Stable complex of nickel(I) with the N 6 macrocycle hexacyclene (original) (raw)
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Inorganic Chemistry, 1982
A new type of binuclear nickel complex [Ni2(PhSa1)4CH3C00]-pipH+ has been synthesized and characterized by X-ray crystallography. The nickel atoms have a distorted octahedral environment, containing one bridging and one nonbridging nickel phenylsalicylaldimine (PhSal) ligand and a single bridging acetate group. The two nickel octahedra are related by a twofold axis and share an edge at the bridging phenolic oxygens of the PhSal ligands; they also share an apex via the bridging acetate group and could therefore be regarded as sharing triangular faces. The strength of antiferromagnetic interaction between the nickel a t o m contrasts with the magnetic properties of a series of closely related edge-sharing (neutral) nickel(I1) complexes in which the bridging acetate is absent. Some of the latter exhibit ferromagnetic interactions and others are more strongly antiferromagnetic than the acetate-bridged ion [Ni2 4CH3C00]-. Crystal data: space group Pbcn; Z = 4; a = 12.092 (6) A, b = 18.745 ( 5 ) A, c = 22.844 (10) A; R = 5.0% for 1455 reflections; exchange constant J = -4.66 cm-I.
Inorganic Chemistry, 1994
The nickel(II) complexes of hexaaza macrocyclic ligands 1-4, which incorporate functional groups such as-OH and-CN into the pendant arms attached at the uncoordinated bridgehead nitrogen atoms, are synthesized by the simple template condensation of ethylenediamine, formaldehyde, and primary amines with the appropriate functional groups. The hydroxyl pendant groups in the nickel(I1) complex of 1 react with acetic anhydride to produce the Ni(I1) complex of 5. The Ni(I1) complexes of 1-5 are in a square-planar geometry in solution. Their UVIvis spectra and electrochemical data are slightly affected by the type of functional group and the length of the pendant chain. The pendant hydroxyl groups in [Ni(1)I2+ and [Ni(2)12+ do not coordinate Ni(II) ion in water at pH 5 13.0 and an ionic strength 1.0 M (NaC104) or at pH 5 10.0 and an ionic strength 0.1 M (NaC104). The nickel(I1) complex with macrocycle 3 forms a coordination polymer on crystallization. [Ni(2)](C104)2 (NiC14H34N6C12010) crystallizes in the monoclinic space group P211c with a = 8.724(2) A, b = 14.581(2) A, c = 9.255(2) A, p = 103.84(1)", and Z = 2. The structure was solved by the direct method and refined to R values of R = 0.0335 and wR(F) = 0.0785 for 175 1 observed reflections (F > 4a(F)) measured with Mo Ka radiation on an Enraf-Nonius CAD-4 diffractometer. The Ni(I1) ion forms a square-planar geometq, coordinated by four secondary nitrogen donors of the macrocycle with the average Ni-N bond distance of 1.929(2) A. The oxygen atoms of the pendant hydroxyl groups form hydrogen bondings with the secondary NH's of the neighboring macrocyclic ligands. Coordination polymer [Ni(3)],(BF&,, (NiC1&8N&Fg) crystallizes in the monoclinic space group P21/n with a = 8.269(1) A, b = 8.559(1) A, c = 15.814(2) A, , 8 = 101.27(1)", and Z = 2. The structure was solved by the direct method and refined to R values of R = 0.0485 and wR(F) = 0.1395 for 1509 observed reflections (F > 6a(F)) measured with Mo Ka radiation on an Enraf-Nonius CAD-4 diffractometer. In the Ni(II) coordination polymer, each Ni(II) ion in the macrocyclic unit is coordinated by two nitrile groups of the neighboring macrocycles. The Ni(I1) atom is virtually in an octahedral geometry with the average Ni-N(macrocyc1e) bond distance of 2.056(3) 8, and the Ni(I1)-N(nitri1e) bond distance of 2.162(4) A.
Polyhedron, 2002
The use of the substituted benzotriazole ligand btaOH (1-hydroxybenzotriazole) in nickel(II) chemistry has yielded a structurally and magnetically interesting polynuclear complex. The [Ni(acac) 2 (H 2 O) 2 ] Á/btaOH ×/H 2 O (4:1, 3:1, 7:4) reaction system in refluxing MeCN gives light green Á/blue [Ni 7 (OH) 2 (acac) 8 (btaO) 4 (H 2 O) 2 ] (4) in good yield ( Â/75%). The structure of 4 ×/MeCN ×/0.9H 2 O was determined by single-crystal X-ray crystallography. The heptanuclear assembly is held together by two m 3 hydroxo ligands, two terminal H 2 O molecules, four chelating acac ( groups, two m 2 acac ( groups, two m 3 acac ( groups, two m 4 btaO ( ligands and two m 2 btaO ( ligands. The Ni(II) atoms have distorted octahedral geometries. The IR and UV Á/Vis data of 4 are discussed in terms of the nature of bonding and the known structure. Variable-temperature magnetic susceptibility data (3 Á/300 K), fitted with a 3-J model, show ferromagnetic and antiferromagnetic interactions. Magnetization data at 4 K are in line with an S 0/1 ground state for 4. The versatility of the 1-hydroxybenzotriazolate ligand is also discussed. #
A new ferromagnetic nickel(II) hexameric structure based on the versatile N,O 3-ligand 2,2 ,2-nitrilotribenzoic acid has been prepared and characterised by X-ray crystallography and magnetic measurements; the compound represents a rare example of a nickel cluster with a dicubane-like core having only oxygen bridges. During the past decade molecule-based magnets have attracted considerable interest. Presently it is understood that the important prerequisites for molecules to show single-molecule magnet (SMM) behaviour are the presence of a high spin ground state and a large zero field splitting parameter D. 1 Single-molecule magnets offer the possibility of information storage at the molecular level and there is an increasing interest to develop synthetic approaches to larger, more complex molecules to further investigate the relationship between structure and molecular properties. By use of simple organic ligands, i.e. carboxylates, clusters containing up to 24 transition metals have been isolated. 2 The number of such complexes containing polydentate ligands such as polycarboxylates 3 is limited, but should produce new polynuclear topologies. We have recently investigated the coordination chemistry of the tripodal N,O 3 ligand 2,2 ,2-nitrilotribenzoic acid (H 3 L) and have isolated monomeric and dimeric complexes, but no compounds of higher nuclearity have been obtained so far. 4 Here we present a new hexameric nickel(II) complex of H 3 L underlining the versatility of this ligand to adopt a variety of coordination modes. While we reported a dimeric nickel(II) complex of H 3 L showing a trigonal-bipyramidal coordination mode, we found that this ligand also supports octahedral coordination. The reaction of six equivalents Ni II with four equivalent H 3 L, deprotonated by triethylamine in acetonitrile, gave the reported {Ni 6 } cluster 1. † The single crystal structure of 1 [HNEt 3 ] 2 [Ni 6 L 4 (l 3-OH) 2 (l-OH 2) 2 ]·5CH 3 CN·2.6H 2 O (Fig. 1) displays a centrosymmetric complex anion, containing six nickel(II) atoms, bridged by the carboxylate groups of four L 3− ligands, two hydroxide and two water molecules. ‡ The two nickel(II) ions Ni1 and Ni3 have a distorted octahedral coordination sphere and bind to the deprotonated ligand L 3− by the central nitrogen atom and the three carboxylate groups. The other two coordination sites are occupied by a carboxylate group of a second ligand and a water molecule in the case of Ni3 and a hydroxide in the case of Ni1. Furthermore these two [NiL] units are joined by the two Ni2 and Ni2 ions, forming a dicubane-like core. The carboxylic groups exhibit three different coordination modes within the cluster: monodentate, monoatomic oxygen bridging (l 1-COO) of two Ni ions and triatomic carboxylic bridging OCO(l 3-COO) of three Ni ions. The Ni · · · Ni distances are in the range 2.987(1)–3.128(1)A ˚. Magnetic susceptibility data for 1 were acquired from a microcrystalline sample in the 2–300 K temperature range at a constant magnetic field of 1 T. The temperature dependence of the reciprocal susceptibility is linear above 50 K and obeys the Curie–Weiss law with a Weiss constant h = 6.0 K and C = Fig. 1 Molecular structure of [Ni 6 L 4 (l 3-OH) 2 (l-OH 2) 2 ] 2− , 1. Hydrogen atoms and solvent molecules have been omitted for clarity. Atoms with a prime () character are at equivalent positions (1 − x,1 − y,1 − z). 7.29 cm 3 K mol −1. The C value corresponds to isolated high-spin Ni II (S = 1) ions with g = 2.21. A plot of temperature dependence of the experimental v m T product is presented in Fig. 2 (where v m is the molar paramagnetic susceptibility corrected for the diamagnetic contribution of the sample). The value of v m T product at room temperature (7.48 cm 3 K mol −1) is close to that expected for six noninteracting Ni II ions with S = 1 and g = 2.21 (7.33). On cooling the v m T product starts to increase slowly up to ca. 100 K, and then its increase becomes faster and below 50 K is quite steep. The curve reaches a maximum at 10 K (9.79 cm 3 K mol −1) and then drops rapidly down to 5.60 cm 3 K mol −1. Such behaviour suggests the presence of ferromagnetic interactions within the cluster which is conditioned by increasing population of low energy level high spin multiplicity states with decreasing temperature. The steep decrease of the v m T product below 6 K often occurring in polynuclear nickel complexes is probably due to the effect of zero-field splitting and might be dependent on the molecular effect of the crystal and antiferromagnetic ordering of the ferromagnetic aggregates. Similar behaviour and characteristic shape of the curve was reported for other nickel(II) clusters of different nuclearity with predominant ferromagnetic interactions, in particular, 4-nuclear dicubane-type complexes, 5 hexanuclear 2 × [Ni 3 ], 6 4-and 5-nuclear clusters. 7 Although 1 evidently represents a new topology of Ni clusters, it contains a tetranuclear dicubane-like core to which two terminal Ni ions are attached. Several dicubane-like Ni clusters are described in the literature. 5,8,9 In most reported cases the Ni ions are linked by monatomic end-on azido and oxo-bridged, and the clusters exhibit global ferromagnetic exchange giving S = 4. Only in one case 9 the antiferromagnetic coupling dominates, however, in the cluster the (N,O)-bridging oximino T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
Zeitschrift für anorganische und allgemeine Chemie, 2008
Tabriz / Iran, Department of Inorganic Chemistry, Faculty of Chemistry, University of Tabriz ... 6,7,8,9,10,11,12,13,20,21-decahydro-5H, 19H-dibenzo[b,m][1,15,5,- 8,11]dioxatriazacyclooctadecin-20-ol (L), which contains N3O3 do-nor set, was ...
Polyhedron, 2015
Two (l-formato)nickel(II) complexes [Ni 2 (HCOO)(bz) 8 (H 2 O) 2 ](HCOO) 3 Á4H 2 O (1) and [Ni(tren)(HCOO)] ClO 4 ÁH 2 O (2) were synthesized and characterized by spectroscopic methods. The structure of complexes has been determined by X-ray crystallography. The formato ligand bridges the Ni(II) central atoms forming a dinuclear cation in 1 and a polymeric cationic chain in 2, respectively. The coordination environment of Ni(II) atom is nearly octahedral. Based upon the magnetic data, these two compounds display an exchange interaction of the antiferromagnetic nature along with the zero-field splitting. The results from magnetic analysis of 1 and 2, namely the isotropic exchange constants and the zero-field splitting parameters were further confirmed and studied by DFT method using at B3LYP/def2-TZVP and by CASSCF/NEVPT2, respectively.
Inorganica Chimica Acta, 1993
The dinucleating macrocycles H,(Lm") containing two 2,6-di(aminomethyl)-4-methylphenol entities combined through two alkane chains,-(CH,),-(m=2, 3) and-(CH,),-(n=2, 3, 4, S), at the amine nitrogens, form mckeI(I1) complexes of the general formula [Nr2(Lmn)(OA~)2] ((m,n)=(2,2), (2,4), (2,5), (3,3)) and [Nr,(L'*')(OAc)(NCS)(CH,OH)]. [Ni,(L',')(OAc),]. 10HzO crystalhzes m the triclinic system of space group Pl with a = 9.983(2), b = 12.832(2), c = 7.932(l) A, LY= 101.29(l), /I= 101.08(2), y= 106.57(2)", V=921.1(3) A' and Z= 1. The refinement converges with R=5.65 and R,=5.89% based on 2308 reflections with IF,] >3u(lF,]). The macrocycle adopts a folded conformation and each nickel has a cis-p octahedral geometry with the N202 donor set of the macrocycle and two oxygens of a bidentate acetate group. The Ni-Ni separation bridged by two phenolic oxygens IS 3.004 A and the Ni-0-Ni angle is 95.6". Cryomagnetic properties (4.2-300 K) of the complexes are well reproduced based on the spin Hamiltonian Z =-XS, .S2-D(.S,,'-S,,') with a positive exchange integral (J= + 10.1 to + 2.1 cm-') and a negative zero-field splitting parameter (D=-0.53 to-2.40 cm-'). Each complex shows two reduction waves and two oxidation waves attributable to the metal centers.
Inorganic Chemistry, 1982
The electrochemical oxidation of NiL2+ (where L = meso-5,7,7,12,14,14-hexamethyl-1,4,8,1l-tetraazacyclotetradecane) in aqueous solutions in the presence of sulfate, phosphate, chloride, and phthalate yields Ni111LX2. The stability constants for the axial coordination of the anions X are estimated from the observed redox potentials and from kinetic measurements. The complexes [Ni111L(S04)H20]C104 and [Ni111L(H2P04)2]C104 were precipitated. The crystal structure of the latter complex was determined. The complex crystallizes in the triclinic space group Pi with a = 11.074 (3) A, b = 9.386 (2) A, c = 14.299 (2) A, a = 88.55 (1)O, @ = 106.33 (2)O, y = 1 1 1.46 (2)O, and two molecules in the unit cell; least-squares refinement based on 4282 reflections led to a conventional R of 0.046. The nickel is located in the plane determined by the four ligating nitrogen atoms, and the configuration of the remainder of the macrocyclic ligand is essentially identical with that reported for the divalent nickel complex with this ligand. The kinetics of decomposition of the complexes were studied and found to be complicated. The results indicate that the complexes Ni111L(S04)2-and Ni11'L(H2P04-)2+ decompose via Nim1L3+ and perhaps also partially via Ni111LS04+ and Ni"'LH2P0:+.
Polyhedron, 2007
Substituted-benzoate complexes of nickel(II) of the types bidentate [Ni(mcN 3 )(Bz)](PF 6 ) and monodentate [Ni(mcN 3 )(Bz) (H 2 O)](PF 6 ) have been prepared by acid-base reaction between the hydroxo complexes [Ni(mcN 3 )(l-OH)] 2 (PF 6 ) 2 (mcN 3 = 2,4,4-trimethyl-1,5,9-triazacyclododec-1-ene (Me 3 -mcN 3 ) or its 9-methyl derivative (Me 4 -mcN 3 )) and the corresponding benzoic acid. The paramagnetic nickel(II) complexes have been characterized in solution by NMR spectroscopy. The influence of the substituents on the hyperfine shift patterns for substituted-benzoate complexes of nickel(II) has been studied. The substituent effects upon the coordination mode of substituted benzoates have been established by X-ray diffraction.