The multiconfigurational spin tensor electron propagator method (MCSTEP) is a Green's function based approach for directly calculating accurately the low lying ionization potentials (IPs) and electron affinities (EAs) of highly correlated closed and open shell molecules. The MCSTEP method has been employed to determine the vertical ionization potentials and adiabatic ionization potentials of BN, BN+ and B2N and the photodetachment energies (PDEs) of BN− and B2N−. These systems have had wide industrial applications and have recently been the focus of considerable attention. For BN, the lowest few MCSTEP vertical and adiabatic ionization potentials are in good agreement with other theoretical values previously reported. For BN− the MCSTEP PDEs are in good agreement with the experimental values and previous theoretical results. MCSTEP vertical and adiabatic IPs for BN+ differ for some states compared with other previously reported theoretical values. This is believed to be the first time that the vertical and adiabatic IPs of B2N have been reported. The MCSTEP PDEs of B2N are in very good agreement with the experimental values. © 2003 Taylor & Francis Group, LLC.