Me2NHBH2NMe2BH3, the nitrogen base site in the parent aminoarsine effectively competes for the BH3 bound in the diborazane. This competition leads to dissociation of the diborazane and formation of a BH3 adduct of the aminoarsine. [Me2NBH2I2 forms and BH3/aminoarsine adduct decomposition yields (MQN)~BH and an alternate route to the As-As-bonded products. These results are consistent with those obtained from our study of the analogous BH3/aminoarsine systems with varying stoichiometry.'
Experimental SectionGenml Dah. Due to the nature of the materials, standard highvacuum-line techniques and a nitrogen-filled dri-lab (Vacuum Atmospheres Model HE-43 Dri-Lab equipped with a Model HE-493 Dri-Train) were used for the storage and manipulation of all compounds. Me2AsNMe2 (74 "C/108 mmHg), MeAs(NMc2), (63 "C/50 mmHg), and As(NMe2), (55-57 OC/10 mmHg) were synthesized by the reaction of Me2AsC1, MeAsCI,, and AsC13, respectively, with a stoichiometric excess of Me2NH.19 M%AsCI (106 0C)20 and MeAsCI, (61-63 OC/50 mmHg)zl were synthesized by previously reported methods. The aminoanines were purified by distillation on a spinning-band column, and their purity was checked by 'H and I3C NMR spectroscopy. p-Me2NB2Hs was synthesized by the procedure described by SpielmanSs Toluene-d8 was purchased from Wilmad Glass Co. and stored over molecular sieves. IH, IlB, and l% NMR spectra were recorded on a GE (Nicolet) 300-MHz multinuclear FT NMR spectrometer operating at 300.1, 96.3, and 75.4 MHz, respectively. IH and "C NMR chemical shifts were measured with respect to Me& as an internal reference. The IIB NMR chemical shifts were measured relative to the signal of BF3-OEt,, high-field shifts being taken as negative. The IlB and I3C NMR spectra were obtained under broadband IH decoupling. Thus, all IlB and I C NMR resonances were observed as singlets. Additionally, some IlB NMR spectra were obtained under coupled conditions to determine the magnitude of 'J(BH). NMR spectral data were independently determined in this laboratory in toluene-d8 solution on prepurified or synthesized compounds identified in the reaction mixtures. The NMR data for all the adducts and prepurified or synthesized compounds are given in Table 1.General Reaction of p-Me2NB2Hs with Aminoarsines. J. Young VNMR tubes were charged with 1 mmol of the aminoarsine in 3.0 mL of toluene-d8, attached to the vacuum line, cooled to -1 15 "C (liquidnitrogen/ethanol slush), and degassed. The vapor of p-Me2NB2Hs were treated as an ideal gas, and the appropriately measured amount of p-Me2NB2Hs was condensed onto the toluene solution. The sealed NMR tube was gently agitated and inserted into the precooled (-95 "C) probe of the spectrometer. The reactions were followed at IO-deg temperature intervals (-95 to +25 "C) by 'H, 'IB, and ')C NMR spectroscopy.
