Iron carbidocarbonyl clusters

Several iron carbidocarbonyl clusters have been examined by l3C NMR (14), and all show large shifts to low field (see Table III). There seems to be no correlation between charge on the molecule and In the series... 

Iron is so far unique in that it alone forms carbidocarbonyl clusters containing only four metal atoms, and the discovery of this class of compounds and the reactivity of its members has provided one of the most... 

Since the completion of this review (mid-1982), the chemistry of carbidocarbonyl clusters has continued to expand rapidly. The task of the reviewer is made even more difficult as fascinating results continue to appear. In resisting the temptation to make a comprehensive update of the field, it would be remiss of me not to direct the reader s attention to the continued investigations of Lewis, Johnson, and co-workers in the chemistry of ruthenium and osmium carbidocarbonyls (89), the report by Longoni and coworkers (90) of the syntheses of the first nickel carbide clusters and some mixed nickel-cobalt carbides, the syntheses by Shapley of a new ruthenium dicarbide cluster [Ru,oC2(CO)24]- (91) and of Os6C(CO)l7 (92), and the work of Shriver which implies the existence of a very reactive tri-iron carbide cluster (93). 

A similar effect was observed with mixed iron-rhodium carbidocarbonyl clusters on oxide supports [14]. Trzeciak and Ziotkowski added Fe(CO)5 to Rh(acac)(CO)L (acac = acetylacetonate) [L=PPh3, P(OPh)3, P(N(C4H4)3)] and achieved in the hydroformylation of 1-hexene at a syngas pressure of 10 atm and 80 C an increase of up to 70% in the yield of the aldehyde [15]. The... 

The first carbidocarbonyl transition metal cluster to be recognized was Fe5C(CO),5 (1), which was isolated in very low yield from the reaction of triiron dodecacarbonyl with methylphenylacetylene and characterized by X-ray diffraction by Dahl and co-workers (2). The molecule (Fig. 1) comprises a square pyramidal Fe5 core with the carbide situated. 08 A below the center of a square face. Each iron atom bears three terminal carbonyls. Improved syntheses of 1 by protonation (5) or oxidation of [Fe6C(CO)l6]2-... 

The hexanuclear iron cluster (37) in the salt [Me4N]s[Fe (CO)uC] is regarded as the first known anionic carbidocarbonyl complex of any metal, ... 

---