Condensation of aryl- and aroylhydrazines and thiosemicarbazide with 2-diphenylphosphinoyloxybenzaldehyde results in formation of the corresponding hydrazones and thiosemicarbazone. The products give rise to conformational equilibrium between rotational and Z,E isomers, which is strongly displaced toward the E,E,Z" isomer and is determined by the nature of substituent in the hydrazine fragment.