In gallium phosphide containing nitrogen ([N-P] > 10(17) cm(-3)) and carbon ([C-P] > 10(16) cm(-3)) a sharp local vibrational mode at 2087.12 cm(-1) at T=7 K is observed. It is shown that the complex responsible for this local vibrational mode is a carbon-nitrogen complex; the carbon-nitrogen bond is a triple bond aligned along the < 001 > axes of the lattice. A microscopic structure of the complex is proposed. It is suggested that the equivalent complex exists in GaAs and is characterized by a local vibrational mode at 2088.50 cm(-1) at T=7 K. The carbon atoms involved in these complexes do not contribute to the carbon p-type doping of the crystals.