The title complex with 2-hydroxyenzoic acid methyl ester, diamine hydrate, and 2-propanone was synthesized and characterized. It falls into the monoclinic space group P2(1)/n with a = 0.482 71 (15), b = 1.560 5 (5), c = 1.420 8 (4) nm, β = 90. 899 (6)°, V = 1.0701 (6) nm^3, Dc = 1.305 g/ cm3, Z = 4, F(000) = 448, R1 = 0.0472, wR2= 0.1043. With the crystal coordinates data, we performed a quantum chemical calculation on this complex by means of G03W program, and obtained its molecular orbitals energies and atomic Mulliken charges...