3-(Pyridin-4-yl)acetylacetone: a donor ligand towards mercury(II) halides and a versatile linker for complex materials

Abstract

The ditopic organic molecule 3-(pyridin-4-yl)acetylacetone (HacacPy) acts as a pyridine-type ligand towards HgX (X = Cl, Br, I). The nature of the anion and the ligand-to-cation ratio dominate the outcome of the reaction. Two different coordination compounds form with HgCl, namely a ligand-rich mononuclear complex, HgCl(HacacPy), and a ligand-deficient one-dimensional chain polymer, [Hg(μ-Cl)(HacacPy)], with five-coordinated Hg cations. Two compounds are also observed for HgBr, a molecular complex isomorphous to the chloride derivative and a chain polymer with the composition [Hg(μ-Br)Br(HacacPy)], in which the cations are four-coordinated. The ligand-rich mononuclear and ligand-deficient polymeric chloride and bromide complexes may be interconverted via thermal degradation and mechanochemical synthesis. In contrast to the chloride and bromide compounds, the reaction product with HgI does not depend on the ligand-to-cation ratio but corresponds to [Hg(μ-I)I(HacacPy)], isomorphous to the bromide derivative. The N-coordinated HacacPy complexes could not be deprotonated and further crosslinked with a second cation. Synthesis of mixed-metal products could be achieved, however, by deprotonation of the acetylacetone moiety in HacacPy and formation of tris-chelated Fe(acacPy) and Al(acacPy) complexes in the first step. These mononuclear building blocks act as bridging poly(pyridine) ligands towards Hg halides and form two structure types. The first represents a one-dimensional ladder, with the tris(ligand) complexes acting as triconnected nodes and the Hg halides acting as linkers. In the alternative unprecedented product, both the tris(ligand) complexes and the [HgX(μ-X)HgX] groups act as equivalent triconnected nodes. They form a uninodal two-dimensional coordination network with vertex symbol 4.8 and fes topology.

Proton disorder in a short intramolecular hydrogen bond investigated by single-crystal neutron diffraction at 2.5 and 170 K

“…3-Cyanoacetylacetone (HacacCN; Burrows et al, 2007;Kondraçka & Englert, 2008; and 3-(pyridin-4-yl)acetylacetone (HacacPy; Mackay et al, 1995;Vreshch et al, 2003Vreshch et al, , 2004Vreshch et al, , 2005Chen et al, 2004;Zhang et al, 2008;Li et al, 2011;Merkens et al, 2013Merkens et al, , 2014Truong et al, 2017b) have been used extensively for crystal engineering. HacacCN has been employed successfully as a building block for a deNO x catalyst precursor ISSN 2053ISSN -2296 # 2018 International Union of Crystallography (Konkol et al, 2016), but its synthesis is demanding (Silvernail et al, 2001;.…”

Coordination of a Potentially Tritopic Ligand via Phosphorus, Nitrogen and Oxygen: From Ligand Design to Heterobimetallic Metal–Organic Frameworks and Supramolecules

“…26 A greater degree of control can be introduced by using heteropolytopic ligands that, for example, incorporate binding sites which differ in their Pearson hardness. 27,28 These can selectively coordinate to a single metal cation, and the emerging metalloligand can subsequently be cross-linked with a second metal cation. 29−34 Among the examples for the second strategy the β-diketone moiety is a frequent choice for a Pearson hard functionality because of its reliable and predictable coordination behavior.…”

“…There are some examples in which a second metal cation can be introduced in a postmodification step . A greater degree of control can be introduced by using heteropolytopic ligands that, for example, incorporate binding sites which differ in their Pearson hardness. , These can selectively coordinate to a single metal cation, and the emerging metalloligand can subsequently be cross-linked with a second metal cation. − …”

Supramolecular Chemistry of Some Metal Acetylacetonates with Auxiliary Pyridyl Sites

“…One possible way of ameliorating β-diketonate ligands for the construction of crystalline extended solids is to combine them with relatively weaker metal-binding sites such as N-donor substituents. − Within this context, 3-cyanopentane-2,4-dione and 3-(pyridin-4-yl)­pentane-2,4-dione have gained the most attention during the past two decades (Scheme , A and B ). Pioneering work by Maverick, , Domasevitch, − Nishikiori, − Englert, − and others , shows that both molecules are effective for the construction of coordination polymers, especially heterobimetallic infinite assemblies. Though to a lesser extent, 3-(pyridin-4-ylmethyl)­pentane-2,4-dione, 3-(2-(pyridin-4-yl)­ethyl)­pentane-2,4-dione, and 3-(3,5-dimethyl-1 H -pyrazol-4-yl)­pentane-2,4-dione , have also been used (Scheme , C – E ).…”