End-on Research Articles

Coexistence of Spin Canting and Metamagnetism in a One-Dimensional Mn(II) Compound Bridged by Alternating Double End-to-End and Double End-On Azido Ligands and the Analog Co(II) Compound

Two new compounds of general formula [M(N3)2(dmbpy)] in which dmbpy = 5,5′-dimethyl-2,2′-bipyridine, and M = Mn(II) or Co(II), have been solvothermally synthesized and characterized structurally and magnetically. The structures consist of zig-zag polymeric chains with alternating bis-µ(azide-N1)2M and bis-µ(azide-N1,N3)2M units in which the cis-octahedrally based coordination geometry is completed by the N,N’-chelating ligand dmbpy. The molecular structures are basically the same for each metal. The Mn(II) compound has a slightly different packing mode compared to the Co(II) compound, resulting from their different space groups. Interestingly, relatively weak interchain interactions are present in both compounds and this originates from π–π stacking between the dmbpy rings. The magnetic properties of both compounds have been investigated down to 2 K. The measurements indicate that the manganese compound shows spin-canted antiferromagnetic ordering with a Néel temperature of TN = 3.4 K and further, a field-induced magnetic transition of metamagnetism at temperatures below the TN. This finding affords the first example of an 1D Mn(II) compound with alternating double end-on (EO) and double end-to-end (EE) azido-bridged ligands, showing the coexistence of spin canting and metamagnetism. The cobalt compound shows a weak ferromagnetism resulting from a spin-canted antiferromagnetism and long-range magnetic ordering with a critical temperature, TC = 16.2 K.

Synthesis, structure and magnetic properties of copper(ii) azide.

A novel azide-bridged copper compound without an auxiliary ligand has been synthesized and characterized by single-crystal diffraction analysis. The compound consists of 1D double chains with end-on (EO) azide bridges. Furthermore, the neighboring chains are connected by weak coordination bonds, which leads to the formation of a 3D architecture. Low-temperature magnetic measurements reveal that antiferromagnetic interactions are dominant, with concomitant spin-canted antiferromagnetism.

Two New Three-Dimensional Pillared-Layer Co(II) and Cu(II) Frameworks Involving a [M₂(EO-N₃)₂] Motif from a Semi-Flexible N-Donor Ligand, 5,5'-Bipyrimidin: Syntheses, Structures and Magnetic Properties.

Two new three-dimensional (3D) Co(II)- and Cu(II)-azido frameworks, [Co2(N3)4(bpym)2]n (1) and [Cu2(N3)4(bpym)]n (2), were successfully synthesized by introducing a semi-flexible N-donor ligand, 5,5′-bipyrimidin (bpym), with different bridging modes and orientations. Compounds 1 and 2 were structurally characterized by X-ray crystallography, IR spectroscopy, thermogravimetry and elemental analysis. Compounds 1 and 2 are 3D pillared-layer frameworks with double end-on (EO) azido bridged dinuclear motifs, [M2(EO-N3)2]. In Compound 1, the bpym ligands show trans μ2-bridging mode and the role as pillars to connect the Co(II)-azido layers, composed of [Co2(EO-N3)2] motifs and single end-to-end (EE) azido bridges, to a 3D network with BN topology. In contrast, in 2, the bpym ligand adopts a twisted μ4-bridging mode, which not only connects the adjacent [Cu2(EO-N3)2] units to a layer, but also functions as a pillar for the layers of the 3D structure. The structural diversities between the two types of architectures can be attributed to the coordination geometry preference of the metal ions (octahedral for Co2+ and square pyramidal for Cu2+). Magnetic investigations revealed that Compound 1 exhibits ferromagnetic-like magnetic ordering due to spin canting with a critical temperature, TC = 33.0 K, and furthers the field-induced magnetic transitions of metamagnetism at temperatures below TC. Compound 2 shows an antiferromagnetic ordering with TN = 3.05 K and a field-induced magnetic transition of spin-flop at temperatures below the TN.

Slow Magnetic Relaxation in One-Dimensional Azido-Bridged CoII Complexes.

Crystal structures and magnetic properties of three one-dimensional (1D) azido-bridged cobalt(II) chains with different amide ligands (L), [Co2(N3)4(DMF)3] (1), [Co4(N3)8(DEF)5] (2), and [Co2(N3)4(DIPF)2] (3) (DMF = N,N-dimethylformamide, DEF = N,N-diethylformamide, and DIPF = N,N-diisopropylformamide), are reported to investigate the influence of L on their structures and magnetic properties. Single-crystal X-ray crystallographic analysis revealed that, although 1-3 all consist of cobalt chains bridged by end-on (EO) azides, the coordination geometry of the CoII ions and the repeating units of the 1D structures are quite different. As the size of L increases, the ratio of L to CoII decreases from 6:4 in 1 to 5:4 and 4:4 in 2 and 3, respectively. In 1, two [CoN5O1] and two [CoN4O2] distorted octahedra form the {[CoN5O1][CoN4O2]2[CoN5O1]} tetramers (denoted as Co4A), which are linked to each other by sharing the N-N edge to form the chain. Similarly, the chain structure of 3 is constructed from a similar tetramer unit {[CoN5][CoN4O2]2[CoN5]} (denoted as Co4B), where half of the CoII centers are in the [CoN5] trigonal bipyramid because of the larger steric effect of the DIPF ligand, while, for compound 2 of the medium-sized amide, it has the transition structure between those of 1 and 3. The chain is composed of two different repeating units: Co4A unit similar to that in 1 and Co4B unit similar to that in 3. Because of their similar structures, compounds 1-3 exhibit analogical magnetic properties. Direct-current magnetic measurements demonstrated that all compounds show intrachain ferromagnetic coupling through the EO azides and interchain anti-ferromagnetic interactions. Alternating-current data revealed the slow magnetic relaxation in the anti-ferromagnetic ordered phases. While compound 1 exhibits spin glass behavior, compounds 2 and 3 behave as the single-chain magnets. This difference might come from the interference of the anti-ferromagnetic ordering on the magnetic dynamic of the magnetic chain.

Synthesis, structural characterization and magnetic properties of polymeric azido Mn(II) complexes based on methyl-pyridine-N-oxide co-ligands

Three different coordination polymeric compounds have been synthesized and structurally characterized in the reaction of aqueous solution of Mn(NO3)2·4H2O with methylpyridine-N-oxide co-ligands (Mepy-N-oxide) in the presence of NaN3 depending on the position of the methyl group in Mepy-N-oxide namely: [Mn(μ(O,O)-2-Mepy-N-oxide)(μ1,3-N3)2]n (1), catena-{[Mn(μ1,1-N3)2(H2O)2](3-Mepy-N-oxide)2} (2) and [Mn3(μ1,1-N3)2(μ1,3-N3)4(μ(O,O)-4-Mepy-N-oxide)2(H2O)2]n (3). Single crystal X-ray crystallography revealed the polymeric nature of the complexes as 2D, 1D and 3D networks, respectively with a doubly end-to-end (EE) azide bridging and μ(O,O) bridging 2-Mepy-N-oxide in 1, and a doubly end-on (EO) azide bridging in 2. In complex 3 within the trinuclear subunit the three Mn(II) atoms are bridged via EO azido groups and μ(O,O) bridging 4-Mepy-N-oxide molecules and the trinuclear subunits are connected further by EE azido bridges to generate the 3D network structure. The magnetic properties of the three complexes were investigated over the temperature range 2–300K. Complex 2, as far as we know, is the first Mn(II) uniform 1D compound with double EO azido bridges which shows antiferromagnetic coupling. The fit of the magnetic data by using the appropriate equation derived from the Hamiltonian H=−∑JSi·Si+1 gives the best fit parameters J=−3.55(1)cm−1, g=2.044(1).

Syntheses, structures, and magnetic properties of a family of end-on azido-bridged CuII-LnIII complexes.

The reaction of Cu(valdmpn) (H2valdmpn = N,N'-bis-(3-methoxysalicylidene)-1,3-diamino-2,2-dimethylpropane), LnCl3·nH2O (Ln = La(1), Ce (2), Pr(3), Nd(4), Sm(5), Eu(6), Gd(7), Tb(8), Dy(9), Ho(10), Er(11), Tm(12), Yb(13), Lu(14)) and NaN3 in methanol led to a whole series of heterometallic CuII-LnIII complexes. The basic structural components of these complexes are the [CuII(valdmpn)LnIII] units with a compartmental Schiff-base ligand. These [CuIILnIII] units were then further connected by the end-on (EO) azides between the Ln3+ centers to form tetranuclear {[CuLn](μ-N3)n[LnCu]} motifs, where n is 3 for the complexes of larger radii lanthanides (1CuLa to 5CuSm) and 2 for the complexes of smaller radii lanthanides (6CuEu to 14CuLu). While compounds 6CuEu to 14CuLu remain isolated tetranuclear clusters, compounds 1CuLa to 5CuSm are one-dimensional chains where tetranuclear motifs are further connected by end-to-end (EE) azides between CuII and LnIII centers. Direct current (dc) magnetic susceptibilities have been measured in the range of 1.8-300 K for all complexes, revealing the different nature of magnetic interactions between the spin centers. Among them, dominant ferromagnetic interactions were found in compounds 7CuGd, 8CuTb and 9CuDy. Alternating current (ac) magnetic measurements performed on 8CuTb, 9CuDy, and 10CuHo demonstrated the presence of slow magnetic relaxation under zero applied dc field. The spin relaxation barrier Ueff was determined to be 19.54 cm-1 (28.12 K) and 10.34 cm-1 (14.87 K) for compounds 8CuTb and 9CuDy. The SMM behavior of 8CuTb was further confirmed by the presence of magnetic hysteresis loops; while no hysteresis loop was observed for 9CuDy and 10CuHo. These results demonstrated that azido-bridged copper(ii)-lanthanide(iii) complexes could be synthesized successfully despite the generally weak azido-lanthanide interaction.

H-bonding directed formation of 1D-single chains, 2D-sheets, and 3D structures in magnetically coupled tetranuclear nickel(II) complexes with incomplete double cubane core

Reactions of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and 2-amino-1,3-propanediol (APD) in the presence of nickel(II) salts, NiX2 (X=CH3CO2−, NO3−, Cl−, ClO4−, BF4−)/sodium azide (NaN3), and triethylamine (TEA), in one pot self-assemble giving tetranuclear coordination complexes of nickel(II) with an incomplete double cubane structural core: [Ni4(H2L−1)2(μ-CH3CO2)2(μ3-X)2(μ-1,1-N3)2]·2CH3OH {X=1,1,1-N3 (1A) and OCH3 (1B)}, [Ni4(H2L−1)2(μ-1,1-N3)2(N3)2(μ3-OCH3)2 (H2O)2] (2), [Ni4(H2L−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2Cl2]·4CH3OH (3), [Ni4(H4L1−1)2(μ3-1,1,1-N3)2(μ-1,1-N3)2(CH3OH)2(OH)2]·2H2O (4), and [Ni4(HL2−2)2(APD−1)2][ClO4]2·2H2O·2CH3OH (5). In 1–3, H2L−1, in 4, H4L1−1, and in 5, HL22− represent a singly deprotonated chiral, potentially pentadentate trianionic double Schiff base ligand, H3L; a singly deprotonated potentially heptadentate pentaanionic double Schiff base ligand, H5L1; and a doubly deprotonated potentially tetradentate trianionic single Schiff base ligand, H3L2 respectively. In 1A, 3, and 4 two dinickel (Ni2) units are connected through two doubly bridging end-on (EO) μ-azido and two triply bridging EO μ3-azido bridges and in 2, though two EO μ-azido and two μ3-1,1,1-methoxy bridges generating tetranuclear units. In each dinuclear unit two nickel centers are bridged through one μ-phenolate oxygen from H2L−1, one μ-CH3CO2−, and one EO μ3-azido nitrogen (1) and through one μ-phenolate oxygen from H2L−1/H4L1−1 and one μ3-methoxy oxygen (2)/one μ3-azido nitrogen (3 and 4). In 5, two nickel(II) ions in the dinuclear unit are bridged though phenoxide oxygen and alkoxide oxygen bridges and two dinuclear units are interconnected via six symmetry related alkoxide bridges forming tetranickel units. In 1–4 neutral tetranuclear [Ni4] units and in 5, cationic tetranickel [Ni4]2+ units are interconnected by a symmetrical network of H-bonding between coordinated/uncoordinated hydroxido groups in the side arms of the double Schiff-base ligands, coordinated hydroxide ion/chloride ion, and uncoordinated methanol/water molecules producing H-bonding stabilized 2D-sheet structures (1, 2, 4), a 1D-single chains (3), and a 3D structure (5). Bulk magnetization measurements on 1–4 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Ni(II) ions with coupling constants (J1, J2, and J3) ranging from 13.19 to 22.10, (−9.05) to (1.74), and 14.79 to 25.59cm−1 respectively (in the Ĥ=-2J1(Ŝ1Ŝ3+Ŝ2Ŝ4)-2J2(Ŝ1Ŝ4+Ŝ2Ŝ3)-2J3(Ŝ1Ŝ2)+D(ŜZ12+ŜZ22+ŜZ32+ŜZ42) expression). [Display omitted]

Tetranuclear manganese(II) complexes of hydrazone and carbohydrazone ligands: Synthesis, crystal structures, magnetic properties, Hirshfeld surface analysis and DFT calculations

The complexes [Mn4(L1)4(N3)4] (1), [Mn4(L2)4(μ-N3)2(N3)2(OCH3)2] (2) and [Mn4(μ-L3)4(NCS)4]·6CH3OH (3) [L1=N-1-(pyridin-2-yl)ethylidenepicolinohydrazonate, L2=N-phenyl(pyridin-2-yl)methylenepicolino hydrazonate, and L3=((phenyl(pyridin-2-yl)methylene)hydrazinyl)((Z)-2-(phenyl(pyridin-2-yl)methylene)hydrazinyl)methanolate] have been synthesized, and their structures characterized. The structures of 1 and 3 can be described as tetranuclear and are formed from four Mn(II) ions bridged by four ligands. Complex 2 exhibits a centrosymmetric tetranuclear structure with two types of Mn(II) centers with double end-on (EO) azido bridges. All the complexes have similar magnetic behavior and exhibit weak intramolecular antiferromagnetic coupling, which is consistent with the oxygen-bridged square structures with large Mn–O–Mn bridge angles. Theoretically obtained J values of −1.7cm−1 (for 1), −0.7cm−1 (for 2) and −3.3cm−1 (for 3) corroborate well the experimental results. Moreover, a Hirshfeld surface (HS) analysis was employed to gain additional insight into interactions responsible for packing of complexes 1–3 (with dnorm and shape-index functions). Quantitative examination of 2D fingerprint plots revealed, amongst others, the dominating participation of H⋯H and H⋯C interactions in the molecular packing.

Two double end-on cyanato-bridged dinuclear manganese(II) complexes exhibiting abnormal magnetic coupling for the Mn(II)–N–Mn(II) linkage

Two cyanato-bridged dinuclear Mn(II) complexes [Mn2(phen)4(μ 1,1-NCO)2][MIII(bpb)(CN)2]·H2O [M = Fe (1) or Co (2)], [phen = 1,10-phenanthroline, bpb2− = 1,2-bis(pyridine-2-carboxamido)benzenate] have been synthesized using the synthetic strategy of big anion inducement. Single-crystal X-ray diffraction analysis reveals that both complexes consist of a double end-on (EO) cyanato-bridged dinuclear Mn(II) unit and two free [M(bpb)(CN)2]− building blocks acting as counter-ions. Magnetic studies show the presence of abnormal antiferromagnetic interactions between the two Mn(II) centers through the EO cyanate bridge with J = −1.58(3) cm−1 for complex 1 and −1.82(2) cm−1 for complex 2. The unusual antiferromagnetic interactions of these complexes can be attributed to their small Mn(II)–N–Mn(II) angles.

2D Compound Constructed by Cu3 Units with Mixed Azido and Tetrazole Double Bridges: Synthesis, Structure, and Theoretical Study on Magnetic Properties

AbstractThe two‐dimensional (2D) layer CuII compound [Cu3(L)2(N3)4] (1) [L = 2‐amino‐3‐(5‐tetrazole)‐methyate‐N‐pyridine] was synthesized by in‐situ hydrothermal reaction of CuCl2·2H2O, NaN3, and 3‐(5‐tetrazole)‐methyate‐N‐pyridine. The central Cu1 and Cu2 atoms are located in five‐coordinate and six‐coordinate arrangements, respectively. Three CuII ions are linked by mixed double EO (end‐on)‐azido‐tetrazole bridges to give trinuclear CuII clusters, which are further extended by EE (end‐to‐end) azido bridges to form 2D metal‐organic layers. The magnetic exchange interactions in complex 1 were investigated by DFT calculations, and the calculated exchange interaction (J = –849 cm–1) revealed that the double EO‐azido‐tetrazole bridges transmit antiferromagnetic coupling between CuII ions.

4-Substituent pyridine directed cobalt(II) azides: solvothermal synthesis, structure, and magnetic properties.

The structure and magnetism of three cobalt(ii)-azide complexes, [Co(N3)2(bepy)2]n (), [Co2(N3)4(vipy)4]n (), and [Co(N3)2(bipy)]n () were tuned by three structurally related 4-substituent pyridines, 4-benzylpyridine (bepy), 4-vinyl pyridine (vipy), and 4,4'-bipyridine (bipy) as co-ligands in solvothermal reactions. With flexible benzyl as a substituent group of the pyridine co-ligand, a one-dimensional (1D) complex with double end-to-end (EE) azide-bridging Co(ii) chain is formed. While using a rigid but small vinyl group as the substituent, a distinct Co(ii)-azide chain with alternate double end-on (EO) and double EE azide bridges was obtained. Finally, when another pyridine group was used instead of the substituent incapable of coordinating in and , a bipyridine, it gave rise to a chiral complex with a three-dimensional (3D) diamondoid Co(ii)-azide framework further reinforced by the bipy ligand. Magnetic studies indicate antiferromagnetic interactions between the Co(ii) ions in the three complexes, but interestingly, weak antiferromagnetism origin of spin canting exists in at low temperatures.

Room Temperature Synthesis, Crystal Structure and Magnetic Property of a Two-Dimensional Copper(II) Polymer Bridged by End-On and End-to-End Azide Bridges

A novel two dimensional (2D) copper(II) polymer [Cu3(N3)6(DMF)2] n (1) has been synthesized and characterized by elemental analysis, IR, X-ray single crystal diffraction and magnetic susceptibility measurements. Complex 1 was formed by a [Cu3(N3)6(DMF)2] trimeric unit through two double symmetric end-on (EO) azide bridges which further constructed 2-D network through asymmetric EO and end–end azide bridges. The magnetic study shows that the compound 1 exhibits ferromagnetic interactions through symmetric EO azide bridges and antiferromagnetic interactions via asymmetric EO azide bridges.

A porous metal organic framework with a bcu-type topology involving in situ ligand formation – synthesis, structure, magnetic property and gas adsorption studies

A three-dimensional (3D) porous metal organic framework namely, {[Cu3(N3)2(4-ptz)4(DMF)2]·2DMF}n, has been synthesized using Cu(CH3COO)2·H2O and ligand 4-ptz [5-(4-pyridyl)-tetrazolate] which was formed in situ from 4-cyanopyridine and sodium azide in presence of water and CuII ions. Crystal structure analysis showed that the complex crystallizes in the monoclinic space group P21/c and has a decorated body centred cubic (bcu) topological net with 8-connected Cu3 cluster as node. Magnetic studies exhibit prominent antiferromagnetic interactions influenced by EO (end on) azide and μ2,η2-tetrazolato bridge among the metal centres. Gas adsorption studies reveal moderate carbon dioxide uptake, which is also reflected in the isosteric heat of adsorption (Qst) value of −28 kJ mol−1.

Syntheses, crystal structures and magnetic studies of new 2D coordination polymers containing dinuclear manganese(II) repetitive units using a ditopic isonicotinhydrazone based N,N,O-donor ligand

Three new complexes of manganese(II) with pseudohalide anions and (E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinhydrazide (HL), namely a 2D polymer with azide bridged dinuclear unit [Mn2(L)2(μ-N3)2]n (1), a 2D coordination polymer [Mn2(L)2(NCS)2]n (2a) and a monomeric [Mn(HL)(NCS)2(OHCH3)] (2b), were synthesized and characterized by elemental analyses and spectroscopic methods. The structures were established by X-ray diffraction, and further studied by magnetic susceptibility measurements. The isonicotinhydrazide ligand acts as a mononegative tetradentate N3O-donor ligand and coordinates to the manganese center in the enolic form (N–NC–O) in 1 and 2a while in complex 2b coordinates as NNO-donor tridentate neutral ligand in keto form (N–NH–CO). Two bridging azide ligands connect the two metal centers in an end-on (EO) fashion in 1. For complex 2a the enolic oxygen of the hydrazone moiety spans two metal centers to form a dinuclear unit containing Mn2O2 four-membered planar ring. Magnetic measurements revealed antiferromagnetic coupling inside the dimers for 1 and ferromagnetic coupling for 2a.

Chiral heterometallic 3d–3d azido complex: Synthesis, structure and magnetic properties

Abstract A novel three-dimensional chiral heterometallic 3d–3d azido complex, [Co2Zn(N3)4(pyzc)2]∞(1) (pyzc = 2-pyrazinecarboxylate), was obtained by assembling CoII, ZnII, azido, and pyrazine carboxylate under solvothermal condition. The structure of the complex can be described as end-on (EO) azido, end-to-end (EE) azido mixed bridged alternate Co–Zn chains linked by the 2-pyrazinecarboxylate. Magnetic studies indicate that dominant anti-ferromagnetic coupling interactions exist in the complex.

Syntheses, crystal structures and magnetic studies of new copper(II) complexes of (E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide containing azide and SCN anions

Three new complexes of copper(II) with pseudohalide anions and (E)-N′-(phenyl(pyridin-2-yl)methylene)isonicotinohydrazide (HL), namely azide bridged dinuclear [Cu(L)(μ-N3)]2 (1), two-dimensional coordination polymer [Cu2(L)2(NCS)2]n (2a) and monomeric [Cu(L-H)(NCS)2] (2b), were synthesized. The complexes were characterized by elemental analyses and spectroscopic methods. The structures were unequivocally confirmed by X-ray diffraction, and further studied by means of EPR and magnetic susceptibility measurements. In all three complexes, the isonicotinohydrazide ligand coordinates to the copper center in the enolic form (–CN–N). In complex 1, the two bridging azide ligands connect the two metal centers in an end-on (EO) fashion, with the metal centers having an asymmetric square pyramidal geometry. Complex 2b is based on a square pyramid with the neutral isonicotinohydrazide ligand coordinating in a tridentate mode. By contrast, the Schiff base (L)− coordinates in a tetradentate ligand fashion in 2a as the oxygen atom of the amide unit in the enol form asymmetrically bridges two Cu centers and a third Cu center is coordinated through the pyridyl-N atom. The EPR spectrum of complex 2a, consisting of two poorly resolved resonance lines, points to the presence of a dynamical Jahn–Teller effect, typical for Cu2+ ions in octahedral environments.

Synthesis, X-ray crystal structure, and electrochemistry of polynuclear azido-bridged manganese(III) and copper(II) Schiff base complexes

Abstract New azido-bridged [MnIII(salabza)(μ-1,3-N3)]n (1), and [CuII4(salabza)2(μ-1,1-N3)2(N3)2(HOCH3)2],(2) complexes with an unsymmetrical Schiff base ligand, {H2salabza = N,N’-bis(salicylidene)-2-aminobenzylamine}, have been synthesized, characterized by spectroscopic and electrochemical methods, and their crystal structures have been determined by X-ray diffraction. In complex 1, each manganese(III) atom is coordinated with N2O2 donor atoms from salabza and two adjacent Mn(III) centers are linked by an end-to-end (EE) azide bridge to form a helical polymeric chain with octahedral geometry around the Mn(III) centers. Complex 2 is a centrosymmetric tetranuclear compound containing two types of Cu(II) centers with square pyramidal geometry. Each terminal copper atom is surrounded by N2O2 atoms of a salabza ligand, and the oxygen atom of the methanol molecule. Each central copper(II) ion is coordinated with two phenoxo oxygen atoms from one salabza, one terminal azido, and two end-on (EO) bridging azido ligands. The central copper(II) ions are linked to each other by the two end-on (EO) azido groups.

Novel heterometallic metal–azido complex synthesized by “one-step” reaction: synthetic strategy and magnetic properties

A novel heterometallic complex, [Ni{sub 2}Mn(N{sub 3}){sub 2}(nic){sub 4}·(H{sub 2}O){sub 2}]{sub n} (1) (nic=nicotinate), was obtained by assembling MnCl{sub 2}·4H{sub 2}O, Ni(NO{sub 3}){sub 2}·6H{sub 2}O, NaN{sub 3} and nicotinic acid with a “one step” synthetic strategy—hydrothermal reaction. The 3D structure of the complex can be described as end-on (EO) azido and syn,syn carboxylates mixed bridged by alternate Ni–Mn–Ni trimers linked by the nicotinate. Dominant ferromagnetic interactions were observed between the Ni{sup II} and Mn{sup II} ions in the trimer. - Graphical abstract: A novel heterometallic 3D complex [Ni{sub 2}Mn(N{sub 3}){sub 2}(nic){sub 4}·(H{sub 2}O){sub 2}]{sub n} (1) (nic=nicotinate) was synthesized by hydrothermal reaction. This complex exhibits interesting structural and magnetic properties. - Highlights: • It is difficult to construct simple coordination complexes with azide as “ligands” to obtain heterometallic metal–azido compounds. • A “one-step” method—hydrothermal reaction— was introduced to avoid the disadvantages of azide mentioned above. • The magnetic property is different with the isostructural homometal–azido complex due to the changed metal center.

Examples of Heterometallic 3d–3d Azido Complexes by One‐Pot Synthesis

AbstractThe assembly of CuII, MII (CoII or NiII), azido, and isonicotinate acid N‐oxide under hydrothermal conditions straightforwardly gives two isomorphic heterometallic 3d–3d azido complexes formulated [Cu2M(N3)4(INO)2(H2O)4]∞ (INO = isonicotinate N‐oxide; M = Co for 1 and Ni for 2). In the structure of the complexes, CuII ions have a trigonal‐bipyramidal‐coordinated configuration, whereas the MII ions have octahedral geometry with two water molecules in the apical positions. The structure of the complexes is based on azido‐carboxylate mixed‐coordination Cu–M–Cu trimers, which are further linked by double end‐on (EO) azido anions through the CuII ions to form a chain structure, and the 1D structure can be described as EO azido/syn–syn carboxylates and double EO azido mixed‐bridge spin‐sequence chains with –1/2–J1–3/2–J1–1/2–J2–1/2– for 1 and –1/2–J1–1–J1–1/2–J2–1/2– for 2. Magnetic studies indicated that 1 and 2 are both metamagnets for the weak antiferromagnetic interactions between the ferromagnetic chains.

Two coordination polymers based on semicarbazone Schiff base and azide: synthesis, crystal structure, electrochemistry, magnetic properties and biological activity

[Mn(L)(μ1,1–N3)2]2 n [Mn(H2O)2(μ1,1–N3)2] n (1) and [Cd(HL)(μ1,1–N3)2] n (2) have been synthesized from HL (HL: pyridine-2-carbaldehyde semicarbazone) and azide ligands, characterized by FT-IR, UV–vis spectroscopy and X-ray crystallography. Single crystal X-ray diffraction revealed that 1 is a coordination polymer consisting of two infinite 1-D chains: chain A with [Mn(L)(μ1,1–N3)2]2 n and chain B with [Mn(H2O)2(μ1,1–N3)2] n . In both chains, Mn centers are connected via two double end-on (EO) azide bridges. 2 is a coordination polymer consisting of a 1-D infinite chain, where Cd centers are connected via two double EO azide bridges. The electrochemistry of HL, 1 and 2 were studied by cyclic voltammetry. Magnetic susceptibility measurements indicate bulk ferromagnetic coupling for 1 below 5 K. Antimicrobial activities of both compounds 1 and 2 were greater than HL, with the strongest effect for 2 consistent with its larger radius and electronegativity of Cd(II) ions.