Boron metal-carbon bonds

The kinetics of the decomposition of higher boron alkyls have not been investigated but in general these compounds undergo olefin elimination rather than metal-carbon bond rupture. 

The efficiency of transmetalation from boron to palladium in the catalytic 1,4-addition of aryl or 1-alkenylboronic acids to enones encouraged us to extend the protocol to the addition of aryl- and 1-alkenylboronic adds to aldehydes in an aqueous solution (Eq. 4). The insertion of carbonyl groups into transition metal-carbon bonds has not received much attention, but the catalytic use of transition metals may allow such addition of various organometallics which are inert without a catalyst, the asymmetric addition using a chiral phosphine complex, or the reaction in an aqueous phase. 

K-bonding electrons to form the metal-carbon bonds their structures may be regarded as mixed metal-carbon clusters, the shapes of which clearly reflect the numbers of electrons available as do the mixed boron-carbon cluster shapes of carboranes. All are members of the same family of hypercarbon systems. 

MgR(PhTpstructurally characterized and compared with [MMe(TpBu)]. The phenyl substituent on boron has an almost negligible effect on the metal-carbon bond lengths.90... 

W. Gerrard, The Chemistry of Boron, Academic Press, New York, 1961 E. L. Muetterties, The Chemistry of Boron and its Compounds, John Wiley, New York, 1967 A. N. Nesmeyanov, R. A. Sokolik, Methods of Elemento-organic Chemistry , North-Holland, Amsterdam, 1967, Vol. 1 R. Koster, Houben-Weyl Methoden der Organischen Chemie, Georg Thieme Verlag, Stuttgart, 1984 D. S. Matteson, in The Chemistry of the Metal-Carbon Bond (Eds. F. Hartley, S. Patai), John Wiley, New York, 1987, Vol. 4, pp. 307-409 ref. [2]. 

What type of compounds will be covered in this overview. Strictly, only compounds which have at least one metal-carbon bond (with the exception of metal carbides) are called organometaiiic. However, this definition was not adopted in this chapter because many families of compounds that are relevant in organometaiiic chemistry would not be included (e.g., alkoxides). By metal we mean any element from groups 1 (except hydrogen), 2, 3 (including lanthanides and actinides), 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 (except boron), 14 (except carbon and silicon), and 15 (antimony and bismuth only). Most of the available thermochemical data for all these species are freely available in a single on-line database the NIST Chemistry WebBook Unless stated otherwise, all the data included in this chapter were quoted from that reference. 

Organometallic compounds are those in which there is a metal-carbon bond. According to this definition, in the case of transition metals, this group of compounds includes not only metal carbonyls, olefin complexes, cyclopentadienyl, and other 7r-complexes, but also cyanide and fulminate compounds. Certain difficulties arise in defining the metal of the main group elements. Usually, organometallic compounds are comprised not only of compounds of typical metals, but also of metalloids such as boron, silicon, phosphorus, arsenic, selenium, etc. In compounds of metals as well as in those of metalloids, the bond is generally polarized as follows C. Consequently, the... 

In this book we are concerned with the properties of compounds which contain metal—carbon bonds. Traditionally organometallic chemistry includes the carbon compounds of the metalloids boron, silicon and arsenic, but excludes those of phosphorus and of other more electronegative elements. Metal carbonyls are discussed, but not cyanides or carbides, which are more usefully considered in conjunction with inorganic rather than organometallic compounds. 

Not only are the organo derivatives of Al Ga and In better acceptors than their boron analogues but they also are much more reactive towards cleavage by protonic acids, probably on account of the greater polarity of the metal-carbon bonds. This has already been noted in connection with their easy hydrolysis. Adducts with primary and secondary amines eliminate methane on heating. 

Iverson CN, Smith III MR.. Reactivity of organoplatinum complexes with C6H4O2B-BO2C6H4 synthesis of a platinnm diboryl complex with, and without, metathesis of boron-boron and metal-carbon bonds. Jz4m Chem Soc. 1995 117 4403-4404. 

In bonding to the ligand the metal is always shifted away from the boron and interacts most strongly with C-4. This slip distortion is larger than expected considering the difference between the covalent radii of boron and carbon alone (22), and thus must partially be of electronic origin (cf. refs. 36 and 37). 

---