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Catherine P Raptopoulou

Publications and source records attributed to Catherine P Raptopoulou.

At least 19 recordsLinked to original sources
PubMed2006

Methanolysis as a route to gallium(III) clusters: synthesis and structural characterization of a decanuclear molecular wheel.

Treatment of a methanolic solution of gallium(III) nitrate with lithium hydroxide in the presence of benzilic acid resulted in the decanuclear cluster [Ga(OMe)2{O2CC(OH)Ph2}]10 (1). The metal and the organic components have assembled to form a cyclic molecule that adopts the structure of a wheel. The 10 Ga(III) ions are approximately coplanar and are coordinated in a distorted octahedral manner by six oxygen atoms. The integrity of the molecular wheel is retained in solution, as evidenced by the 1NMR spectrum of 1 in DMSO-d6, while no signal in the 71Ga NMR could be detected.

Journal Article↗
PubMed2006

Reactivity and structural and physical studies of tetranuclear iron(III) clusters containing the [Fe4(mu3-O)2]8+ "butterfly" core: an FeIII4 cluster with an S = 1 ground state.

The initial use of di-2-pyridyl ketone oxime [(py)2CNOH] in iron(III) carboxylate chemistry has yielded the tetranuclear complex [Fe4O2Cl2(O2CMe)2{(py)2CNO}4] (1). Compound 1 can be synthesized either by the 1:2:1 molar ratio reaction between Fe(III), MeCO2-, and (py)2CNOH (complex 1a) or by the 1:3 molar ratio reaction between [Fe3O(O2CMe)6(H2O)3]Cl and (py)2CNOH (complex 1b). The presence of N3- in both reaction mixtures has afforded the tetranuclear complex [Fe4O2(N3)2(O2CMe)2{(py)2CNO}4] (2), which can be alternatively synthesized by the reaction of 1 with N3-. Compound 1a crystallizes in the tetragonal space group /-4 with (at 25 degrees C) a = 35.06(2) A, b = 35.06(2) A, c = 13.255(6) A, V = 16293(2) A(3), and Z = 8. Compound 1b crystallizes in the monoclinic space group P2(1)/c with (at 25 degrees C) a = 22.577(7) A, b = 17.078(6) A, c = 17.394(6) A, beta = 93.50(1) degrees , V = 6694(4) A(3), and Z = 4. Compound 2 crystallizes in the triclinic space group P1 with (at 25 degrees C) a = 13.658(9) A, b = 15.815(9) A, c = 17.29(1) A, alpha = 97.08(3) degrees , beta = 98.55(3) degrees , gamma = 112.12(3) degrees , V = 3355(4) A(3), and Z = 2. The structures of 1 and 2 contain the [Fe4(mu3-O)2]8+ core comprising four Fe(III) ions in a "butterfly" disposition and two mu3-O2- ions, each bridging three Fe(III) ions forming the "wings" of the "butterfly". The Mössbauer spectra of 1b and 2 consist of composite quadrupole-split doublets, with parameters typical for high-spin Fe(III) in octahedral environments. Magnetic susceptibility measurements on 1a revealed antiferromagnetic interactions between the S = 5/2 ferric ions, with best-fit parameters being J(wb) = -40.2 cm(-1) and J(bb) = -59.4 cm(-1) (H = -2SigmaJiJj) for wingtip-body and body-body interactions, respectively, yielding an S = 1 ground state. Both wingtip-body and body-body interactions are well determined.

Journal Article↗
PubMed2006

Structure and biological properties of the copper(II) complex with the quinolone antibacterial drug N-propyl-norfloxacin and 2,2'-bipyridine.

The neutral mononuclear copper complex with the quinolone antibacterial drug N-propyl-protected norfloxacin, Hpr-norfloxacin, in the presence of the nitrogen donor heterocyclic ligand 2,2'-bipyridine has been prepared and characterized. The crystal structure of (chloro)(2,2'-bipyridine)(pr-norfloxacinato)copper(II), 1, has been determined and refined with X-ray crystallography. X-band electron paramagnetic resonance (=EPR) spectroscopy at liquid helium temperatures from powdered samples indicates the presence of dimeric units in consistency with the crystal structure. In aqueous solutions of 1 the EPR behavior indicates mixture of dimeric and monomeric species. The antimicrobial activity of the complex has been tested on three different microorganisms and the best inhibition (MIC=0.25mugmL(-1)) has been exhibited against Escherichia coli. The study of the interaction of the complex with calf-thymus DNA has been performed with diverse spectroscopic techniques and has shown that complex 1 is bound to calf-thymus DNA by the intercalative mode. Potential anticancer cytostatic and cytotoxic effects of complex 1 on human promyelocytic leukemia HL-60 and human chronic myelogenous leukemia K562 cell lines have been investigated. Complex 1 shows an increased antiproliferative and necrotic effect on both HL-60 and K562 human leukemia cells in comparison to the free pr-norfloxacin.

2,2'-Dipyridyl↗
PubMed2006

Synthesis, structure and biological activity of copper(II) complexes with oxolinic acid.

The neutral mononuclear copper complexes with the quinolone antibacterial drug oxolinic acid in the presence or not of a nitrogen donor heterocyclic ligand 1,10-phenanthroline, 2,2'-bipyridine or 2,2'-dipyridylamine have been synthesized and characterized with infrared, UV-visible and electron paramagnetic resonance spectroscopies. The experimental data suggest that oxolinic acid acts as a deprotonated bidentate ligand and is coordinated to the metal ion through the pyridone and one carboxylate oxygen atoms. The crystal structure of (chloro)(1,10-phenanthroline)(oxolinato) copper(II), 2, has been determined with X-ray crystallography. For all complexes a distorted square pyramidal environment around Cu(II) is suggested. The EPR (electron paramagnetic resonance) behavior of 2 in aqueous solutions indicates mixture of dimeric and monomeric species. The investigation of the interaction of the complexes with calf-thymus DNA has been performed with diverse spectroscopic techniques and showed that the complexes are bound to calf-thymus DNA. The antimicrobial activity of the complexes has been tested on three different microorganisms. The complexes show a decreased biological activity in comparison to the free oxolinic acid.

Animals↗
PubMed2006

Crystal structure, spectroscopic, and biological study of the copper(II) complex with third-generation quinolone antibiotic sparfloxacin.

The neutral mononuclear copper(II) complex with the quinolone antibacterial drug sparfloxacin has been prepared and characterized with IR, UV-vis, and EPR spectroscopies and X-ray crystallography. The interaction of the complex with calf-thymus DNA has also been investigated and the antimicrobial activity has been evaluated against three different microorganisms.

Anti-Bacterial Agents↗
PubMed2006

Neutral and cationic mononuclear copper(II) complexes with enrofloxacin: structure and biological activity.

The mononuclear copper complexes with the quinolone antibacterial drug enrofloxacin (=Herx) in the presence or not of a nitrogen donor heterocyclic ligand 1,10-phenanthroline (=phen) and 2,2'-bipyridine (=bipy) have been prepared and characterized. Interaction of copper(II) with deprotonated enrofloxacin leads to the formation of the neutral complex Cu(erx)2(H2O), 1, while the presence of phen or bipy leads to the formation of a neutral or a cationic mononuclear complex, respectively. The crystal structures of (chloro)(1,10-phenanthroline)(enrofloxacinato)copper(II), 2, and (aqua)(2,2'-bipyridine)(enrofloxacinato)copper(II) chloride, 3, have been determined with X-ray crystallography. The complexes have been studied with X-band electron paramagnetic resonance in aqueous solutions at liquid helium temperature. The study of the interaction of the complexes with calf-thymus DNA has been performed with diverse spectroscopic techniques and has showed that all complexes are bound to DNA by the intercalative mode. The antimicrobial efficiency of the complexes has been tested on three different microorganisms and the available evidence supports that the best inhibition is provided by Cu(erx)2(H2O) (minimum inhibitory concentration=0.125 microg mL(-1)) against Escherichia coli and Pseudomonas aeruginosa.

Anti-Infective Agents↗
PubMed2006

Hexanuclear iron(III) salicylaldoximato complexes presenting the [Fe6(mu3-O)2(mu2-OR)2]12+ core: syntheses, crystal structures, and spectroscopic and magnetic characterization.

The use of salicylaldehyde oxime (H2salox) in iron(III) carboxylate chemistry has yielded two new hexanuclear compounds [Fe6(mu3-O)2(O2CPh)10(salox)2(L)2].xMeCN.yH2O [L = MeCONH2, x = 6, y = 0 (1); L = H2O, x = 2, y = 3 (2)]. Compound 1 crystallizes in the triclinic space group P with (at 25 degrees C) a = 13.210(8) A, b = 13.87(1) A, c = 17.04(1) A, alpha = 105.79(2) degrees , beta = 96.72(2) degrees , gamma = 116.69(2) degrees , V = 2578.17(2) A(3), and Z = 1. Compound 2 crystallizes in the monoclinic space group C2/c with (at 25 degrees C) a = 21.81(1) A, b = 17.93(1) A, c = 27.72(1) A, beta = 111.70(2) degrees , V = 10070(10) A(3), and Z = 4. Complexes 1 and 2 contain the [Fe6(mu3-O)2(mu2-OR)2]12+ core and can be considered as two [Fe3(mu3-O)] triangular subunits linked by two mu2-oximato O atoms of the salox2- ligands, which show the less common mu3:eta1:eta2:eta1 coordination mode. The benzoato ligands are coordinated through the usual syn,syn-mu2:eta1:eta1 mode. The terminal MeCONH2 ligand in 1 is the hydrolysis product of the acetonitrile solvent in the presence of the metal ions. Mössbauer spectra from powdered samples of 2 give rise to two well-resolved doublets with an average isomer shift consistent with that of high-spin Fe(III) ions. The two doublets, at an approximate 1:2 ratio, are characterized by different quadrupole splittings and are assigned to the nonequivalent Fe(III) ions of the cluster. Magnetic measurements of 2 in the 2-300 K temperature range reveal antiferromagnetic interactions between the Fe(III) ions, stabilizing an S = 0 ground state. NMR relaxation data have been used to investigate the energy separation between the low-lying states, and the results are in agreement with the susceptibility data.

Chemistry, Inorganic↗
PubMed2005

Initial example of a triangular single-molecule magnet from ligand-induced structural distortion of a [MnIII3O]7+ complex.

The reaction of [Mn3O(O2CR)6(py)3](ClO4) (R = Me, Et) with methyl 2-pyridyl ketone oxime (mpkoH) in a 1:3 molar ratio in MeOH/MeCN leads to [Mn3O(O2CR)3(mpko)3](ClO4) in 80-90% isolated yield. Ferromagnetic exchange interactions between the three MnIII ions in the nonplanar [MnIII3O]7+ triangular core lead to a spin ground state of S = 6; single-crystal studies reveal the temperature and sweep rate dependent hysteresis loops expected for a single-molecule magnet.

Journal Article↗
PubMed2005

The first cobalt metallacrowns: preparation and characterization of mixed-valence cobalt(II/III), inverse 12-metallacrown-4 complexes.

Aerobic reactions of Co(O(2)CMe)(2).4H(2)O with di-2-pyridyl ketone oxime (Hpko) in the presence of counterions (ClO(4)(-), PF(6-)) give the tetranuclear, mixed-valence cobalt(II/III) clusters [Co(II)(2)Co(III)(2)(OR)(2)(O(2)CMe)(2)(pko)(4)S(2)]X(2) [R = H, S = MeOH, X = ClO(4) (1); R = Me, S = EtOH, X = PF(6) (2)] depending on the solvent mixture. Complexes 1 and 2 are the first Co members in the family of metallacrowns adopting the extremely rare inverse 12-metallacrown-4 motif.

Journal Article↗
PubMed2005

Di-2-pyridyl ketone oxime [(py)2CNOH] in manganese carboxylate chemistry: mononuclear, dinuclear and tetranuclear complexes, and partial transformation of (py)2CNOH to the gem-diolate(2-) derivative of di-2-pyridyl ketone leading to the formation of NO3-.

The use of di-2-pyridyl ketone oxime, (py)2CNOH, in manganese carboxylate chemistry has been investigated. Using a variety of synthetic routes complexes [Mn(O2CPh)2{(py)2CNOH}2].0.25H2O (1.0.25H2O), Mn4(O2CPh)2{(py)2CO2}2{(py)2CNO}2Br2].MeCN (2.MeCN), [Mn4(O2CPh)2{(py)2CO2}2{(py)2CNO}2Cl(2)].2MeCN (3.2MeCN), [Mn4(O2CMe)2{(py)2CO2}2{(py)2CNO}2Br2].2MeCN (4.2MeCN), [Mn4(O2CMe)2{(py)2CO2}2{(py)2CNO}2(NO3)2].MeCN.H2O (5.MeCN.H2O) and [Mn2(O2CCF3)2(hfac)2{(py)2CNOH}2] (6) have been isolated in good yields. Remarkable features of the reactions are the in situ transformation of an amount of (py)2CNOH to yield the coordination dianion, (py)2CO2(2-), of the gem-diol derivative of di-2-pyridyl ketone in 2-5, the coordination of nitrate ligands in 5 although the starting materials are nitrate-free and the incorporation of CF3CO2- ligands 6 in which was prepared from Mn(hfac)(2).3H2O (hfac(-)= hexafluoroacetylacetonate). Complexes 2-4 have completely analogous molecular structures. The centrosymmetric tetranuclear molecule contains two MnII and two MnIII six-coordinate ions held together by four mu-oxygen atoms from the two 3.2211 (py)2CO2(2-) ligands to give the unprecedented [MnII(mu-OR)MnIII(mu-OR)2MnIII(mu-OR)MnII]6+ core consisting of a planar zig-zag array of the four metal ions. Peripheral ligation is provided by two 2.111 (py)2CNO-, two 2.11 PhCO2- and two terminal Br- ligands. The overall molecular structure 5 of is very similar to that of 2-4 except for the X- being chelating NO3-. A tentative reaction scheme was proposed that explains the observed oxime transformation and nitrate generation. The CF3CO2- ligand is one of the decomposition products of the hfac- ligand. The two Mn(II) ions are bridged by two neutral (py)2CNOH ligands which adopt the 2.0111 coordination mode. A chelating hfac- ligand and a terminal CF3CO2- ion complete a distorted octahedral geometry at each metal ion. The CV of complex reveals irreversible reduction and oxidation processes. Variable-temperature magnetic susceptibility studies in the 2-300 K range for the representative tetranuclear clusters 2 and 4 reveal weak antiferromagnetic exchange interactions, leading to non-magnetic ST = 0 ground states. Best-fit parameters obtained by means of the program CLUMAG and applying the appropriate Hamiltonian are J(Mn(II)Mn((III))=-1.7 (2), -1.5 (4) cm(-1) and J(Mn(III)Mn(III))=-3.0 (2, 4) cm(-1).

2,2'-Dipyridyl↗
PubMed2005

Inter-conversion of 15-MC-5 to 12-MC-4 manganese metallacrowns: structure and bioactivity of metallacrowns hosting carboxylato complexes.

Interaction of manganese with salicylhydroxamic ligands (shi) in methanol, in the presence of pyridine, leads to the formation of a series of 15-membered metallacrown (MC) Mn(II)(L)2[15-MCMn(III)N(shi)-5](py)6 or 7, (L=formato, benzoate or alkanoato ligand, py=pyridine). In the absence of pyridine, the Mn(II)(L)2[12-MCMn(III)N(shi)-4](MeOH)6 metallacrown was isolated and structurally characterized. The crystal structure of {[Mn(II)(HCOO)2][(15-MCMn(III)N(shi)-5)(py)7]}.py.1.9CH3OH.H2O (1) contains a neutral 15-membered metallacrown ring consisting of five Mn(III) and five shi(-3) ligands. The 15-membered metallacrown ring is formed by the succession of five structural moieties of the type [Mn(III)-N-O]. The diverse in the configuration (planar or propeller) for the ring Mn(III) ions gives the metallacrown core a bending structure. The crystal structure of {[Mn(II)(C6H5COO)2][(12-MCMn(III)N(shi)-4)(CH3OH)6]}.2CH3OH (2) contains a neutral 12-membered metallacrown ring consisting of four Mn(III) and four shi(-3) ligands. The 12-membered metallacrown ring is formed by the same way of succession of four structural moieties of the type [Mn(III)-N-O], while the presence of a planar only configuration of shi ligands around ring Mn(III) ions gives to the metallacrown core a planar structure. The encapsulated Mn(II) is six and seven-coordinate for (1) and (2), respectively, and is bound to the hydroximate oxygen of the metallacrown core and two oxygen atoms from the carboxylate ligands. Antibacterial screening data showed that, among all the compounds tested, manganese metallacrowns are more active compared to the simple manganese herbicide or carboxylate complexes, with increased efficiency for [15-MCMn(III)N(shi)-5] compared to the analogous [12-MCMn(III)N(shi)-4].

Anti-Bacterial Agents↗
PubMed2005

Dinuclear versus tetranuclear cluster formation in zinc(II) nitrate/di-2-pyridyl ketone chemistry: synthetic, structural and spectroscopic studies.

The use of di-2-pyridyl ketone, (py)2CO, in zinc(II) nitrate chemistry has yielded a dinuclear complex and a cationic tetranuclear cluster. The 1:1 Zn(NO3)2.4H2O/(py)2CO reaction system in EtOH gives [Zn2(NO3)2{(py)2C(OEt)O}2].0.5H2O (1.0.5H2O), whereas the same reaction system in MeCN yields [Zn4(NO3)3{(py)2C(OH)O}4(H2O)](NO3) (2). The monoanionic derivatives of the hemiacetal and the gem-diol forms of di-2-pyridyl ketone have been derived from the ZnII-mediated addition of solvent (EtOH, H2O involved in MeCN) on the carbonyl group of (py)2CO. Each (py)2C(OEt)O- ion functions as an eta1:eta2:eta1:mu2 ligand in 1.0.5H2O chelating the two ZnII atoms through the 2-pyridyl nitrogen atoms and the common bridging, deprotonated oxygen atom; one asymmetric chelating nitrate completes six coordination at each metal center. The tetranuclear cluster cation of 2 has a cubane topology with the ZnII ions and the deprotonated oxygen atoms from the four eta1:eta3:eta1:mu3 (py)2C(OH)O- ligands occupying alternate vertices. Three monodentate nitrates and one aqua ligand complete the sixth coordination site at the metal ions. The two complexes have been characterized by IR and far-IR spectroscopies. Characteristic bands are discussed in terms of the known structures and the coordination modes of the nitrato ligands. Upon excitation at 371 nm, complex 2 displays blue photoluminescence in the solid state at room temperature with two emission maxima at 430 and 455 nm.

2,2'-Dipyridyl↗
PubMed2004

Monomeric oxovanadium(IV) compounds of the general formula cis-[V(IV)(=O)(X)(L(NN))(2)](+/0) [X = OH(-), Cl(-), SO(4)(2)(-) and L(NN) = 2,2'-bipyridine (bipy) or 4,4'-disubstituted bipy].

Reaction of [V(IV)OCl(2)(THF)(2)] in aqueous solution with 2 equiv of AgBF(4) or AgSbF(6) and then with 2 equiv of 2,2'-bipyridine (bipy), 4,4'-di-tert-butyl-2,2'-bipyridine (4,4'-dtbipy), or 4,4'-di-methyl-2,2'-bipyridine (4,4'-dmbipy) affords compounds of the general formula cis-[V(IV)O(OH)(L(NN))(2)]Y [where L(NN) = bipy, Y = BF(4)(-) (1), L(NN) = 4,4'-dtbipy, Y = BF(4)(-) (2.1.2H(2)O), L(NN) = 4,4'-dmbipy, Y = BF(4)(-) (3.2H(2)O), and L(NN) = 4,4'-dtbipy, Y = SbF(6)(-) (4)]. Sequential addition of 1 equiv of Ba(ClO(4))(2) and then of 2 equiv of bipy to an aqueous solution containing 1 equiv of V(IV)OSO(4).5H(2)O yields cis-[V(IV)O(OH)(bipy)(2)]ClO(4) (5). The monomeric compounds 1-5 contain the cis-[V(IV)O(OH)](+) structural unit. Reaction of 1 equiv of V(IV)OSO(4).5H(2)O in water and of 1 equiv of [V(IV)OCl(2)(THF)(2)] in ethanol with 2 equiv of bipy gives the compounds cis-[V(IV)O(OSO(3))(bipy)(2)].CH(3)OH.1.5H(2)O (6.CH(3)OH.1.5H(2)O) and cis-[V(IV)OCl(bipy)(2)]Cl (7), respectively, while reaction of 1 equiv of [V(IV)OCl(2)(THF)(2)] in CH(2)Cl(2) with 2 equiv of 4,4'-dtbipy gives the compound cis-[V(IV)OCl(4,4'-dtbipy)(2)]Cl.0.5CH(2)Cl(2) (8.0.5CH(2)Cl(2)). Compounds cis-[V(IV)O(BF(4))(4,4'-dtbipy)(2)]BF(4) (9), cis-[V(IV)O(BF(4))(4,4'-dmbipy)(2)]BF(4) (10), and cis-[V(IV)O(SbF(6))(4,4'-dtbipy)(2)]SbF(6) (11) were synthesized by sequential addition of 2 equiv of 4,4'-dtbipy or 4,4'-dmbipy and 2 equiv of AgBF(4) or AgSbF(6) to a dichloromethane solution containing 1 equiv of [V(IV)OCl(2)(THF)(2)]. The crystal structures of 2.1.2H(2)O, 6.CH(3)OH.1.5H(2)O, and 8.0.5CH(2)Cl(2) were demonstrated by X-ray diffraction analysis. Crystal data are as follows: Compound 2.1.2H(2)O crystallizes in the orthorhombic space group Pbca with (at 298 K) a = 21.62(1) A, b = 13.33(1) A, c = 27.25(2) A, V = 7851(2) A(3), Z = 8. Compound 6.CH(3)OH.1.5H(2)O crystallizes in the monoclinic space group P2(1)/a with (at 298 K) a = 12.581(4) A, b = 14.204(5) A, c = 14.613(6) A, beta = 114.88(1) degrees, V = 2369(1), Z = 4. Compound 8.0.5CH(2)Cl(2) crystallizes in the orthorhombic space group Pca2(1) with (at 298 K) a = 23.072(2) A, b = 24.176(2) A, c = 13.676(1) A, V = 7628(2) A(3), Z = 8 with two crystallographically independent molecules per asymmetric unit. In addition to the synthesis and crystallographic studies, we report the optical, infrared, magnetic, conductivity, and CW EPR properties of these oxovanadium(IV) compounds as well as theoretical studies on [V(IV)O(bipy)(2)](2+) and [V(IV)OX(bipy)(2)](+/0) species (X = OH(-), SO(4)(2)(-), Cl(-)).

Journal Article↗
PubMed2004

Synthetic analogue approach to metallobleomycins: syntheses, structure and properties of mononuclear and tetranuclear gallium(III) complexes of a ligand that resembles the metal-binding site of bleomycin.

As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the peptide ligand N-(2-(4-imidazolyl)ethyl)pyridine-2-carboxamide (pypepH2) resembling a fragment of the metal-binding domain of bleomycins (BLMs), have been isolated. Reaction of pypepH2 with (Et4N)[GaCl4] and Ga(acac)3 [acac- is the acetylacetonate(-1) ion] affords the mononuclear complex [Ga(pypepH)2]Cl.2H2O (1) and the tetranuclear complex [Ga4(acac)4(pypep)4].4.4H2O (2), respectively. Both complexes were characterized by single-crystal X-ray crystallography, IR spectroscopy and thermal decomposition data. The pypepH- ion in 1 behaves as a N(pyridyl), N(deprotonated amide), N(pyridine-type imidazole) chelating ligand. The doubly deprotonated pypep2- ion in 2 behaves as a N(pyridyl), N(deprotonated amide), N(imidazolate), N'(imidazolate) mu2 ligand and binds to one Ga(III) atom at its pyridyl, amide and one of the imidazolate nitrogens, and to a second metal ion at the other imidazolate nitrogen; a chelating acac- ligand completes six coordination at each Ga(III) centre. The IR data are discussed in terms of the nature of bonding and known structures. The 1H NMR spectrum of 1 suggests that the cation of the complex maintains its integrity in dimethylsulfoxide (DMSO) solution. Complexes 1 and 2 are the first synthetic analogues of metallobleomycins with gallium(III).

Binding Sites↗
PubMed2003

Synthesis and characterization of novel 99gTc(V) and Re(V) complexes with water-soluble tetraaza diamido dipyridino ligands: single-crystal X-ray structural investigations of mono- and dinuclear complexes.

Rhenium and technetium are known for their useful applications in nuclear medicine with similar properties. In this study, new diamido dipyridino (N(4)) water-soluble ligands (2-C(5)H(4)NCH(2)NHCO)(2)CH(2), 1 (L(1)H2), (2-C(5)H(4)NNHNHCO)(2)CH(2), 2, and [2-C(5)H(4)N(+)(O)(-)CH(2)NHCO](2)CH(2), 3, were synthesized. Reaction of L(1)H2 with ReOCl(3)(PPh(3))(2) resulted in the novel six-coordinated rhenium(V) complex, trans-ReO(L(1))(OEt), 4. The complex was characterized by spectroscopic methods, and its X-ray crystallographic analysis revealed that rhenium is coordinated to four nitrogen atoms of the ligand and to two oxygen atoms from the deprotonated ethanol and the oxo group respectively in a distorted octahedral geometry. In solution, complex 4 was transformed to a new complex 5, which was proved to be the dinuclear complex mu-oxo [ReO(L(1))](2)O. Reaction of 1 with [n-Bu(4)N][ReOCl(4)] resulted in the neutral complex 6, trans-[ReO(L(1))]Cl. Similarly, when ligand 1 was reacted with [n-Bu(4)N][(99g)TcOCl(4)], the neutral trans-[(99)TcO(L(1))]Cl complex 7 was formed, which upon dissolution transformed into a cationic complex 8, trans-[(99)TcO(L(1))(OH(2))](+)Cl(-). The single-crystal X-ray structure of 8 reveals that the coordination sphere about technetium is a distorted octahedron with four nitrogen atoms in the equitorial plane, while doubly bonded oxygen and coordinated water occupy the apical positions. Further dissolution of 8 resulted in the formation of dinuclear mu-oxo [TcO(L(1))](2)O, 9. This study shows that Tc and Re have similar metal core structures in solution for diamido dipyridino systems, besides similarity in geometrical structure, proved by the X-ray structures on the same ligands.

Amines↗
PubMed2003

Octanuclearity and tetradecanuclearity in manganese chemistry: an octanuclear manganese(II)/(III) complex featuring the novel [Mn8(mu4-O)2(mu3-OH)2]14+ core and [Mn10(II)Mn4(III)O4(O2CMe)20[(2-py)2C(OH)O]4] (2-py = 2-pyridyl).

Reactions of Mn sources with di-2-pyridyl ketone, (2-py)2CO, and phenyl 2-pyridyl ketone oxime, (ph)(2-py)CNOH, give the novel clusters [Mn10(II)Mn4(III)O4(O2CMe)20[(2-py)2C(OH)O]4] 1 and [Mn4(II)Mn4(III)O2(OH)2(O2CPh)10[(ph)(2-py)CNO]4] 2, respectively, which possess low-spin ground states; the observed tetradecanuclearity in 1 is extremely rare in 3d-metal chemistry, while the core of 2 has a unique topology consisting of two linked [Mn2(II)Mn2(III)O(OH)] units.

Journal Article↗