Carbon sigma bonds, actinide

The purpose of this article is to review recent results on the carbonylation chemistry of actinide-to-carbon sigma bonds, bearing in mind the unique properties of 5f-organometallics cited above. We focus our attention on the properties of bis(pentamethylcyclopentadienyl) actinide acyls. Just as transition metal acyls (A) occupy a pivotal role in classical carbonylation chemistry, it will be seen that many of the unusual... 

This article reviews recent results on the chemical, spectral and structural properties of bis(pentamethylcyclopentadienyl) thorium and uranium dihaptoacyl complexes produced by migratory insertion of carbon monoxide into actinide-carbon sigma bonds. 

ABSTRACT, This chapter presents an overview of recent chemical progress involving molecules with actinide-to-carbon and actinide-to-hydrogen sigma bonds. The synthetic, structural, chemical/mechanistic, thermochemical, and bonding aspects of this chemistry are developing at a rapid rate. 

However, at low temperatures, all of these hydrides react rapidly (l.e., at a rate which is rapid on the nmr time scale by ca. -40 C) and reversibly with CO to yield bright-yellow complexes, which are formulated on the basis of spectroscopic data as dihaptoformyls [82,83] (eq.(64)). There is no infrared spectroscopic evidence for actinide carbonyl complexes. The enedlolate forming reaction is too rapid to allow complete characterization of the Wa-derlved formyl. In regard to thermodynamics, it is found by van t Hoff measurements that for 3Cb, AH - -4.5(9) kcal/mol, AS = -11.7(4.3) e.u. and for Ya—Yb, AH = -5.9(1.5) kcal/mol, AS = -23.9(7.4) e.u.. Migratory Insertion of carbon monoxide into an actlnlde-to-hydrogen sigma bond is clearly exothermic [83]. 

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