Octahedral clusters derivatives

Octahedral clusters derived from the 6-12 type are, as usual, interstitially stabilized. Two types of trans edge-connected octahedral chains are now known both with the dicarbon imit as the interstitial. The chains are, however, distorted in both cases ... 

Clusters derived from metals which have only a few valence electrons can relieve their electron deficit by incorporating atoms inside. This is an option especially for octahedral clusters which are able to enclose a binding electron pair anyway. The interstitial atom usually contributes all of its valence electrons to the electron balance. Nonmetal atoms such as H, B, C, N, and Si as well as metal atoms such as Be, Al, Mn, Fe, Co, and Ir have been found as interstitial atoms. 

Another organometaliic derivative of 19 is formed as a minor by-product in the synthesis of 16 by treatment of Ru3(CO),2 with ethylene (48). Ru6C(CO)15(CH3CH = CH—CH = CHCH3) produced in this reaction is an octahedral cluster, with the trans.trans-2,4-hexadiene molecule coordinated to adjacent ruthenium atoms (Fig. 21). 

To illustrate some of the points outlined above the following is a derivation of the symmetries of the L°, V1 and IA orbitals of a general 6-vertex octahedral cluster and a 4-vertex tetrahedral cluster. 

The two isostructural clusters [Co6N(CO)i5] and [Rh6N(CO)i5] were synthesized by reaction of the octahedral clusters [M6(CO)i5] (M = Co, Rh) with nitrosonium tetrafluoborate. Better yields of the rhodium species were obtained by treatment, in a strongly reducing medium, of [RhyjCOjie] " with NO (diluted 1 1 with CO). The reactions are complex and no intermediate step could be identified. However, a nitrosyl derivative is very likely to be involved, and subsequent reduction, by the reaction medium or the starting reduced carbonyl itself, would yield the nitrido cluster. 

All the cobalt and rhodium nitrido species reported so far derive from the prototypical trigonal-prismatic anions [M6N(CO)i5] (M = Co or Rh). - The octahedral cluster [Co(,N(CO)i3j "" has been obtained by mild pyrolysis of its precursor and is regenerated upon exposure to CO. 

Torardi, C. C. McCarley, R. E. (1979). Sodium Tetramolybdenum Hexoxide (NaMo40g). A Metallic Infinite-Chain Polymer Derived by Condensation of Octahedral Clusters/ J. Am. Chem. Soc. 101, 3963-3964. 

Octahedral cluster iridiiam carbonyl derivatives have also been described (275), but these have been investigated in less detail than their cobalt or rhodium analogs. They are obtained by the alkali-metal reduction of Irit(C0)i2 in a manner somewhat similar to the preparation of octahedral cluster cobalt carbonyl derivatives by the alkali-metal reduction of Coit(C0)i2 Reaction of Irij(C0)i2 with sodium metal in tetrahydrofuTcin first gives the tetrahedral cluster anion Hirij (CX7) i" aind then the dark brown, octahedral cluster anion Ir0(CO)i5 , which can be isolated as its tetraethylammonixam salt (275). ... 

A mixed octahedral cluster metal carbonyl emion Ni2Co4(CO)14 has been prepared by decomposition of certain [Ni (base) 5] [Co (CO) i ] 2 derivatives (75). 

The structure of threadgoldite determined by Piret and co-workers shows a complicated derivative of the autunite structure. The structure consists of [U02P04]n layers that are only slightly distorted from the square array. The stacking of the layers shifts parallel to c (the a-axis corresponds to the c-axis in the tetragonal forms) to accommodate an interlayer AI2O10 double octahedral cluster and to yield a monoclinic structure. 

A new derivative (15) has been isolated from the complicated reaction of [Cog(CO)s] and CSg. Full details of the preparation and structure of the paramagnetic cluster [COi(CO)i(p-CO)6(Ps-C)] have appeared and the unpaired electron appears to be located outside the octahedral cluster in front of the longest Co-[Pg.167]

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