Nickel(II) and copper(II) complexes of aza macrocycles derived from trichloromethane

Syntheses of nickel(II) complexes of the tetraaza macrocycles 2,7-dichloro-1,3,6,8-tetraazacyclodecane (DCCD) and 2,8-dichloro-1,3,7,9-tetraazacyclododecane (DICD) and a copper(II) complex of 2,6,8,12,13,17-hexaazabicyclo[5.5.5]heptadecane (HBCH) are reported in the template condensation of trichloromethane with 1,2-diaminoethane or 1,3-diaminopropane. Formulation of the synthesized products [Ni(DCCD)(H₂O)₂]Cl₂, [Ni(DICD)(H₂O)₂]Cl₂?·?H₂O, and [Cu₃(HBCH)(H₂O)₆]Cl₆, and the metal-free ligand hydrochloride HBCH?·?6HCl has been confirmed by elemental analyses, conductivity measurements, and spectral studies. Potentiometric studies of nickel(II) and copper(II) complexes of HBCH and structurally similar 2,5,8,10,13,16,17,20,23-nonaazabicyclo[7.7.7]tricosane (NACT, earlier derived from trichloromethane and diethylenetriamine) have also been performed in the structural support of HBCH. In 1?:?1, metal?:?HBCH solution, copper(II) is coordinated to four N-donors of two-HN(CH₂)₃NH– groups of the ligand in a non-planar tetraaza cavity. The equilibrium constant value (log?K?=?15.41) for the reaction Cu^2+?+?A???CuA²⁺ (A?=?HBCH) is in favor of the cyclic structure of the ligand. A high value (log?K?=?23.27) for corresponding reaction in the NACT system is due to conformational change in the ligand, where copper(II) organizes the macrocycle to form a nearly planar cavity in which the cation fits well.     

Structures of Nickel(II) and Copper(II) Complexes of 14-Membered Macrocyclic Quadridentate Ligands

The structures of 41 Ni(II) and 17 Cu(II) complexes of macrocyclic quadridentate ligands have been analyzed, and are discussed about bond lengths, bond angles, conformations, and configurations, upon which many conclusions are formed. The inter- or intra-molecular hydrogen bonds exist among ligands and hydrates in many compounds and play an important role in the structures. There are exhibited two distinct peaks on the histogram of the average Ni-N distances, corresponding to four coordination and six coordination; these average Ni-N distances are 1.95(4) Å and 2.10(5) Å, respectively. The most probable structures of Ni(II) macrocyclic compounds have coordination number six for the metal ion, chair forms for six-membered rings, planar structure for the metal ion and the four donor atoms of the quadridentate ligand and an inversion center at the central metal ion.     

Synthesis and Characterization of Two Trinuclear Nickel(II) Complexes

Two novel trinuclear nickel(II) complexes have been synthesized and characterized by X‐ray single crystal diffraction. Compound [Ni₃(ashz)₃(py)₂(DMF)₂]·(DMF)₂ ( 1 ) crystallizes in the monoclinic, space group C2/c, with a = 22.114(2), b = 10.509(9), c = 19.485(2) Å, β = 114.443(1)°, Z = 4; compound [Ni₃(acshz)₃(py)₂(DMF)₂]·(DMF)₂ ( 2 ) crystallizes in the monoclinic space group P2₁/n with a = 20.0620(2), b = 9.7017(6), c = 25.0533(2) Å, β = 97.0610(2)°, Z = 4, where ashz and acshz are deprotonated N‐acetylsalicylhydrazide (H₃ashz) and N‐acetyl‐5‐chlorosalicylhydrazide (H₃acshz), respectively. The crystal structure analysis of 1 and 2 showed that three Ni²⁺ ions in a linear arrangement are bridged by two ligands ((ashz)^3? or (acshz)^3?) to form a neutral nuclear with two four‐coordinate square‐planar nickel ions linked by a six‐coordinate octahedral central nickel ion.     

Synthesis and Crystal Structure of Two Succinato‐Bridged Macrocyclic Nickel(II) Complexes

Two dinuclear succinato‐bridged nickel(II) complexes [Ni(RR‐L)]₂(μ‐SA)(ClO₄)₂ ( 1 ) and [Ni(SS‐L)]₂(μ‐SA)(ClO₄)₂ ( 2 ) (L = 5, 5, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, SA = succinic acid) were synthesized and characterized by EA, Circular dichroism (CD), as well as IR and UV/Vis spectroscopy. Single crystal X‐ray diffraction analyses revealed that the Ni^II atoms display a distorted octahedral coordination arrangement, and the succinato ligand bridges two central Ni^II atoms in a bis bidentate fashion to form dimers in 1 and 2 . The monomers of {[Ni(RR‐L)]₂(μ‐SA)}²⁺ and {[Ni(SS‐L)]₂(μ‐SA)}²⁺ are connected by O–H ··· O and N–H ··· O hydrogen bonds into a 1D right‐handed and left‐handed helical chain along the b axis, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.     

New Tetraaza Macrobicyclic Ditopic Receptors for Metal Ions: Synthesis,Redox Response and Kinetics of Phosphate Hydrolysis of Unsymmetrical Macrobicyclic Mono- and Binuclear Nickel(II) Complexes

A new series of macrobicyclic ditopic receptors is derived from the precursor compound 3,4:10,11-dibenzo-1,13[N,N′-bis{(3-formyl-2-hydroxy-5-methyl)benzyl}di-aza]-5,9-dioxocyclohexadecane. Using this precursor, mono- and binuclear nickel(II) complexes of type [NiL](ClO₄) and [Ni₂L](ClO₄)₂ have been synthesized to undertake electrochemical and catalytic studies on the basis of macrocyclic ring size. The receptor is a tricompartmental macrocycle consisting of ether oxygen, tertiary nitrogen and imine nitrogen atoms. The redox studies of these systems show that the nickel(II) complexes undergo quasi-reversible one-electron reduction and oxidation. All the nickel(II) complexes have square planar geometry and are EPR silent. Examination of the kinetics of the hydrolysis of 4-nitrophenyl phosphate shows that the catalytic activities of the complexes increase with the macrocyclic ring size of the complexes. As the macrocyclic ring size of the complexes increases, the spectral, electrochemical and catalytic studies of the complexes show considerable variation due to distortion in the geometry around the nickel(II) centre.     

New POCOP-type pincer complexes of Nickel(II)

The pincer complex [(POCOP)Ni(NCMe)][OSO₂CF₃] (1: POCOP = {2,6-(i-Pr₂PO)₂C₆H₃}) undergoes an acetonitrile substitution reaction in the presence of CN(t-Bu), KCN, and KOCN to give the new complexes [(POCOP)Ni{CN(t-Bu)}][O₃SCF₃] and (POCOP)Ni(X) (X = CN and NCO). The Ni-CN derivative is also obtained from a gradual decomposition of the Ni-CN(t-Bu) derivative, while the aquo derivative [(POCOP)Ni(OH₂)][O₃SCF₃] was obtained from slow hydrolysis of (POCOP)Ni(OSO₂CF₃). All new complexes have been characterized spectroscopically and by X-ray crystallography. IR and solid state structural data indicate that Ni-L/X interactions are dominated by ligand-to-metal σ-donation; presence of little or no π-backbonding is consistent with the electrophilicity of the cationic fragment [(POCOP)Ni]⁺.     

Syntheses,Structural, and Spectroscopic Properties of Copper(II) Complexes of Constrained Macrocyclic Ligands

The complexes [Cu(L¹)(H₂O)₂](BF₄)₂ · 2H₂O ( 1 ) [L¹ = 5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 0^1.18,0^7.12)docosane] and 0.5[Cu(L²)(NO₃)₂][Cu(L²)](NO₃)₂ ( 2 ) [L² = dibenzyl‐5, 16‐dimethyl‐2, 6, 13, 17‐tetraazatricyclo(14, 4, 0^1.18,0^7.12)docosane] were synthesized and characterized by single crystal X‐ray analyses. In these constrained macrocycles, the central copper(II) atoms are in a tetragonally distorted octahedral environment with four nitrogen atoms of the macrocyclic ligands in equatorial positions and oxygen atoms from either water molecules or nitrato groups in axial positions. The macrocyclic ligands in both complexes adopt the most stable trans‐III conformation. The Cu–N distances [1.999(7)–2.095(7) Å] are typical for such complexes, but the axial ligands are weakly coordinating Cu–OH₂ bonds [2.693(3) Å] and Cu–ONO₂ bonds [2.873(7) Å] due to the combination of the pseudo Jahn–Teller effect and strong in‐plane ligand field. The crystals are stabilized by a three‐dimensional network by hydrogen bonds that are formed among the secondary nitrogen hydrogen atoms, oxygen atoms of water molecules, fluorine atoms of BF₄^–, and oxygen atoms of NO₃^–. The electronic absorption and IR spectroscopic properties are also discussed.     

Copper(II), Cobalt(II), and Nickel(II) Complexes of two Novel Pyridine‐derived Macrocyclic Ligands bearing o‐ and pNitrobenzyl Pendant Groups

The pendant‐armed ligands L¹ and L² were synthesized by N‐alkylation of the four secondary amine groups of the macrocyclic precursor L using o‐nitrobenzylbromide (L¹) and p‐nitrobenzylbromide (L²). Nitrates and perchlorates of Cu^II, Ni^II and Co^II were used to synthesize the metal complexes of both ligands and the complexes were characterized by microanalysis, MS‐FAB, conductivity measurements, IR and UV‐Vis spectroscopy and magnetic studies. The crystal structures of L¹, [CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN, [CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH and [NiL²](ClO₄)₂·3CH₃CN·H₂O were determined by single crystal X‐ray crystallography. These structural analysis reveal the free ligand L¹, three mononuclear endomacrocyclic complexes {[CuL¹](ClO₄)₂·CH₃CN·H₂O, [CuL²](ClO₄)₂·6CH₃CN and [NiL²](ClO₄)₂·3CH₃CN·H₂O} and one binuclear complex {[CuL²][Cu(NO₃)₄]·5CH₃CN·0.5CH₃OH} in which one of the metals is in the macrocyclic framework and the other metal is outside the ligand cavity and coordinated to four nitrate ions.     

小型氧化铝交换柱分离—电位滴定法测定氢氧化镍中硫酸根

报道了小型氧化铝交换柱分离－电位滴定法测定氢氧化镍中的硫酸根。采用小型氧化铝交换柱将氢氧化镍中的硫酸根定量地与基体的镍分离，然后用铅离子电化学传感器作指示电极，电位滴定法测定硫酸根，对分离条件和滴定条件进行了研究。     

Neutral Nickel(II) and Copper(II) Tetraazamacrocyclic Complexes as Molecular Rods Attached to Gold Electrodes

New dithiolated derivatives of neutral Cu^II and Ni^II tetraazamacrocyclic complexes have been synthesized and characterized by spectroscopic and diffractional methods. These rod‐shaped molecules were assembled in monocomponent and mixed monolayers on gold electrodes. In the mixed monolayers, the active molecules were embedded in a hexanethiol matrix. The dithiolated complexes are oriented perpendicularly to the electrode, and reveal faster kinetics of electron transfer than those assembled in a single‐component monolayer. They appear as protrusions, which are easily addressed by using the STM method. In the presence of a suitable electron acceptor in the solution, the donor properties of the anchored Cu complex were weakened, which revealed donor–acceptor interactions with the monolayer. The peak position in the voltammogram indicates a stronger interaction of the solution‐based acceptor with the reduced Cu^II form than with the Cu^III complex. This suggests the possibility of switching the association on or off by applying an appropriate potential.     

Heterodinukleare Cobalt(II)‐, Nickel(II)‐, Kupfer(II)‐, Zink(II)und Palladium(II)‐Komplexe mit einem makrocyclischen Liganden vom Schiff‐Basen‐Typ: Synthesen und Strukturen

Complexes with Macrocyclic Ligands. IV. Heterodinuclear Cobalt(II), Nickel(II), Copper(II), Zinc(II) and Palladium(II) Complexes with a Macrocyclic Ligand of Schiff‐Base Type: Syntheses and Structures The synthesis and properties of nickel(II), copper(II), and palladium(II) complexes, [ML^Ph] ( 3 ; L^Ph = N,N′‐phenylene‐bis(3‐formyl‐5‐tert.‐butyl‐salicylaldimine)), are described. These neutral mononuclear complexes react with metal(II) perchlorate and 1,3‐propylenediamine to form heterodinuclear, macrocyclic, cationic complexes of the type [MM′(L^Ph,3)]²⁺ ( 4 ; M = Ni, Cu, Pd; M′ = Co, Cu, Zn). The structures of the five new compounds [NiCo(L^Ph,3)](ClO₄)₂, [NiCu(L^Ph,3)](ClO₄)₂, [CuCu(L^Ph,3)](ClO₄)₂, [CuZn(L^Ph,3)](ClO₄)₂, and [PdCu(L^Ph,3)](ClO₄)₂ were determined by X‐ray diffraction.     

Bis‐NHC Chelate Complexes of Nickel(0) and Platinum(0)

For a long time d¹⁰‐ML₂ fragments have been known for their potential to activate unreactive bonds by oxidative addition. In the development of more active species, two approaches have proven successful: the use of strong σ‐donating ligands leading to electron‐rich metal centers and the employment of chelating ligands resulting in a bent coordination geometry. Combining these two strategies, we synthesized bis‐NHC chelate complexes of nickel(0) and platinum(0). Bis(1,5‐cyclooctadiene)nickel(0) and ‐platinum(0) react with bisimidazolium salts, deprotonated in situ at room temperature, to yield tetrahedral or trigonal‐planar bis‐NHC chelate olefin complexes. The synthesis and characterization of these complexes as well as a first example of C? C bond activation with these systems are reported. Due to the enforced cis arrangement of two NHCs, these compounds should open interesting perspectives for bond‐activation chemistry and catalysis.     

New Complexes of Nickel(II) Containing Macrocyclic Diaminodiiminepiperazine Ligands: Synthesis and Electrochemical Properties

Complexes of Ni(ClO₄)₂ with 1,4-bis(2-aminobenzyl)piperidine (1) and 1,4-bis(2-amino-4-tertbutyl)piperidine (2) and products of their cyclization with ortho-phthalic aldehyde in methanol [NiL3][ClO₄]₂ (3) and [NiL4][ClO₄]₂ (4), respectively, are synthesized. Complexes 1 and 2 can be reduced on a platinum electrode irreversibly. Cyclic complexes 3 and 4 undergo reduction reversibly or quasi-reversibly in two or three stages. The reduction products react with n-BuI or n–BuBr (Bu = butyl) via an inner-sphere mechanism of oxidative attachment, probably, with the formation of the Ni–C bond.     

Thermodynamics of the High-Spin-Low-Spin Conversion of Nickel(II)Complexes with Tetraamine Ligands

Six tetraamine ligands, 2,5,8,11-tetraazadodecane, 2,5,9,12-tetraazatridecane, 3,7-dimethyl-3,7-diazanonane-l,9-diamine, 2,6,9,13-tetraazatetradecane, 4,7-dimethyl-4,7-diazadecane-l,10-diamine, 4-methy]-4,7-diazadecane-l,10-diamine, and their nickel(II) complexes have been synthesized. The equilibrium constants and thermodynamic parameters of the high-spin-low-spin conversion of these complexes at various temperatures in 0.10 M NaC1O⁴ have been investigated by spectrophotometric techniques. Influences of the enthalpies of these reactions are attributed to an endothermic contribution due to the breaking of the two Ni-OH² bonds, an exothermic contribution due to the strengthening of the four in-plane Ni-N bonds, an exothermic contribution due to the different ligand field stabilization energies of the square-planar and the octahedral complexes, an endothermic contribution due to the steric repulsions between the N-methyl group(s) and methylene groups as well as that between the two N-methyl groups of the tetraamine, an exothermic contribution due to the steric repulsions between the N-methyl group(s) and the coordinated water molecules, and an exothermic contribution due to the inductive effect of the N-methyl group(s). The important factors influencing the values of the entropies of these reactions are a negative term due to the reduction of spin multiplicity and a large positive term due to the release or the mobilization of the two coordinated water molecules.     

Metallkomplexe mit N2O2S2‐Koordinationssphäre. Synthese und Charakterisierung der Cobalt(II)‐, Nickel(II)‐ und Kupfer(II)‐Komplexe eines 15‐ und eines 16‐gliedrigen N,N′‐bis(2‐hydroxyethyl)‐funktionalisierten makrocyclischen Liganden

Metal Complexes with N₂O₂S₂ Donor Set. Synthesis and Characterization of the Cobalt(II), Nickel(II), and Copper(II) Complexes of a 15‐ and a 16‐Membered Bis(2‐hydroxyethyl) Pendant Macrocyclic Ligand The macrocyclic ligands 6, 10‐bis(2‐hydroxyethyl)‐7, 8, 9, 11, 17, 18‐hexahydro‐dibenzo‐[e, n][1, 4, 8, 12]‐dithiadiaza‐cyclopentadecine ( 1 ) (L¹) and 5, 13‐bis(2‐hydroxyethyl)‐7, 8, 9, 10, 16, 17, 18, 19, 20‐nonahydro‐dibenzo‐[g, o][1, 9, 5, 13]‐dithiadiaza‐cyclohexadecine (L⁴) have been prepared. They form the stable complexes [CoL¹(‐H)CoL¹](ClO₄)₃ ( 2 ), [NiL¹](ClO₄)₂·MeOH ( 3 ), Λ‐[CuL¹](ClO₄)₂·MeOH ( 4a ) and rac‐[CuL¹](ClO₄)₂·MeOH ( 4b ), [NiL⁴](ClO₄)₂ ( 5 ), and [CuL⁴](ClO₄)₂ ( 6 ). The compounds 1 to 6 have been characterized by standard methods and single‐crystal X‐ray diffraction. In the complexes 2 to 6 the metal atoms are octahedrally coordinated by the N₂O₂S₂ donor set of the ligands. L¹ and L⁴ are folded herein along the N···M···S‐ and the N···M···N′‐axes, respectively. This results at the metal atom in a all‐cis‐configuration for the complexes of L¹ and a trans‐N₂‐cis‐O₂‐cis‐S₂‐configuration for the complexes of L⁴. The cobalt(II) complex 2 is a dimer, bridged by a rather short hydrogen bridge of 2.402(12)Å length. The copper(II) complexes of L¹ and L⁴ differ with respect to the Jahn‐Teller‐distortion.     

Solid-phase thermal decomposition of polynuclear nickel(II) and cobalt(II) complexes

Solid-phase thermal decomposition of polynuclear Ni^II and Co^II pivalate complexes was studied by differential scanning calorimetry and thermogravimetry. The decomposition of the polynuclear (from bi-to hexanuclear) Co^II carboxylate complexes is accompanied by aggregation to form a volatile octanuclear complex. Thermolysis of the polynuclear NiII carboxylates results in their destructure, and the phase composition of the decomposition products is determined by the nature of coordinated ligands. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 250—260, February, 2006.     

Mono- and Binuclear Copper(II) and Nickel(II) Complexes with the 3,6-Bis(picolylamino)-1,2,4,5-Tetrazine Ligand

Four new compounds of formulas [Cu(hfac)₂(L)] (1), [Ni(hfac)₂(L)] (2), [{Cu(hfac)₂}₂(µ-L)]·2CH₃OH (3) and [{Ni(hfac)₂}₂(µ-L)]·2CH₃CN (4) [Hhfac = hexafluoroacetylacetone and L = 3,6-bis(picolylamino)-1,2,4,5-tetrazine] have been prepared and their structures determined by X-ray diffraction on single crystals. Compounds 1 and 2 are isostructural mononuclear complexes where the metal ions [copper(II) (1) and nickel(II) (2)] are six-coordinated in distorted octahedral MN₂O₄ surroundings which are built by two bidentate hfac ligands plus another bidentate L molecule. This last ligand coordinates to the metal ions through the nitrogen atoms of the picolylamine fragment. Compounds 3 and 4 are centrosymmetric homodinuclear compounds where two bidentate hfac units are the bidentate capping ligands at each metal center and a bis-bidentate L molecule acts as a bridge. The values of the intramolecular metal···metal separation are 7.97 (3) and 7.82 Å (4). Static (dc) magnetic susceptibility measurements were carried out for polycrystalline samples 1–4 in the temperature range 1.9–300 K. Curie law behaviors were observed for 1 and 2, the downturn of χ_MT in the low temperature region for 2 being due to the zero-field splitting of the nickel(II) ion. Very weak [J = −0.247(2) cm⁻¹] and relatively weak intramolecular antiferromagnetic interactions [J = −4.86(2) cm⁻¹] occurred in 3 and 4, respectively (the spin Hamiltonian being defined as H = −JS₁·S₂). Simple symmetry considerations about the overlap between the magnetic orbitals across the extended bis-bidentate L bridge in 3 and 4 account for their magnetic properties.