B Additional Boron Cations

Closely related to the spiro-cations described above are a few examples of ions containing three bridging pyrazolyl groups between the same two boron atoms. Such species were first obtained on interaction of pyrazolide anion with ethylboryl ditosylate, C2H5B(0S02C6H4-4-CH3)2 

3 Mpz -b 2 C2H5B(0S02C6H4-4-CH3)2 3 M(0S02CgH4-4-CH3) [C2H5B(ik)3BC2H5] (0S02CgH4-4-CH3) (5) 

The X-ray crystal and moleciHar structure of the salt [C2HjB(pz)3BC2Hj]PFg has been described Also, the salts [HB(pz )3BH]MClg (Hpz = 3,5-dimethylpyrazole  

M = Nb, Ta) were obtained in an unusual process on interaction of K[HB(pz )3] with MClj. Their structure was again confirmed by X-ray diffraction and also NMR data Another series of interesting cyclic boron cations of tyj 15 has been reported 

These were obtained from the reaction of a geminal dipyrazolylalkane with a trigonal borane containing a ready leaving group, R2BX. However, little is known about 

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