Complexes of Bis-Bidentate B pz J

Although usually coordinating in tridentate fashion, i.e., as [pzB(pz)3] , the ligand [B(pz)J can also be bis-bidentate when chelating a metal or metalloid which prefers four-coordination. The formation of polyboron spiro cations of the type [R2B(pz)2B(pz)2BR2] from the reaction of [B(pz)J with two molecules of RjBX has already been noted (see Sect. V.A.). The same principal structure can also be 

Additional examples of bis-bidentate coordination of the [B(pz)J include [(C5H5)2Ti(pz)2Ti(C5H5y+ [B(pz) Th(pz)2B(pz)2Th(pz), Bp+ and also the rather complex derivative [ (CgH5)3P (CO)(CH3CHCN)Ru(pz)2B(pz)2RuCl(CO) 

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