Bridging CO groups

M ,(CO) Metal carbonyl clusters with bridging CO groups M-C(0) M... 

The structures of the dinuclear metal carbonyls (containing two metal atoms) involve either metal-metal bonds or bridging CO groups, or both. For example, the structure of Fe2(CO)9, diiron nonacar-bonyl, contains three CO ligands that form bridges between the iron atoms, and each iron atom also has three other CO groups attached only to that atom. 

On the basis of the infrared spectra, the alkenyl complexes are considered to have a structure of the type shown in Fig. 23a, with a bridging CO group. This structure is related to those of the rhodium cyclo-pentadienyl adducts Rh3(C5H5)3(alkyne)(CO) (137). In the rhodium... 

AlBr3 and related compounds indicate that the Lewis acid interacts with a bridging CO group... 

The structure of the cluster compound [H2FeRu3(CO)j3] is based on a tetrahedron of metal atoms. There are three terminal CO groups bonded to each Ru, two terminal CO groups bonded to Fe, two asymmetric bridging CO groups bonded between Fe and Ru atoms, and it is suggested that the two... 

QC-[H3RU4(C0),3] 0.059 Tetrahedron of Ru atoms. Contains eleven terminal and two bridging CO groups. e... 

There are only two simple tricobalt clusters, namely [CpCofCO)], obtained by photolysis of CpCo(CO)2 386, 387), and [(R3P)Co(CO)2]3 obtained from [(R3P) Co (00)312 under hydroformylation conditions 322). Both are found to contain three bridging CO groups. 

The spectra of the compounds RSn[Co(CO)4]3 (R=Me, CH CH2, Ph, Cl, Br, or I) have been reported (190, 191), confirming that the complexes had this formulation rather than RSn[Co(CO)3]3 (132). Only when R= Me or Ph was the parent ion observed, although (M — CO)+ was always present in medium to high abundance. The high stability was explained by a structure (I) involving a bridging CO group and cobalt-cobalt bond. Some... 

Fig. 17. Deformation density of [(C5Hs)Fe(CO)2]2 (52). Contours are at intervals of 0.1 e A 3. (a) A section containing the Fe—Fe bond and the terminal CO group, (b) A section perpendicular to (a) and containing the Fe—C—O bond, (c) A section containing the Fe—Fe bond and the bridged CO group, (d) A section parallel to the cyclopentadienyl ring and through a Fe atom.

Form A, as confirmed by an X-ray diffraction study (3), has structure XI (see Fig. 4) with six terminal and eight face-bridging CO groups (vco = 1640-1680 cm-1), whereas form B should have some edge-bridging carbonyl groups (rco = 1710-1760 cm-1) (37). On oxidation both... 

Molecular structure of some carbonyl cluster anions containing encapsulated heteroatoms all terminal CO groups are omitted for clarity (a) [CosNi2(C)2(CO)16]2 only the bridging CO groups are shown (b) [Osi8Hg3(C)2(CO)42]2 (c) 11 -Cf,Nif,(N)2fCO>2412 ... 

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