ESR and solid-state natural abundance 13C CP/MAS NMR study of crystalline alkyl (R = C2H5, i-C3H7, i-C4H9, s-C4H9, and C5H11) xanthate copper(II) and thallium(I) complexes

Crystalline thallium(I) alkylxanthate complexes [Tl{S(S)COR}]_n (R = C₂H₅, i-C₃H₇, i-C₄H₉, s-C₄H₉, and C₅H₁₁) and isotope-substituted heteropolynuclear Cu(II)Tl(I) complexes [⁶³⁽⁶⁵⁾CuTl₆(S₂COR)₈] (R= i-C₄H₉ and C₅H₁₁) were obtained and studied by ESR and high-resolution solid-state ¹³C CP/MAS NMR spectroscopy. According to the ¹³C NMR data, polynuclear thallium(I) complexes contain structurally equivalent alkylxanthate ligands. The ESR study revealed the Jahn-Teller dynamic effect in Cu(II)Tl(I) complexes; the nuclei of six Tl atoms are involved in the hyperfine interaction.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 1, 2005, pp. 48–54.Original Russian Text Copyright © 2005 by Ivanov, Bredyuk, Antzutkin, Forsling.     

Heterobimetallische phosphanido-verbrückte Zweikern-Komplexe - Synthese von cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6−iPr3C6H2)}2M(CO)4] (RMe,MCr,Mo; RH,MMo)

Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C₅H₄R)₂Zr{PH(2,4,6-ⁱPr₃C₆H₂)}₂] (R?Me, H) react with [(NBD)M(CO)₄] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C₅H₅)₂Zr{PH(2,4,6-^tBu₃ C₆H₂)}₂] and [Pt(PPh₃)₄]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS₂, (NO)BF₄, Me₃NO or PH(2,4,6-Me₃C₆H₂)₂. With Et₂AlH or PhC?CH decomposition of 3 was observed.     

Structural Organization of Nickel(II), Zinc(II), and Copper(II) Complexes with Diisobutyldithiocarbamate: EPR, <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR,and X-Ray Diffraction Studies

The structures and spectroscopic properties of nickel(II), zinc(II), and copper(II) complexes with dibutyl- and diisobutyldithiocarbamate were studied by EPR and ¹³C and ¹⁵N CP/MAS NMR spectroscopy and X-ray diffraction analysis. According to the EPR data, copper(II) forms mononuclear [^63/65Cu{S₂CNR₂}₂] and heterobinuclear complexes [^63/65CuZn{S₂CNR₂}₄] under magnetic dilution conditions. The isomeric forms of nickel(II) and zinc(II) diisobutyldithiocarbamates were detected by ¹³C and ¹⁵N NMR spectroscopy. The crystalline zinc(II) diisobutyldithiocarbamate was found to have a unique structural organization with alternating mononuclear [Zn{S₂CN(i-C₄H₉)₂}₂] and binuclear molecular forms [Zn₂{ S₂CN(i-C₄H₉)₂}₄] in the 1 : 1 ratio.     

Adducts of zinc and copper(II) dialkyldithiocarbamate complexes with dibutyl-and diisobutylamines: Synthesis,structures, EPR and solid-state natural abundance <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR spectra

Crystalline adducts of zinc and copper(II) dithiocarbamate complexes with dibutyl-and diisobutylamines of the general formula [M(NHR′₂)(S₂CNR₂)₂] (M = Zn, ⁶³Cu, and ⁶⁵Cu; R = CH₃ and C₂H₅; R₂ = (CH₂)₄O; R′ = C₄H₉ and i-C₄H₉) were synthesized. Their structures and spectroscopic properties were studied by EPR and solid-state natural abundance ¹³C and ¹⁵N CP/MAS NMR spectroscopy. Experimental EPR data and computer-assisted modeling confirmed the individual character of copper(II) adducts. The geometries of the copper coordination polyhedra were found to be intermediate between a tetragonal pyramid and a trigonal bipyramid (TBP). The contributions from TBP to the geometries of the adducts obtained were calculated from the EPR data. According to the X-ray diffraction data, the adduct of zinc diethyldithiocarbamate with diisobutylamine exists in two isomeric forms. The ¹³C and ¹⁵N CP/MAS NMR signals were assigned to the atomic positions in two crystallographically independent conformer molecules.     

Structures of polynuclear thallium(I) and copper(II)-thallium(I) complexes with dialkyldithiocarbamates: 13C and 15N CP/MAS NMR, EPR, and X-ray diffraction studies

A comparative study of polynuclear thallium complexes with dialkyldithiocarbamates [Tl₂{S₂CNR₂}₂]_n (R = CH₃, i-C₃H₇, C₄H₉, and i-C₄H₉; R₂ = (CH₂)₆) was performed by solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy. The dithiocarbamate groups were found to be structurally equivalent in the complexes studied. An increase in the positive inductive effect of alkyl substituents at the N atom increased ¹⁵N chemical shifts as a result of a combination of positive inductive effect of the alkyl substituents and the mesomeric effect of=NC(S)S-groups. The first representative of thallium(I) complexes with a cyclic dithiocarbamate ligand [Tl₂{S₂CN(CH₂)₆}₂]_n was obtained. Its molecular structure was determined from X-ray diffraction data. The β-form of the isotope-substituted complex [^63/65CuTl₂{S₂CN(CH₂)₆}₄] was obtained and examined by EPR spectroscopy. The EPR spectra were modeled at the second order of the perturbation theory. The spin density at the thallium atoms was calculated and its distribution over the AOs of thallium was determined.     

Bis(dimethyldithiocarbamato)(pyridine)zinc and -copper(II) and Their Benzene Solvates: EPR and Solid-State Natural Abundance (13C, 15N) CP/MAS NMR

Adducts of bis(dimethyldithiocarbamato)zinc and -copper(II) complexes with pyridine, [M(Py)(Mdtc)₂], and their benzene solvates [M(Py)(Mdtc)₂] · 0.5C₆H₆ were synthesized. The electron paramagnetic resonance method and solid-state ¹³C and ¹⁵N CP/MAS NMR spectroscopy were used to perform a comparative study of the compounds obtained. The EPR data showed that the geometry of Cu(II) coordination polyhedra both in the adduct itself [Cu(Py)(Mdtc)₂], and in its solvate, [Cu(Py)(Mdtc)₂] · 0.5C₆H₆ is intermediate between a square pyramid (SP) and a trigonal bipyramid (TBP), the contribution from the latter being dominant (75%) in [Cu(Py)(Mdtc)₂]. In the solvated adduct [Cu(Py)(Mdtc)₂] · 0.5C₆H₆, the copper(II) polyhedron is distorted to form an SP-enriched structure (the contribution from TBP is reduced to 55%). It was found NMR data that [Zn(Py)(Mdtc)₂] exists in a single high-symmetry molecular form. Coordinated pyridine molecule shows molecular motion about the Zn–N bond. The solvation of the adduct results in structural nonequivalence of the Mdtc^–ligands in [Zn(Py)(Mdtc)₂] · 0.5C₆H₆. Signals in the ¹⁵N NMR spectra were assigned to the structural positions of the atoms in the previously described molecular structure of a solvated adduct. It was found that the heterogeneous reaction of adduct formation during the absorption of pyridine from the gas phase by polycrystalline [Zn₂(Mdtc)₄] species is accompanied by the dissociation of binuclear molecules.     

Spectroscopic,crystal structure and thermal studies of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) with 5-amino-4-arylazo-3-methyl-1-phenylpyrazole (aryl=C6H5,o-C6H4COOH,o-C6H4OH)

5-Amino-4-arylazo-3-methyl-1-phenylpyrazole (aryl?=?C₆H₅,o-C₆H₄COOH,o-C₆H₄OH) and its complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions were synthesized. The complexes are in the ratio 1?:?1 and 1?:?2 (metal?:?ligand). Ligands and complexes were subjected to elemental analysis, IR, Raman, UV-Vis and ¹H-NMR spectroscopy. The mass spectra of the ligands were discussed. Thermal analysis and magnetic measurements were carried out for the prepared complexes. The X-ray single crystal structure of [Ni(L1)₂] was performed. The investigated pyrazole compounds coordinate as bidentate ligands through amino and azo nitrogens or tridentate through NNO. The molar conductance of the chelates is measured and reflected the non-electrolytic nature of the prepared complexes.     

Synthesis and characteristics of novel pentanuclear complexes [(OC)3Mn(η1,η5-C5H4)Fe(CO)2(η1,η5-C5H4CO2)]2M(η5-C5H5)2 (M=Ti, Zr)

The reaction of Cp₂MCl₂ complexes (M=Ti and Zr) with 2 equiv. of (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄COONa) results in the formation of the pentanuclear complexes (OC)₃Mn(η¹,η⁵-C₅H₄)Fe(CO)₂(η⁵-C₅H₄CO₂)]₂M(η⁵-C₅H₅)₂, which are characterized by IR and¹H NMR spectroscopy and cyclic voltammetry. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1055–1058, May, 1997.     

Adducts of zinc and copper(II) dialkyldithiocarbamate complexes with dialkylamines: Synthesis,EPR, and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR

Crystalline adducts of zinc and copper(II) dithiocarbamate (Dtc) complexes with dialkylamines [M(NHR′₂)(S₂CNR₂)₂] (M = Zn, ⁶³Cu, ⁶⁵Cu; R = CH₃, C₂H₅, or R₂ = (CH₂)₄O; R′ = C₂H₅, C₃H₇) have been preparatively isolated. The structures and spectral properties of the adducts have been studied by EPR and ¹³C and ¹⁵N MAS NMR. Chemisorption of bases on powders of dinuclear dithiocarbamates leads to their dissociation into monomeric adducts. Computer simulation demonstrates that the experimental EPR spectra of isotope-substituted copper(II) adducts have an individual character. The geometry of the copper polyhedra is intermediate between a trigonal bipyramid (TBP) and a tetragonal pyramid (TP). The TBP and TP contributions have been quantified based on EPR data. ¹³C and ¹⁵N MAS NMR data show that the Dtc ligands incorporated into the zinc adduct molecule are structurally nonequivalent. The dependence of the isotropic ¹⁵N chemical shifts of the Dtc groups on the alkyl substituents at the nitrogen atom is interpreted based on the concept of joint manifestation of the (+)inductive effect of the alkyl substituents and the mesomeric effect of the Dtc groups.     

Structural organization of mercury(II) and copper(II) dithiocarbamates from EPR and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N MAS NMR spectra and X-ray diffraction analysis

The structures and spectroscopic properties of mononuclear and binuclear mercury(II) and copper(II) complexes with four dithiocarbamate ligands R₂NC(S)S^? (R = CH₃, C₂H₅, or iso-C₃H₇; R₂ = (CH₂)₆) were studied by solid-state ¹³C and ¹⁵N CP/MAS NMR and EPR spectroscopy. Mercury(II) N,N-cyclohexamethylenedithiocarbamate [Hg₂{S₂CN(CH₂)₆}₄] was obtained and characterized in detail by X-ray diffraction analysis at 299 K. The binuclear molecule of the complex is centrosymmetric; the central tricyclic fragment [Hg₂S₄C₂] is in the chair conformation. In the ¹³C and ¹⁵N NMR spectra, the signals were assigned to the dithiocarbamate ligands with different structural functions: bidentate chelating and combined (both chelating and bridging) ones. The differences between the isotropic ¹⁵N chemical shifts for the dialkyldithiocarbamate ligands were interpreted in terms of combination of the mesomeric effect of the =NC(S)S-groups and the inductive effect of the alkyl substituents. According to the EPR data, copper(II) in magnetically diluted systems is mainly found in heterobinuclear molecules [CuHg(S₂CNR₂)₄] and the geometry of the chromophores [CuS₅] approximates to a tetragonal pyramid.     

Monomeric [Ni(2,2"-Bipy){(i-C4H9)2PS2}2] and [Ni(Pz)2{(i-C4H9)2PS2}2] and Polymeric [Ni(Pz){(i-C4H9)2PS2}2]nComplexes (Pz = Pyrazine): Synthesis,Structures, and Properties

Diamagnetic [Ni(i-Bu₂PS₂)₂] compound (I) in ethanol reacts with 2,2"-bipyridine or pyrazine to give the paramagnetic complexes [Ni(2,2"-Bipy)(i-Bu₂PS₂)₂] (II), [Ni(Pz)₂(i-Bu₂PS₂)₂] (III), and [Ni(Pz)(i-Bu₂PS₂)₂] _n (IV) (_eff= 2.91–3.12 _B). Single crystals of IIwere grown for X-ray diffraction study. The crystals are monoclinic, a= 14.669(3) Å, b= 19.693(4) Å, c= 12.155(2) Å, = 107.51(3)°, V= 3348(1) ų, Z= 4; _calcd= 1.257 g/cm³, space group P2₁/c. The structure is built from monomeric molecules. The coordination polyhedron of the Ni atom is a distorted octahedron formed by four S atoms of two bidentate chelating i-Bu₂PS^– ₂ligands and by two N atoms of bidentate cyclic 2,2"-Bipy. Preliminary data for complexes IIIand IVindicate that they also contain an octahedral NiN₂S₄fragment. The structures of complexes I(square planar) and ofII–IV(octahedral) were confirmed by data from electron spectroscopy. Electronic absorption spectra were used to determine the rankings of the i-Bu₂PS^– ₂ions and Pz on a spectrochemical scale.     

Bis -(3,5-dimethyl-pyrazolyl-1-methyl)-(3-phosphanyl-propyl)-amine complexes of copper(II), nickel(II), and cobalt(II)

A series of Cu(II), Co(II), and Ni(II) complexes of bis-(3,5-dimethyl-pyrazolyl-1-methyl)-(3-phosphanyl-propyl)-amine C₁₅H₂₆N₅P (1), prepared from 3-aminopropylphosphine and 1-hydroxymethyl-3,5-dimethylpyrazole were characterized. The nature of bonding and the geometry of the complexes have been deduced from elemental analysis, infrared, electronic, ¹H NMR, ³¹P NMR spectra, magnetic susceptibility, and conductivity measurements. The studies indicate octahedral geometry for nickel complex and square pyramidal geometry for copper and cobalt complexes. The EPR spectra of copper complex in acetonitrile at 300 K and 77 K were recorded. Biological activities of the ligand and metal complexes have been studied on Staphylococcus aureus, Escherichia coli, Aspergillus niger, and Aspergillus flavus by well-diffusion method. The zone of inhibition values were measured at 37°C for a period of 24 h. The electrochemical behavior of copper complexes was studied by cyclic voltammetry. Catalytic study indicates the copper complex has efficient catalytic activity in oxidation of amitriptyline.     

Spektroskopische Untersuchungen an Eisen(II)-nitrosodicyan-methanid- und -nitrosocarbamoylcyanmethanid-Komplexen [Fe(NOC(CN)2)2(C5H5N)4] und [Fe(NOC(CN)C(O)NH2)2(C5H5N)2]

Spectroscopic Investigations of the Iron(II) Nitrosodicyanomethanide and Nitrosocarbamoylcyanomethanide Complexes [Fe(NOC(CN)₂)₂(C₅H₅N)₄] and [Fe(NOC(CN)C(O)NH₂)₂(C₅H₅N)₂] The syntheses of new iron(II) complexes of the nonlinear pseudohalides [NOC(CN)₂]^? and [NOC(CN)C(O)NH₂]^? is reported. The Structures of the compounds are discussed on the basis of IR, Mößbauer, ¹³C, and ¹⁴N NMR spectra as well as of the results of magnetic measurements.     

Complexes of Some 3d-Metal Salts with N,N-Dimethylhydrazide of 4-Nitrobenzoic Acid

The [M(HL)₂(H₂O)₂]X₂ complexes were synthesized (M = Mn(II), Co(II), Ni(II), Cu(II), Zn; X = CH₃COO^–, Cl^–, BF₄ ^–) that incorporate bidentately coordinated molecules of N,N-dimethylhydrazide of 4-nitrobenzoic acid (HL). The latter molecules chelate the metal atom through the carbonyl O atom and the N atom of dimethylamino group. The square-planar complexes of Cu and Ni with deprotonated form of a ligand with composition ML₂ were also isolated. The synthesized complexes were studied by IR, electronic and EPR spectroscopies, and by cyclic voltammetry.     

Synthesis and multinuclear NMR study of Hg(II), Cd(II), and Pd(II) complexes with biphenylmethylenetriphenylphosphorane: X-ray crystal structure of [{C6H5C6H4CO{(C6H5)3P}CH}HgI2]2

Reactions of title ylide, {(C₆H₅)₃PCHCOC₆H₄C₆H₅)} (BPPPY), with mercury(II) halides in equimolar ratios in methanol yielded dinuclear complexes [(BPPPY)HgCl₂]₂ (1), [(BPPPY)HgBr₂]₂ (2), and [(BPPPY)HgI₂]₂ (3). Reactions of BPPPY with CdCl₂ in equimolar ratios gave [(BPPPY)CdCl₂]₂ (4). Reaction of PdCl₂ with BPPPY (1/2) in acetonitrile at room temperature gave cis/trans [PdCl₂{CH(PPh₃)COC₆H₄C₆H₅}₂] (5). The same reaction at reflux gave the orthopalladated complex [Pd{CH{P(2-C₆H₄)Ph}(COC₆H₄C₆H₅)}(μ-Cl)]₂ (6) along with the phosphonium salt [Ph₃PCHCOC₆H₄C₆H₅]Br. The compounds were characterized by elemental analysis, IR-, ¹H-, ¹³C-, and ³¹P-NMR spectroscopy. Single crystal X-ray analysis of 3 reveals the centrosymmetric dimeric structure containing the ylide and HgI₂. Crystallographic data for 3 are: crystal system, monoclinic; space group, P 2₁/n, a = 15.7744(7), b = 23.0288(9), c = 20.2867(9) Å, β = 112.237(3)°, V = 6821.4(5) ų, and Z = 1.     

Preparation and characterization of copper sulfide nanoparticles from symmetrical [(Bu)2NC(S)NC(O)C6H3(3,5-NO2)2]2Cu(II) and [(Bu)2NC(S)NC(O)C6H4(4-NO2)]2Cu(II) complexes by thermolysis

Trigonal copper sulfide nanoparticles were synthesized from symmetrical [(Bu)₂NC(S)NC(O)C₆H₃(3,5-NO₂)₂]₂Cu(II) and [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) complexes by thermolysis in the presence of surfactant oleylamine. The symmetrical copper complexes were synthesized by reaction of copper(II) acetate with N-(3,5-dinitrobenzoyl)-N′,N′-dibutylthiourea and N-(4-nitrobenzoyl)-N′,N′-dibutylthiourea. The symmetrical copper complexes were characterized by FT-IR spectroscopy, elemental analysis, and mass spectrometry (MS-APCI). The single-crystal X-ray structure of [(Bu)₂NC(S)NC(O)C₆H₄(4-NO₂)]₂Cu(II) has been determined from single-crystal X-ray diffraction data. These metal complexes have been used as single source precursors for the preparation of copper sulfide nanoparticles. The deposited copper sulfide nanoparticles were characterized by X-ray powder diffraction and transmission electron microscopy.     

Synthesis and spectroscopic,magnetic and cyclic voltammetric characterization of some metal complexes of methionine: [(C5H10NO2S)2MII]; MII = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II)

Some metal complexes of DL–methionine were prepared in aqueous medium and characterized by different physico-chemical methods. Methionine forms 1:2 complexes with metal, M(II). The general empirical formula of the complexes is proposed as [(C₅H₁₀NO₂S)₂M^II]; where M^II = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II). All the complexes are extremely stable in light and air and optically inactive. Magnetic susceptibility data of the complexes demonstrate that they are high spin paramagnetic complex except Zn(II), Cd(II) and Hg(II) complexes. The bonding pattern in the complexes are similar to each other as indicated by electronic absorption spectra and FTIR spectral analysis. The current potential data, peak separation (AE) and the peak current ratio (i_pa/i_pc) of the (Mn, Cu and Cd) complexes indicate that the charge transfer processes are irreversible, the systems are diffusion controlled and also adsorptive controlled. The charge transfer rate constant of metals in their complexes are less than those in their metal salts at identical experimental conditions due to the coordination of metal with methionine.     

Synthesis and structural characterization of ruthenium(II) and iron(II) complexes containing 1,2-di-(2-thienyl)-ethene derived ligands as chromophores

A new family of three-legged piano stool structured organometallic compounds containing the η⁵-cyclopentadienylruthenium(II)/iron(II) fragments {M(η⁵-C₅H₅) (DPPE)}⁺, {Ru(η⁵-C₅H₅)(PPh₃)₂}⁺ and {Ru(η⁵-C₅H₅)(TMEDA)}⁺ with coordinated thiophene based chromophores, namely 5-(2-thiophen-2-yl-vinyl)-thiophene-2-carbonitrile (L1) and 5-[2-(5-Nitro-thiophen-2-yl)-vinyl]-thiophene-2-carbonitrile (L2) has been synthesized and fully characterized by ¹H, ¹³C, ³¹P NMR, IR and UV-Vis spectroscopies. Also, electrochemical studies were carried out by cyclic voltammetry and all experimental data are interpreted and compared with related compounds under the scope of NLO properties. Compounds [Ru(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₃S))][CF₃SO₃] (1′Ru) [Fe(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₃S))] [PF₆] (1Fe) and [Ru(η⁵-C₅H₅)(DPPE)(NC(C₄H₂S)C(H)C(H)(C₄H₂S)NO₂)][CF₃SO₃] (4′Ru) were also crystallographically characterized.     

Copper(II) complexes with derivatives of salen and tetrahydrosalen: a spectroscopic, electrochemical and structural study

Salen type complexes, CuL, the corresponding tetrahydrosalen type complexes, Cu[H₄]L, and N,N′-dimethylated tetrahydrosalen type complexes, Cu[H₂Me₂]L, were investigated using cyclic voltammetry, and electronic and ESR spectroscopy. In addition, the analogous copper(II) complexes with a derivative of the tetradentate ligand ‘salphen’ [salphen=H₂salphen=N,N′-disalicylidene-1,2-diaminobenzene] were studied. Solutions of CuL, Cu[H₄]L and Cu[H₂Me₂]L are air-stable at ambient temperature, except for the complex Cu(^tBu, Me)[H₄]salphen [H₂(^tBu, Me)[H₄]salphen=N,N′-bis(2-hydroxy-3-tert-butyl-5-methylbenzyl)-1,2-diaminobenzene]. Cu(^tBu, Me)[H₄]salphen interacts with dioxygen and the ligand is oxidatively dehydrogenated (–CH₂–NH–→–C=N–) to form Cu(^tBu, Me)[H₂]salphen and finally, in the presence of base, Cu(^tBu, Me)salphen. X-ray structure analysis of Cu(^tBu, Me)[H₂Me₂]salen confirms a slightly tetrahedrally distorted planar geometry of the CuN₂O₂ coordination core. The complexes were subjected to spectrophotometric titration with pyridine, to determine the equilibrium constants for adduct formation. It was found that the metal center in the complexes studied is only of weak Lewis acidity. In dichlormethane, the oxidation Cu(II)/Cu(III) is quasireversible for the CuL type complexes, but irreversible for the Cu[H₄]L and Cu[H₂Me₂]L type. A poorly defined wave was observed for the irreversible reduction Cu(II)/Cu(I) at potentials less than −1.0 V. The ESR spectra of CuL at both 77 K and room temperature reveal that very well resolved lines can be attributed to the interaction of an unpaired electron spin with the copper nuclear spin, ¹⁴N donor nuclei and to a distant interaction with two equivalent protons [A^Cu(iso)≈253 MHz, A^N(iso)≈43 MHz, A^N(iso)≈20 MHz]. These protons are attached to the carbon atoms adjacent to the ¹⁴N nuclei. In contrast to CuL, the number of lines in the spectra of the complexes Cu[H₄]L and Cu[H₂Me₂]L is greatly reduced. At room temperature, only a quintet with a considerably smaller nitrogen shf splitting constant [A^N(iso)≈27 MHz] is observed. Both factors, planarity and conjugation, are thus essential for the observation of distant hydrogen shf splitting in CuL. Due to the C=N bond hydrogenation, the coordination polyhedra of the complexes Cu[H₄]L and Cu[H₂Me₂]L is more flexible and more sensitive to ligand modification than that of CuL. The electron-withdrawing effect of the phenyl ring of the phenylenediamine bridge is reflected in a reduction of the copper hyperfine coupling constants in Cu(^tBu, Me)[H₄]salphen and Cu(^tBu, Me)[H₂Me₂]salphen complexes [A^Cu(iso)≈215 MHz].     

Synthesis and characterization of complexes η5,η5-(CO)3Mn(C5H4-C5H4)(CO)2Fe-η1,η5-C5H4Mn(CO)3 and μ-(C≡C)[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3]2

The complex η⁵,η⁵-(CO)₃Mn(C₅H₄-C₅H₄)(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ was synthesized by the reaction of η⁵-Cp(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with BuⁿLi (THF, ?78 °C) and then with anhydrous CuCl₂. The complex μ-(C≡C)[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃]₂ was prepared by the reaction of η⁵-IC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ with Me₃SnC≡CSnMe₃ (2:1) in the presence of Pd(MeCN)₂Cl₂.