Synthesis, Crystal Structures and Magnetic Properties of MIICuII Chains (M=Mn and Co) with Sterically Hindered Alkyl-Substituted Phenyloxamate Bridging Ligands

Tandem Amination/Oxetane Ring Opening toward Benzomorpholines

Herein, a tandem approach that allows rapid access to the benzomorpholine scaffold is reported. This operationally simple method allows for valuable heterocycles to be isolated in moderate to high yields. The overall transformation consists of an initial C-N coupling, demonstrated using traditional Ullmann or Buchwald-Hartwig conditions, followed by an in situ oxetane ring opening. A range of functionality is tolerated on the aryl ring, and the cyclization exposes a pendant hydroxymethyl substituent, providing opportunities for further functionalization.

Magnetic relaxation in a Co(ii) chain complex: synthesis, structure, and DFT computational coupling constant

We report a homospin non-solvated Co^II chain compound constructed by two similar tridentate ligands and chloride ions, which displays slow magnetic relaxation below 5 K.

Nickel-Catalyzed Intramolecular Desulfitative C-N Coupling: A Synthesis of Aromatic Amines

A nickel-catalyzed intramolecular C-N coupling reaction via SO₂ extrusion is presented. The use of a catalytic amount of BPh₃ allows the transformation to take place under much milder conditions (60 °C) than previously reported C-N coupling reactions by CO or CO₂ extrusion (160-180 °C). In addition, this method displays good functional group tolerance and versatility, as it can be applied to the synthesis of dialkyl aryl amines, alkyl diaryl amines, and triaryl amines. The robustness of the desulfitative C-N coupling is demonstrated by three high-yielding gram-scale reactions.

Promotion of antiferromagnetic exchange interaction in multinuclear copper(ii) complexes via fused oxamato/oxamidato ligands

Treatment of N,N'-bis(2-aminophenyl)oxalamide (bapoxH6, 1) with ethyl oxalyl chloride in THF afforded oxamide-N,N'-bis(o-phenylene oxamic acid ethyl ester) (L1H4Et2, 2), which was converted to 3 (oxamide-(o-phenylene oxamic acid ethyl ester)(o-phenylene-N1-methyloxalamide); L2H5EtMe) and 4 (oxamide-N,N'-bis(o-phenylene-N1-methyloxalamide); L3H6Me2) by the addition of appropriate equivalents of MeNH2. Successive treatment of 2-4 with six equivalents of [nBu4N]OH and two equivalents of CuII salt resulted in the formation of the binuclear complexes [nBu4N]2[Cu2(L1)] (5), [nBu4N]2[Cu2(L2Me)] (6) and [nBu4N]2[Cu2(L3Me2)] (7). Upon addition of one equivalent of [Cu(pmdta)(NO3)2] (pmdta = N,N,N',N'',N''-pentamethyldiethylenetriamine) to 5-7, the trinuclear complexes [Cu3(L1)(pmdta)] (8), [Cu3(L2Me)(pmdta)] (9) and [Cu3(L3Me2)(pmdta)] (10) were obtained, while the addition of two equivalents of [Cu(pmdta)(NO3)2] gave rise to the tetranuclear complexes [Cu4(L1)(pmdta)2](NO3)2 (11), [Cu4(L2Me)(pmdta)2](NO3)2 (12) and [Cu4(L3Me2)(pmdta)2](NO3)2 (13). The identities of compounds 2-4 were established by elemental analyses, NMR and IR spectroscopy, and ESI-MS measurements. For the multinuclear complexes 5-13, elemental analysis and IR spectroscopy were applied to confirm their identities. Furthermore, the solid-state structures of 5-8 and 11-13 were determined by single crystal X-ray diffraction studies. The magnetic behavior of 5-8 and 11-13 was studied by direct current susceptibility measurements as a function of temperature. For the binuclear complexes 5-7, exceptionally large antiferromagnetic exchange interactions with J1,2 values of -378, -397 and -419 cm-1 were determined. Astonishingly, the tendency of these series of magnetic exchange interactions can be smoothly associated with the d-d transitions of 5-7 measured through UV-Vis spectroscopy. The J1,2 value of 8 amounts to -507 cm-1, while for the tetranuclear complexes 11-13, this value is significantly smaller and amounts to -294, -292 and -370 cm-1. The second antiferromagnetic exchange interactions J2,3 and J1,4 are equal due to inversion symmetry and are -100, -135, -80 and -108 cm-1 for 8 and 11-13, respectively, in the expected range. Magneto-structural correlations are used to discuss the variable magnetic exchange interactions of all here reported multinuclear complexes.

2D and 3D mixed MII/CuIImetal–organic frameworks (M = Ca and Sr) withN,N′-2,6-pyridinebis(oxamate) and oxalate: preparation and magneto-structural study

Heterobimetallic coordination polymers with either antiferro- of ferromagnetic interactions are described herein.

Synthetic ability of dinuclear mesocates containing 1,3-bis(diazinecarboxamide)benzene bridging ligands to form complexes of increased nuclearity. Crystal structures, magnetic properties and theoretical studies

Triple stranded Ni-metallacyclic complexes Na_2.5[Ni₂(bpcb)₃]·0.5OH·18.5H₂O (1) and Na₂[Ni₂(bpzcb)₃]·16H₂O (2), and double stranded Cu-metallacyclic complexes [Cu₂(bpcb)₂(H₂O)₂]·8H₂O (3) and [Cu₂(bpzcb)₂(H₂O)₂]·4H₂O (4) have been assembled from the tailored bisbidentate bridging ligands, 1,3-bis(pyrimidine-2-carboxamide)benzene (H₂bpcb) and 1,3-bis(pyrazine-2-carboxamide)benzene (H₂bpzcb), and the corresponding nitrate salts of the metal ions. Following the "complex as ligand" strategy, 1 can be assembled with either Ni²⁺, Co²⁺ ions or the [Mn(acen)Cl] complex to afford unique, neutral, bent trinuclear molecules [M^IINi(bpcb)₃]·xH₂O (5 and 6) and the 2D honeycomb-like complex (PPh₄){[Ni₂(bpcb)₃]₂[Mn(acen)]₃} (7), respectively. In these cases, the Ni₂ units are linked to the corresponding metal ions through amidate oxygen atoms and the outward nitrogen atom of one of the pyrimidine rings of the bcpb ligand. The assembly of 2 with Ln³⁺ ions (Ln³⁺ = Tb, Gd) leads to one dimensional complexes of formula [{[Ni₂(bpzcb)₃]Tb(H₂O)₅}(CF₃SO₃)·THF·5H₂O]_n (8) and [{[Ni₂(bpzcb)₃]Ln(H₂O)₄(NO₃)}·2THF·nH₂O]_n (9 and 10) (Ln³⁺ = Gd and Tb), where the dinuclear Ni₂ units are joined to two Ln³⁺ ions exclusively through amidate oxygen atoms of two different ligands. The analyses of the magnetic data indicate that 1-4 exhibit intradinuclear ferromagnetic interactions between the metal ions through a spin polarisation mechanism, as supported by DFT calculations. Trinuclear complexes 5 and 6 show predominant antiferromagnetic coupling, which is a result of an antiferromagnetic interaction between one of the Ni²⁺ ions of the Ni₂ unit and the M²⁺ ion through the pyrimidine bridging fragment that is stronger than the polarised ferromagnetic interaction between the Ni²⁺ ions through the bpcb ligand in the dinuclear [Ni₂(bpcb)₃]^2- moiety. Complex 7 shows a dominant antiferromagnetic interaction between the Ni²⁺ and Mn²⁺, whereas the Ni₂Ln (Ln³⁺ = Gd, Tb) chain complexes present ferromagnetic interactions inside the Ni₂ mesocate unit as well as between the Ni²⁺ ions of the Ni₂ unit and the Ln³⁺ ions. The magnetic exchange interactions in these new materials have been experimentally analysed and supported by theoretical DFT studies.

Ferromagnetic ordering and slow magnetic relaxation observed in a triple-bridged azido-Cu(ii) chain compound with mixed carboxylate/ethanol linkers

A triple-bridged Cu(ii) chain compound with μ-1,1-(EO)azido, syn,syn-carboxylate, and μ2-ethanol linkers exhibits slow-relaxation and long-range magnetic ordering.

A substituent effect of phenylacetic acid coligand perturbed structures and magnetic properties observed in two triple-bridged azido-Cu(ii) chain compounds with ferromagnetic ordering and slow magnetic relaxation

Two triple-bridged azido-Cu(ii) chains exhibit distinct magnetic behaviors.

Tuning Interchain Interactions in Two-Dimensional Networks of Mn(III) Schiff-Base Complexes and Dicarboxylic Acids by Varying the Linker

Two-dimensional (2D) coordination polymers consisting of Mn(III) Schiff-base complexes and dicarboxylic acids, [{Mn(salen)}4(L1)](PF6)2·(CH3OH)2 (C4; H2L1 = adipid acid) and [{Mn(salen)}4(L2)](PF6)2·(CH3OH)4 (C4'; H2L2 = E,E-1,3-butadiene-1,4-dicarboxylic acid) (salen(2-) = N,N'-(ethylene)bis(salicylideneiminato), were synthesized by using a one-pot reaction and characterized by using single-crystal X-ray crystallographic analysis. One-dimensional (1D) chains composed of Mn(salen) dimers, [Mn2], bridged by carboxylato ligands (-[Mn2]-OCO--[Mn2]-), were linked by dicarboxylato ligands with n-butyl (-C4H8-) (C4) and butadienyl aliphatic groups (-C4H4-) (C4'). From static magnetic measurements on both C4 and C4', there were ferromagnetic interactions between the Mn(III) ions through the phenoxo oxygen atoms of the salen(2-), and antiferromagnetic interactions between the Mn(III) ions through carboxylato ligands (-OCO-). As a result, weak ferromagnetism occurred because of the zigzag-shaped chain structure of C4 and C4', and magnetic anisotropy for Mn(salen). In the magnetization curves for C4', weak interchain interactions (Jlinker) occurred through the π-conjugated butadienyl linkers in C4', which C4 did not have. In other words, changing from saturated to unsaturated aliphatic groups in the dicarboxylic acid linkers resulted in weak interactions between 1D-magnetic chain moieties. Therefore, in the case of only C4', antiferromagnetic phase transition appeared at 2.3 K. Both coordination polymers exhibited slow relaxation of the magnetizations, which originated from SCM moieties, because C4 and C4' showed magnetic correlations. It is noteworthy that alternating current (ac) susceptibilities for C4' are frequency-dependent around the Néel temperature. From analysis of the ac susceptibilities for C4, α (dispersion coefficient of the relaxation of magnetization) varied linearly with 1/T. This signifies that C4 behaved as an SCM with a single relaxation process. On the other hand, in α versus 1/T plots for C4', an inflection point was observed at the Néel temperature, indicating that Jlinkers had an effect on the distribution of the relaxation times. Moreover, the inflection point for C4' disappeared when a dc magnetic field was applied. This is the first report showing a direct correlation between an antiferromagnetic phase transition and slow magnetic relaxation.

A heterobimetallic [MnII5CuII5] nanowheel modulated by a flexible bis-oxamate type ligand

The reaction of the dicopper(ii) metallacyclophane [Cu₂(edpba)₂]²⁻ with fully solvated manganese(ii) ions yields the nanowheel [Mn₅Cu₅(edpba)₅] with a S = 10 low-lying spin state.

Towards a better understanding of honeycomb alternating magnetic networks

The honeycomb mixed-ligand complex {[Co₂(bpm)(ox)₂]_n·5nH₂O} was prepared and magneto-structurally characterized. The values of the antiferromagnetic interactions through bpm (J_bpm= −5.0 cm⁻¹) and ox (J_ox= −11.1 cm⁻¹) ligands obtained by fit were suported by DFT type calculations.

N-(1-Oxy-2-picolyl)oxalamic acids as a new type of O,O-ligands for the Cu-catalyzed N-arylation of azoles with aryl halides in water or organic solvent

A new type of chelators was identified as efficient ligands for promoting Cu-catalyzed N-arylation of azoles with applicability to different solvents.

Oxamato-based coordination polymers: recent advances in multifunctional magnetic materials

The design and synthesis of novel examples of multifunctional magnetic materials based on the so-called coordination polymers (CPs) have become very attractive for chemists and physicists due to their potential applications in nanoscience and nanotechnology.

An unusual water-bridged homospin CoII single-chain magnet

A 3D coordination polymer has been constructed by linking water-bridged cobalt chains via dicarboxylic ligands to show interesting SCM behaviour.

A triple-bridged azido-Cu(ii) chain compound fine-tuned by mixed carboxylate/ethanol linkers displays slow-relaxation and ferromagnetic order: synthesis, crystal structure, magnetic properties and DFT calculations

A triple-bridged azido-Cu(ii) compound has been synthesized and magnetically characterized.

Copper(I) complexes with trispyrazolylmethane ligands: synthesis, characterization, and catalytic activity in cross-coupling reactions

Three novel Cu(I) complexes bearing tris(pyrazolyl)methane ligands, Tpm(x), have been prepared from reactions of equimolar amounts of CuI and the ligands Tpm, (HC(pz)(3)), Tpm*, (HC(3,5-Me(2)-pz)(3)), and Tpm(Ms), (HC(3-Ms-pz)(3)). X-ray diffraction studies have shown that the Tpm and Tpm(Ms) derivatives exhibit a 2:1 Cu:ligand ratio, whereas the Tpm* complex is a mononuclear species in nature. The latter has been employed as a precatalyst in the arylation of amides and aromatic thiols with good activity. The synthesis of a Tpm*Cu(I)-phthalimidate, a feasible intermediate in this catalytic process, has also been performed. Low temperature (1)H NMR studies in CDCl(3) have indicated that this complex exists in solution as a mixture of two, neutral and ionic forms. Conductivity measurements have reinforced this proposal, the ionic form predominating in a very polar solvent such as DMSO. The reaction of Tpm*Cu(I)-phthalimidate with iodobenzene afforded the expected C-N coupling product in 76% yield accounting for its role as an intermediate in this transformation.