Metal cyclopentadienyl cluster

Note - Many clusters exist in several oxidation states because of the degeneracy of their HOMOs and LUMOs (several orbitals with the same energy due to symmetry) and the sterie protection by the ligands of the metal-based redox centers. In particular, this is the case for the metal-cyclopentadienyl clusters. For instance, the above clnster has been isolated in the forms [FeCp(CO)]4 with n = -1, 0, -1-1 and +2. A consequence, in cyclic voltammetry, is the cascade of several chemically reversible waves (no decomposition of the oxidized and rednced species the anodic and cathodic intensities are the same) that are also electrochemically reversible (fast electron transfer, which means that there is no significant structural change in the course of electron transfer the potentials of the anodic and cathodic waves differ by 58/n mV at 20°C and do not change when the sweep rate varies). 

Just as for group 5, 6, and 7 ( -CsF MCU species, Fehlner has shown that BH3-THF or Li[BH4] react with group 8 and 9 cyclopentadienyl metal halides to result in metallaborane clusters, many of them having a metal boron ratio of 1 3 and 1 4, and much of the synthetic chemistry and reactivity shows close connections with the earlier transition metals. The main difference between the early and later transition metallaboranes that result is that the latter are generally electron precise cluster species, while as has been shown, the former often adopt condensed structures. Indeed, as has been pointed out by King, many of the later transition metallaborane clusters that result from these syntheses have structures closely related to binary boranes and, in some cases, metal carbonyl clusters such as H2Os6(CO)18.159... 

Although most known metallocarboranes have only 1 metal atom per polyhedron, the existence of an increasing number of metallocarboranes with 2 or more metal atoms per cluster emphasizes the close relationship between metal clusters and borane clusters. Since they can be synthesized from cZoao-carboranes by replacing BH units by metal-carbonyl or metal-cyclopentadienyl residues, carborane clusters can effectively be used as disposable templates on which to fabricate... 

NLO properties, 12, 128 organometallic complexes, 3, 318 as reaction materials, 3, 368 and selenium nucleophiles, 9, 471 surface chemistry on oxides, 12, 502 in triruthenium cyclopentadienyl clusters, 6, 799 trivalent halides, with metal carbonyl monoanions, 3, 347 Group 14 elements... 

Metal dimers containing cyclopentadienyl ligands also can be separated to monomers with Hj as for (h -CjH5)2Cr2(CO) at 150 atm (15 MPa) and 70°C to yield HCr(CjHj-h )(CO)3. Mixed-metal hydride clusters may be synthesized from the H -assisted condensation of two different metal carbonyls. When Os3(CO),2 Or Ru3(CO),2 reacts with Ni2(C5Hj-h )2(CO)2 in the presence of at atm P, the mixed-metal clusters M3(ja-H)3Ni(C5H5-h5)(CO), [M = Ru (39%), Os (70%)] are formed l... 

Cyclopentadienyl clusters of the group 6 metals are numerous. A few examples are [Mo3cp3(PPh2)3(CO)3], [(OC) cpRe()U-CO)2Mocp2], [(OC)... 

Metal carbonyl clusters are also numerous. In addition to dinuclear carbonyls such as M2(CO)io (M = Mn, Tc, Re), many hydrido clusters and ionic species exist which contain three or more metal atoms [M3H3(CO)i2] (M = Mn, Tc, Re), Mn3(CO)i (linear compound, 1)4 ), and Re3(/i-H)(CO)i4 (the Re —Re —Re angle is 90°). Rhenium forms a number of tetranuclear compounds. Some of them have a butterfly structure while others adopt a triangle of rhenium atoms with one Re attached to it Re4(/i3-H)4(CO)i2, [(Re4( -H)4(CO)i3] , [Re4( -H)6(CO)i4], and [Re4(CO)i6]. Rhenium also forms mixed metal carbonyls possessing several metal atoms (Table 3.14). There are numerous clusters of the group 7 metals containing cyclopentadienyl groups, ... 

Many stable cyclopentadienyl clusters of metals of the nickel group are also known [Ni3Cp3(CO)J, [Ni3Cp3(NBuO], [Ni4Cp4H3], [Ni2Pt2W4(/i3-CPh)4(CO)gCp4]/ >... 

This account makes a few references to the related clusters that have fused-ring cyclopentadienyl derivatives, such as indenyl, azulene, and acenaphthylene, in addition to the cyclopentadienyl clusters with common CsRs groups. Some interesting trinuclear ruthenium complexes are also referred to even though they have no metal-metal bonds in the molecule. 

CO2MC] were obtained by metal exchange liom (he same ruthenium-dicobalt precursor and analogous functionalized (cyclopentadienyl)metal carbonyl Related reactions of the selenido-containing cluster RuCo2(/r rSe)... 

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