Alkylidynetricobalt nonacarbonyl complexes

INTRODUCTION GENERAL PROPERTIES OF ALKYLIDYNETRICOBALT NONACARBONYL COMPLEXES... 

In 1971 we reviewed the chemistry of alkylidynetricobalt nonacarbonyl2 complexes (1). We have continued our research in this area and have made substantial progress in the development of the organic chemistry of this interesting class of organometallic compounds. In this article we review principally the chemistry of carbon-functional alkylidynetricobalt nonacarbonyl complexes. 

The alkylidynetricobalt nonacarbonyl complexes all are highly colored, with colors ranging from red to purple to brown to black, depending on the apical substituent. Their thermal stability also depends on the apical substituent some survive heating to 100°-18o° and many may be sublimed in vacuum at 50°-80°C. Most, but not all, are air-stable (in contrast to their pyrophoric parent, dicobalt octacarbonyl) in the solid and in solution. 

Preparation of Alkylidynetricobalt Nonacarbonyl Complexes by Reactions of Polyhalides with Dicobalt Octacarbonyl0... 

This reaction has potential for useful application in organic synthesis. Oxidation of alkylidynetricobalt nonacarbonyl complexes with halogens was the key reaction that led Kriierke and Hubei to the correct assignment of their structure (3a) ... 

From the discussion of the organic chemistry of the alkylidynetricobalt nonacarbonyl complexes given in this review, it is apparent that this has been a fruitful area of research. We think that it shall continue to be so. Admittedly, the sensitivity of these cluster complexes to diverse bases, nucleophiles, and oxidizing agents will seriously limit the chemistry that can be carried out, but even with these limitations it should be possible to continue a broad development of the organo-functional interconversions of these complexes. 

We were first drawn into studies on alkylidynetricobalt nonacarbonyl complexes because in these one is dealing with a carbon atom in a most unusual environment. We felt that this novel class of complexes would show some rather interesting organic and organometallic chemistry and we... 

Alkylidynetricobalt nonacarbonyl complexes are an interesting class of clusters (78). They can be synthesized by treatment of a tri- or tetrahaloal-kane with cobalt carbonyl under phase-transfer conditions [e.g., 71] (28). Partially or completely dehalogenated by-products were often isolated from these reactions. 

C. Conversion of Alkylidynetricobalt Nonacarbonyl Complexes to Wholly Organic Compounds... 

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