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Polynuclear carbonyl hydrides

In this chapter we have examined examples of polynuclear metal carbonyl complexes as well as simple metal carbonyl hydrides. Consider now the polynuclear carbonyl hydride complex, H,Os,(CO)i2- Rationalize the formulation of this species. From your application of the 18-electron rule, what can you say about the structure of this molecule1 How is it similar to or different from the complex Os COln shown in Figure 5.9 (See Churchill M. R. Wasserman, H. J. Iticrg, Chen. 1980, 19, 2391-2395.)... [Pg.380]

In the case of polynuclear carbonyl hydride species the location of the hydrogen atoms has generally proved elusive. In no case has this problem yet been definitively solved by neutron diffraction. In some cases, their probable positions have been inferred indirectly. For example, in... [Pg.706]

Perhaps the most important development in polynuclear carbonyl hydride complexes was the observation by Kaesz et al. that good yields of hydridocarbonyls could be obtained by direct reaction of hydrogen with polynuclear carbonyls (82). This has been applied to a number of systems. Thus, the anion [Rh,2(00)39 yields the cluster anion... [Pg.268]

Many of the methods used for the preparation of mononuclear hydrides may be applied to the polynuclear systems. Base attack on metal carbonyls, which furnished one of the first methods for the production of carbonyl hydride species, is applicable to a wide range of carbonyls. Borohydride reduction leads to a variety of products, depending upon the reaction conditions, Os3(CO)12 reacting with NaBH in di-oxane under reflux to give, after 4 hours, a mixture of the anions [H30s4(C0)12] and [H2Os4(CO)i2]2 (79). The related reaction in tetra-hydrofuran for 1 hour yields the anion [HOs3(CO)n]- as the main product with minor amounts of the two tetranuclear anions. [Pg.277]

The principle of reacting a silicon hydride HSiR3 with a polynuclear carbonyl (or carbonyl cyclopentadienyl derivative) was successfully applied to other transition metals such as Mo 37 Mn40,137 81,207 Re135> 137> 207),... [Pg.134]

Some compounds and their reactions have been noted in Section 18-G-2. The homoleptic carbonyls are clusters such as M4(CO)i2 and M6(CO)i8. The hydride, HRh(CO)4, is very much less stable than HCo(CO)4 and has been made only under ca. 1400 atm pressure since it readily loses H2 to give clusters. Both Rh and Ir give anions [M(CO)4] and [M(CO)3]4 as R3NH+ salts as well as various cluster anions such as [Ir8(CO)22]2 and [Rh5(CO)i5] . Hydrido and other substituted polynuclear carbonyls are known. [Pg.1060]

In Bi- and Polynuclear Metal Carbonyl Anions and Carbonyl Hydrides 9.2.4.2.I. By Reactions of Monomeric Carbonyls. [Pg.67]

Polynuclear metal carbonyl hydrides have also been studied. The IMS spectra of [Os3(CO)io(p2-H)2] and [Os4(CO)i2H4][74] are shown in Fig. 11.21. A twofold bridging hydride has three modes symmetric and antisymmetric stretch and an out-of-plane bend. The stretches are expected to occur at about twice the frequency of the bend. Fig. 11.21a approximates to this expectation, however, there are more bands observed than expected. In particular, the observation of two bands for the out-of-plane bend at 672 and 738 cm shows that the hydrides are coupled. This is surprising since the massive osmium atoms would mechanically decouple the hydride motions. So the coupling is likely to be electronic in nature. [Pg.514]

The treatment of many of the metal carbonyls with bases affords complex polynuclear carbonylates (see (140) for a recent review). As is the case for the mononuclear carbonylate anions, hydrolysis of the anions, often with dilute acids, affords diamagnetic metal carbonyl hydride complexes (see Table VI). The majority of these complexes which are described below have not been studied by infrared and proton magnetic resonance spectroscopy their formulations are based primarily on analysis and mode of decomposition, and thus remain tentative. [Pg.153]

These and related methods of structure prediction depend upon the allocation of specific electron counts to different framework geometries and these applications have been very successful in assigning structures to cluster carbonyls and their derivatives. However, for the higher polynuclear carbonyls as the molecularity of the compounds increases the predictive power of the theories becomes less decisive in differentiating between alternative structures. In essence the Wade-Mingos approach assumes that the frontier orbitals of the complex primarily involve metal orbitals so that any variation in the electron occupation will be reffected in a structural change in the metal framework. The Wade theory also requires that the structure of the complexes are based on triangulated polyhedra as found for the boron hydrides. [Pg.1761]

This and the next compound are complex salts of polynuclear iron carbonyl hydrides. [Pg.1756]

Reduction of RU3(CO)12 with sodium in liquid ammonia gives a mixture of Na2Ru(C0)ij and NaHRu(CO)tt, which yields colorless, very unstable, volatile H2Ru(C0)i upon acidification with phosphoric acid (108). Decomposition of H2Ru(CO)i+ occurs rapidly at room temperature to give an inconpletely characterized polynuclear ruthenium carbonyl hydride, tentatively formulated as H2Ru3(CO)i2 ... [Pg.352]


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See also in sourсe #XX -- [ Pg.8 ]




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Polynuclear carbonylation

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