[Pd(sac)(terpy)](sac)center dot 4H(2)O (1), [Pt(sac)(terpy)](sac)center dot 5H(2)O (2), [PdCl(terpy)](sac)center dot 2H(2)O (3) and [PtCl(terpy)](sac)center dot 2H(2)O (4) (sac = saccharinate, and terpy = 2,2': 6',2 ''-terpyridine) have been synthesized and characterized by elemental analysis, FT-IR, H-1 NMR and C-13 NMR. In 1 and 2, a tridentate terpy ligand together with an N-coordinated sac ligand form the square-planar geometry around the palladium(II) or platinum(II) ions, while one sac anion remains outside the coordination sphere as a counter-ion. Xray single crystal studies show that the [M(sac)(terpy)](+) ions in 1 and 2 reside in the centers of a hydrogen bonded honeycomb network formed by the uncoordinated sac ions and the lattice water molecules. Complexes 3 and 4 are isostructural and consist of a [M(Cl)(terpy)](+) cation, a sac anion and two lattice water molecules. The [M(Cl)(terpy)](+) ions interact with each other via M-M and pi-pi stacking interactions and these p interacted units are assembled to a 2D network by water bridges involving the sac ions and lattice water molecules. Convenient synthetic paths for 1-4 are also presented, and spectral, luminescence and thermal properties were discussed. (C) 2009 Elsevier B. V. All rights reserved.