The electronic structure of typical s = 1 Haldane gap compounds such as [Ni(NH2(CH2)(3)NH2)(2)N-3]ClO4 (NINAZ), [Ni(NH2CH2C(CH3)(2)CH2NH2)(2)N-3]ClO4 (NDMAZ) and [Ni(NH2CH2C(CH3)(2)CH2NH2)(2)N-3]PF6(NDMAP) have been investigated by means of discrete variational (DV)-X alpha molecular orbital calculation. The DV-X alpha calculations of these compounds reveal the importance of the overlap population analysis of bridging N-3(-) ligands, suggesting the tendency of the well-balance intramolecular overlap dispersion in the bridged N-3(-) molecule is correlated with the larger Haldane gap E-g.