Chini complex

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Lately, an IR band with very low C-0 frequency, A u(CO) = -186 cm , was measured for terminal CO molecules on Pt species, formed by decomposition of the Chini complex [Pt3(CO)3(//-CO)3]3 in NaX zeolite [242]. That frequency shift was attributed to a negative charge of the encapsulated platinum cluster, in good agreement with our correlation [243]. 

Figure 3.16. The layered Chini complexes are constructed from Pts(CO)6 units.

The anion [Fe3Co(CO)12] has recently been reported to be prepared by Chini from the redox reaction of Fe3(CO)12 with Co(CO)infrared spectra indicate a Co4(CO)i2 structure with nickel in the basal plane (234). 

Chini has recently reported the redox condensation between Fe3(CO)12 and the anion [Co(CO)4] to yield the anion [Fe3Co(CO)13] , but no details of the structure or stability of the complex are cited (234). 

When the irradiation of metal ion solutions is performed in the presence of the ligands CO or PPhs, metal reduction, ligandation, and aggregation reactions compete, leading to reduced metal complexes and then to stable molecular clusters, such as Chini clusters Pt3(CO)6] with m = 3-10 (i.e., 9-30 Pt atoms) [97], or other metal clusters [98]. The synthesis is selective and m is controlled by adjusting the dose m decreases at high doses). The mechanism of the reduction has been determined recently by pulse radiolysis [99]. Molecular clusters [Pt3(CO)6]5 have been observed by STM [100]. 

Chini and co-workers (42) found that [CofCOJJ- reacts with Cul and Agl to give high yields of [(CO)4CoCuCo(CO)4] and [(CO)4CoAgCo(CO)4] of structure 43. The copper complex is less stable than the silver species and readily dissociates in CH3CN. Reaction (108), however, is reversible, and the starting material can be recovered after solvent removal. 

Paolo Chini began his work in the late 1950s with the characterization of cobalt carbonyl species involved in the hydroformylation of olefins with cobalt catalysts, and in the course of these studies developed improved synthetic methods for the known cobalt carbonyls Co2(CO)8 and Co4(CO)12 [132]. His next steps were the preparation of the heterometallic hydrido complex HFe-Co3(CO)i2 (isoelectronic to Co4(CO)12) and the corresponding anion [FeCo3(CO)12], both a novelty at that time, and of the new hexanuclear cobalt clusters [Co6(CO)15]2, [Co6(CO)14]4, and Co6(CO)16 [133-139]. This work was followed by the synthesis of carbido carbonyl cluster anions [Co6(CO)i4C], [Co6(CO)15C]2 and [Co8(CO)i8C]2, containing an interstitial... 

One Dimensional Inorganic Complexes, J. S. Miller and A. J. Epstein, Prog. Inorg. Chem., 1976, 20, 1. Applications of Carbon-13 NMR in Inorganic Chemistry, M. H. Chisholm and S. Godleski, ibid., p. 299. Hi Nuclearity Metal Carbonyl Clusters, P. Chini, G. Longoni, and V. G. Albano, Adv. Organometallic Chem., 1976,14, 285. 

Consequently whilst we have a pure octahedron in Rh6(CO)i6 [7], we can observe either a small distortion as in AueLg" (L = PPha) [77] or a higher distortion as in [Ni3(CO)3(/X2 CO)3]r [78] (Figure 16). This latter kind of distortion, which however does not really produce a poly-tetrahedral metal cage, has been observed with more complex nuclearity, as in the polymeric anionic species of Chini et al [79] [Pts(CO)sQi2 CO)3] (a2 = 2, 3, 4, 5), that we shall consider it in detail later on. 

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