Linear Trinuclear Copper(II) Complexes Derived from the Nucleophilic Addition Products of Dicyanonitrosomethanide [C(CN)2(NO)]–: Syntheses, Structures, and Magnetic Properties (original) (raw)
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Polyhedron, 2019
The pyrimidinyl hydrazone ligand O=C{NHN=C(Me)(pm)} 2 (pm = 2-pyrimidinyl) (L 3 H 2) has two potentially protic H atoms and multiple donor atoms. The reaction of L 3 H 2 with CuCl 2 •2H 2 O yielded the tetranuclear complex [Cu 4 (L 3 H) 2 Cl 6 (CH 3 OH) 2 ] (1). Structural studies on 1 reveal the molecule is located about a crystallographic inversion centre, affording two crystallographically independent Cu(II) centres with the two symmetry equivalent [Cu 2 (L 3 H)Cl 3 CH 3 OH] units connected via µ 2-Cl bridges to generate a linear tetranuclear copper complex. The ligand is singly deprotonated (L 3 H −) and twisted around the diazine N-N´ bond, affording an N 3 donor set for the Cu1 centre and an N 2 O donor set for the Cu2 centre. The Cu1 ion is five coordinate with an [N 3 ] donor set from the L 3 H − ligand and the remaining two sites occupied by Clanions. The Cu2 ion is six coordinate with the L 3 H − ligand offering a mer [N 2 O] donor set, with the three remaining sites occupied by two Cl − anions and a MeOH molecule. Magnetic studies reveal the presence of strong antiferromagnetic interactions via the diazine bridge linking the Cu1 and Cu2 ions and moderate ferromagnetic interactions via the chloro bridges located about the inversion centre, connecting the Cu2 and Cu2i ions.
Strong antiferromagnetic coupling in doubly N, O oximato-bridged dinuclear copper(II) complexes
Polyhedron, 2010
The use of di-2-pyridyl ketone oxime, (py)pkoH, and phenyl 2-pyridyl ketone oxime, ppkoH, in copper(II) hexafluoroacetylacetonate chemistry is reported. The reaction of CuCl 2 Á2H 2 O with one and two equivalents of ppkoH and Na(hfac), respectively, in CH 2 Cl 2 affords the dinuclear complex [Cu 2 (hfac) 2 (ppko) 2 ] (1) in excellent yield. The replacement of ppkoH by (py)pkoH gives the isostructural compound [Cu 2 (hfac) 2 {(py)pko} 2 ] (2) in good yield. The Cu II atoms in both 1 and 2 are doubly bridged by the oximate groups of two g 1 :g 1 :g 1 :l 2 ppko À and (py)pko À ligands, respectively. The bridging Cu-(R-NO)-Cu 0 units are not planar, with the torsion angles being 23.2°(1) and 20.3°(2). A bidentate chelating hfac À ligand completes five-coordination at each square pyramidal metal ion. The hfac À -free reaction system CuCl 2 Á2H 2 O/(py)pkoH/NEt 3 (1:2:1) gives instead the mononuclear complex [CuCl{(py)pko}{(py)pkoH}] (3) in very good yield. The Cu II atom is coordinated by two N,N 0 -bidentate (py)pko À /(py)pkoH chelates and a monodentate chloride anion resulting in a distorted square pyramidal geometry around the metal center. Variable-temperature, solid-state dc magnetic studies were carried out on the representative dinuclear complex 1 in the 2.0-300 K range. The data indicate a very strong antiferromagnetic exchange interaction and a resulting S = 0 ground state, which is well isolated from the S = 1 excited state. The J value of À720 cm À1 was derived from the fitting of the experimental data using the Hamiltonian H = ÀJ(S 1 Á S 2 ).
Inorganica Chimica Acta, 1996
The syntheses of three new tfinuc!ear copper(lI) complexes with the ligand 1,9-bis-(3-amino-4H-triazol-5-yl)-3,7-dithianonane (attn) are described. The X-ray structures of two of them, [Cu3(attn)2(HzO):Cl:]Cl4(H20)4 (1) and [Cu3(attn)2(ZnC14)2C12] (HzO)~ (2), have been solved. The magnetic properties of these and those of the third related complex, [Cu3(attn)2(H20)2Br:]Br4(H20)~ (3), have been studied. Crystallographic data: !: Cu3CI6C22H52NIrOrS4, PL a = 8.003(3), b= 11.330(4), c= 13.072 A, c¢= 112.36(3),/3= 90.62(3), 3,= 96.64(3)°, Z= 1, V= 1087( 1 ) A3 least-squares refinement based on 8956 significant reflections converged to R (Rw) = 0.028 (0.037); 2: Cu3Zn2CI m Cz2H4sNI604Sa, P21/C, a = 8.248 (5), b = 28.203 (3), c = 10.405 (4) .~,/3 = 93.07 (2) °, Z = 2, V = 2417 (2) ~3, refinement based on 1510 significant reflections converged to R (Rw) = 0.043 (0.049); 3 is isomorphous to 1. The structures consist of linear trinuclear units of three copper(lI) ions bridged by two triazole N1N2 bridges and one chloride. The central copper ion lies on a centre of symmetry, coordinated by 4 N and 2 C1. The coordination d~stances in/1, are: 1: Cu-N =2.040( 1 ) and 1.985( 1 ), Cu-Cl(bridging) =2.7390(3); 2: Cu-N = 2.04( 1 ) and 1.98( 1 ), and Cu-Cl(bridging) = 2.878(3). The terminal copper ions are coordinated by N2S2CIIO ~ (1) and N2S2C12 (2), respectively. The distances in A are for 1: Cu-N = 2.003 ( 1 ) and 2.023 ( 1 ), Cu-S = 2.3854(3) and 2.3637 (3), Cu-Cl(bridging) = 2.5505 (3), Cu-O(water) =2.659(1) ; for 2: Cu-N = 1.99(I) and 1.98 , Cu-S =2.369(4) and 2.390(4,), Cu-Cl(bridging) = 2.713(4), Cu-C1-ZnCI3 = 2.979(5). The shortest Cu-Cu distances within one cluster are 3.5426( 1 ) and 3.620(3) A for 1 and 2, respectively. The magnetic susceptibility data have been interpreted on the basis of Heisenberg intracluster interactions (J = -75.1, -70.9, -72.3 cm-~ for compounds 1, 2, 3, respectively); a small intercluster exchange (zj '= + 1.47, +0.81, +2.03 cm -~ for 1, 2 and 3, respectively) has been taken into account in the mean field approximation.
Inorganic Chemistry, 2005
The new tetranuclear carbonate complex [Cu 2 L) 2 (CO 3)]‚8H 2 O (1‚8H 2 O) (H 3 L) (2-(2-hydroxyphenyl)-1,3-bis[4-(2hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine) has been obtained by two different synthetic routes and fully characterized. Recrystallization of 1‚8H 2 O in methanol yields single crystals of {[(Cu 2 L) 2 (CO 3)]} 2 ‚12H 2 O (1‚6H 2 O), suitable for X-ray diffraction studies. The crystal structure of 1‚6H 2 O shows two crystallographically different tetranuclear molecules in the asymmetric unit, 1a and 1b. Both molecules can be understood as self-assembled from two dinuclear [Cu 2 L] + cations, joined by a µ 4-η 2 :η 1 :η 1 carbonate ligand. The copper atoms of each crystallographically different [(Cu 2 L) 2 (CO 3)] molecule present miscellaneous coordination polyhedra: in both 1a and 1b, two metal centers are in square pyramidal environments, one displays a square planar chromophore and the other one has a geometry that can be considered as an intermediate between square pyramid and trigonal bipyramid. Magnetic studies reveal net intramolecular ferromagnetic coupling between the metal atoms. Density functional calculations allow the assignment of the different magnetic coupling constants and explain the unexpected ferromagnetic behavior, because of the presence of an unusual NCN bridging moiety and countercomplementarity of the phenoxo (or carbonate) and NCN bridges.
Polyhedron, 2006
A group of dinuclear copper(II) compounds containing the macrocyclic complexes Cu 2 L 2+ (LH 2 = C 24 H 28 N 4 O 4 : a ligand derived from the condensation of 4-methyl-2,6-diformylphenol with 1,3-diamine-2-propanol) have been prepared, and characterised both structurally and magnetically. The compounds, containing different counterions, were formulated as: [Cu 2 LCl 2 ] AE 2H 2 O (1); [Cu 2 L(l 2-acetate)](acetate) (2a), [Cu 2 L(acetate) 2 (H 2 O) 2 ] AE 6H 2 O (2b) and [Cu 2 L(H 2 O) 2 ] 2 (SO 4 H) AE 2H 2 O (3). The copper(II) ions present a square pyramidal geometry in three of the reported moieties, with axially coordinated halogens in 1, syn-syn acetate ligands in 2b, and water molecules in 3. Compound 2a is different in that the cations display distorted octahedral environments, with aqua and acetate oxygens at the apices. Compound 2b which co-crystallised with 2a, presents a folded structure of the macrocyclic ligand due to the presence of the bridging acetate molecule. There is a significant dependence of the bulk magnetic properties of the compounds studied with the nature of the counteranions used, evidenced in the large À2J span observed throughout the series (306 to >1015 cm À1). This might be due to the structural differences, both in molecular geometries as well as in crystal packing, introduced by the different counterions.
Inorganica Chimica Acta, 2008
Four trinuclear Cu(II) complexes, [(CuL 1 ) 3 (l 3 -OH)](NO 3 ) 2 (1), [(CuL 2 ) 3 (l 3 -OH)](I) 2 AEH 2 O (2), [(CuL 3 ) 3 (l 3 -OH)](I) 2 (3) and [(CuL 1 ) 3 (l 3 -OH)][Cu I I 3 ] (4), where HL 1 (8-amino-4-methyl-5-azaoct-3-en-2-one), HL 2 [7-amino-4-methyl-5-azaoct-3-en-2-one] and HL 3 [7-amino-4-methyl-5-azahept-3-en-2-one] are the three tridentate Schiff bases, have been synthesized and structurally characterized by X-ray crystallography. All four complexes contain a partial cubane core, [(CuL) 3 (l 3 -OH)] 2+ in which the three [CuL] subunits are interconnected through two types of oxygen bridges afforded by the oxygen atoms of the ligands and the central OH À group. The copper(II) ions are in a distorted square-pyramidal environment. The equatorial plane consists of the bridging oxygen of the central OH À group together with three atoms (N, N, O) from the Schiff base. The oxygen atom of the Schiff base also coordinates to the axial position of Cu(II) of another subunit to form the cyclic trimer. Magnetic susceptibilities have been determined for these complexes over the temperature range of 2-300 K. The isotropic Hamiltonian, H = ÀJ 12 S 1 S 2 À J 13 S 1 S 3 À J 23 S 2 S 3 has been used to interpret the magnetic data. The best fit parameters obtained are: J = À54.98 cm À1 , g = 2.24 for 1; J = À56.66 cm À1 , g = 2.19 for 2; J = À44.39 cm À1 , g = 2.16 for 3; J = À89.92 cm À1 , g = 2.25 for 4. The EPR data at low temperature indicate that the phenomenon of spin frustration occurs for complexes 1-3.
Polyhedron, 2007
Reaction of Cu(NO 3) 2 AE 3H 2 O, N,N,N 0 ,N 0-tetramethyl-ethylenediamine (L) and sodium dicyanamide (Nadca) in aqueous medium yields a complex the {[Cu 2 L 2 (l-1,5-dca) 2 (dca) 2 ]} n complex, 1. Single crystal X-ray analysis reveals that complex 1 has a 1D infinite chain structure in which copper(II) ions are bridged by single dicyanamide anions in an end-to-end fashion. The coordination environment around copper(II) is distorted square pyramidal. Two among the four coordination sites of the basal plane are occupied by the nitrogen atoms of the diamine and two remaining sites are occupied by the terminal nitrogen atom of a bridging and of a monodentate dca anions. The fifth coordination site (apical) is occupied by a nitrogen atom from a bridging dca anion of an adjacent CuL(dca) 2 moiety, yielding the [Cu 2 L 2 (l-1,5-dca) 2 (dca) 2 ] dinuclear unit. Dimeric units are connected to each other by single l-1,5-dicyanamido group to form infinite 1D chains which propagate parallel to the crystallographic c-axis. The variable temperature magnetic susceptibility measurements evidenced weakly antiferromagnetic interactions (J = À0.26 cm À1) in {[Cu 2 L 2 (l-1,5-dca) 2 (dca) 2 ]} n , 1.
Cation-Dependent Nuclearity of the Copper−Azido Moiety: Synthesis, Structure, and Magnetic Study
Inorganic Chemistry, 2005
in which symmetry-related [Cu 3 (N 3 ) 8 ] 2moieties are doubly µ 1,1 -azido bridged to form unprecedented infinite zigzag chains parallel to the crystallographic a-axis. In the case of [Et 4 N] + , the mononuclear species [Et 4 N] 2 [Cu(N 3 ) 4 ], 3, has been formed. All complexes have been characterized structurally by single-crystal X-ray analysis: 1, C 32 H 72 N 20 Cu 2 , triclinic, space group P1 h, a ) 10.671(9) Å, b ) 12.239(9) Å, c ) 10.591(5) Å, R ) 110.01(4)°, ) 93.91(5)°, γ ) 113.28(5)°, V ) 1160.0(1) Å 3 ; 2, C 24 H 56 N 26 Cu 3 , monoclinic, space group P2 1 /n, a ) 8.811 Å, b ) 37.266(3) Å, c ) 13.796(1) Å, ) 107.05(1)°, V ) 4330.8(10) Å 3 ; 3, C 16 H 40 N 14 Cu, tetragonal, space group I4/m, a ) b ) 10.487(1) Å, c ) 12.084(2) Å, V ) 1328.9(3) Å 3 . The variable-temperature magnetic susceptibility measurements showed that although the magnetic interaction in [Bu 4 N] 2 -[Cu 2 (µ 1,1 -N 3 ) 2 (N 3 ) 4 ], 1, is antiferromagnetic (J ) −36 cm -1 ), it is ferromagnetic in {[Pr 4 N] 2 [Cu 3 (µ 1,1 -N 3 ) 4 (N 3 ) 4 ]} n , 2 (J ) 7 cm -1 ). As expected, the [Et 4 N] 2 [Cu(N 3 ) 4 ] complex, 3, is paramagnetic.
Inorganic Chemistry, 2008
Use of PhPyCNO -/X -"blends" (PhPyCNOH ) phenyl 2-pyridyl ketoxime; X -) OH -, alkanoato, ClO 4 -) in copper chemistry yielded trinuclear clusters that have been characterized as inverse-9-metallacrown-3 compounds and accommodate one or two guest ligands. The magnetic behavior showed a large antiferromagnetic interaction and a discrepancy between the low-temperature magnetic behavior observed experimentally and that predicted from a magnetic model. The discrepancy between the Brillouin curve and the experimental result provides clear evidence of the influence of the antisymmetric interaction. Introducing the antisymmetric terms derived from the fit of the susceptibility data into the magnetization formula caused the simulated curve to become nearly superimposable on the experimental one. The EPR data indicated that the compound [Cu 3 (PhPyCNO) 3 (µ 3 -OH)(2,4,5-T) 2 ] (1), where 2,4,5-T is 2,4,5-trichlorophenoxyacetate, has isosceles or lower magnetic symmetry (δ * 0), that antisymmetric exchange is important (G * 0), and that ∆E > hν. The structures of the complexes 1 and [Cu 3 (PhPyCNO) 3 (µ 3 -OH)(H 2 O)(ClO 4 ) 2 ] (2) were determined using singlecrystal X-ray crystallography. Theoretical calculations based on density functional theory were performed using the full crystal structures of 1, 2, [Cu 3 (PhPyCNO) 3 (OH)(CH 3 OH) 2 (ClO 4 ) 2 ] (3), and [Cu 3 (PhPyCNO) 3 (µ 3 -OMe)(Cl)(ClO 4 )] (4). The geometries of the model compounds [Cu 3 (κ 3 N,N,O-HNCHCHNO) 3 (µ 3 -OH)(µ 2 -HCOO)(HCOO)] (5), [Cu 3 (κ 3 N,N,O-HNCHCHNO) 3 (µ 2 -HCOO)(HCOO)] + (6), [Cu 3 (κ 3 N,N,O-HNCHCHNO) 3 (µ 3 -O)] + (7), and [Cu 3 (κ 3 N,N,O-HNCHCHNO) 3 ] 3+