Topologically Unique Heterometallic CuII/Li Coordination Polymers Self-Assembled from N,N-bis(2-Hydroxyethyl)-2-aminoethanesulfonic Acid Biobuffer: Versatile Catalyst Precursors for Mild Hydrocarboxylation of Alkanes to Carboxylic Acids

摘要

The facile aqueous medium reactions of copper(II) nitrate with BES biobuffer [(HOCH2CH2)2N(CH2CH2SO3H), hereinafter referred as H3bes] in the presence of various benzenecarboxylic acids [benzoic (Hba), 3-hydroxybenzoic (Hhba), and 3,5-dihydroxybenzoic (Hdhba) acid] and lithium hydroxide gave rise to the self-assembly generation of three new heterometallic CuII/Li materials, [Li(H2O)4][Cu4(μ2-Hbes)4(μ2-ba)]·H2O (1) and [Cu4(μ3-Hbes)4(L){Li(H2O)2}]n·3nH2O {L = μ2-hba (2) and μ2-dhba (3)}. They were isolated as air-stable crystalline solids and fully characterized by infrared (IR) and UV–vis spectroscopy and electrospray ionization (ESI)-MS(±), elemental, thermal, and single-crystal X-ray diffraction analyses. The latter revealed that 1–3 have comparable packing patterns and unit cell parameters, being composed of similar [Cu4(μ-Hbes)4(μ-carboxylate)]− cores and [Li(H2O)4]+ cations (in 1) or [μ-Li(H2O)2]+ groups (in 2 and 3), which are arranged into discrete 0D aggregates in 1 or infinite 3D noninterpenetrating metal–organic networks in 2 and 3. The topological analysis of the coordination polymers 2 and 3 disclosed the trinodal 3,3,4-connected underlying nets with an unprecedented topology defined by the point symbol of (4.6.8)4(42.6)2(62.162.182), further simplification of which resulted in the binodal 4,4-connected nets with the pts (PtS) topology. Apart from representing very rare examples of coordination compounds derived from H3bes, 1–3 feature solubility in water and were applied as efficient and versatile catalyst precursors for the mild (60 °C) single-pot hydrocarboxylation, by CO and H2O, of various gaseous, linear, and cyclic Cn (n = 2–9) alkanes into the corresponding Cn+1 carboxylic acids, in H2O/MeCN medium under homogeneous conditions and in the presence of potassium peroxodisulfate. Total yields (based on alkane) of carboxylic acids up to 78% were achieved, which are remarkable in the field of alkane functionalization under mild conditions, especially for a C–C bond formation reaction in aqueous acid-solvent-free medium.