PREPARATION, B-11 NMR AND VIBRATIONAL-SPE CTRA OF MU-AMIDO-BIS(HEXAHYDRO-CLOSO-HEXABORATE)(1-) AND CRYSTAL-STRUCTURE OF [AS(C6H5)(4)][B6H6(NH2)B6H6]

By reduction of [B6H5(NO)B6H5](3-) with Fe2+ in aqueous alkaline solut ion [B6H5(NH2)B6H5](3-) is formed. It reacts as a Bronsted base and be comes protonated in neutral medium to give the mono anion [B6H6(NH2)B6 H6](-). The crystal structure of the salt [As(C6H5)(4)][B6H6(NH2)B6H6] has been determined by single crystal X-ray diffraction analysis; tri clinic space group <P(1)over bar> with a = 8.284(2), b = 12.619(2), c = 15.543(3)Angstrom and alpha = 69.193(13)degrees; beta = 88.59(2)degr ees, gamma = 87.24(2)degrees. The B-11 NMR spectrum is consistent with mono hetero substituted octahedral B-6 cages with local C-4v symmetry . The IR and Raman spectra exhibit characteristic N-H, B-H and B-6 vib rations.