The first 1-D cyanide-bridged complex assembled from a covalently tethered [CoII(N3O2)Cl(OH2)]22+ macrocyclic building block

Roland, Thierry; Gavey, Emma L.; Wang, Jian; Rawson, Jeremy M.; Pilkington, Melanie

doi:10.1016/j.poly.2014.04.001

Cited by 7 publications

(4 citation statements)

References 47 publications

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“…In a large group of mononuclear 3d-SMMs, which usually consist of complexes with lower coordination numbers (ranging between 2 and 6), the seven-coordinate complexes represent a relatively small and interesting family of compounds in comparison with a large group of tetra-/pentacoordinate complexes . In most cases, seven-coordinate complexes of Ni II , Fe II , and Co II with pentagonal–bipyramidal geometry involving polyamino/oxo or Schiff base ligands with an open-chain structure, e.g., H 2 L1a , − H 2 L1b , , H 2 L1c , and H 2 L2 , or macrocyclic, e.g., 15-pydienN 3 O 2 , , 15-pydienN 5 , 15-pyN 3 O 2 = L , L3 , L4 , L5 , L6 , and L7 (Figure ) were investigated. Ni II and Fe II complexes revealed usually large easy-axis magnetic anisotropy ( D < 0) with slow relaxation of magnetization observed in the case of heteronuclear complexes [{Ni(H 2 L1a )} 3 {W(CN) 8 } 2 ] (below the blocking temperature T N = 3.6 K, τ 0 = 1.6 × 10 –9 s, U eff = 30 K) and [Fe(H 2 L1a )Ni(CN) 4 ] n (polymeric one-dimensional (1D) chain with τ 0 = 2 × 10 –9 s and U eff = 34 cm –1 ), and more recently also in the case of mononuclear complexes [Fe(H 2 L1a )Cl 2 ] and [Fe(H 2 L1c )Cl 2 ] (τ 0 = 5 × 10 –9 s and U eff = 53 cm –1 ) .…”

Section: Introductionmentioning

confidence: 99%

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

2017

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The structural and magnetic features of a series of mononuclear seven-coordinate Co complexes with the general formula [Co(L)X], where L is a 15-membered pyridine-based macrocyclic ligand (3,12,18-triaza-6,9-dioxabicyclo[12.3.1]octadeca-1(18),14,16-triene) and X = Cl (1), Br (2), or I (3), were investigated experimentally and theoretically in order to reveal how the corresponding halogenido coligands in the apical positions of a distorted pentagonal-bipyramidal coordination polyhedron may affect the magnetic properties of the prepared compounds. The thorough analyses of the magnetic data revealed a large easy-plane type of the magnetic anisotropy (D > 0) for all three compounds, with the D-values increasing in the order 35 cm for 3 (I), 38 cm for 1 (Cl), and 41 cm for 2 (Br). Various theoretical methods like the Angular Overlap Model, density functional theory, CASSCF/CASPT2, CASSCF/NEVPT2 were utilized in order to understand the observed trend in magnetic anisotropy. The D-values correlated well with the Mayer bond order (decreasing in order Co-I > Co-Cl > Co-Br), which could be a consequence of two competing factors: (a) the ligand field splitting and (b) the covalence of the Co-X bond. All the complexes also behave as field-induced single-molecule magnets with the spin reversal barrier U increasing in order 1 (Cl) < 2 (Br) < 3 (I); however, taking into account the easy-plane type of the magnetic anisotropy, the Raman relaxation process is most likely responsible for slow relaxation of the magnetization. The results of the work revealed that the previously suggested and fully accepted strategy employing heavier halogenido ligands in order to increase the magnetic anisotropy has some limitations in the case of pentagonal-bipyramidal Co complexes.

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Section: Introductionmentioning

confidence: 99%

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

2017

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“…1,3a Over the past two decades researchers in the field of molecular magnetism have exploited the axial ligands of this macrocycle for the self-assembly of clusters, chains and networks affording materials with a broad range of interesting magnetic properties. 7,8 One of the major challenges facing chemists targeting technologically desirable SCO properties is controlling the nature of the spin transition. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Following the latter approach, our strategy was initially to prepare the back-to-back macrocycle 2 which afforded MnĲII) and CoĲII) dimers, as well as a 1-D CoĲII) chain. 7,8 One of the major challenges facing chemists targeting technologically desirable SCO properties is controlling the nature of the spin transition. 9 In this context, such properties are determined by the efficiency with which structural changes at individual SCO metal sites are transmitted throughout the bulk material, referred to as the cooperativity, and are essentially equivalent to the propagation of a first order phase transition through a crystalline material.…”

Section: Introductionmentioning

confidence: 99%

Probing the structural changes accompanying a spin crossover transition in a chiral [Fe(ii)(N₃O₂)(CN)₂] macrocycle by X-ray crystallography

Roland

Pilkington

2015

CrystEngComm

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The preparation and characterization of a novel chiral macrocycle S,S-ĳFe II ĲPhCH 2 OCH 2 ) 2 ĲN 3 O 2 )ĲCN) 2 ] (4) is presented. Magnetic susceptibility studies reveal that this complex undergoes a gradual spin crossover in the solid state with no thermal hysteresis. Variable temperature X-ray diffraction studies on single crystals of 4 reveal that at 150 K the complex is comprised of two crystallographically independent octahedral FeĲII) centres. Warming the crystal to 300 K results in a subtle change in coordination geometry of one of the octahedral FeĲII) centers towards a 7-coordinate, pentagonal bipyramidal geometry that is accompanied by a conformation change in one of the PhCH 2 OCH 2 substituents. CrystEngComm This journal isScheme 1 Structural changes in coordination geometry of the FeĲII) centre of the parent ĳFeĲN 3 O 2 )ĲCN) 2 ] complex (1) on cooling and warming. 3

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“…Cyanide salts such as KCN and NaCN are well known as po tential bridging material [6][7][8]. However, they are very poisonous.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, and crystal structure of a novel cyanide-bridged heteronuclear Co(III)-Mn(III) complex derived from N,N′-ethylene-bis(chlorosalicylideneimine)

et al. 2015

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With a bis Schiff base N,N' ethylene bis(5 chlorosalicylideneimine) (H 2 L) and K 3 [Co(CN) 6 ], a novel cyanide bridged heteronuclear Co(III)-Mn(III) complex was prepared and characterized by elemen tal analysis, IR spectroscopy and X ray structure determination (CIF file CCDC no. 1029225). The complex crystallizes in the monoclinic space group P2 1 /c with unit cell dimensions a = 10.741 (2), b = 14.015(3), c = 15.074(3) Å, β = 94.237(2)°, V = 2263.0(8) Å 3 , Z = 2, R 1 = 0.0441, and wR 2 = 0.0999. Single crystal X ray diffraction analysis reveals that two [Mn(L)(OH 2 )] + units are linked through a [Co(CN) 6 ] 3-bridge, forming a trinuclear Mn-Co-Mn moiety. The Mn-Co-Mn moieties are further linked through K atoms to form a 1D chain. The chains are stacked through π···π interactions. The Mn and Co atoms are in octahedral coor dination, and the K atom is in square planar geometry.

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The first 1-D cyanide-bridged complex assembled from a covalently tethered [CoII(N3O2)Cl(OH2)]22+ macrocyclic building block

Cited by 7 publications

References 47 publications

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

Probing the structural changes accompanying a spin crossover transition in a chiral [Fe(ii)(N₃O₂)(CN)₂] macrocycle by X-ray crystallography

Synthesis, characterization, and crystal structure of a novel cyanide-bridged heteronuclear Co(III)-Mn(III) complex derived from N,N′-ethylene-bis(chlorosalicylideneimine)

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The first 1-D cyanide-bridged complex assembled from a covalently tethered [CoII(N3O2)Cl(OH2)]22+ macrocyclic building block

Cited by 7 publications

References 47 publications

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

Impact of Halogenido Coligands on Magnetic Anisotropy in Seven-Coordinate Co(II) Complexes

Probing the structural changes accompanying a spin crossover transition in a chiral [Fe(ii)(N3O2)(CN)2] macrocycle by X-ray crystallography

Synthesis, characterization, and crystal structure of a novel cyanide-bridged heteronuclear Co(III)-Mn(III) complex derived from N,N′-ethylene-bis(chlorosalicylideneimine)

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Probing the structural changes accompanying a spin crossover transition in a chiral [Fe(ii)(N₃O₂)(CN)₂] macrocycle by X-ray crystallography