Di-, tri- and oligometallic platforms: Versatile components for use in metallo-supramolecular chemistry

Heterometallic Molecular Architectures Based on Fluorinated β-Diketone Ligands

This review summarizes the data on the synthesis of coordination compounds containing two or more different metal ions based on fluorinated β-diketonates. Heterometallic systems are of high interest in terms of their potential use in catalysis, medicine and diagnostics, as well as in the development of effective sensor devices and functional materials. Having a rich history in coordination chemistry, fluorinated β-diketones are well-known ligands generating a wide variety of heterometallic complexes. In this context, we focused on both the synthetic approaches to β-dicarbonyl ligands with additional coordination centers and their possible transformations in complexation reactions. The review describes bi- and polynuclear structures in which β-diketones are the key building blocks in the formation of a heterometallic framework, including the examples of both homo- and heteroleptic complexes.

Self-Assembly of a Rare High Spin FeII/PdII Tetradecanuclear Cubic Cage Constructed via the Metalloligand Approach

Polynuclear heterobimetallic coordination cages in which different metal cations are connected within a ligand scaffold are known to adopt a variety of polyhedral architectures, many of which display interesting functions. Within the extensive array of coordination cages incorporating Fe(II) centres reported so far, the majority contain low-spin (LS) Fe(II), with high-spin (HS) Fe(II) being less common. Herein, we present the synthesis and characterisation of a new tetradecanuclear heterobimetallic [Fe8Pd6L8](BF4]28 (1) cubic cage utilising the metalloligand approach. Use of the tripodal tris-imidazolimine derivative (2) permitted the formation of the tripodal HS Fe(II) metalloligand [FeL](BF4)2·CH3OH (3) that was subsequently used to form the coordination cage 1. Magnetic and structural analyses gave insight into the manner in which the HS environment of the metalloligand was transferred into the cage architecture along with the structural changes that accompanied its occupancy of the eight corners of the discrete cubic structure.

Self-assembled lanthanide-based helixes: synthetic control of the helical handedness by chirality of the ligand

The control of the self-assembly of lanthanide helical chain and their helical handedness have been investigated for the first time. Δ- and Λ-form lanthanide chain complexes were obtained by introducing thiazolidine ligands that were synthesised from L- and D-cysteine, respectively, and shared the same formula: [Ln₂(L)₃(H₂O)₅]_∞·3H₂O (Ln: Sm and Eu) (L: 2-(2-hydroxy-3,5-dinitrophenyl)thiazolidine-4-carboxylic acid). The crystallographic, circular dichroism, and luminescence properties of these novel lanthanide chain complexes were studied.

Dinuclear triple stranded phenyl-spaced 1,3-bis-β-diketonato lanthanide(iii) complexes: synthesis, structures and spectroscopy

The synthesis and crystal structures of a series of Ln(iii) (Ln = Gd, Nd, Yb as well as Y) complexes of a bis-β-diketone ligand incorporating a 1,3-substituted phenyl ring between its two β-diketone domains (1,1'-(1,3-phenylene)bis(4,4-dimethylpentane-1,3-dione), H₂L¹) is reported. The crystal structures show the complexes are seven coordinate in the solid state with the general formula [Ln₂L¹₃(solvent)₂]. The photophysical properties of the complexes were explored in both solution and the solid state, which show an increase in coordination number in solution.

Discrete and polymeric ensembles based on dinuclear molybdenum(vi) building blocks with adaptive carbohydrazide ligands: from the design to catalytic epoxidation

Discrete and polymeric ensembles based on dimolybdenum(vi) units with adaptive carbohydrazide ligands are described. The polymeric complexes are efficient catalysts for cyclooctene epoxidation under eco-friendly conditions.

Functional metallosupramolecular architectures using 1,2,3-triazole ligands: it's as easy as 1,2,3 “click”

Self-assembled metallosupramolecular architectures generated using “click” ligands have become an increasingly popular area of inorganic chemistry.

Unique Occurrence of Cationic and Anionic Bis-1,2-diaminocyclohexane Copper(II) Units in a Double Complex Salt

The reaction of (±)-trans-diaminocyclohexane (dach) with copper(ii) sulfate in water resulted in the spontaneous formation of a double complex salt of type [Cu(dach)2(H2O)2][Cu(dach)2(SO4)2]·6H2O, whose X-ray structure confirmed the presence of the same square-planar Cu(dach)22+ coordination motif in both the complex cation and anion. Each copper centre adopts a Jahn–Teller-distorted octahedral geometry. Both axial positions of the metal centre in the complex cation are occupied by water molecules, whereas two monodentate sulfato ions occupy the corresponding sites in the complex anion, leading to a trans N4O2-donor coordination environment in each ion.

Enlarging the ring by incorporating a phosphonate coligand: from the cyclic hexanuclear to octanuclear dysprosium clusters

Solvothermal reaction of a double pyrazinyl hydrazone ligand EDDC(2-) with Dy(OAc)3 results in a cyclic hexanuclear cluster [Dy6(EDDC)2(OAc)14(H2O)2]·MeOH·2H2O (). The addition of 1-naphthylphosphonate to the reaction mixture expands the ring size with the formation of a cyclic octanuclear cluster [Dy8(EDDC)4(O3PC10H7)4(OAc)8(H2O)4]·12H2O (). The latter shows slow magnetization relaxation below 12 K, characteristic of single molecule magnet behavior.

Formation of a Dicopper Platform Based Polyrotaxane Whose "String" and "Bead" Are Constructed from the Same Components

The combination of the dicopper platform [Cu2(L)2(THF)2] (1·2THF), where H2L is 1,1'-(1,3-phenylene)-bis-4,4-dimethylpentane-1,3-dione, and 1,4-bis(4-pyridyl)piperazine (bpp), afforded the first example of a one-dimensional polyrotaxane {[(1)(μ2-bpp)][(1)2(bpp)2]}n whose "string" and "bead" are constructed from the same components. The bead of stoichiometry [(1)2(bpp)2] has a large rectangular cavity of dimensions 7.40 × 15.64 Å and is threaded onto a stair-like string of composition [(1)(μ2-bpp)]n. The formation of the polyrotaxane is driven by π-π stacking between the string and the beads with precise electronic and steric complementarity between these components. A pathway for the formation of the polyrotaxane is proposed.

New coordination features; a bridging pyridine and the forced shortest non-covalent distance between two CO32- species

The aerobic reaction of the multidentate ligand 2,6-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-pyridine, H4L, with Co(ii) salts in strong basic conditions produces the clusters [Co4(L)2(OH)(py)7]NO3 (1) and [Co8Na4(L)4(OH)2(CO3)2(py)10](BF4)2 (2). Analysis of their structure unveils unusual coordination features including a very rare bridging pyridine ligand or two trapped carbonate anions within one coordination cage, forced to stay at an extremely close distance (dO···O = 1.946 Å). This unprecedented non-bonding proximity represents a meeting point between long covalent interactions and "intermolecular" contacts. These original motifs have been analysed here through DFT calculations, which have yielded interaction energies and the reduced repulsion energy experimented by both CO32- anions when located in close proximity inside the coordination cage.

Size dependent effect of new organometallic triptycene tectons on the dimensions of self-assembled macrocycles

The effect of changing the dimension of triptycene-based acceptor building blocks on the shape and size of the resulting supramolecular framework is reported.

A mixed valent heterometallic CuII/NaI coordination polymer with sodium–phenyl bonds

A mixed valent heterometallic Cu^II/Na^I coordination polymer (1) is generated by the reaction of a Schiff base ligand, (6,6′-(1E,1′E)-(2-hydroxypropane-1,3-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(2-methoxyphenol)) with copper(ii) acetate and sodium perchlorate.

Triptycene based organometallic complexes: a new class of acceptor synthons for supramolecular ensembles

New triptycene based organometallic complexes have been synthesized and subsequently used for design of the triptycene motif containing nanoscalar trigonal prisms. Flexible 3,3′-bipyridine is employed as a donor unit.