Trinuclear Molecules Research Articles

Face-Sharing Heterotrinuclear MII−LnIII−MII (M = Mn, Fe, Co, Zn; Ln = La, Gd, Tb, Dy) Complexes: Synthesis, Structures, and Magnetic Properties

Trinuclear linear 3d-4f-3d complexes (3d = Mn(II), Fe(II), Co(II), Zn(II) and 4f = La(III), Gd(III), Tb(III), Dy(III)) were prepared by using a tripodal nonadentate Schiff base ligand, N,N',N''-tris(2-hydroxy-3-methoxybenzilidene)-2-(aminomethyl)-2-methyl-1,3-propanediamine. The structural determinations showed that in these complexes two distorted trigonal prismatic transition metal complexes of identical chirality are assembled through 4f cations. The Mn and Fe entities crystallize in the chiral space group P2(1)2(1)2(1) as pure enantiomers; the cobalt complexes exhibit a less straightforward behavior. All Mn, Fe, and Co complexes experience M(II)-Ln(III) ferromagnetic interactions. The Mn-Gd interaction is weak (0.08 cm(-1)) in comparison to the Fe-Gd (0.69 cm(-1)) and Co-Gd (0.52 cm(-1)) ones while the single ion zero field splitting (ZFS) term D is larger for the Fe complexes (5.7 cm(-1)) than for the cobalt ones. The cobalt complexes behave as single-molecules magnets (SMMs) with large magnetization hysteresis loops, as a consequence of the particularly slow magnetic relaxation characterizing these trinuclear molecules. Such large hysteresis loops, which are observed for the first time in Co-Ln complexes, confirm that quantum tunnelling of the magnetization does not operate in the Co-Gd-Co complex.

Bis[μ-N′-acetyl-1-oxidonaphthalene-2-carbohydrazidato(3−)]tetrapyridinetricopper(II)

There are two half-mol­ecules in the asymmetric unit of the title compound, [Cu3(C13H9N2O3)2(C5H5N)4], and crystallographic inversion symmetry completes each trinuclear mol­ecule. In both mol­ecules, the central Cu atom (site symmetry ) adopts a distorted trans-CuO2N4 octa­hedral geometry, arising from its coordination by two N,O-bidentate aroylhydrazine ligands and two pyridine mol­ecules. The peripheral Cu atoms adopt trans-CuN2O2 square-planar coordinations arising from an N,O,O-tri­dentate ligand (that also bonds to the central Cu atom) and a pyridine mol­ecule.

Copper(II) complex with 3-(2-hydroxy-3-sulfo-5-nitrophenylhydrazo)pentane-2,4-dione: Synthesis and structure

The copper(II) complex with 3-(2-hydroxy-3-sulfo-5-nitrophenylhydrazo)pentane-2,4-dione (H3L) is studied, and its crystal structure is studied by X-ray diffraction analysis. The crystals of [Cu(H2O)2]2(μ-L)2[Cu(H2O)4] (I) are triclinic (space group P\( \bar 1 \)) at 100 K, a = 7.085(3), b = 10.373(5), c = 12.265(6) A, α = 0.842(5)°, β = 104.996(6)°, γ = 99.156(6)°, Z = 1). The C=O and NH groups of hydrazone and the OH and SO3H groups from the aromatic moiety of the molecule are involved in coordination with the copper(II) atom. In the centrosymmetric trinuclear molecule the central Cu(2) atom has the coordination number six, and the terminal Cu(1) atoms have the coordination number five. The thermal properties of complex I are studied. The complex formation of copper(II) with the H3L ligand in an aqueous solution at temperatures 298 ± 0.5, 308 ± 0.5, and 318 ± 0.5 K is studied by potentiometric titration. The standard thermodynamic functions of the complex formation are determined.

New Class of Single-Source Precursors for the Synthesis of Main Group−Transition Metal Oxides: Heterobimetallic Pb−Mn β-Diketonates

Heterometallic lead-manganese beta-diketonates have been isolated in pure form by several synthetic methods that include solid-state and solution techniques. Two compounds with different Pb/Mn ratios, PbMn(2)(hfac)(6) (1) and PbMn(hfac)(4) (2) (hfac = hexafluoroacetylacetonate), can be obtained in quantitative yield by using different starting materials. Single crystal X-ray investigation revealed that the solid-state structure of 1 contains trinuclear molecules in which lead metal center is sandwiched between two [Mn(hfac)(3)] units, while 2 consists of infinite chains of alternating [Pb(hfac)(2)] and [Mn(hfac)(2)] fragments. The heterometallic structures are held together by strong Lewis acid-base interactions between metal atoms and diketonate ligands acting in chelating-bridging fashion. Spectroscopic investigation confirmed the retention of heterometallic structures in solutions of non-coordinating solvents as well as upon sublimation-deposition procedure. Thermal decomposition of heterometallic diketonates has been systematically investigated in a wide range of temperatures and annealing times. For the first time, it has been shown that thermal decomposition of heterometallic diketonates results in mixed-metal oxides, while both the structure of precursors and the thermolysis conditions have a significant influence on the nature of the resulting oxides. Five different Pb-Mn oxides have been detected by X-ray powder diffraction when studying the decomposition of 1 and 2 in the temperature range 500-800 degrees C. The phase that has been previously reported as "Pb(0.43)MnO(2.18)" was synthesized in the pure form by decomposition of 1, and crystallographically characterized. The orthorhombic unit cell parameters of this oxide, obtained by electron diffraction technique, have been subsequently refined using X-ray powder diffraction data. Besides that, a previously unknown lead-manganese oxide has been obtained at low temperature decomposition and short annealing times. The parameters of its monoclinically distorted unit cell have been determined. The EDX analysis revealed that this compound has a Pb/Mn ratio close to 1:4 and contains no appreciable amount of fluorine.

Synthesis, Crystal Structure and Magnetic Properties of a New cis‐Heterotrinuclear [CuL‐Mn‐CuL] Complex

AbstractA new dissymmetrical Schiff base copper precursor complex KCuL and a cis‐heterotrinuclear complex with the chemical formula [(CuL)2Mn(H2O)2]·CH3OH, have been synthesized and characterized by means of elemental analysis and IR, where H3L= (E)‐N‐[2‐(5‐chloro‐2‐hydroxybenzylideneamino)ethyl]‐2‐hydroxybenzamide. The crystal structure of the cis‐heterotrinuclear complex was determined by X‐ray analysis. Each cell unit of the complex contains one neutral cis‐heterotrinuclear molecule and two disordered methanol molecules. The central Mn2+ ion is located at the site of O6 with a distorted octahedral geometry, and two coordination anions [CuL]− are aligned in cis‐configuration. The magnetic properties indicate that the trinuclear complex not only has antiferromagnetic interactions in the internal trinuclear molecule but also has weak ferromagnetic interactions between the trinuclear units. The best‐fit parameters are J= −12.1 cm−1, g=2.20 and zj′=1.37 cm−1.

Crystal structure of 4,4-bipyridine-containing complexes of copper(II) nitrate with 1-[(2-Hydroxyethylimino)methyl]naphthalen-2-ol and 2-[(2-hydroxyethylimino)methyl]phenol

The crystal structures of (μ-4,4-bipyridine)-di(nitrato-1-[(2-hydroxyethylimino)methyl]naphthalen-2-olocopper (I) and catena-di(μ-4,4’-bipyridine)di(μ-4,4’-bipyridine)-di(nitrato-2-[2-(hydroxyethylimino) methyl]phenolocopper)diaquacopper(II) nitrate (II) were determined. In the crystal of I, each of the two copper atoms coordinates a singly deprotonated tridentate azomethine molecule, a nitrate ion, and bipyridine, which functions as a bridge between the central atoms. The copper coordination polyhedron is a slightly distorted tetragonal pyramid with the base formed by the imine and bipyridine nitrogen atoms and the phenol and alcohol oxygen atoms. The axial site in the pyramid is occupied by the oxygen atom of the monodentate nitrate groups. In the trinuclear structure II with C2 crystal chemical symmetry, the terminal coordination unit is composed through copper coordination of monodeprotonated 2-[2-(hydroxyethylimino)methyl]phenol, bipyridine, and the nitrate anion. In the crystal, the trinuclear molecules form infinite ribbons along the z axis in which the pyridine molecules perform the bridging function. The central copper atom has an octahedral configuration formed by the nitrogen atoms of four 4,4’-bipyridine molecules and oxygen of two water molecules.

Dinuclear versus trinuclear complex formation in zinc(II) benzoate/pyridyl oxime chemistry depending on the position of the oxime group

The initial employment of pyridine-3-carbaldehyde oxime, (3-py)C(H)NOH, and pyridine-4-carbaldehyde oxime, (4-py)C(H)NOH, in zinc(II) carboxylate chemistry is reported. The syntheses, crystal structures and IR characterization are described for [Zn 3(O 2CPh) 6{(3-py)C(H)NOH} 2] ( 1) and [Zn 2(O 2CPh) 4{(4-py)C(H)NOH} 2] ( 2). The trinuclear molecule of 1 has a linear structure, with one monoatomically bridging η 1:η 2:μ and two syn, syn-η 1:η 1:μ benzoate groups spanning each pair of Zn II ions; the terminal metal ions are each capped by one (3-py)C(H)NOH ligand coordinating through its pyridyl nitrogen. Complex 2 exhibits a dinuclear paddle–wheel structure with a Zn···Zn distance of 2.990(2) Å; each Zn II ion has a square pyramidal geometry with four carboxylate oxygens in the basal plane and the pyridyl nitrogen of one monodentate (4-py)C(H)NOH ligand at the apex. Both complexes form 1D architectures by virtue of hydrogen bonding interactions involving the free oxime group as donor and the oxime nitrogen ( 1) or carboxylate oxygens ( 2) as acceptors. IR data are discussed in terms of the known structures and coordination modes of the ligands.

Bis(2,2′-bipyridyl)-1κ2N,N′;3κ2N,N′-bis(4-bromo-2-formylphenolato)-1κ2O,O′;3κ2O,O′-bis[μ-2-(5-bromo-2-oxidobenzylideneamino)ethanesulfonato]-1:2κ3O:N,O2;2:3κ3N,O2:O-tricopper(II) monohydrate

The title complex, [Cu3(C9H8BrNO4S)2(C7H4BrO2)2(C10H8N2)2]·H2O, lies on an inversion center located on the central Cu atom, which is four-coordinated in a square-planar geometry, whereas the outer Cu atoms related by symmetry are five-coordinated in a square-pyramidal geometry. The trinuclear mol­ecules, with an intramolecular Cu⋯Cu separation of 6.313 (3) Å, are linked to each other, forming a chain through O—H⋯O and O—H⋯Br hydrogen bonds involving the half-occupied water mol­ecule. Futhermore, weak C—H⋯O inter­actions link the chains to form a supra­molecular network.

Linear [formula omitted] and cubane [formula omitted] carboxylate clusters derived from di-2-pyridyl ketone: Synthesis, characterization and magnetic properties

The employment of di-2-pyridyl ketone, (py) 2CO, in manganese(II) benzoate chemistry is reported. The syntheses, crystal structures and spectroscopic (IR, EPR) characterization are described for [ Mn 3 II (O 2CPh) 6{(py) 2CO} 2] ( 1), [ Mn 3 II (O 2CPh) 6{(py) 2CO} 2] · 2MeCN ( 2 · 2MeCN) and [ Mn 4 II (O 2CPh) 4{(py) 2C(OH)O} 4] ( 3), where (py) 2C(OH)O − is the monoanion of the gem-diol form of (py) 2CO. Variable-temperature, magnetic susceptibility studies on 3 have also been performed. Complexes 1 and 2 · 2MeCN are linkage isomers. The trinuclear molecules of both complexes have a linear structure, with one η 1:η 2:μ 2 and two syn, syn- η 1:η 1:μ 2 PhCO 2 - groups spanning each pair of Mn II atoms. The terminal Mn II atoms are each capped by one κ 2 N,N′ (py) 2CO ligand in orange 1 and one κ 2 N,Ο (py) 2CO molecule in the yellow isomer 2 · 2MeCN. The molecule of 3 has a cubane topology with the Mn II centers and the deprotonated oxygen atoms from the η 1:η 3:η 1:μ 3 ligands occupying alternate vertices of the cube. A terminal monodentate PhCO 2 - group completes a distorted octahedral coordination at each Mn II atom. The IR data are discussed in terms of the coordination modes of the ligands that are present in the complexes. The X-band EPR spectra of powdered 1 and 2 at 4 K indicate that the populated spin states exhibit a zero-field splitting, while the spectrum of 3 at 18 K is consistent with the presence of magnetically interacting Mn II atoms in the solid state. The magnetic properties of 3 in the 300–5 K range have been modelled with two J values, which reveal weak antiferromagnetic interactions within the molecule. Some suggestions have been made concerning the great stability of complex 3.

Manganese(II) Trimeric Systems Derived from Pyridyldioximato Ligands: Synthesis, Crystal Structure, and Magnetic Characterization

AbstractThree new manganese compounds have been obtained by reaction of the 2,6‐diacetylpyridine dioxime (dapdoH2) ligand with several MnII salts. By using a variety of manganese(II) carboxylates, three MnII derivatives with general formula [Mn3(RCOO)6(dapdoH2)2], where RCOO– = formate (1), acetate (2), and benzoate (3), were obtained. Structural analysis reveals chains of trinuclear units for 1 and isolated trinuclear molecules for 2. Compound 1 provides an example of a new topology for the [Mn3(RCOO)6(L)2] general formula. Magnetic susceptibility studies reveal topological ferrimagnetism for 1 and conventional antiferromagnetic response for 2 and 3, with coupling constants of –3.1, –3.2, and –1.4 cm–1 inside the trimeric units of 1, 2, and 3, respectively.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

PH-Directed assembly and magnetic properties of two polynuclear Mn II complexes: (Δ, Λ)-{Mn 3(phen) 2(OOCCH 3) 6} and 1-D [Mn(phen)Cl 2] n

When the reaction conditions are deliberately controlled by the pH, two different polynuclear manganese complexes, (Δ, Λ)-{Mn 3(phen) 2 (CH 3COO) 6} ( 1) and [Mn(phen)Cl 2] n ( 2) (phen = 1,10-phenanthroline), have been synthesized from the same raw materials. The structural analyses show that 1 has a structure formed by neutral chiral linear trinuclear molecules, while 2 has a structure consisting of one-dimensional infinite chains. A study of the temperature dependent magnetic susceptibilities reveal that 1 is an antiferromagnetically coupled trimer molecule while 2 shows ferromagnetic interactions within the chain.

Synthesis, Structure and Properties of a Trinuclear μ‐Cyano Tetracyanodinitrosylferrate Copper Complex

AbstractNitroprusside reacts with [Cu(dohpn)(H2O)]ClO4 (dohpn = 2,3,9,10‐tetramethyl‐1,4,8,11‐tetraazaundecane‐1,3,8,10‐tetraen‐11‐ol‐1‐olate) in methanol to produce the title complex. Single‐crystal structure analysis shows a neutral discrete trinuclear molecule containing two [Cu(dohpn)]+ units linked by one [Fe(CN)4(NO)2]2− anion through bridging‐cyanide ligands. Mössbauer data and magnetic measurements are consistent with a low‐spin iron(II) configuration. The observed paramagnetic behavior is in quantitative agreement with two isolated copper(II) (S = 1/2) sites with a very weak antiferromagnetic interaction.

Synthesis, Structures, and Magnetic Properties of Doubly Face-Sharing Heterotrinuclear NiII–LnIII–NiII (Ln = Eu, Gd, Tb, and Dy) Complexes

Abstract Heterotrinuclear [(NiIIL)2LnIII(NO3)] complexes (where H3L = 1,1,1-tris[(salicylideneamino)methyl]ethane and Ln = Gd (1), Eu (2), Tb (3), and Dy (4)) were prepared by treating [Ni(H1.5L)]Cl0.5 with Ln(NO3)3·6H2O in the presence of triethylamine. Complexes 1·2CH3OH, 3·2CH3OH, and 4·C2H5OH·0.5H2O crystallized in the triclinic space group,Z=2, while 2·CH3OH·0.5H2O crystallized in the tetragonal space group, I41⁄a (No. 88), with Z=8. All the complexes had very similar structures. Each complex was a doubly face-sharing trinuclear molecule. The NiII ion is coordinated by the L3− ligand in an N3O3 coordination sphere, and the three phenolate oxygen atoms coordinate to an LnIII ion as bridging atoms. The LnIII ion is eight coordinate with six phenolate oxygen atoms of the two L3− ligands and two oxygen atoms of NO3−. Coordination of the NO3− group entails a bending of the Ni···Ln···Ni angle (ca. 140°). All the complexes involve π–π and CH–π interactions between the neighboring molecules to form a three-dimensional structure. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements on 1 showed a ferromagnetic interaction between the NiII and GdIII atoms. A ferromagnetic interaction was also suggested for NiII–TbIII (3) and NiII–DyIII (4).(No. 2), with

The use of di-2-pyridyl ketone in manganese(II) benzoate chemistry: Two novel [formula omitted] linkage isomers containing the ketone form of the ligand and a neutral [formula omitted] cubane containing the ligand in its gem-diolate(-1) form

The use of di-2-pyridyl ketone, (py) 2CO, in manganese(II) benzoate chemistry has yielded two Mn 3 II linkage isomers containing the ketone form of the ligand and a neutral Mn 4 II cubane cluster containing the gem-diolate(-1) form of the ligand. The 3:2 Mn(O 2CPh) 2 · 2H 2O/(py) 2CO reaction system in MeCN gives a mixture of the orange complex [Mn 3(O 2CPh) 6{(py) 2CO-κ 2 N, N′} 2] ( 1) and the yellow compound [Mn 3(O 2CPh) 6{(py) 2CO-κ 2 N, O} 2] · 2MeCN ( 2 · 2MeCN). The known compound [Mn 6O 2(O 2CPh) 10(MeCN) 4] ( 3) appears as a by-product when the initial reaction solution, that leads to 1 and 2 · 2MeCN, is allowed to slowly evaporate in the air. The trinuclear molecules adopt a linear structure in both complexes, with one monoatomically bridging η 1:η 1:μ 2 and two syn, syn-η 1:η 1:μ 2 carboxylate groups spanning each pair of Mn II ions. The terminal Mn II ions are each capped by one chelating- N, N′ (py) 2CO ligand in 1 and by one chelating- N, O (py) 2CO molecule in 2. The 1:1 reaction of Mn(O 2CPh) 2 · 2H 2O and (py) 2CO in CH 2Cl 2 results in the isolation of[Mn 4(O 2CPh) 4{(py) 2C(OH)O} 4] ( 4). The tetranuclear molecule has a cubane topology with the Mn II ions and the deprotonated oxygen atoms from the (py) 2C(OH)O − ligands occupying alternate vertices. The IR data are discussed in terms of the nature of the bonding. The magnetic properties of 4 in the 300–5 K range have been modeled with two J values and reveal weak intramolecular antiferromagnetic interactions. The low temperature X-band EPR spectra of 1, 2 and 4 are also discussed.

Synthesis and Crystal Structure of a Cyano-Bridged Bimetallic Nickel(II)–Silver(I) Complex, [Ni(dmen)2{Ag(CN)2}2] · 0.5H2O

A cyano-bridged heteronuclear bimetallic complex [Ni(dmen)2{Ag(CN)2}2] · 0.5H2O (dmen = N,N′-dimethylethylenediamine) has been prepared and characterized by IR spectroscopy and X-ray Crystallography. The compound crystallizes in the monoclinic space group P21/c. The crystal structure of the complex consists of two independent centrosymmetric trinuclear molecules made up of a [Ni(dmen)2] +2 unit linked to two [Ag(CN)2]− anions in a trans configuration. The trinuclear units are joined by hydrogen bonding to form irregular chains.

Crystal structure of zinc(II) hydrated trinuclear complex with monoprotonated ethylenediaminetetraacetate anion(3−), [Zn3(HEdta)2(H2O)6

The crystal structure of the [Zn{sub 3}(HEdta){sub 2}(H{sub 2}O){sub 6}] complex (I) is determined by X-ray diffraction analysis. The crystals are orthorhombic, a = 14.780 A, b = 29.699 A, c = 7.032 A, Z = 4, and space group Pna2{sub 1}. The structural units of crystals I are trinuclear linear molecules, in which the peripheral atoms Zn(1) and Zn(2) each coordinate two N atoms and three O atoms of the HEdta{sup 3-} ligand and the O(w) atom of the H{sub 2}O molecule, whereas the central Zn(3) atom coordinates four O(w) atoms of the H{sub 2}O molecules and two terminal O atoms of the two HEdta{sup 3-} ligands. The HEdta{sup 3-} ligand fulfills a hexadentate chelating-bridging function. The bond lengths are as follows: Zn-O(HEdta), 2.006(4)-2.123(4) A; Zn-N, 2.214(6) and 2.128(5) A; and Zn-O(w), 2.006(6)-2.225(5) A. In structure I, there is a specific contact formed by hydrogen bonds, owing to which the distance between the central atoms of individual molecules appears to be shorter than that in covalently bonded complexes.

Molecular and electronic structures by design: tuning symmetrical and unsymmetrical linear trichromium chains.

The preparation, properties, and crystal structures of 12 trichromium extended metal atom chain (EMAC) compounds of the type Cr(3)(L)(4)X(2) (L = equatorial ligands dipyridylamide (dpa) or di-4,4'-ethyl-2,2'-pyridylamide (depa), and X = axial ligands, e.g., halide or pseudohalide ions) with large variations in metal-metal distances are reported here. These complexes, which belong to a broad class of fundamentally interesting trinuclear molecules over which the electrons may or may not be delocalized, pose significant theoretical and experimental challenges which are dealt with in this report. Complexes with strongly donating axial or equatorial ligands tend to favor a symmetrical (D(4)) molecular structure, while more weakly donating ligands give rise to unsymmetrical (C(4)) structures; the physical properties of these two classes of compounds are discussed fully, and important comparisons with a reported DFT model of the electronic structures of the compounds are made.

Synthesis and characterisation of four new heterometal alkoxides: potential precursors for the MOCVD of ferroelectric oxides

The new strontium–niobium heterometal complexes [SrNb2(OEt)8(μ2-OEt)2(μ2-O- dmae)2] 1, [SrNb2(OEt)8(μ2-OEt)2(μ2-O-dmae)2(EtOH)2] 2, and [SrNb2(OEt)6(μ2-OEt)4(μ2-O-bis-dmap)2] 3, and have been prepared from the reaction between [SrNb2(OEt)12] and the donor-functionalised alcohols dmaeH (dmaeH = N,N-dimethylaminoethanol) and bis-dmap [bis-dmapH = 1,3-bis(dimethylamino)propan-2-ol]. The new strontium–tantalum complex [SrTa2(OPri)8(μ2-OPri)2(μ2-O-dmae)2] 4, has been prepared from [SrTa2(OPri)8(μ2-OPri)4(PriOH)2] and dmaeH in an analogous manner. The complexes 2, 3, and 4 have been structurally characterised by single crystal X-ray diffraction, and are shown to be discrete alkoxide-bridged trinuclear molecules. The complexes are potential ‘single-source’ Sr–Nb and Sr–Ta precursors for the MOCVD of SrBi2Ta2O9 and SrBi2(TaxNb1−x)2O9, illustrated by the successful use of 1 for the MOCVD of strontium niobate, SrNb2O6.

Palladium nitrosyl carboxylate complexes X-ray structures of Pd 4(μ-NO) 2(μ-OCOCMe 3) 6 and Pd 3(NO) 2(μ-OCOCF 3) 4·2C 6H 5Me

Two types of palladium nitrosyl carboxylate complexes were synthesized and their structures were characterized by several methods including an X-ray diffraction analysis. The tetranuclear complexes Pd 4(μ-NO) 2(OCOR) 6 (R=CMe 3, Me, Ph, CHMe 2, CH 2Cl, IIa– e, respectively) were synthesized by the reaction of Pd(NO)Cl with silver carboxylates Ag(OCOR). The structure of IIa was determined by a single crystal X-ray diffractometry. Crystals of IIa are monoclinic, space group P2 1/ n, a=12.104(7), b=23.970(8), c=15.495(4) Å, β=90.30(4)°, V=4496(4) Å 3. The least-square structure refinement on F 2 was converged to R=0.0714 for 6228 reflections [ I>2 σ( I)]. In IIa the palladium atoms form near regular rectangle Pd 4, with the edges bridged by the ligands. Two bridging NO groups occupying the opposite sides of the rectangle are in the cis-positions with respect to the Pd 4 plane. These groups are symmetric, with the PdNO angles ranging from 120.4(5) to 121.8(5)°. The coordination polyhedrons of the Pd atoms are close to square planar ones. The reaction of the Pd 4(CO) 4(OCOCF 3) 4 clusters with nitrogen monoxide leads to a substitution of the carbonyl groups and formation of the low stable complex Pd 4(NO) 4(OCOCF 3) 4 ( III) that was characterized by the spectroscopic and analytical data. The transformation of III during slow recrystallization from toluene gives Pd 3(NO) 2(OCOCF 3) 4·2C 6H 5Me ( IV) and palladium black. The structure of IV was determined by an X-ray diffraction analysis. Crystals of IV are monoclinic, space group P2 1/ n, a=9.2340(2), b=9.2859(2), c=18.0460(4) Å, β=92.339(1)°, V=1546.08(6) Å 3. The least-square refinement on F 2 was converged to R=0.0205 for 3209 reflections [ I>2 σ( I)]. In the linear tri-nuclear molecule of IV, any adjacent metal atoms are linked with a couple of the CF 3CO 2 ligands and are separated by 3.0755(2) Å. Additionally, the terminal Pd atoms bear the NO and the η 2-toluene ligands. The configuration of the N atoms corresponds to the ideal sp 2-hybridization. The PdNO angle is 117.2(2)°. The N atoms form short contacts with the aromatic rings. The distance between the center of the ring and the nitrogen atom is 2.70 Å. Complex IV is the first example of the Pd complex with the terminal nitrosyl ligand. The scheme of transformation of complex III to complex IV was proposed.

Synthesis, structure and magnetism of a hydrogen-bond-linked three-dimensional network of a novel nickel(II)-cobalt (II)-nickel(II) complex containing a new macrocyclic mononuclear complex ligand

A novel trinuclear complex, [Co(NiL)2(H2O)2](ClO4)2 · 2C2H5OH, was prepared by self-assembly using [NiL] as a new complex ligand; L is the dianion of dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. The structure of the trinuclear complex was determined by X-ray crystallography. The CoII ion is at the center of the trinuclear complex cation and occupies a distorted octahedral O6 environment, approximating to Oh with a 4T1g ground state for CoII that has an unquenched spin–orbit coupling reflected in the magnetic properties. Two NiII ions reside in completely same and slightly distorted square-planar N4 coordination geometries. CoII and each NiII are bridged by an oxamido group from one of the two macrocyclic ligands (L). O—H...O and π...π interactions link the trinuclear fragments, perchlorate ions and C2H5OH molecules to form a three-dimensional supramolecular architecture.