Syntheses,structures and luminescent properties of a series of ladder-shaped [Ln2Sr3] heterometal-organic frameworks

A series of Ln^III–Sr^II heterometallic coordination polymers formulated as [Ln₂Sr₃(pda)₆(H₂O)₁₈]·nH₂O (Ln = Pr-1, n = 14; Nd-2, n = 12; Sm-3, n = 11; Eu-4, n = 11; Gd-5, n = 16; Tb-6, n = 13; Dy-7, n = 13) were synthesized via assembly of Ln(NO₃)₃·6H₂O, SrCl₂·6H₂O, pyridine-2,6-dicarboxylic acid (H₂pda) and imidazole (im) in H₂O/C₂H₅OH solution. Single crystal X-ray diffraction revealed that they are isostructural. All of these complexes possess ladder-shaped 1-D chain structures. The luminescent properties of Sm-3, Eu-4, Gd-5, Tb-6 and Dy-7 have been investigated. The solid-state quantum yields and the lifetimes of Eu-4 and Tb-6 are also studied.     

3D Heterometallic 3d–4f coordination polymers based on organodisulfonate ligand with isonicotinic acid as a co-ligand: synthesis,crystal structures,photoluminescent and magnetic properties

The hydrothermal reaction of rare earth nitrates, CuCN, 2,7-naphthalenedisulfonate (2,7-nds), and isonicotinic acid (Hina) affords a new family of 3-D heterometallic 3d–4f coordination polymers, [Ln₂Cu(2,7-nds)₂(ina)₄(H₂O)₄]·4H₂O (Ln = Nd (1), Sm (2), Eu (3), Gd (4); 2,7-nds = 2,7-naphthalenedisulfonate, Hina = isonicotinic acid). Complexes 1–4 are structurally characterized by single crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy (IR), powder X-ray diffraction, and thermogravimetric analyses. X-ray crystal structure analyses reveal that 1–4 are isomorphous with dinuclear subunit [Sm₂(ina)₄] binding Cu ions to generate 2-D networks. Such 2-D networks are pillared by linking 2,7-nds ligands to result in the 3-D layer-pillared Ln(III)–Cu(II) coordination architectures. The valence of Cu salts changed in the reaction. In addition, the luminescence properties of 1–3 and the magnetic properties of 3 and 4 have also been investigated.     

Syntheses,structures, thermal stabilities and bacteriostatic activities of four lanthanide complexes

Four lanthanide complexes, [La₂(2,4-DClBA)₆(5,5′-DM-2,2′-bipy)₂(H₂O)₂]·2C₂H₅OH (1) and [Ln(2,4-DClBA)₃(5,5′-DM-2,2′-bipy)(C₂H₅OH)]₂ (Ln = Pr(2), Sm(3), Gd(4); 2,4-DClBA = 2,4-dichlorobenzoate; 5,5′-DM-2,2′-bipy = 5,5′-dimethyl-2,2′-bipyridine), were synthesized and characterized via elemental analysis, infrared spectra and thermogravimetric analysis (TG). The crystal structures of 1 and 2–4 are different; Each La³⁺ is nine-coordinate adopting a distorted mono-capped square antiprism, while the Ln³⁺ ions of 2–4 are all eight-coordinate with a distorted square antiprismatic molecular geometry. There are subtle changes in the local coordination geometry of the lanthanide–5,5′-DM-2,2′-bipy complexes. Binuclear 1 complexes are stitched together via two kinds of hydrogen bonding interactions (OH?O and CH?O) to form 1-D chains along the y axis, while the units of 2–4 are stitched together via CH?O to form 1-D chains along the x axis. TG analysis revealed thermal decomposition processes and thermal stabilities of the complexes. The bacteriostatic activities of the complexes were evaluated against Candida albicans, Escherichia coli, and Staphylococcus aureus.     

Influence of secondary ligand on structures and topologies of lanthanide coordination polymers with 1,3,5-triazine-2,4,6-triamine hexaacetic acid

A series of new lanthanide coordination polymers has been synthesized and structurally characterized; [Ln₄(TTHA)₂(pzac)(H₃O)₂(H₂O)]·5H₂O (Ln = Pr (1a) and Nd (1b)), [Sm₈(TTHA)₄(pzac)_0.5(H₃O)(H₂O)_7.5]·4H₂O (2), [Ln₄(HTTHA)₂(SO₄)(H₂O)₄]·5H₂O (Ln = Pr (3a) and Nd (3b)), where H₆TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, and H₂pzac = 2,5-dioxo-piperazine-1,4-diacetic acid. The compounds feature 3-D frameworks comprising the deprotonated H₆TTHA as the primary ligand and either the in situ generated pzac^2? or sulfate as the secondary ligands. The influence of the deprotonated H₆TTHA in directing the framework structures through preferential coordination modes and molecular conformation is described. The effect of the secondary ligands in increasing the compactness of the frameworks and in the alternation of the framework topologies based on the four-connected pts type is described.     

Multiple modulator-induced syntheses,crystal structures,and luminescent properties on hippuric acid and bovine serum albumin of Ln(III) complexes with 2,2′-oxybis(benzoic acid)

Six new coordination complexes, Ln₂(2,2′-oba)₂(phen)₂(ox)(H₂O)₂ (Ln = Eu 1, Tb 2), Ln₄(2,2′-oba)₆(phen)₂ (Ln = Eu 3, Tb 4), Eu₄(2,2′-oba)₆(phen)₂(H₂O) (5), and K[Eu(2,2′-oba)₂(phen)₂] (6) [2,2′-H₂oba = 2,2′-oxybis(benzoic acid), phen = 1,10-phenanthroline, H₂ox = oxalic acid] were synthesized by hydrothermal reactions with the same compound molar ratios but different modulatory reagents (MRs). Complexes 1–5 have different 1-D chain structures and 6 shows a mononuclear structure. These complexes form diverse 3-D supramolecular networks through hydrogen bonds. The interaction between these complexes and hippuric acid (HA) or bovine serum albumin (BSA) was investigated by fluorescence spectral analysis. Interestingly, the hippuric acid could quench the luminescence of these complexes while the fluorescence of BSA could be quenched by these complexes. Results suggested that the complexes may be potential luminescent testing reagents for HA or BSA by significant fluorescence quenching of Ln³⁺ or BSA, respectively, through a static and dynamic quenching process.     

Synthesis,characterization, and magnetochemical properties of two Mn4 clusters derived from 2-pyridinecarboxaldehyde Schiff base ligands

Two tetranuclear manganese complexes, [Mn₄(L¹)₆](ClO₄)₂?2.75H₂O (1) [HL¹ = 4-methyl-2-((pyridin-2-ylmethylene)amino)phenol] and [Mn₄(L²)₄(NO₃)₃(OH)]?pz?3H₂O (2) [HL² = (1H-pyrazol-1-yl)(pyridin-2-yl)methanol, pz = pyrazole], have been synthesized and characterized by IR spectroscopy, elemental analysis, single-crystal X-ray diffraction, and magnetic measurements. The structural analysis revealed that the central manganese ion is linked with three apical manganese ions through six phenoxo-bridges creating a Mn₄O₆ core for 1; 2 has a cubane-like topology with the Mn(II) ions and the deprotonated oxygens from L² alternatively occupying vertices. The magnetic studies indicated a weak ferromagnetic coupling interaction (J = 0.48 ± 0.087 cm^?1, g = 2.00, θ = ?0.78 K) for 1 and a weak antiferromagnetic spin-exchange interaction (J₁ = ?0.50 ± 0.075 cm^?1, J₂ = ?0.13 ± 0.082 cm^?1, g = 1.98) between Mn(II) ions for 2. The magnetostructural correlations of the two Mn₄ clusters have been discussed tentatively.     

Structural diversity for three Zn(II) coordination polymers from 4-nitrobenzene-1,2-dicarboxylate and bispyridyl ligand

Three Zn(II) complexes, [Zn₂(bpp)₂(FNA)₂]·H₂O (1), [Zn(bpp)(FNA)]·H₂O (2), and Zn₂(bpp)₂(FNA)₂ (3) (bpp = 1,3-bi(4-pyridyl)propane, H₂FNA = 4-nitrobenzene-1,2-dicarboxylic acid), were synthesized and characterized by single-crystal and powder X-ray diffraction methods, IR spectroscopy, TG analyses, elemental analyses, and fluorescent analysis. In 1, the Zn(II) ions are linked by FNA anions and bpp into 2-D layers. The Zn(II) ions in 2 are bridged by FNA anions into chiral chains, which are interlinked by bpp into 3-D metal–organic framework with (6⁵·8) CdS topology. Complex 3 features 1-D zigzag chains, which are interconnected by bpp ligands to give a 3-D framework with (6·7⁴·8)(6⁴·7·8) topology. Complexes 2 and 3 exhibit significant ferroelectric behavior (for 2 remnant polarization Pr = 0.050 μC cm^?2, coercive field Ec = 1.13 kV cm^?1, saturation of the spontaneous polarization Ps = 0.239 μC cm^?2; for 3 Pr = 0.192 μC cm^?2, Ec = 4.64 kV cm^?1, Ps = 0.298 μC cm^?2).     

Synthesis,characterization, and properties of four lanthanide-based coordination polymers with mixed ligands of 4-((4′-carboxybenzyl)oxy)benzoic acid and oxalic acid

A series of lanthanide-based coordination polymers (Ln₂(CBOB)₂(OX)·H₂O, where Ln = Gd (1), Eu (2), Pr (3), and Tb (4); CBOB = 4-[(4′-carboxybenzyl)oxy]benzoate; OX = oxalate), were obtained from the reaction of H₂OX, H₂CBOB, and Ln(NO₃)₃ with the metal salts. Single-crystal measurements show that both 1 and 2 feature unique 3-D structures with the [Ln(COO)_n(C₂O₄)_m] layers connected by CBOB ligands. Moreover, 1, 3, and 4 are antiferromagnetic and 2 and 4 display obvious luminescence emission peaks. Furthermore, quantum Monte Carlo (QMC) simulations and the experimental results reveal that the magnetic coupling parameters of adjacent Gd(III) ions in 1 are ?0.026(2) and ?0.0069(3) cm^─1.     

Two new 1-D lanthanide selenidogermanates with the [Ge2Se6]4− anion as a bridging ligand to a lanthanide complex cation

Two new 1-D lanthanide selenidogermanates [Ln₂(tepa)₂(μ-OH)₂(μ-Ge₂Se₆)]_n·xnH₂O (Ln = Tb (1), x = 0.5; Ln = Tm (2), x = 0; tepa = tetraethylenepentamine) have been solvothermally synthesized and structurally characterized. Compounds 1 and 2 contain 1-D polymeric chains [Ln₂(tepa)₂(μ-OH)₂(μ-Ge₂Se₆)]_n constructed by a [Ge₂Se₆]^4? anion as a bridging ligand with trans terminal Se atoms linking [Ln₂(μ-OH)₂(tepa)₂]⁴⁺ complex cations, but the stacking patterns of these neutral chains are different. The 1-D chains of 1 are alternately stacked in a crossing manner, while the infinite chains of 2 are arranged in a parallel manner. Although a few lanthanide selenidogermanates containing the [Ge₂Se₆]^4? anion have been reported, their [Ge₂Se₆]^4? anions are usually discrete. Compounds 1 and 2 provide the rare example of [Ge₂Se₆]^4? anion as a bridging ligand to a lanthanide complex cation. Their optical and magnetic properties have also been studied.     

Mono-, di-, and trinuclear phosphonate oxygen-bridged copper(II) complexes: syntheses,structures, and properties

Reactions of copper salts, zoledronic acid, and 2,2′-bipyridine/1,10-phenanthroline in aqueous ethanolic solutions afforded four phosphonate oxygen-bridged copper complexes, Cu(bipy)(H₄zdn)(HSO₄) (1), [Cu₂(bipy)₂(H₂zdn)(H₂O)(Cl)]·4H₂O (2), [Cu₂(phen)₂(H₂zdn)(H₂O)(Cl)]·2.5H₂O (3), and [Cu₃(bipy)₃(H₄zdn)(H₂zdn)(SO₄)]·5H₂O (4) (H₅zdn = zoledronic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline). The copper centers of 1–4 have square pyramidal coordination geometries. The Cu(II) ions are coordinated to bipy/phen, zoledronate, and HSO₄^?/Cl^? forming mononuclear units for 1, dinuclear for 2 and 3, and trinuclear for 4. These building units are further extended into 3-D supramolecular networks via multiple hydrogen bond interactions. Temperature-dependent magnetic properties of 2 and 4 suggest weak antiferromagnetic coupling (J = ?4.53(8) cm^?1 for 2, J = ?1.69(4) cm^?1 for 4). The antitumor activity of 2 was evaluated against the human lung cancer cell line and indicates effective time- and dose-dependent cytotoxic effects.     

One-pot synthesis,characterization, DNA binding and enzymatic studies of 4-methyl trans-cinnamate zinc(II)-mixed ligand complexes

Four new zinc(II) complexes formulated as [Zn(L)₂] (1), [Zn(L)₂(phen)] (2), [Zn(L)₂(bipy)H₂O] (3), and [Zn(en)₂(H₂O)₂](L)₂(H₂O)₂ (4), where HL = 4-methyl trans-cinnamic acid, bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline, and en = ethylenediamine, have been synthesized and characterized by FT-IR and NMR spectroscopy. Single-crystal XRD revealed distorted square-pyramidal structure for 3 and octahedral for 4. The complexes were screened for DNA interaction via viscommetry and UV–visible spectroscopy. The apparent binding constants were calculated to be 1.18 × 10⁴, 1.26 × 10⁵, 4.64 × 10⁴_, and 1.89 × 10⁴ for 1–4, respectively. The binding propensity to salmon sperm DNA was in the order: K₂ > K₃ > K₄ > K₁. Furthermore, these complexes demonstrated efficient inhibition of alkaline phosphatase, which was attributed to the binding of zinc(II) to the enzyme’s active site.     

Four Mixed 3d-4f 12-Metallacrown-4 Complexes: Syntheses,Structures and Magnetic Properties

The incorporation of Ln^III ions into the 12-metallacrown-4 topology affords the formation of four mixed 3d-4f pentanuclear complexes of compositions [NH(C₂H₅)₃]{[Ln(OAc)₄] [12-MC _Mn ^III _(N)shi-4]}·xH₂O (Ln = Sm (1), Gd (2), Tb (3), Dy (4); x = 0.5 for 1 and 3, x = 0.25 for 2, x = 0 for 4; H₃shi = salicylhydroxamic acid). Compounds 1–4 were obtained from the reactions of H₃shi with Mn(CH₃COO)₂·4H₂O and Ln(NO₃)₃·6H₂O, in the presence of N(C₂H₅)₃. They all contain a crown-like [Mn₄Ln(μ-NO)₄]¹¹⁺ core with four Mn^III atoms being at the rim of the crown and an Ln^III ion occupying the dome of the crown. The peripheral ligation about the core is provided by four η¹:η¹:µ acetate groups. The identity of the Ln^III ions slightly affects the 12-metallacrown-4 frameworks, as demonstrated by the gradual decrease of the distances between the Ln^III ions and the centres of the Mn₄ planes (1.85 Å for 1, 1.81 Å for 2, 1.80 Å for 3, and 1.77 Å for 4). Variable-temperature dc magnetic susceptibility studies were carried out on polycrystalline samples of 1–4. Antiferromagnetic interactions are determined for complexes 1–4.     

Supramolecular structures of Mn2+, Co2+ and Zn2+ complexes containing 1,3-bis(4-pyridyl)propane and aminosalicylate anion

In this study, the synthesis, spectroscopic properties and crystal structures of three new supramolecular compounds named [Mn₂(bpp)₄(H₂O)₄](AS)₄·H₂O (1), [Co₂(bpp)₄(H₂O)₄](AS)₄·H₂O (2) and [Zn(bpp)(AS)₂] (3), have been described, where bpp is 1,3-bis(4-pyridil)propane and AS^?  is aminosalicylate anion. By analysing the similarities between the X-ray powder diffraction results, it has been observed that compounds 1 and 2 are isomorphous, exhibiting an orthorhombic system with space group Pccn; for compound 3, another orthorhombic system was observed, with space group Aba2, which displays coordination between the Zn²⁺ metal ion and the aminosalicylate anion; this can be considered the first case in the literature involving the direct coordination to the metal ion. The vibrational spectra of compounds 1 and 2 are very similar. In the Raman spectra, the main bands are observed at ca. 1625 and 1020 cm^? 1, referring to the ^? O–C = O and CC/CN stretching modes of AS^?  and bpp ligands, respectively.     

New members of the [Mn6/oxime] family and analogues with converging [Mn3] planes

The synthesis, structural, and magnetic characterization of five new members of the hexanuclear oximate [Mn^III₆] family are reported. All five clusters can be described with the general formula [Mn^III₆O₂(R-sao)₆(R′-CO₂)₂(sol)_x(H₂O)_y] (where R-saoH₂ = salicylaldoxime substituted at the oxime carbon with R = H, Me and Et; R′ = 1-naphthalene, 2-naphthalene, and 1-pyrene; sol = MeOH, EtOH, or MeCN; x = 0–4 and y = 0–4). More specifically, the reaction of Mn(ClO₄)₂·6H₂O with salicylaldoxime-like ligands and the appropriate carboxylic acid in alcoholic or MeCN solutions in the presence of base afforded complexes 1–5: [Mn₆O₂(Me-sao)₆(1-naphth-CO₂)₂(H₂O)(MeCN)]·4MeCN (1·4MeCN); [Mn₆O₂(Me-sao)₆(2-naphth-CO₂)₂(H₂O)(MeCN)]·3MeCN·0.1H₂O (2·3MeCN·0.1H₂O); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(EtOH)₄(H₂O)₂] (3); [Mn₆O₂(Et-sao)₆(2-naphth-CO₂)₂(MeOH)₆] (4) and [Mn₆O₂(sao)₆(1-pyrene-CO₂)₂(H₂O)₂(EtOH)₂]·6EtOH (5·6EtOH). Clusters 3, 4, and 5 display the usual [Mn₆/oximate] structural motif consisting of two [Mn₃O] subunits bridged by two O_oximate atoms from two R-sao^2? ligands to form the hexanuclear complex in which the two triangular [Mn₃] units are parallel to each other. On the contrary, clusters 1 and 2 display a highly distorted stacking arrangement of the two [Mn₃] subunits resulting in two converging planes, forming a novel motif in the [Mn₆] family. Investigation of the magnetic properties for all complexes reveal dominant antiferromagnetic interactions for 1, 2, and 5, while 3 and 4 display dominant ferromagnetic interactions with a ground state of S = 12 for both clusters. Finally, 3 and 4 display single-molecule magnet behavior with U_eff = 63 and 36 K, respectively.     

Two tetranuclear Ni(II) complexes from substituted imidazole dicarboxylates: syntheses,structures, thermal and magnetic properties

Two tetranuclear nickel(II) complexes, [Ni₄ (p-BrPhHIDC)₄(py)₄(H₂O)₄]·CH₃OH (p-BrPhH₃IDC = 2-(p-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid) (1) and [Ni₄(p-ClPhHIDC)₄ (CH₃CN)₄(H₂O)₄]·4H₂O (p-ClPhH₃IDC = 2-(p-chlorophenyl)-1H-imidazole-4,5-dicarboxylic acid, py = pyridine) (2), have been solvothermally synthesised and structurally characterised. Both compounds consist of similar tetranuclear Ni(II) cores, in which the imidazole dicarboxylate ligands adopt the similar coordination mode. The thermal properties of 1 and 2 have been investigated. Also, it is discovered that there exists antiferromagnetic coupling between the Ni(II) ions in 1 and 2; the best fittings to the experimental magnetic susceptibilities gave J = ? 9.89 cm^? 1 and g = 2.18 for 1, and J = ? 10.54 cm^? 1 and g = 2.14 for 2.     

Self-assembly and crystal structures of coordination polymers constructed by 4′-hydroxyisoflavone-3′-sulfonates with Cs(I) and Rb(I)

Four coordination polymers, [CsL1(H₂O)₂]·H₂O (1), [CsL2(H₂O)₂]·H₂O (2), [Rb₂(L2)₂(H₂O)₂]·2H₂O (3) and [RbL3(H₂O)] (4), were synthesized by Cs(I), Rb(I) and 4′-hydroxyisoflavone-3′-sulfonates L1–L3 [L1 = 7-methoxy-4′-hydroxyisoflavone-3′-sulfonate, L2 = 7-ethoxy-4′-hydroxyisoflavone-3′-sulfonate, L3 = 7-ethoxy-4′,5-dihydroxyisoflavone-3′-sulfonate]. The crystal structures of 1–4 were determined by single-crystal X-ray diffraction. The influences of 4′-hydroxyisoflavone-3′-sulfonate ligands and Cs⁺, Rb⁺ on their structural features and self-assembly were investigated. The sulfonates of L1–L3 not only coordinate with Cs⁺ or Rb⁺ directly, but also bridge the organic region and the inorganic region in 1–4. Non-covalent interactions such as coordination interaction, π–π stacking interaction and hydrogen bonding assembled 1–4 into 3-D networks together with the electrostatic interactions between Cs⁺, Rb⁺ and the sulfonate anions.     

Synthesis,Crystal Structures,and Photoluminescence of Lanthanide Coordination Polymers with 4‐Acetamidobenzoate

The reactions of Ln(NO₃)₃ · 6H₂O and 4‐acetamidobenzoic acid (Haba) with 4,4′‐bipyridine (4,4′‐bpy) in ethanol solution resulted in three new lanthanide coordination polymers, namely {[Ln(aba)₃(H₂O)₂] · 0.5(4,4′‐bpy) · 2H₂O}_∞ [Ln = Sm ( 1 ), Gd ( 2 ), and Er ( 3 ), aba = 4‐acetamidobenzoate]. Compounds 1 – 3 are isomorphous and have one‐dimensional chains bridged by four aba anions. 4,4′‐Bipyridine molecules don’t take part in the coordination with Ln^III ions and occur in the lattice as guest molecules. Moreover, the adjacent 1D chains in the complex are further linked through numerous N–H ··· O and O–H ··· O hydrogen bonds to form a 3D supramolecular network. In addition, complex 1 in the solid state shows characteristic emission in the visible region at room temperature.     

Effect of the lanthanoid-size on the structure of a series of lanthanoid-anilato 2-D lattices*

Abstract

We report the synthesis and characterization of a series of Ln-based bromoanilato 2-D lattices with dimethyl sulfoxide (DMSO): [Ln₂(C₆O₄Br₂)₃(DMSO)_n]·2DMSO·mH₂O with n = 6 and m = 0 for Ln = La (1), Ce (2), Pr (3), Nd (4), Sm (5), Eu (6) and Gd (7); n = 4 and m = 2 for Ln = Tb (8), Dy (9), Ho (10), Er (11), Tm (12) and Yb (13) (C₆O₄Br₂^2? = 3,6-dibromo-2,5-dihydroxy-1,4-benzoquinone = bromoanilato). The X-ray analysis shows that the largest Ln(III) ions (La-Gd, 1-7) crystallize in the monoclinic P21/n space group (phase I), whereas the smaller Ln(III) ions (Tb–Yb, 8–13) crystallize in the triclinic P-1 space group (phase II). Both phases present a (6,3)-2-D topology but show important differences derived from the different coordination number of the Ln(III) in both phases. In phase I, the Ln(III) ions are nine-coordinate with a tri-capped trigonal prism geometry and rectangular cavities with no solvent molecules. In phase II, the Ln(III) ions are eight-coordinate with a triangular dodecahedral geometry and distorted hexagonal cavities having two water molecules. These differences are due to the lanthanoid contraction. The magnetic properties show that the Ln(III) ions are isolated and do not present any noticeable magnetic interactions as expected for bromoanilato bridges and Ln(III) ions.     

Six lanthanide(III) coordination polymers with 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole: syntheses,structures, and photoluminescence

Six 3-D lanthanide(III)-metal-organic frameworks (MOFs) through multidentate 3,5-bis(4′-carboxy-phenyl)-1,2,4-triazole (H₂BCPT); acetic acid (HOAc); and corresponding trivalent rare earth chloride, {[Ln(BCPT)(OAc)(H₂O)]·(H₂O)}_n (Ln = Nd³⁺ (1); Sm³⁺ (2), Gd³⁺ (3), Tb³⁺ (4), Ho³⁺ (5), Yb³⁺ (6)), have been synthesized. MOFs 1–6 were characterized via FT-IR spectroscopy, elemental analysis, X-ray single-crystal diffraction, thermal analysis, and fluorescence. MOFs 1–6 are isomorphous, which can be described as a 3-D construction containing a dinuclear cluster [Tb₂(CO₂)₂(O)₂]. The 3-D structure with (4,4) topologies have been extended through BCPT^2? using μ₄-kO;kO;kO;kO coordination modes. Solid-state luminescence of 1–4 and 6 shows the characteristic bands of Nd³⁺, Sm³⁺, Tb³⁺, and Yb³⁺ from visible to near-infrared spectral regions.     

Conformational preferences of heteronuclear Fischer carbene complexes of cymantrene and cyclopentadienyl rhenium tricarbonyl

Homo- and heteronuclear bimetallic carbene complexes of group VII transition metals (Mn and Re), with cymantrene or cyclopentadienyl rhenium tricarbonyl as the starting synthon, have been synthesized according to classic Fischer methodology. Crystal structures of the carbene complexes with general formula [RC₅H₄ M'(CO)₂{C(OEt)(C₅H₄ M(CO)₃)}], where M = M′ = Mn, R = H (1), R = Me (2); M = Mn, M′ = Re, R = H (3); M = M′ = Re, R = H (4); and M = Re, M′ = Mn, R = H (5), are reported. A density functional theory (DFT) study was undertaken to determine natural bonding orbitals (NBOs) and conformational as well as isomeric aspects of the binuclear complexes. Application of second-order perturbation theory (SOPT) of the NBO method revealed stabilizing interactions between the methylene C–H bonds and the carbonyl ligands of the carbene metal moiety. Energy calculations in the gas phase of the cis and trans conformations of the Cp rings relative to one another are comparable, with the trans conformation slightly lower in energy. The theoretical findings have also been confirmed with single-crystal X-ray diffraction, and all solid-state structures are found in the trans geometry.