Ruthenium complexes tetrahedral

The normally tetrahedral phosphorous acid (5.212b) is stabilised in the phosphite form (5.212a) as the chromium pentacarbonyl complex (8.207a) and the ruthenium complex (8.207b). 

More recently, tetranuclear complexes, related to those previously obtained for both ruthenium and osmium, have been obtained for iron, and their structures have been established by X-ray analysis 118). The reported adducts are [Fe4(CO)11(RC2R1)2] (R = H, R1 = Me, Et, n-Pr R = R1 = Me), and are obtained in very low yield (<1%). For R = H, R1 = C2H5, the structure is shown in Fig. 16. This involves a distorted tetrahedral metal system with the two alkyne groups bonding in a manner similar to that observed for the "butterfly molecule [Co4(CO)10(EtC2Et)] 119). 

One of the most studied ligand-metal complexes is the bis(oxazoline)-ruthe-nium(ll) complex.Kurasowa and co-workers proposed that the aqua and amine complexes of bis(oxazoline)-ruthenium(ll) 17a-d also adopt a tetrahedral geometry about the metal center. These are only a few of many examples of the complexes formed between a variety of transition metals and bis(oxazoline) ligands that have been studied. ... 

The compound Ru4(jt-H)4(CO)12 is obtained as a yellow air-stable powder, which is soluble in most organic solvents, but insoluble in water. The IR spectrum contains v(CO) bands at 2081 (s), 2067 (vs), 2030 (m), 2024(s), and 2009(w)cm-1 (cyclohexane solution) the HNMR spectrum has a resonance at <5 — 17.98 (CDC13 solution). The molecular structure of Ru4(/i-H)4(CO)12 has been determined by X-ray diffraction the four hydrogen atoms bridge the edges of the tetrahedral Ru4 core in a D2d arrangement, while three CO ligands are terminally bonded to each ruthenium.8 The deuterated complex Ru4(/i-D)4(CO)12 can be prepared in the same way if D2 is used in place of H2.6... 

A considerable range of iron carbonyl clusters is now known to contain antimony or bismuth, and later developments have seen this extended to ruthenium and osmium complexes. Whitmire (711) has described the reaction between NaBi03 and methanolic [Fe(CO)5], which affords the anionic triiron cluster [BiFe3(CO)10] (108), which contains a tetrahedral BiFe3 core. Cluster 108 is an example of a closo tetrahedral cluster with three first-row... 

It is generally accepted that the ICC of nickel, copper, and ruthenium, on the basis of ligands of type 426, have trans-planar configuration 427, while a tetrahedral polyhedron is characteristic for cobalt and zinc chelates [270,401,751-754], It was also accepted that a cis-planar configuration for ICC of o-hydroxyazo compounds and chelates of o-hydroxyazomethines in 422 (R = Aik, Ar, Het) is not likely or, at best, only scarcely possible. However, a cis-planar complex 428 has recently been prepared and characterized [755] ... 

We have mentioned only in passing other cluster complexes in which a tetrahedral core of 1 carbon and 3 metal atoms is present. Such complexes in which the metal atoms are nickel, ruthenium, and osmium have been prepared XIII (81), XIV (82, 83), and XV (66, 82). Their chemistry remains largely unexplored, except for the transformations of compound XV in strong acid medium which we mentioned in the previous section. 

Ruthenium-( —n), -(0), and -(i).—A single-crystal A-ray analysis of the complex [Ru(NO)2(PPh3)2] has revealed a distorted tetrahedral co-ordination about the... 

The coordination of stable silylenes to metal complexes was also reported to produce transition metal silylenoids.40,41 Exposure of unsaturated silylene 16 to Ni(CO)4 resulted in the formation of the disilylene-substituted tetrahedral nickel complex 17 (Scheme 7.3).42,43 Similarly, mixing Ph PAuCI with decamethylsilico-cene 18 produced the silylgold complex 19.44 The 29 Si H NMR spectrum of 19 (8 78 ppm) revealed its silylenoid character. In addition to nickel and gold, other metals, including tungsten,41 platinum,45 iron,40 and ruthenium,46 have been utilized to form silylmetal complexes of stable silylenes. 

The ruthenium sulfoximido complex HRu3(C0)9 NS(0)MePh is of note because it formally has two electrons fewer than the normal tetrahedral structure [Eq. (64)].170 Upon addition of CO it is converted into an electron-precise /a-imido complex [Eq. (65)170]. 

While copper and iron Lewis acids are the most prominent late transition metal Diels-Alder catalysts, there are reports on the use of other chiral complexes derived from ruthenium [97,98],rhodium [99],andzinc [100] in enantioselective cycloaddition reactions, with variable levels of success. As a comparison study, the reactions of a zinc(II)-bis(oxazoline) catalyst 41 and zinc(II)-pyridylbis(ox-azoline) catalyst 42 were evaluated side-by-side with their copper(II) counterparts (Scheme 34) [101]. The study concluded that zinc(II) Lewis acids catalyzed a few cycloadditions selectively, but, in contrast to the [Cu(f-Bubox)](SbFg)2 complex 31b (Sect. 3.2.1), enantioselectivity was not maintained over a range of temperatures or substitution patterns on the dienophile. An X-ray crystal structure of [Zn(Ph-box)] (01)2 revealed a tetrahedral metal center the absolute stereochemistry of the adduct was consistent with the reaction from that geometry and opposite that obtained with Cu(II) complex 31. 

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