Ligand Salt Research Articles

Sandwich-type lanthanide(III) complexes of a tetraiminodiphenol macrocyclic ligand derived from 4-methyl-2,6-diformylphenol and 1,3-diaminopropane: structure, NMR and luminescence

The macrocyclic ligand salt [H2LH2](ClO4)2, derived from the [2+2] condensation process involving 4-methyl-2,6-diformylphenol and 1,3-diaminopropane, has been used to synthesize the sandwich-type lanthanide(III) complexes [Ln(LH2)2](ClO4)3·2H2O (1–6, Ln=La–Eu, except Pm), [Ln(LH2)2](ClO4)3·CH3CN (7–13, Ln=Gd–Lu, except Er) and [Ln(LH2)(LH)](BPh4)2 (14–16, Ln=La, Nd and Sm). The X-ray crystal structures of the compounds 1, 7, 12, 13, 14 and 15 have been determined. In the isostructural [Ln(LH2)2](ClO4)3·CH3CN complexes of Gd (7), Yb (12) and Lu (13), the two macrocyclic ligands are considerably folded, albeit to different extents, and not symmetrically bound to the metal center. In these compounds, the metal center is coordinated with two imine nitrogen atoms and two phenolate oxygen atoms of each of the ligands (LH2), whose two other uncoordinated imine nitrogens are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The structures determined for the La (14) and Nd (15) complexes of [Ln(LH2)(LH)](BPh4)2 are found to be identical. In these complexes, the ligand LH contains one N–H⋯O hydrogen-bonded unit, as against two in the ligand LH2. The [Ln(N2O2)2] coordination polyhedron in all the cases is a distorted square antiprism, although the extent of distortion in 7, 12 and 13 is less compared to that in 14 and 15. 1H NMR spectra of the [Ln(LH2)2]3+complexes in solution indicate a C2 symmetry. The 1H and 13C NMR signals of the EuIII complex 6 have been assigned on the basis of COSY, DEPT, HMQC and NOESY spectra. The photoluminescence spectra of the Sm(III) (5) and Eu(III) (6) complexes have been studied in a methanol–ethanol (1:4) glassy matrix at 77K. The luminescence intensity of the hypersensitive 5D0→7F2 transition in 6 increases with the addition of triethylamine due to the formation of [Eu(LH2)(LH)]2+ and [Eu(LH)2]+ species, which in turn partially attenuate the quenching effect of the N–H⋯O oscillators on the emitting states of the metal ion.

Ionophoric properties of a tetra-tetrazole functionalised calix[4]arene

The synthesis and characterisation of p-t-butylcalix[4]arene functionalised at the lower rim with four tetrazole moieties is reported. The macrocycle is found to be a poorer ionophore for lanthanoid cations than the bis-tetrazole–substituted analogue. Solution-phase photophysical studies strongly suggested that the cations interacted only weakly with the calixarene ligand. A mixed sodium/triethylammonium salt of the calixarene ligand was crystallised in the presence of lanthanoid cations and structurally characterised. Strong intramolecular interactions are hypothesised to be the cause of the observed behaviour.

Phosphorus–nitrogen compounds: Part 31. Syntheses, structural and stereogenic properties, in vitro cytotoxic and antimicrobial activities, and DNA interactions of bicyclotetraphosphazenes containing bulky side group

Hexachlorocyclotriphosphazene, N3P3Cl6, and octachlorocyclotetraphosphazene, N4P4Cl8, were reacted with K2N2O2 salt of symmetric tetradentate ligand to obtain spiro-bino-spiro [(sbs) (2)] and 2,6-spiro-ansa-spiro [(2,6-sas) (3)] phosphazenes, respectively. The sbs was obtained in a very poor yield, whereas, 2,6-sas was obtained in a moderate yield. The derivatives of 2,6-sas with mono- and diamines were synthesized. When the reactions were carried out, one equimolar amount of 2,6-sas with an excess pyrrolidine, piperidine, morpholine, 1,4-dioxa-8-azaspiro[4,5]decane (DASD), N-methylethane-1,2-diamine, N-ethylethane-1,2-diamine and N-methylpropane-1,3-diamine, along with the fully substituted 2,6-sas-cyclotetraphosphazene derivatives (4a, 4b and 5a–7a), were prepared. However, the excess morpholine and DASD with 2,6-sas yielded the geminal bis- (4c and 4e) and tris- (4d and 4f) cyclotetraphosphazenes, respectively. The Cl replacement reaction of 2,6-sas with one equimolar amount of 7 led to the formation of partly substituted 2,6-sas (7b). The structures of the compounds were verified by elemental analyses, MS, FTIR, 1H, 13C{1H}, 31P NMR, HSQC, HMBC and X-ray crystallography (for 3 and 4a) techniques. All the 2,6-sas cyclotetraphosphazenes (except 3, 4a and 4b) have stereogenic P-atoms. All the compounds were screened for antibacterial and antifungal activities against bacteria and yeast strains. The interactions of the compounds with supercoiled plasmid pBR322 DNA were investigated. The evaluations for cytotoxic activity, and apoptotic and necrotic effects against A549 lung cancer and L929 fibroblast cell lines were introduced.

NMR studies of platinum bisphosphine complexes of phenylphosphonamidodiselenoate

A series of platinum(II) bisphosphine complexes 1–20 [Pt(R′NH(Ph)PSe2)(PR3)2] (where R=Ph3, Ph2Me, Me2Ph, PMe3 and R′=iPr, nBu, sBu, tBu, Benz) have been prepared by reaction of cis-[Pt(PR3)2Cl2)] and the alkyl ammonium salt of the ligand. The novel compounds were characterised by multinuclear NMR, and in one case X-ray crystallography. The molecular structures of two ligand salts and [Pt(sBu′NH(Ph)PSe2)(PPh3)2] are reported.

Amidate-Ligated Complexes of Rhodium(I): A Showcase of Coordination Flexibility

Reaction of the amidate ligand salts Na[N(Dipp)C(O)R] (R = Ph (1a), tBu (1b); Dipp = 2,6-diisopropylphenyl) with [Rh(NBD)Cl]2 (NBD = norbornadiene) proceeds to give the dirhodium(I) complexes [Rh2{μ2-N,O-N(Dipp)C(O)R}2(NBD)2] (R = Ph (2a), tBu (2b)) with variable coordination behavior. For complex 2b, a monomer–dimer equilibrium with the mononuclear complex [Rh{κ2-N,O-N(Dipp)C(O)tBu}(NBD)] (3b) was established for the first time. Precursors 2a,b were treated with PPh3 and PCy3, giving the distorted-square-planar κ2-N,O amidates [Rh{κ2-N,O-N(Dipp)C(O)R}(PPh3)2] (R = Ph (4a), tBu (4b)) or the κ1-O complexes [Rh{κ1-O-N(Dipp)C(O)R}(NBD)(PCy3)] (R = Ph (5a), tBu (5b)). Initial reactivity screening showed that complex 4b undergoes O2 activation, providing Ph3P═O; via the transient peroxo complex 6b, which was characterized in the solution phase. The κ2-N,O amidate coordination in 6b has been conclusively established by diagnostic 13C{1H} NMR spectroscopy.

Synthesis, spectral, thermal behaviors, and antimicrobial studies of some nanostructure five coordinated Hg(II) complexes

A series of novel five coordinated mercury(II) complexes of a new recently synthesized tridentate ligand are presented. The mercury(II) complexes were characterized by various spectral and physical techniques such as FTIR, UV–visible, 1H and 13C NMR spectra, thermal analyses, and decomposition temperature and conductivity measurement. Also nanostructure size of titled mercury coordination compounds have been prepared by the reaction of ligand and mercury salts under ultrasonic conditions. The nanostructure size of the complexes was confirmed by XRD patterns, scanning electron microscopy, and transmission electron microscopy. According to the mentioned analyses, the molecular formula of HgLX2 (X = halide and/or pseudo-halide anions and L = ligand) was suggested for the complexes. Thereafter all mercury(II) complexes were tested for their in vitro antibacterial activities against two Gram-positive (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains. Also in vitro antifungal activities of them against Candida albicans and Aspergillus niger were investigated. The results indicated that all compounds can act as antibacterial and antifungal agents. Moreover, thermal behaviors of the complexes were studied in the range of 20–900 °C. Thermogravimetric study indicated that the mercury complexes are thermally degraded via 3–9 thermal steps.

Reactivity of the Ln2+ Complexes [K(2.2.2-cryptand)][(C5H4SiMe3)3Ln]: Reduction of Naphthalene and Biphenyl

The reductive capacity of the recently discovered Ln2+ complexes [K(2.2.2-cryptand)][Cp′3Ln], 1-Ln (Cp′ = C5H4SiMe3; Ln = Y, La, Ce, Dy), has been probed by examining their reactions with aromatic hydrocarbons. [K(2.2.2-cryptand)][Cp′3Y], 1-Y, is capable of reducing naphthalene and forms a mixture of the naphthalenide dianion complex [K(2.2.2-cryptand)][Cp′2Y(η4-C10H8)], 2-Y, as well as the ligand redistribution product [K(2.2.2-cryptand)][Cp′4Y], 3-Y, and the cyclopentadienyl ligand salt [K(2.2.2-cryptand)][Cp′], 4. Naphthalene is reduced analogously by 1-La, 1-Ce, and 1-Dy. Each complex in the yttrium reaction was synthesized independently to confirm its identity in the mixture. Complex 2-Y was prepared from [Cp′2Y(THF)2][BPh4], 5 (synthesized from [Et3NH][BPh4] and Cp′3Y), and K/naphthalene. Complex 3-Y was obtained by adding KCp′ to Cp′3Y in the presence of 2.2.2-cryptand. [K(2.2.2-cryptand)][Cp′] was synthesized from 2.2.2-cryptand and KCp′. Each C10 unit in the reduced naphthalene products, 2-Y, 2-L...

Synthesis, characterization and application of a novel carbon bridged half-metallocene chromium catalyst for methyl methacrylate polymerization

A new carbon bridged cyclopentadienyl chromium complex of the type [(C5H4)C(CH3)2 CH2(C5H4N)]CrCl2 was prepared by treatment of CrCl3·(THF)3 in THF solution with the lithium salt of ligand containing cyclopentadienyl and pyridyl groups. The chromium complex was characterized by 1H NMR and elemental analysis(EA), and the crystal structure was determined by X-ray diffraction analysis. Activated by Al(i-Bu)3, the chromium complex displayed a very high activity for methyl methacrylate (MMA) polymerization. After 24 hours,more than 95.5% MMA was converted to polymethyl methacrylate (PMMA) with a viscosity average molecular weight (Wη) of 416000 g·mol−1 at 60 °C for MMA/Al(i-Bu)3/chromium catalyst molar ratio of up to 2000:20:1. Effects of temperature, molar ratios of MMA/catalyst and catalyst/cocatalyst on the polymerization have been studied. The high conversion of MMA and high molecular weight of PMMA with narrow molecular weight distribution is caused by the unique stable active site formed by the new chromium complex and aluminum cocatalyst.

Synthesis, characterization, and thermal behavior of some new biological-active zinc halide/pseudohalide complexes

A new ligand entitled as N,N’-bis-[3-(4-dimethylaminophenyl)-allylidene]-propane-1,3-diamine(L) was synthesized and then used for preparation of a new series of zinc halide/pseudohalide complexes with general formula of ZnLX2, wherein X is chloride, bromide, iodide, thiocyanate, and azide anions. The ligand and its complexes were characterized by analytical and spectral data such as conductivity measurements, elemental analysis, FT-IR, UV–Visible, and 1H NMR spectroscopy. Elemental analyses (CHN) suggested that the reaction between ligand and zinc salts has been occurred in 1:1 molar ratio. The low values for molar conductivities of the zinc complexes indicated non-electrolyte nature for them. Spectral data confirmed that the ligand behaves as a bidentate chelate and is coordinated via nitrogen atoms of imine groups. Moreover, thermal analysis of ligand and its complexes were studied in the range of room temperature to 1,000 °C with a heating rate of 10 °C min−1. TG/DTG/DTA plots show that the ligand and its complexes are thermally decomposed via 2–4 thermal steps. In final, the ligand and its complexes were subjected to antimicrobial screening by determining of minimum inhibitory concentration (MIC) and inhibition zone of the microbial growth. Also DNA cleavage potential of all compounds was evaluated by gel electrophoresis method.

Thermal and spectroscopic study of the lanthanide 2-aminoterephthalate compounds in the solid state

Lanthanides 2-aminoterephthalate compounds were synthetized and characterized on the basis of TG–DTA data in order to study their thermal behavior, as well as to establish hydration grade and stoichiometry, while TG/FTIR system identified the gaseous products evolved during the thermal decomposition of these compounds in each step of the TG curve, in which water and carbon dioxide were the main products with a small amount of carbon monoxide and ammonia. Through the FT-IR spectroscopic data of the compounds in the solid state, information concerning the coordination mode of the carboxylate groups to the metal was provided, and by analysis of fluorescence, with excitation at 405 nm, the respective electronic transitions supported by the data reported in the literature were identified. In addition, the excitation was made for the ligand salt and acid with the aim of understanding the contribution of the ligand in the emission of the compounds. In summary, the ligand influenced on the fluorescence of lanthanide ions, being more intense for the compounds of La, Ce, Pr, and Nd, making this material interesting for optical and photonic applications.

Cu(II) and Ni(II) Complexes of Novel Three 2-{1′-Phenyl-3′-(4″-Halophenyl)-1H-Pyrazole-4-yl}-1H-Benzimidazoles: Synthesis and Structural Depiction

Novel three 2-{1′-Phenyl-3′-(4″-halophenyl)-1H-pyrazole-4-yl}-1H-benzimidazoles (HBa–c) synthesized by the condensation of o-phenylenediamine and substituted-1H-pyrazole aldehydes in the presence of H2O2 through Ceric ammonium nitrate in catalytic amount and the nonchelated monodentate benzimidazoles complexes of 2-{1′-Phenyl-3′-(4″-halophenyl)-1H-pyrazole-4-yl}-1H-benzimidazoles were synthesized with a choice of metal salts in 2:1 mole ratio of ligand and metal salts, respectively, in ethanolic solution. The confirmed structures and characteristics of complexes were in good agreement with various physicochemical studies. The monodentate behavior of the ligands was proposed on the basis of spectral studies. The newly synthesized complexes possess octahedral and tetrahedral, square pyramidal and square planar geometry.

Ethylene (co-)polymerization by long-lifetime half-sandwich zirconium catalyst bearing a [SSO]-carborane ligand

Half-sandwich zirconium complex 3 containing tridentate carborane [S,S,O] ligand 2 [(HOC6H2R2-4,6)(CH2)SC(B10H10) C(Ph)2P=S, R= t Bu] was synthesized by the reaction of CpZrCl3 (Cp= η 5-C5H5) with sodium salt of ligand 2. Zirconium complex 3 was characterized by elemental and NMR analyses. DFT calculations were also performed on complex 3 to analyze the stereochemistry. The results from DFT calculations indicate that structure S1, in which no sulfur atom bonds to the zirconium atom, exists at the lowest energy level. In the presence of methylaluminoxane (MAO), complex 3 exhibited good catalytic activities for ethylene polymerization and long life-time up to 10 h. Moreover, the complex 3/MAO system displayed excellent catalytic activities toword ethylene copolymerization with 1-hexene or polar olefins.

Di‐ and Tetranuclear Complexes of Bis‐Tetradentate Pyrimidine‐Based Ligands with All‐Methylene‐ Versus Mixed Methylene/Ethylene‐Linked Arms

Eleven dinuclear and six tetranuclear complexes of two bis-tetradentate ligands, 4,6-bis[N,N-bis(2???-pyridylmethyl)aminomethyl]-2-phenylpyrimidine (LMe) and 4,6-[(2???-pyridylmethyl)(2???-pyridylethyl)aminomethyl]-2-phenylpyrimidine (LMix), have been prepared through reactions of ligand and metal salt in a ratio of 1:2 in MeCN or MeOH: FeII2LMe(H2O)4(MeCN)2(BF4)4 (1), FeII2LMix(H2O)4(BF4)4 (2), [CoII2LMe(H2O)(MeCN)](BF4)4??3/2H2O (3), [CoII2LMix(H2O)(MeCN)3](BF4)4??2H2O (4), [NiII2LMe(H2O)4](BF4)4??H2O (5), [NiII2LMix(H2O)3(MeCN)](BF4)4 (6), CuII2LMe(H2O)(MeCN)(BF4)4 (7), [CuII2Mix(MeCN)2(BF4)4] (8), [ZnII2LMe(H2O)(MeCN)3(BF4)4] (9), [ZnII2LMix(MeCN)3(H2O)(BF4)4] (10), [ZnII2LMe(H2O)2L(MeCN)2](ClO4)4 (11), FeII2FeIII2(LMe)2F4(BF4)6??1/2H2O (12), FeII4(LMix)2F4(BF4)4??5H2O (13), CoII2CoIII2(LMe)2F4(BF4)6 (14), [CoII4(LMix)2F4](BF4)4??3H2O (15), [NiII4(LMe)2F4](BF4)4 (16) and NiII4(LMix)2F4(BF4)4??8H2O (17). Dinuclear complexes were obtained from the reactions conducted in MeCN, whereas tetranuclear complexes resulted from reactions performed in MeOH. Five dimetallic (3??????6??? and 9???) and one tetrametallic complex (15???) were structurally characterized: the ligands are bis-tetradentate and the metal centres are bridged through the pyrimidine ring. In the tetrametallic 15???, two such dimetallic fragments are bridged by two pairs of fluoride anions. Variable-temperature magnetic susceptibility measurements and Heisenberg fitting of dinuclear 1???8 and tetranuclear 13???15 in all cases revealed weak intramolecular anti-ferromagnetic exchange coupling between the high-spin metal centres. A rigorous spin???orbit and exchange analysis was also performed on the dicobalt(II) complex 4. The dicopper(II) complexes 7 and 8 underwent a two-electron quasi-reversible reduction (CuII2 ??? CuI2), in both cases at a more negative potential (7: Em = ???0.18 V; 8: Em = ???0.19 V vs. 0.01 M AgNO3/Ag) than the analogous LEt (all-ethylene-armed ligand) complex (Em = +0.11 V vs. 0.01 M AgNO3/Ag), consistent with LMe and LMix being better able to stabilize copper(II) than LEt.

A 2D coordination polymer based on Co3-SBU showing spin-canting ferromagnetic behaviour

A 2D MOF with the secondary building unit [Co3(CTC)6(Py)2(OH)2] is synthesized using the sodium salt of a flexible ligand, cis,cis-cyclohexane-1,3,5-tricarboxylate (Na-CTC), and a cobalt trimer ([Co3O(CH3COO)6(Py)3]·ClO4). Structural analysis shows that the complex crystallizes in the monoclinic space group P21/n and forms a 2D framework with channel sizes of 9.0 × 4.2 A2. Magnetic characterization shows spin-canting ferromagnetic behaviour at low temperatures. Frequency dependency for in-phase (χ′M) and out-of-phase (χ′′M) signals at low temperatures is observed from the AC measurements. The gas adsorption behaviour suggests selectivity towards CO2 over N2, and demonstrates enhancement of CO2 uptake (19–33 cm3 g−1) on lowering the temperature (273–195 K).

Syntheses and Characterization of Samarium and Erbium Borohydrido Complexes Supported by N‐Aryliminopyrrole Ligand

AbstractReaction of potassium salt of N‐aryliminopyrrole ligand [2‐(2, 6‐iPr2C6H3N=CH)–C4H3NK] (1) with samarium tris‐boro‐hydride [Sm(BH4)3(THF)3] gave a samarium ate complex [η2‐{2‐(2, 6‐iPr2C6H3N=CH)–C4H3N}3Sm(η1‐BH4){K(THF)6] (2); whereas similar treatment with erbium borohydride [Er(BH4)3(THF)3] afforded the mono(iminopyrrolyl) complex [η2‐{2‐(2, 6‐iPr2C6H3N=CH)–C4H3N}Er(η3‐BH4)2(THF)2] (3). In the solid‐state structures, the samarium complex 2 shows a rarely observed η1 and the erbium complex 3 shows a usual η3 coordination mode of the borohydrido ligand.

New Supramolecular Triorganotin(IV) Dithiocarboxylates as Potential Antibacterial Agents

ABSTRACTFour triorganotin derivatives of general formula C10H10NS2SnR3,, where R = CH3 (1), C4H9 (2), C6H11 (3), and C6H5 (4), have been synthesized by the metathesis reaction of 1,2,3,4‐tetrahydroisoquinolnium salt of ligand with triorganotin(IV) chloride in the 1:1 ratio. These complexes were characterized by elemental analysis, Raman, IR, multinuclear NMR (1H, 13C, and 119Sn), and mass spectrometry. The crystal structure confirmed a supramolecular zig‐zag chain structure mediated by S–H (2.968 Å) for complex 4 with the central Sn atom exists in a distorted trigonal bipyramidal geometry. A subsequent antibacterial study indicates that the compounds are biologically active.

Regioselective reactions of electrophilic iron dicarbonyl cations, [(η5-C5R5)(CO)2Fe]+ (R = H, CH3) with heterofunctional amine ligands

The reactions of the ether salts [(η5-C5R5)(CO)2Fe(E)]BF4, (R = H, E = Et2O; R = CH3, E = THF) with various ligands possessing two different coordination sites have been investigated. It was established that [(Cp(CO)2Fe(OEt2)]BF4 (Cp = η5-C5H5), 1, and [Cp*(CO)2Fe(THF)]BF4 (Cp* = η5-C5(CH3)5), 2, react with 1-aminopropanol, 4-methoxybenzylamine and 3-aminopropyltriethoxysilane to give only mononuclear complexes of the type [(η5-C5R5)(CO)2Fe(L)]+, irrespective of the reactant ratios. On the other hand, the reaction of 1 with one equivalent of 4-aminobenzonitrile (ABN) furnished both mononuclear and dinuclear complexes, [Cp(CO)2Fe(ABN)]+ and [{Cp(CO)2Fe}2(μ-ABN)]2+ isolated as tetrafluoroborate salts, with the mononuclear complex being the major product. The reaction of [(η5-C5R5)(CO)2Fe(E)]BF4 with 1,4-phenylenedimethanamine (PDA) afforded only the dinuclear complex [{(η5-C5R5)(CO)2Fe}2(μ-PDA)]2+ regardless of the reactant ratios. The reaction of 2 with one equivalent of the compound [Cp(CO)2Fe(ABN)]BF4 gave the mixed ligand salt [Cp(CO)2Fe(ABN)Fe(CO)2Cp*](BF4)2. The reactions of dipropylamine with [Cp(CO)2Fe(OEt2)]BF4 gave the dipropylamine salt [Cp(CO)2Fe{NH(CH2CH2CH3)2}]BF4. All these compounds are reported for the first time and have been fully characterized by 1H NMR, 13C NMR, IR spectroscopy and elemental analysis. Molecular structures of [Cp(CO)2Fe{NH(CH2CH2CH3)2}]BF4, [Cp*(CO)2Fe{NH2(CH2)2CH2OH}]BF4 and [Cp*(CO)2Fe(NH2C6H4OCH3)]BF4 have been confirmed by single crystal X-ray crystallography.

Design and Synthesis of a Functional Derivative of the Triazinium Cation and Its Rhodium Complex that Shows Photoinduced DNA Cleavage Activity and Photocytotoxicity

AbstractThe design and synthesis of an intensely blue rhodium(III) complex [3]+ of a new N,N‐donor ligand, 8‐(quinolin‐8‐ylamino)pyrido[2,1‐c][1,2,4]benzotriazin‐11‐ium, [2]+, which contains a planar pendant triazinium arm, is described. Structural characterization for [3]+ was carried out by using various spectroscopic techniques and single‐crystal X‐ray crystallography. The organometallic rhodium(III) compound shows a ligand‐based reversible reduction at –0.65 V. The electrochemically reduced compound displays a single‐line EPR spectrum that signifies the formation of ligand‐based free radicals. Compound [3]+ shows a binding propensity to calf thymus DNA to give a Kapp value of 6.05 × 105 M–1. The parent triazinium salt, pyrido[2,1‐c][1,2,4]benzotriazin‐11‐ium [1]+ and the ligand salt [2]+ exhibit photoinduced cleavage of DNA in UV‐A light, whereas the reference Rh complex [3]+ photocleaves DNA with red light (647.1 nm). The compounds show photonuclease activities under both aerobic and anaerobic conditions. Mechanistic investigations under aerobic conditions with several inhibitors indicate the formation of hydroxyl radicals by means of a photoredox pathway. Under anaerobic conditions, it is believed that a photoinduced oxidation of DNA mechanism is operative. Compound [3]+ exhibits photocytotoxicity in HeLa cervical cancer cells to give IC50 values of (12 ± 0.9) μM in UV‐A light at 365 nm and (31.4 ± 1.1) μM in the dark.

Axial Functionalization of Sterically Hindered Titanium Phthalocyanines

Several axially functionalized, weakly aggregating titanium phthalocyanines (Pc) have been synthesized and characterized. Soluble titanium dichlorido tetrakis-(1,1,4,4-tetramethyl-6,7-tetralino)-porphyrazine [Pc(#)TiCl(2)] (5) has been prepared by reductive cyclotetramerization of the respective dinitrile precursor in the presence of TiCl(4). 5 and the analogous oxido compound [Pc(#)TiO] (1) are versatile starting materials for the formation of other axially functionalized titanium phthalocyanines such as organoimido (6, 7), alkoxido and aryloxido (8, 9), peroxido (10), sulfido (12), disulfido (11), selenido (14) or diselenido (13) species. Furthermore the deprotonated ligand salts [Pc(#)M(2)] (M = Li (2), Na (3), K (4) are described. The reactivity of the titanium compounds was studied in atom group transfer reactions and ethene polymerization. The crystal structures of 5 and the free ligand Pc(#)H(2) are reported. 5 crystallizes from dichloromethane in the cubic space group Im3. The two chlorido ligands exhibit a cis arrangement. The free ligand Pc(#)H(2) crystallizes in the trigonal space group R3.

Synthesis and magnetic properties of a series of 3d/4f/3d heterometallic trinuclear complexes incorporating in situ ligand formation

The dicyanonitrosomethanide (dcnm) ligand undergoes an in situ transition metal promoted nucleophilic addition of methanol to a nitrile group to form cyano(imino(methoxy)methyl)nitrosomethanide (cmnm) in the formation of the 3d/4f heterometallic complexes (Me4N)[{Ni(cmnm)3}2Ln(cmnm)2] (1Ln; 1Ln=1La, 1Ce, 1Pr, 1Nd, 1Sm). A change in the counter-ions of the metal and ligand salts employed under alternate reaction conditions results in the formation of (Et4N)2[{Ni(cmnm)3}2Ln(dcnm)2](ClO4) (2Ln; 2Ln=2La, 2Ce), in which unreacted dcnm ligands are coordinated to the central lanthanoid. In both types of complexes three cmnm ligands chelate to a nickel metal centre to form a [Ni(cmnm)3] metalloligand. Two of these metalloligands are then bound to a central lanthanoid via the nitroso oxygen atoms, resulting in a trinuclear complex in which each nickel cation is connected to the lanthanoid by three bridging nitroso groups. Variable temperature magnetic susceptibilities on these {Ni(S=1), Ln(f0 to f5), Ni(S=1)} spin systems reveal very weak to zero Ln–Ni or Ni–Ni exchange coupling with the thermal depopulation between Stark levels on the Ln centres being of similar magnitude, and the Ni2Ce and Ni2Pr cases giving strongest evidence for exchange coupling.