Derivatization of an especially electron-rich diborane

Starting with electron-rich ditriflato-diborane B-2(hpp)(2)(OTf)(2) (hpp = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-alpha]pyrimidinate), novel symmetric and unsymmetric diboranes B-2(hpp)(2)X-2 and B-2(hpp)(2)XY with X,Y = Br, NCS, N-3 or OTf are synthesized by substitution reactions with S(N)1 mechanisms. The stability of the unsymmetric diboranes with respect to dismutation equilibria is evaluated.