Borate complexes nomenclature

Throughout, the standard conventions of poly(pyrazolyl)borate abbreviated nomenclature will be applied i.e. Tp and Bp for the parent hydrotris- and dihydrobis(pyrazolyl)borate ligands, with pyrazole substituents denoted in the form TpR 4R R where superscripts R, 4R and R" indicate substituents in the 3, 4 and 5 positions respectively (omitted if none). Similarly, TpR denotes equivalent substituents in the 3/5 positions and TpR all three equivalents. The non-systematic but commonly employed abbreviations Bp and Tp will be used to indicate ligands derived from 3,5-dimethylpyrazole, i.e. Bp and Tp. More complex systems will be defined where appropriate. 

Ebelman and Bouquet prepared the first examples of boric acid esters in 1846 from boron trichloride and alcohols. Literature reviews of this subject are available. B The general class of boric acid esters includes the more common orthoboric acid based trialkoxy- and triaryloxyboranes, B(0R)3 (1), and also the cyclic boroxins, (ROBO)3, which are based on metaboric acid (2). The boranes can be simple trialkoxyboranes, cyclic diol derivatives, or more complex trigonal and tetrahedral derivatives of polyhydric alcohols. Nomenclature is confusing in boric acid ester chemistry. Many trialkoxy- and triaryloxyboranes such as methyl, ethyl, and phenyl are commonly referred to simply as methyl, ethyl, and phenyl borates. The lUPAC boron nomenclature committee has recommended the use of trialkoxy- and triaryloxyboranes for these compounds, but they are referred to in the literature as boric acid esters, trialkoxy and triaryloxy borates, trialkyl and triaryl borates or orthoborates, and boron alkoxides and aryloxides. The lUPAC nomenclature will be used in this review except for relatively common compounds such as methyl borate. Boroxins are also referred to as metaborates and more commonly as boroxines. Boroxin is preferred by the lUPAC nomenclature committee and will be used in this review. 

Silver complexes have also been described for the cyclopropanation reaction. When using benzene, the use of Tp Ag(thf) (where Tp "" =hydrotris(3, 5-bis(trisfluoromethyl)pyrazolyl)borate for the rules of nomenclature of Tp" ligands see reE ) provided products derived from the addition of the carbene moiety to the arene ring (Scheme 7a), followed by ring expansion into a cycloheptatriene, in the... 

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