A Series of CuII-Azide Polymers of Cu6 Building Units and the Role of Chelating Diamine in Controlling their Dimensionality: Synthesis, Structures, and Magnetic Behavior

[4-(2-Aminoethyl)morpholine-κ2N,N']di-bromidocadmium(II): synthesis, crystal structure and Hirshfeld surface analysis

The title compound, [CdBr2(C6H14N2O)], was synthesized upon complexation of 4-(2-aminoethyl)morpholine and cadmium(II) bromide tetra-hydrate at 303 K. It crystallizes as a centrosymmetric dimer, with one cadmium atom, two bromine atoms and one N,N'-bidentate 4-(2-aminoethyl)morpholine ligand in the asymmetric unit. The metal atom is six-coordinated and has a distorted octa-hedral geometry. In the crystal, O⋯Cd inter-actions link the dimers into a polymeric double chain and inter-molecular C-H⋯O hydrogen bonds form R 2 2(6) ring motifs. Further C-H⋯Br and N-H⋯Br hydrogen bonds link the components into a three-dimensional network. As the N-H⋯Br hydrogen bonds are shorter than the C-H⋯Br inter-actions, they have a larger effect on the packing. A Hirshfeld surface analysis reveals that the largest contributions to the packing are from H⋯H (46.1%) and Br⋯H/H⋯Br (38.9%) inter-actions with smaller contributions from the O⋯H/H⋯O (4.7%), Br⋯Cd/Cd⋯Br (4.4%), O⋯Cd/Cd⋯O (3.5%), Br⋯Br (1.1%), Cd⋯H/H⋯Cd (0.9%), Br⋯O/O⋯Br (0.3%) and O⋯N/N⋯O (0.1%) contacts.

Change in molecular shapes of the trinuclear CuII2ZnII complexes on Schiff base reduction: structural and theoretical investigations

Structural analyses and theoretical studies of two new Cu₂Zn compounds and other analogous species established that subtle modification in a ligand system can stabilize various structures with versatile coordinating azide ion and flexible trinuclear core.

Magnetic dimensionality and the crystal structure of two copper(ii) coordination polymers containing Cu6 and Cu2 building units

The preparation, structural characterization, EPR spectroscopy and magnetic structural correlation of two Cu(ii) coordination polymers are reported.

The use of a semi-flexible bipyrimidyl ligand for the construction of azide-based coordination polymers: structural diversities and magnetic properties

Using a semi-flexible quadritopic N-donor ligand, 5,5'-bipyrimidine (bpym), four new azide-based coordination polymers, {[Co2(bpym)(N3)4]·MeCN}n (1), [Co(bpym)(N3)2]n (2), [Mn(bpym)(N3)2]n (3) and {[Ni3(bpym)3(N3)6]·2H2O}n (4) were synthesized and structurally characterized. With bpym aciting as a planar μ4-bridging ligand, the resulting compound, 1, comprised a net-to-net 3D framework composed of two grid-like 44-subnets, Co(EE-N3)2-based and Co2(bpym)-based sheets, with a (4,6)-connected (42·64)(48·66·8)2 topology. Compound 2 adopted a 3D pillared-layer framework with a pts topology based on six-connected Co(ii) centers and four-connected twisted μ4-bpym ligands, while compound 3 adopted a 3D pillared-layer structure with a bcu topology based on Co(EE-N3)2-based 44-layers and two-connected twisted μ2-bpym pillars. In contrast, compound 4 had a 2D layered structure composed of 1D Ni(ii) chains with alternating double EE-N3 and double EO-N3 bridges in an EE-EE-EO sequence and two-connected bpym linkers. The magnetic properties of 1-4 were investigated. The findings indicate that 1 showed weak ferromagnetism due to spin-canted antiferromagnetism and long-range magnetic ordering with a critical temperature, TC = 12.6 K. In contrast, compound 2 exhibited weak ferromagnetism due to spin-canted antiferromagnetism and antiferromagnetic ordering. In compound 3, antiferromagnetic interactions dominated between the Mn(ii) centers through the EE-N3 bridges. In compound 4, the antiferromagnetic and ferromagnetic interactions were transmitted through double EE-N3 and double EO-N3 bridges, respectively, resulting in an AF-AF-F topological ferrimagnetic Ni(ii) chain. Furthermore, field-induced magnetic phase transitions of metamagnetism for 2 and 4 were also observed below TN = 3.6 K and 8.2 K, respectively.

Crystal structure of diazido-bis(μ2-pyridin-2-ylmethanolato-κ2 N:O)-bis(pyridin-2-ylmethanolato-κ2 N,O)dicobalt(III) – methanol (1/3), C27H35Co2N10O7

C27H35Co2N10O7, orthorhombic, Pna21 (no. 33), a = 29.6280(13) Å, b = 7.5784(3) Å, c = 14.3600(7) Å, V = 3224.3(2) Å3, Z = 4, R gt(F) = 0.0409, wR ref(F 2) = 0.1133, T = 296(2) K.

Structure, magnetic properties and DFT calculations of azido-copper(ii) complexes with different azido-bonding, nuclearity and dimensionality

Cu(ii) compounds derived from diamine substituted alkyl or phenyl groups with azido acting as the bridging ligand were synthesized and were structurally and magnetically characterized.

Ligand directed structural diversity and magnetism in copper(ii)–azido assemblies with isomeric aminopyridines: synthesis, structure, magnetism and theoretical studies

Ligand geometry and molar ratios play an influential role in directing the supramolecular assemblage and associated magnetic properties as described for the Cu(ii) complexes involving isomeric aminopyridines and azide.

Syntheses, crystal structures, magnetochemistry and catechol oxidase activity of a tetracopper(ii) compound and a new type of dicopper(ii)-based 1D coordination polymer

One phenoxo–hydroxo bridged tetranuclear cluster and one phenoxo-µ_1,1-azido-µ_1,3-azido bridged one-dimensional coordination polymer of copper(ii) derived from a Schiff base ligand are described.

Diversified magnetic behaviors of new nickel(ii) and copper(ii) azido coordination polymers templated by diethyl or triethyl amines

The reactions of Ni^II or Cu^II ions with N₃⁻ anions in the presence of templated diethyl or triethyl amines afford three new azido-bridged coordination polymers, which exhibit metamagnetism, spin glass and canted ferromagnetism, respectively.

Stabilization of Cu7 clusters in azide networks: syntheses, structures and magnetic behaviour

Two new azide bridged copper(II) coordination polymer compounds, [Cu7(N3)14(C3H10N2)(C4H13N3)]n (I) and [Cu7(N3)14(C3H10N2)(C5H15N3)2]n (II) [where C3H10N2 = 1,2-diaminopropane (1,2-DAP); C4H13N3 = diethylenetriamine (DETA); C5H15N3 = N-2-aminoethyl-1,3-propanediamine (AEDAP)] were prepared by employing a room temperature diffusion technique involving three layers. Single crystal studies reveal that both compounds I and II, have similar connectivity forming Cu7 clusters through end-on (EO) bonding of the azide. The Cu7 clusters are connected through end-to-end (EE) connectivity of the azides forming three-dimensional structures. Magnetic studies confirmed the ferromagnetic interactions within the Cu7 units and revealed the occurrence of concomitant ferro- and antiferro-magnetic interactions between these clusters. As a result I behaves as a weak-ferromagnet with TC = 10 K.

Sonochemical syntheses of binuclear lead(II)-azido supramolecule with ligand 3,4,7,8-tetramethyl-1,10-phenanthroline as precursor for preparation of lead(II) oxide nanoparticles

The new neutral binuclear lead(II) azido coordination compound, [Pb ₂(tmph) ₂(μ-N₃)₂(CH₃COO) ₂] (1) [tmph = 3,4,7,8-tetramethyl-1,10-phenanthroline], has been synthesized by a sonochemical method. Single crystal X-ray structure shows that the overall structure of 1 is binuclear unit. Complex 1 has a bridging azido pathway, end-to-end bridging azides between a pair of lead(II) centers. This is further extended into a one-dimensional (1D) and three-dimensional (3D) supramolecular structure by Pb⋯C and π–π weak directional intermolecular interactions. The coordination number of lead(II) ions is seven, PbN₄O₃, with two N-donor atoms from tmph ligands and three O-donors from acetate anions and two N-donors from two azide anions. It has a "stereo-chemically active" electron lone pair, and the coordination sphere is hemidirected. The PbO nanoparticles were obtained by thermolysis of 1 at 180 °C with oleic acid as a surfactant. The morphology and size of the prepared PbO samples were further observed using scanning electron microscopy (SEM).

Synthesis, crystal structure and magnetic properties of two alternating double μ1,1 and μ1,3 azido bridged Cu(ii) and Ni(ii) chains

Two new alternating double μ_1,1 and μ_1,3 azido bridged 1D Cu(ii) and Ni(ii) complexes have been synthesized and their magnetic data were fitted to an alternating ferro/antiferromagnetic chain model.

Structural variation in Zn(ii) coordination polymers built with a semi-rigid tetracarboxylate and different pyridine linkers: synthesis and selective CO2 adsorption studies

The C_2v or C_s symmetry in the flexible 3,3′,5,5′-tetracarboxydiphenylmethane ligand directs the stability and porosity of the resulting frameworks in the presence of Zn(ii) ions, and pyridine linkers of comparable lengths.

A cyano and end-to-end azido bridged 3D copper(ii)–copper(i) mixed-valence coordination polymer and its transformation to copper nitride nanoparticles

Syntheses and characterization of a CN and end-to-end N₃ bridged three-dimensional Cu(II)–Cu(I) mixed valence polymer (1), with Cu-N₃ system without CN (2) and a CN-bridged Cu analogue without N₃ (3) are reported and solid-state transformation of the 1 to copper nitride nanoparticles performed.

Versatility of azide in serendipitous assembly of copper(II) magnetic polyclusters

Engineering at the molecular level is one of the most exciting new developments for the generation of functional materials. However, the concept of designing polynuclear extended structures from bottom up is still not mature. Although progress has been made with secondary building units (SBUs) in metal organic frameworks (MOFs), the control seems to be just an illusion when it comes to bridging ligands such as the azide ion. When we say that the azido ligand is versatile in its bridging capabilities, what we mean is that it would be difficult to predict or control its bridging properties. However, this kind of serendipity is not always bad news. For example, scientists have shown that the azido ligand can mediate magnetic exchanges between paramagnetic metals in a predictable fashion (usually depending upon the bonding geometries). Therefore, it is a well-respected ligand in polynuclear assemblies. Serendipitous assemblies offer new magnetic structures that we may not otherwise even think about synthesizing. The azido ligand forms a variety of complexes with copper(II) using different blocking amines or pyridine based ligands. Its structural nature changes upon changing the substitution on amine, as well as the amount of blocking ligand. In principle, if we take any of these complexes and provide more coordination sites to the bridging azido ligands by removing a fraction of the blocking ligands, we can get new complexes with intricate structural networks and therefore different magnetic properties with the same components as used for the parent complex. In this Account, we mainly discuss the development of a number of new topological and magnetic exchange systems synthesized using this concept. Not all of these new complexes can be grouped according to their basic building structures or even by the ratio of the metal to blocking ligand. Therefore, we divided the discussion by the nuclearity of the basic building structures. Some of the complexes with the same nuclearities have very similar or even almost identical basic structures. However, the way these building units are joined together (by the azido bridges) to form the overall extended structures differ almost in every case. The complexes having the Cu6 core are particularly interesting from a structural point of view. Although they have almost identical basic structures, some of them are extended in three dimensions, but two of them are extended in two dimensions by two different bridging networks. In the complexes having linear Cu4 basic units, we find that using similar ligands does not always give the same bridging networks even within the basic building structures. These complexes have also enriched the field of molecular magnetism. One of the complexes with a Cu3 building unit has provided us with the opportunity to study the competing behavior of two different kinds of magnetic exchange mechanism (ferromagnetic and antiferromagnetic) acting simultaneously between two metal ions. Through density functional theory calculations, we showed how they work independently and their additive nature to produce the overall effect. The exciting methodology for the generation of copper(II) polyclusters presented in this Account will provide the opportunity to explore analogous serendipitous assembly of diverse structures with interesting magnetic behavior using other transition metal ions having more than one unpaired electrons.