Synthesis, Crystal Structures, and Magnetic Properties of Ternary M(II)-Dicyanamide-hydroxypyridine Complexes

Abstract

Three two-dimensional (2D) and 3D supramolecular coordination architectures based on ternary M(II)-dicyanamide-2-hydro- (2), and [Mn(hepH) 2 (dca) 2 ] (3) (dca = dicyanamide, hmpH = 2-(hydroxymethyl)pyridine, hepH = 2-(hydroxyethyl)pyridine), have been synthesized. 1 is a mononuclear Co(II) complex. The mononuclear units are interlinked into a 2D (4,4) hydrogen-bonded layer via O-H⋅ ⋅ ⋅ N hydrogen bonds between the hydroxyl groups and the noncoordinating nitrile ends. These 2D layers are further extended into a 3D supramolecular architecture via the interlayer pyridyl-pyridyl stacking interaction. 2 has a 1D coordination chain structure formed by the double 1,5 -dca bridged dinuclear [Cu2( 1,5 -dca) 2 (hmpH) 2 ] unit and the 1,3 -dca bridges via weak Cu-N coordination, and these 1D coordination chains are further extended into 2D hydrogen-bonded layers via strong O-H⋅ ⋅ ⋅ N hydrogen-bonding interaction between the hydroxyl groups and the noncoordinating nitrile ends. 3 is a 2D (4,4) coordination network made of 1D [Mn(hepH)( 1,5 -dca)] helical chain units and interchain double ( 1,5 -dca) bridges. Pairs of [Mn(hepH)( 1,5 -dca)] helical chains are interlinked by the double ( 1,5 -dca) bridges into a racemic coordination layer structure, which is further extended into a 3D hydrogen-bonded network. Magnetic studies reveal that weak antiferromagnetic exchange occurs in 3.

Synthesis, Crystal Structure, and Antimicrobial Properties of a Novel 1-D Cobalt Coordination Polymer with Dicyanamide and 2-Aminopyridine

“…In the equatorial plane, the bonding configuration of dca around the Co1 atoms is nonlinear as evidenced by the bond angles C6-N3-Co1 (164.9 ∘ ) and C7-N5-Co1 (157.7 ∘ ). This observation is consistent with the literature reports [30]. Each Co1 atom is linked to two Co1 atoms through two 1,5-2 -dca bridges resulting in a 1-D polymeric chain structure (Figure 3).…”

“…The Co1-N1 bond length is slightly longer than that reported for other cobalt complexes wih 2-ampy [4,7,9,20]. The Co1-N3 (2.126Å) and Co1-N5 (2.128Å) bond lengths are similar to values reported in the literature for other Co-N bonds with nitrile N [26,30]. The dca ligand adopts a bridging coordination mode through the terminal nitrile N-atoms.…”

“…N4 iv N3 iv C6 iv show strong absorption bands in the 2310-2100 cm −1 region attributed to the ] s + ] as (C≡N), ] as (C≡N), and ] s (C≡N) vibrational modes of dca [27,30]. The appearance of two new characteristic bands, 434 cm −1 and 560 cm −1 in the spectrum of the complex, which were not found in the spectra of the ligands, indicates the presence of M-N bonding between the metal and the nitrogen atoms of both 2-aminopyridine and dca.…”

“…Dicyanamide (dca) has been used extensively as a building block in supramolecular chemistry and crystal engineering [26]. This pseudohalide shows versatility in its coordination modes; it can act as a monodentate ligand through 2 International Journal of Inorganic Chemistry nitrile nitrogen, as a bidentate ligand through terminal nitrile nitrogen atoms, or as a bridging ligand in varied bridging modes [26][27][28][29][30][31]. The versatile coordination ability of dca has led to the design and synthesis of several metal-dicyanamide complexes with varied topologies and magnetic properties [26,27].…”

“…The chemistry of cobalt(II) complexes with O-and Ndonor ligands has been extensively studied and it was found to have diverse properties [1,7,20,30,32]. Some of the complexes have been shown to possess antitumor properties [33], as well as antimicrobial activity against resistant microbial strains [12,34,35].…”