Merged jet copyrolysis reactions of diborane, B2H6, with PH3, (CH3)3P
and PF3 were attempted, followed by trapping into argon matrices. Cont
rary to previous studies of the reactions of B2H6 with nitrogen, oxyge
n and sulfur bases, only the H3B . P (CH3)3 adduct was observed, with
no further elimination products. The lack of observation of the H3B .
PH3 and H3B . PF3 adducts under these conditions indicates that the eq
uilibrium constant for adduct formation is very small at room temperat
ure. The absence of H-2 or HF elimination products (e.g. H2BPH2) provi
des indirect support for the previously proposed reaction mechanism in
volving initial adduct formation.