Two new coordination complexes {[(L)Cu-2(mu-L)(NO3)-(CH3OH)(0.3)(H2O)(0.7)]center dot NO3}[Cu(L)(NO3)(CH3OH)] (1) and [Mn-2(mu-L)(2)(H2O)(mu(1)-N-3)(2)(CH3OH)] (2) derived from (E)-N'-(2-hydroxy-3-methoxybenzylidene)acetohydrazide [LH] have been synthesized. The new potentially tetradentate ONOO donor hydrazone ligand [LH] has shown considerable metal ion selective phenoxo bridging in 1 and 2. It has coordinated copper(II) ions in its tridentate as well as in tetradentate fashion whereas for manganese(II) ions it solely showed its tetradentate character. In I the two adjacent pentacoordinate copper(II) centers are connected by a rare single phenoxo linkage of the hydrazone ligand whereas 2 is a doubly phenoxo-bridged heptacoordinated manganese(II) dinuclear species. The 3D supramolecular networks of I and 2 have resulted from extensive H-bonding interactions in the respective complexes. Structural variations observed for 1 and 2 have been described by performing single-crystal X-ray analysis. The ligand and the complexes are characterized by elemental analyses, IR, UV/Vis and H-1 NMR spectroscopy. Cryomagnetic investigations, DFT studies and EPR analysis, of I and 2 have also been studied in detail.