction can be described as a dehydrogenative double silylation, in that two Si-H bonds are activated rather than an Si-Si bond. The system is best catalyzed by Pt(CH2=CH2)(PPh3)2 other Pt, Pd, Ru, and Rh complexes give only very low yields of the double-silylated products. Alkynes, alkenes, and dienes undergo reaction with the bis (hydrosilane) with a range of results. Silicon-oxygen bonds and silicon-nitrogen bonds can also be formed by this method and are discussed in the appropriate sections later. 

Top S, El Hafa H, Vessieres A, Huche M, Vaissermann J, Jaouen G (2002) Novel estradiol derivatives labeled with Ru, W, and Co complexes. Influence on hormone receptor affinity of several organometallic groups at the 170 position. Chem Eur J 8 5241-5249... 

Ru and Ir complexes are invariably diamagnetic and octahedral they thus resemble spin-paired Co complexes. 

To clarify the mechanism of propylene adsorption on Ru-Co clusters the quantum-chemical calculation of interaction between it and Ru-Co, Ru-Ru, and Co-Co clusters were carried out. During the calculation it was assumed that carbon atoms of C-C bond are situated parallel to metal-metal bond. The distance at which the cluster and absorbable molecule begin to interact is characterized by the nature of active center. Full optimization of C3H6 molecule geometry confirms that propylene adsorbs associatively on Co-Co cluster and forms Jt-type complex. In other cases the dissociate adsorption of propylene is occurred. The presence of Ru atom provides significant electron density transfer from olefin molecule orbitals to d-orbitals of ruthenium in bimetallic Ru-Co- or monometallic Ru-Ru-clasters (independently on either the tertiary carbon atom is located on ruthenium or cobalt atom.). At the same time the olefin C-C bond loosens substantially down to their break. 

CpRh(C2H5)SiR3 [14], This reaction cycle unexpectedly involves the generation of Rh intermediates and fails to re-form CpRh(C2H4)(SiR3)H directly. Numerous examples of olefin insertion into M-Si bonds, which have been demonstrated for Fe, Co, Ru, and Rh complexes support the generality of this reaction mechanism [6,9],... 

Organic substrates (alkanes alkenes, alcohols) are also photooxidized by trans-dioxo Ru and Os complexes [93]. The interest in these catalysts may lie in the transformation of cyclohexane to cyclohexanone and cyclohexanol in reasonable yields. The presence of alcohol, ester, and ketone functional groups is tolerated in the catalytic functionalization [94] with polyoxometallates and Pt as co-catalyst [95]. 

The silylene migration may be involved in some stoichiometric reactions of hydrodisilanes with transition-metal complexes, forming disilanyl complexes through activation of Si-H bonds. Binuclear Ru and Os complexes 39 having terminal silyl groups and silylene bridges are isolated in the reactions of pentame-thyldisilane with Ru3(CO)12 and Os3(CO)12, respectively, albeit in low yields (Eq. 16) [33]. Similar silylene migration may be involved in the reactions of hydrodisilane with other transition-metal carbonyls such as Fe2(CO)9 and Co2(CO)8 [34]. 

The II state, d6. An enormous number of Ru and Os complexes with CO, PR3 and similar 7t-acid ligands are known. For other ligands, the main chemistry is that of chloro, ammonia and other amine ligands, and again I large numbers of complexes exist. The aquo ion, [Ru(H20)6]2 + has been prepared, but it is readily oxidized to [Ru(H20)6]3+. For osmium the best characterized complexes are those with aromatic amines. 

Soft metals such as Ag+, Cu+ and MeHg+ coordinate to Co SR" complexes and uncoordinated thioethers with about equal ease. Thus it seems that Co" and R" " have similar effects on the binding power of RS , reducing it by about 10 (Table 90 equation 167). This property has implications for electron transfer since ligation of coordinated thiol to a second metal centre is probably the first step in inner-sphere electron transfer. Data given in Table 90 demonstrate that Co" —SR" retains some Lewis basicity towards soft metals. These studies have utilized [Co(R-—S)(en)2] systems (R—S = cyst, tga) but the metals Ru"" and Co" also form very stable... 

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