Thermal Decomposition of Donor‐Stabilized Phosphinoborane PH 2 BH 2 NMe 3 : A Tensimetry Study

The thermal decomposition of PH 2 BH 2 · NMe 3 ( 1 ) in closed system was studied by static tensimetry with membrane null‐manometer. Compound 1 is unstable already at room temperature and partially decomposes with the release of gaseous trimethylamine and nonvolatile polymeric material. Storage of 1 at 311 K for 53 days results in evolution of small amounts of hydrogen and phosphine. At temperatures up to 329 K, PH 3 evolution and BH 3 NMe 3 adduct formation is observed after 3 days, and above 387 K, considerable amount of hydrogen gas is released. The data obtained indicate that the pyrolysis of 1 in the closed system may result in the enrichment of the condensed phase with boron due to phosphine loss.