Phenylborane complexes

The synthesis of the dibenzyl bis(alkylamido)phenylborane complex Ti(GH2Ph)2(ButN-BPh-NBut) (Scheme 60) has been described and its molecular structure determined by X-ray diffraction methods.129... 

The direct borylation of arenes was catalyzed by iridium complexes [61-63]. Iridium complex generated from [lrCl(cod)]2 and 2,2 -bipyridine (bpy) showed the high catalytic activity of the reaction of bis (pinaco la to) diboron (B2Pin2) 138 with benzene 139 to afford phenylborane 140 (Equation 10.36) [61]. Various arenes and heteroarenes are allowed to react with B2Pin2 and pinacolborane (HBpin) in the presence of [lrCl(cod)]2/bipyridne or [lr(OMe)(cod)]2/bipyridine to produce corresponding aryl- and heteroarylboron compounds [62]. The reaction is considered to proceed via the formation of a tris(boryl)iridium(lll) species and its oxidative addition to an aromahc C—H bond. 

Dibenzyl bis(alkylamido)phenylboranes, with Ti(IV), 4, 347 Dibenzyl bis(benzamidinato) complexes, with Ti(IV),... 

The aromatic moiety in phenylboranes and phenylb-orates may serve as a 6-electron n donor ligand to transition-metal complexes. Half-sandwich complexes of chromium, Mes2[B( -Mes)Cr(CO)3] (56), MesB[ -MesCr(CO)3]2 (57), andB[ -MesCr(CO)3]3 (58), containing trimesitylborane as a ligand have been prepared and structurally characterized.1 1 The Cr(CO)3 moieties interact weakly in the multinnclear systems (57) and (58) as shown by... 

It is in the field of the co-ordination compounds of boron that some of the most conflicting results have been obtained. It is however generally recognized that the transformation of the sp hybridization of the boron atom to an sp hybridized state on complex formation results in a shift to high field. In our laboratories, we have designated this chemical-shift difference between the free and complexed boron acceptor molecule as the A value. We have found it very convenient to use this A value although it is not always applicable, e.g., in borane BH3, which exists as the dimer, diborane, and in phenylborane, PhBH2, which we have not yet isolated in the free state. 

Greenwood et alP have measured the B shifts of the substituted borane complexes of triethylamine EtaN BH2X (where X = Cl, Br, I and Ph). The B shifts of the complexes of pyridine and substituted pyridine with both borane and phenylborane have been compared the order of the basic strengths was explained in terms of steric strain on the introduction of the phenyl group. 

Reetz, M. T. WUluhn, M. Psiorz, C. Goddard, R. Donor complexes of bis( 1-indenyl)phenylborane dichlorozirconium as isospecific catalysts in propene polymerization. Chem. Commun. 1999, 1105-1106. 

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