Triosmium carbonyl cluster

Spectroscopic evidence (IR, Raman, NMR and EXFAS) [155] shows that the triosmium carbonyl clusters Os3(CO)i2 and Os3(CO)io( i-H) react with a silica surface to yield the monosiloxy species [( x-=SiO)((x-H)Os3(CO)io]. The monosiloxy molecular analogue [((x-OSiEt3)Os3( t-H)(CO)io] has been obtained from Et3SiOH [156]. Disilanols Ph2Si(OH)2 and (OH)Ph2SiOSiPh2(OH) lead to the same triosmium monosiloxy motif, [( t-0)Os3( t-H)(CO)io] [157], and the thermal and chemical... 

A unique approach to covalent modification of ITO electrode surfaces was presented by Cho and coworkers. Using the complex shown, covalent attachment to ITO is achieved with a siloxane linkage and the remainder of the sensitizer consists of C6o linked to a triosmium carbonyl cluster that also links to a tetraphenylporphyrin derivative. The work describes a photocurrent generation quantum yield of over 19% [124]. 

Molecular rearrangements of diynes coordinated to triosmium carbonyl clusters have been reported.179 Triosmium clusters can act as templates for the rearrangement of l,4-dipyridylbuta-l,3-diyne, leading to the formation of fused-ring organic products, in a manner similar to that previously reported for other 1,3-diyne compounds. 

Some water-soluble triosmium carbonyl clusters have also been shown to damage DNA, to inhibit... 

In contrast, when thiophenes react with triosmium carbonyl clusters it is C-H bond activation that occurs in preference to C-S bond cleavage. The direct reaction of [Os3(CO)i2], or the -acetonitrile complex [Os3(CO)io(NCMe)2], with thio-phene results in the oxidative addition of a C-H bond to give the exo- and endo isomers of the n, -thienyl hydrido cluster [Os3(//-H)(/z-C4H3S)(CO)io] (21a, 22a) (Scheme 7). These isomers are in rapid equilibrium at room temperature. The complex [Os3(/i-H)2(/X3-C4H2S)(CO)9] (23a) also results from his reaction, presumably by additional thermal C-H bond activation and decarbonylation of the thienyl complex. This cluster contains a triply bridging cyclic alkyne ligand related to /i3-benzyne. " ... 

Small proteins may be labeled using triosmium carbonyl clusters, for example, 133, acting as markers for G=C bond containing estrogens (Figure 32). ... 

Fig. 7.1 Glucose sensor. A glucose molecule brings 4-mercaptophenylboronic acid-triosmium carbonyl cluster conjugate (Os-BA) to the substrate via formation of a bidentate complex. The short lines extending from Os represent carbonyl (CO) ligands (adapted with permission from Kong et al. 2013. Copyright 2013 American Chemical Society)...

Os-BA 4-MercaptophenyIboronic acid-triosmium carbonyl cluster conjugate ... 

An early example of surface-mediated synthesis led to the conversion of Os3(CO)i2 into [Os5C(CO)i4] [13]. Quantitative characterization of the formation of this cluster on MgO by C NMR spectroscopy [15] showed that the synthesis gave [OssCCCOIh] " in a yield of about 65% other products included triosmium and tetraosmiimi carbonyl clusters. A schematic representation of the surface chemistry is shown in Fig. 1. 

Metal carbonyl cluster compounds which contain three ruthenium or three osmium atoms in the cluster core are common.1 Potentially useful reagents for syntheses of these compounds are the triruthenium and triosmium dianions [M3(CO)h]2 (M = Ru, Os).2 Therefore, it is desirable to develop good synthetic routes to obtain [M3(CO)11]2- (M = Ru, Os) of high purity in high yields. A method that is particularly useful for generating [M3(CO)n]2 (M = Ru, Os) is the designed stoichiometric reduction of M3(CO)12 (M = Ru, Os) using an electron carrier such as potassium-benzophenone.3... 

Although the reactions between alkynes or alkenes and metal clusters are the main source of alkyne-substituted complexes, there are other reagents which can produce similar products. Two such reagents are tetraphenylcyclopentadienone, which in the reaction with Ru3(CO)i2 produces Ru3(CO)10(PhCCPh) (167), and dimethyl-vinylarsine, which has been made to react with several carbonyl clusters [Eq. (8)] (168, 169). In the reaction of M3(CO)12 (M = Ru, Os) with a number of tertiary phosphines and aromatic alcohols, an oxidative addition takes place and benzyne-triosmium compounds are obtained (170-176). The fact that Os3(CO)uPEt3 can be converted into an alkyne compound (177) suggests that the conversion goes through substituted intermediates. Carbene derivatives of clusters have also... 

Osmium forms stronger metal-metal bonds than either iron or ruthenium consequently, there are a large number of osmium carbonyl clusters see Cluster) and these complexes have a large body of reaction chemistry. The triosmium cluster are prepared from Os3(CO)i2. Most are diamagnetic... 

IR, Raman, and EXAFS Characterization of -0-Bridged Triosmium and Triruthenium Carbonyl Clusters Bound to Si O and AI O ... 

On heating to the temperatures above 423 K, the resulting triosmium or triruthenium hydrido carbonyl clusters are fragmented to monomeric Os or Ru carbonyl species which are identified in IR spectra by analogy to molecular di- and tricarbonyls such as [Os(CO)3X2]2 (X = Cl, Br) and [Os(CO)2l2] . 

Bridges between trinuclear metal clusters [of Ru, Os] Synthesis of ruthenium and osmium carbonyl clusters with unsaturated organic rings Oxyligand derivatives of triosmium dodecacarbonyl... 

MgO, a mononuclear complex is formed of the type Os(CO)2(0-Mg)4. Heating of this complex in CO restores a triosmium carbonyl similar to the starting carbonyl, Os3(CO)i2- This is assumed to mean that the Os ions formed by breaking of the Os3-cluster are so strongly bonded to the 0 ions that they almost retain their initial position. A similar result has been found for Rh complexes on AI2O3 (vide infra). 

The literature includes only a few examples of zeolite encaged clusters which have been characterized with EXAFS spectroscopy with a thorough analysis of the data. Examples of relatively thorough data analysis are those for clusters inferred to be triosmium carbonyls [53] in NaNj-treated NaY zeolite, [Ir4(CO)i2] [67] and [Irg(CO)i6] [5] in NaY zeolite, and [Ir6(CO)i5] [60] in NaX zeolite. 

Important pioneer work in the synthesis of polynuclear metal carbonyls was made by reduction of simple metal salts in the presence of carbon monoxide or similar ligands. The best results are obtained in general for the most stable clusters such as triruthenium, triosmium, tetrarhodium, and tetrairidium dodecacarbonyls. Thus, heterogeneous pyrolysis reactions of metal halides with carbon monoxide in the presence of halide acceptors such as Cu or Zn under relative drastic conditions of temperature and pressure can be used for preparing these types of three and tetranuclear carbonyl clusters ... 

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