The structure and energy properties of the H2O/C3O2 (D2O/C3O2) and NH3/C3O2 ((NH3)-N-15/C3O2) 1:1 complexes have been investigated in solid argon matrices with FT-infrared spectroscopy and ab initio calculations at the MP2/6-31G** level. These complexes trapped in argon matrices are characterized by a large shift of the upsilon(CCO) stretching modes to lower frequencies. Predicted frequency shifts for the T-Nu shaped structure were found to be in good agreement with the observed complex vibrational frequency shifts. These complexes are indicative of a nucleophilic attack of the oxygen (or nitrogen) atom on the C4 atom of the C3O2 moiety. At the same time, we observe very short intermolecular distances between the O1 oxygen atom of the suboxide subunit and the hydrogen atom of H2O (D2O), or NH3 ((NH3)-N-15), lying in the C3O2 plane (2.77 and 2.96 Angstrom for H2O (D2O) and NH3 ((NH3)-N-15), respectively). These values are indicative of a hydrogen bond between these atoms. Examination of the T-Nu complex structures shows for the C3O2 subunit the pinching of the CCC (-22 degrees and -26 degrees for H2O and NH3, respectively) and the CCO valence bond angles (-3 degrees for H2O and NH3). The geometries of the complexes and the structural modifications of the complex's suboxide moiety suggest pre-reactive intermediates of an 1,4 nucleophilic addition.