Reaction of carbene-stabilized diphosphorus, L:P–P:L (L: = :C{N(2,6-Pri2C6H3)CH}2, 1), with excess BH3·THF affords the boronium salt [L:P(μ-BH2)P:L]+[B2H7]−, 2, which contains a three-membered P2B ring. When 2 is dissolved in THF, compounds 1 and 2 exist in a dynamic solution equilibrium.
