Assignment of the 11b Nmr Spectrum of the Tridecahydro Decaborate(1-) Ion

IN A VARIETY of donor solvents, decaborane behaves as a monoprotic acid and, upon treatment with suitable bases such as amines or ylides, affords the tridecahydrodecaborate(1-) ion, B10H13-[1]. Previous HB NMR studies[2], done at lower field strengths, did not allow an interpretation of these spectra. In this communication, spectra of B~0HI~and some of its derivatives, recorded at 70.6 MHz, are reported. They are sufficient to allow an assignment of the HB NMR spectrum. The 70-6 MHz I~B spectrum of (CzHs)3NH+B~0H~3 in acetonitrile, Fig. la, is substantially more complex than the 32 MHz HB spectrum reported by Norman et al. [3]. It consists of four doublets of relative intensity 2 : 1 : 5 : 2 in order of increasing field. The spectrum of this salt is relatively insensitive to solvent: in acetonitrile-diethyl sulfide, the two doublets at lowest field begin to merge, while in benzene-dichloromethane, there is in addition a loss of apparent splitting in the doublet of relative intensity 5. Similar effects, although smaller in degree, are seen in dichloromethane solvent. The similarity of the spectra in both noncoordinating and donor solvents strongly indicates that one is not observing a species of the type B~0H13"L-, where L is a coordinated solvent. The spectrum of (C2H~)3NH + 1,2,3,4-B~0D4Hgis shown in Fig. lb. Deuteration in these positions causes collapse of the doublets a t 2 . 0 and 35.4 ppm. The collapse is complete, and there is no alteration of the doublets a t 6 8 and 5-0