Structural Versatility of Alkali Metal Coordination Polymers Driven by Arylhydrazones of β‑Diketones

The
self-assembly reaction of arylhydrazones of β-diketones
(AHBD), namely 2-[2-(2,4-dioxopentan-3-ylidene)­hydrazinyl]­benzenesulfonic
acid (H2L1) and 2-[2-(4,4-dimethyl-2,6-dioxocyclohexylidene)­hydrazinyl]­benzenesulfonic
acid (H2L2), with sodium or potassium hydroxides
in MeOH/H2O (1/1, v/v) produces a series of coordination
compounds, [Na3(μ3-HL1)2(μ4-HL1)­(μ-H2O)­(H2O)2]n (1), [Na2(HL1)2(μ-H2O)2(H2O)4]·4H2O (2), [Na­(HL2)­(μ-H2O)­(H2O)2]n·nH2O (3), [K­(μ4-HL1)­(μ3-H2O)]n (4), and [K­(μ4-HL2)­(H2O)]n (5), which include the one-dimensional (3), two-dimensional
(2D) (1, 4), and three-dimensional (3D)
(5) coordination polymers, as well as the zero-dimensional
dimer (2). Compounds 1–5 were isolated as air stable crystalline solids and characterized
by IR, 1H, and 13C­{1H} NMR spectroscopy,
elemental, differential thermal, and single-crystal X-ray diffraction
analysis. The latter shows that the monodeprotonated HL1– (L = L1, L2) anions act as multiple O-donors
through the sulfonate and carbonyl groups and are also capable of
simultaneously bridging three and/or four metal cations (in 1, 4, and 5), thus giving rise to
the intricate 2D and 3D coordination networks. Their topological analysis
reveals the trinodal 3,4,7-connected (in 4) and pentanodal
3,4-connected (in 1) underlying 2D nets with novel types
of topologies, as well as the uninodal 4-connected 3D framework with
the sra (SrAl2) topology (in 5).