Formation of Coordination Polymers or Discrete Adducts via Reactions of Gadolinium(III)–Copper(II) 15-Metallacrown‑5 Complexes with Polycarboxylates: Synthesis, Structures and Magnetic Properties

Reactions of the copper­(II)–gadolinium­(III) 15-metallacrown-5 complex [GdCu₅(Glyha)₅(NO₃)₂(H₂O)₆]­(NO₃) (Glyha^2– = dianion of glycinehydroxamic acid) with different di/tricarboxylates (1,3-phthalate, 1,4-phthalate, biphenyl-4,4′-dicarboxylate, citrate) resulted in formation of different types of products: {[(GdCu₅(Glyha)₅(H₂O)₂)­(GdCu₅(Glyha)₅(H₂O)₃)­(1,3-bdc)₃]·16H₂O}_<i>n</i> (<b>1</b>), {[(GdCu₅(Glyha)₅(H₂O)₃)₂(1,4-bdc)₂]­(1,4-bdc)·8H₂O}_<i>n</i> (<b>2</b>), {[(GdCu₅(Glyha)₅(H₂O)₄)₂(1,4-bdc)₃]·8H₂O}_<i>n</i> (<b>3</b>), [GdCu₅(Glyha)₅(Citr)­(H₂O)₄]·7H₂O (<b>4</b>), {[GdCu₅(Glyha)₅(H₂O)₅]­(μ₂-CO₃)­[Cu­(Fgg)]}·7H₂O (<b>5</b>) and [Cu­(Gly)₂(H₂O)]_<i>n</i> (<b>6</b>) (where bdc^2– is the corresponding phthalate (benzenedicarboxylate), Citr^3– is citrate, Fgg^3– is the trianion of [(<i>N</i>-formylaminoacetyl)­amino]­acetic acid and Gly^– is glycinate). Complexes <b>1</b>–<b>5</b> contain the [GdCu₅(Glyha)₅]³⁺ cation. Complexes <b>2</b> and <b>3</b> possess the same composition but differ by the mode of <i>p</i>-phthalate coordination to the [GdCu₅(Glyha)₅]³⁺ unit. In compounds <b>1</b>–<b>3</b>, metallacrown cations are linked by the corresponding phthalates in 1D, 1D and 2D polymers, respectively, whereas <b>4</b> and <b>5</b> are discrete molecules. Compound <b>5</b> is the product of a multistep reaction, which finally involves atmospheric CO₂ capture. Hydrolysis of hydroxamate in this reaction is confirmed by isolation of a mononuclear copper glycine complex 6. The χ_M<i>T</i> vs <i>T</i> data for <b>1</b> were fitted using a model based on the Hamiltonian <i><b>Ĥ</b></i> (GdCu₅) = −2<i>J</i>₁(<i>S</i>₁ × <i>S</i>_Gd + <i>S</i>₂ × <i>S</i>_Gd + <i>S</i>₃ × <i>S</i>_Gd + <i>S</i>₄ × <i>S</i>_Gd + <i>S</i>₅ × <i>S</i>_Gd) – 2<i>J</i>₂(<i>S</i>₁ × <i>S</i>₂ + <i>S</i>₂ × <i>S</i>₃ + <i>S</i>₃ × <i>S</i>₄ + <i>S</i>₄ × <i>S</i>₁ + <i>S</i>₅ × <i>S</i>₁. The best fit corresponded to <i>J</i>₁ = +0.60(2) cm^–1, <i>J</i>₂ = −61.0(5) cm^–1 and z<i>J′</i> = −0.035(4) cm^–1. Complex <b>1</b> is the first example of a 15-metallacrown-5 system, for which numerical values of exchange parameters have been reported. The isotherm for methanol absorption by compound <b>1</b> at 293 K was typical for microporous sorbents, whereas ethanol sorption was negligibly small

High Nuclearity Assemblies and One-Dimensional (1D) Coordination Polymers Based on Lanthanide–Copper 15-Metallacrown‑5 Complexes (Ln^III = Pr, Nd, Sm, Eu)

Complexes {[LnCu₅(GlyHA)₅(<i>m</i>-bdc)­(H₂O)_4–<i>x</i>]₂[LnCu₅(GlyHA)₅(SO₄)­(<i>m</i>-bdc)­(H₂O)₄]₂}·(30 + 2<i>x</i>)­H₂O (where GlyHA^2– = glycinehydroxamate, <i>m</i>-bdc^2– = <i>m</i>-phthalate; Ln = Pr and <i>x</i> = 0.21 for compound <b>1</b>, or Ln = Sm and <i>x</i> = 0.24 for <b>3</b>) and one-dimensional (1D) coordination polymers {[NdCu₅(GlyHA)₅(H₂O)₅(<i>m</i>-bdc)]<i>_nn</i>[NdCu₅(GlyHA)₅(H₂O)₄(μ-CO₃)­(<i>m</i>-bdc)]}·13<i>n</i>H₂O (<b>2</b>) and {[EuCu₅(GlyHA)₅(H₂O)₃]­(<i>m</i>-bdc)₂[EuCu₅(GlyHA)₅(<i>m</i>-bdc)­(H₂O)₃]}_<i>n</i>·17<i>n</i>H₂O (<b>4</b>) were obtained starting from the 15-metallacrown-5 complexes {[LnCu₅(GlyHA)₅(SO₄)­(H₂O)_6.5]}₂(SO₄)·6H₂O (Ln = Pr, Nd, Sm, Eu) by the partial or complete metathesis of sulfate anions with <i>m</i>-phthalate. Compounds <b>1</b> and <b>3</b> contain unprecedented quadruple-decker neutral metallacrown assemblies, where the [LnCu₅(GlyHA)₅]³⁺ cations are linked by <i>m</i>-phthalate dianions. In contrast, in complexes <b>2</b> and <b>4</b>, these components assemble into 1D chains of coordination polymers, the adjacent {[NdCu₅(GlyHA)₅(H₂O)₅(<i>m</i>-bdc)]⁺}<i>_n</i> 1D chains in <b>2</b> being separated by discrete [NdCu₅(GlyHA)₅(H₂O)₄(μ-CO₃)­(<i>m</i>-bdc)]}⁻ complex anions. The crystal lattices of <b>2</b> and <b>4</b> contain voids filled by solvent molecules. Desolvated <b>4</b> is able to absorb up to 0.12 cm³/g of methanol vapor or 0.04 cm³/g of ethanol at 293 K. The isotherm for methanol absorption by compound <b>4</b> is consistent with a possible “gate opening” mechanism upon interaction with this substrate. The χ_M<i>T</i> vs <i>T</i> data for complexes <b>1</b>–<b>4</b> and their simpler starting materials {[LnCu₅(GlyHA)₅(SO₄)­(H₂O)_6.5]}₂(SO₄)·6H₂O (Ln­(III) = Pr, Nd, Sm, Eu) were fitted using an additive model, which takes into account exchange interactions between lanthanide­(III) and copper­(II) ions in the metallamacrocycles via a molecular field model. The exchange interactions between adjacent Cu­(II) ions in metallacrown fragments were found to fall in the range of −47 < <i>J</i>_Cu–Cu < −63 cm^–1. These complexes are the first examples of a Ln­(III)-Cu­(II) 15-metallacrowns-5 (Ln­(III) = Pr, Nd, Sm, Eu), for which values of exchange parameters have now been reported

Solvent-Induced Change of Electronic Spectra and Magnetic Susceptibility of Co^II Coordination Polymer with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine

One-dimensional coordination polymer [Co­(Piv)₂(4-ptz)­(C₂H₅OH)₂]_<i>n</i> (compound <b>1</b>, Piv^– = pivalate, 4-ptz = 2,4,6-tris­(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co^II pivalate with 4-ptz. Desolvation of <b>1</b> led to formation of [Co­(Piv)₂(4-ptz)]<i>_n</i> (compound <b>2</b>), which adsorbed N₂ and H₂ at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by <b>2</b> at 295 K led to structural transformation probably connected with coordination of these alcohols to Co^II. Formation of <b>2</b> from <b>1</b> was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χ_M) in the temperature range from 2 to 300 K. Resolvation of <b>2</b> by ethanol or water resulted in restoration of spectral characteristics and χ_M values almost to the level of that of <b>1</b>. χ_M<i>T</i> versus <i>T</i> curves for <b>1</b> and samples, obtained by resolvation of <b>2</b> by H₂O or C₂H₅OH, were fitted using a model for Co^II complex with zero-field splitting of this ion

Solvent-Induced Change of Electronic Spectra and Magnetic Susceptibility of Co^II Coordination Polymer with 2,4,6-Tris(4-pyridyl)-1,3,5-triazine

One-dimensional coordination polymer [Co­(Piv)₂(4-ptz)­(C₂H₅OH)₂]_<i>n</i> (compound <b>1</b>, Piv^– = pivalate, 4-ptz = 2,4,6-tris­(4-pyridyl)-1,3,5-triazine) was synthesized by interaction of Co^II pivalate with 4-ptz. Desolvation of <b>1</b> led to formation of [Co­(Piv)₂(4-ptz)]<i>_n</i> (compound <b>2</b>), which adsorbed N₂ and H₂ at 78 K as a typical microporous sorbent. In contrast, absorption of methanol and ethanol by <b>2</b> at 295 K led to structural transformation probably connected with coordination of these alcohols to Co^II. Formation of <b>2</b> from <b>1</b> was accompanied by change of color of sample from orange to brown and more than 2-fold decrease of molar magnetic susceptibility (χ_M) in the temperature range from 2 to 300 K. Resolvation of <b>2</b> by ethanol or water resulted in restoration of spectral characteristics and χ_M values almost to the level of that of <b>1</b>. χ_M<i>T</i> versus <i>T</i> curves for <b>1</b> and samples, obtained by resolvation of <b>2</b> by H₂O or C₂H₅OH, were fitted using a model for Co^II complex with zero-field splitting of this ion

Heterometallic Coordination Polymers Assembled from Trigonal Trinuclear Fe₂Ni-Pivalate Blocks and Polypyridine Spacers: Topological Diversity, Sorption, and Catalytic Properties

Linkage of the trigonal complex [Fe₂NiO­(Piv)₆] (where Piv^– = pivalate) by a series of polypyridine ligands, namely, tris­(4-pyridyl)­triazine (L²), 2,6-bis­(3-pyridyl)-4-(4-pyridyl)­pyridine (L³), <i>N</i>-(bis-2,2-(4-pyridyloxymethyl)-3-(4-pyridyloxy)­propyl))­pyridone-4 (L⁴), and 4-(<i>N</i>,<i>N</i>-diethylamino)­phenyl-bis-2,6-(4-pyridyl)­pyridine (L⁵) resulted in the formation of novel coordination polymers [Fe₂NiO­(Piv)₆(L²)]_<i>n</i> (<b>2</b>), [Fe₂NiO­(Piv)₆(L³)]_<i>n</i> (<b>3</b>), [Fe₂NiO­(Piv)₆(L⁴)]_<i>n</i>·<i>n</i>HPiv (<b>4</b>), and [{Fe₂NiO­(Piv)₆}₄{L⁵}₆]<i>_n</i>·3<i>n</i>DEF (<b>5</b>, where DEF is <i>N</i>,<i>N</i>-diethylformamide), which were crystallographically characterized. The topological analysis of <b>3</b>, <b>4</b>, and <b>5</b> disclosed the 3,3,4,4-connected 2D (<b>3</b>, <b>4</b>) or 3,4,4-connected 1D (<b>5</b>) underlying networks which, upon further simplification, gave rise to the uninodal 3-connected nets with the respective fes (<b>3</b>, <b>4</b>) or SP 1-periodic net (4,4)­(0,2) (<b>5</b>) topologies, driven by the cluster [Fe₂Ni­(μ₃-O)­(μ-Piv)₆] nodes and the polypyridine μ₃-L^3,4 or μ₂-L⁵ blocks. The obtained topologies were compared with those identified in other closely related derivatives [Fe₂NiO­(Piv)₆(L¹)]_<i>n</i> (<b>1</b>) and {Fe₂NiO­(Piv)₆}₈{L⁶}₁₂ (<b>6</b>), where L¹ and L⁶ are tris­(4-pyridyl)­pyridine and 4-(<i>N</i>,<i>N</i>-dimethylamino)­phenyl-bis-2,6-(4-pyridyl)­pyridine, respectively. It was shown that a key structure-driven role in defining the dimensionality and topology of the resulting coordination network is played by the type of polypyridine spacer. Compounds <b>2</b> and <b>3</b> possess a porous structure, as confirmed by the N₂ and H₂ sorption data at 78 K. Methanol and ethanol sorption by <b>2</b> was also studied indicating that the pores filled by these substrates did not induce any structural rearrangement of this sorbent. Additionally, porous coordination polymer <b>2</b> was also applied as a heterogeneous catalyst for the condensation of salicylaldehyde or 9-anthracenecarbaldehyde with malononitrile. The best activity of <b>2</b> was observed in the case of salicylaldehyde substrate, resulting in up to 88% conversion into 2-imino-2<i>H</i>-chromen-3-carbonitrile