The copolymerization of ethene and carbon monoxide can be catalyzed with square planar arenidotriphenylphosphane nickel(II) complexes containing an N,O -chelate ligand. To examine the influence of the phosphorus ligand on the catalytic activity, five new nickel(II) complexes with P -ligands of different basicities and different steric demands were synthesized and fully characterized including the determination of the crystal structures of three of the complexes. The investigation of the catalytic activity of the new compounds showed a decisive influence of the steric properties of the P -ligand. A minimum steric demand is essential to ensure catalytic activity.

Square planar arenido(triphenylphosphane)nickel(II) complexes containing a heterocyclic bidentate N,O-chelate ligand are catalysts for the copolymerisation of ethene and carbon monoxide. To examine the influence of the N,O-ligand on the catalytic activity new nickel(II) complexes with altered heterocyclic ring size in the corresponding N,O-ligands were synthesised and fully characterised. The crystal structures of all protonated N,O-ligands and the corresponding nickel complexes were determined. The catalytic activity of the new complexes in the copolymerisation reaction of ethene and carbon monoxide as well as in the polymerisation reaction of ethene were studied.

The influence of different heteroaryl and functionalized aryl substituents on the electron-donating ability and basicity of the phosphorus atoms in heteroaryl phosphines and diphosphines has been determined by the use of the direct (1)J(PSe) coupling constants of the corresponding selenides. The generality of the use of P-31-Se-77 spin-spin coupling constants as probe for the basicity of phosphines is discussed as well as the scope and limits of this concept.

The square planar Ni complex (SP-4-3)-[Ni(2-tol)(PPh3)(N,O)] (N,O=(Z)-4,4,5,5,6,6,6-heptafluoro-3-oxo-2-(pyrrolidine-2-ylidene)-hexanenitrile) is an active catalyst for the co-polymerisation of CO and ethene yielding aliphatic polyketone. Addition of Lewis acids like BPh3 or B(C6F5)3 as co-catalyst accelerates the polymerisation but not the lifetime of the catalyst and leads to a mixture of polyethylene and polyketone. Addition of the Lewis base triphenylphosphane (PPh3) completely suppresses the formation of polyethylene. The polymers formed were characterised by IR spectroscopy, 13C cross polarisation (CP) magic angle spinning (MAS) solid state NMR spectroscopy, differential scanning calorimetry (DSC) and size exclusion chromatography (SEC).

Planar chiral and achiral arenido(triphenylphosphane)nickel(II) complexes (arenido = mesitylenido, 2-toluenido) comprising electronically delocalised N,O chelating ligands were studied by H-1 and F-19 NMR using 1D and 2D techniques. Results from complexes and corresponding ligands are discussed in the light of molecular structures obtained from X-ray diffraction.

Planar chiral and achiral arenido(triphenylphosphane)nickel(II) complexes (arenido = mesitylenido, 2-toluenido) comprising electronically delocalised N,O chelating ligands were studied by 1H and 19F NMR using 1D and 2D techniques. Results from complexes and corresponding ligands are discussed in the light of molecular structures obtained from X-ray diffraction. GRAPHICAL ABSTRACT

Nickel(II) complexes comprising electronically delocalised N,O-chelating ligands are active catalysts in the copolymerisation of carbon monoxide and ethene. Elucidating the mechanism of catalysis presupposes the basic understanding of the intramolecular flexibility of such transition metal complexes. Several nickel(II) complexes with or without planar chirality were synthesised and characterised by NMR spectroscopic techniques and X-ray diffraction.

Breath gas analysis offers fascinating new opportunities as it is completely noninvasive and provides a unique window to various biochemical processes in the organism. Requirements for clinical application of this innovative technique include on site and point of care applicability. As most analytical methods like sensors are often not fast enough to realize breath-to-breath sampling additional effort is necessary to provide breath samples of well defined and reproducible composition. For that purpose, we built an automatic CO 2 controlled device from standard industrial components that enables adjustable breath sampling in any phase of expiration. Control of sampling was realized by fast responding infrared CO 2 sensors. The electrical signal of these sensors was used to trigger a micro pump and a valve. In order to render the device as versatile as possible direct coupling with sensors as well as continuous or discrete sampling via a sample loop or traps was possible. CO 2 concentrations, gas flow, and sample volumes were continuously recorded. Reliability and reproducibility of the device were evaluated and compared with an already established and validated manual sampling method. Alveolar concentrations of selected volatile organic compounds (VOCs) were determined in the corresponding samples taken in rest and during treadmill exercise. Substance concentrations of breath biomarkers in the automatically and manually collected alveolar samples were identical. Reliable sampling was possible with the automatic device up to respiratory rates of 40/min. Controlled and versatile alveolar sampling represents an indispensable requirement of application of most analytical methods and sensor technology in breath analysis.

Square planar arenido-(triphenylphosphane)nickel(II) complexes (3) containing a N,O-chelate ligand are catalysts for the carbon monoxide/ethene copolymerisation reaction. Pathways for catalyst deactivation have been elucidated by investigating the reactions of such complexes with aliphatic unsaturated compounds like olefins and alkynes. We have shown that the double or triple bond, respectively, inserts into the nickel-carbon bond followed by beta-hydride elimination resulting in aryl-substituted olefins and allenes, which have been identified by means of GC/MS. The remaining nickel forms a bis(N,O-chelate ligand)nickel complex, the crystal structure of which has been determined The nickel atom is coordinated in a square-planar manner by two ligands. Additional coordination of two neighbouring complexes via their nitrile groups completes the coordination of the nickel to a distorted octahedron and forms a two-dimensional metal-organic framework (MOP).

Polyketones are synthesised by a transition-metal-catalysed copolymerisation of olefins and carbon monoxide. Nickel complexes with N,O-chelating ligands turned out to be promising catalysts in that field. In this work a series of new N,O ligands with an electronically delocalised β-enaminone backbone were synthesised and fully characterised. The ligand design was inspired by the ligand found in the most efficient nickel catalyst for polyketone synthesis and developed to a highly modular LEGO®-like arsenal of reactions to versatile substituted β-enaminone ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

The synthesis and characterization of sodium 3,5-diacetyl-1,2,4-triazolate (4 Me ) and sodium 3,5-dibenzoyl-1,2,4-triazolate (4 Ph ), both of which can be used as head unit building blocks in Schiff-base reactions, are reported. The crystal structures of sodium 3,5-diacetyl-1,2,4-triazolate, as [4 Me (H2O)]∞, and sodium 3,5-dibenzoyl-1,2,4-triazolate, as [4 Ph (CH3OH)2]2, have been determined. The former is a helical polymer whilst the latter is a methanol-bridged dimer. The lead(II) templated cyclization reaction of sodium 3,5-dibenzoyl-1,2,4-triazolate (4 Ph ) with 1,3-diaminopropane or 1,4-diaminobutane, respectively, leads to the formation of two new [2 + 2] Schiff-base macrocycles as their lead(II) complexes, [Pb2 L 3Ph (μ-OH)]ClO4 (5) and [Pb2 L 4Ph (μ-OH)]ClO4 (6), respectively. Transmetallation of 5 with nickel(II) ions yields a novel, structurally characterized, dinickel(II) macrocyclic complex, [Ni2 L 3Ph (NCS)2] (7), which features double triazolate bridging of the two five-coordinate nickel(II) ions.

The structure of the cocrystallized 1:1 adduct of (S,S)-4-amino-3,5-bis(1-hydroxyethyl)-1,2,4-triazole and (S,S)-1,2-bis(2-hydroxypropionyl)hydrazine, C6H12N4O2.C6H12N2O4, has tetragonal symmetry. All eight O- and N-bound H atoms are involved in intermolecular hydrogen bonds, resulting in infinite zigzag chains of the triazole molecules, with the hydrazine molecules filling the gaps between the chains and completing a three-dimensional hydrogen-bonded array.

The structure of the cocrystallized 1:1 adduct of ( S , S )-4-amino-3,5-bis­(1-hydroxy­ethyl)-1,2,4-triazole and ( S , S )-1,2-bis­(2-hydroxy­propionyl)­hydrazine, C 6 H 12 N 4 O 2 ·C 6 H 12 N 2 O 4 , has tetra­gonal symmetry. All eight O- and N-bound H atoms are involved in inter­molecular hydrogen bonds, resulting in infinite zigzag chains of the triazole mol­ecules, with the hydrazine mol­ecules filling the gaps between the chains and completing a three-dimensional hydrogen-bonded array.

The synthesis and characterisation of two dicopper(II) and two dinickel(II) macrocyclic complexes, [CuII2LPr] (10), [CuII2LBu] (11), [NiII2LPr] (12) and [NiII2LBu] (13), are reported. The two new Schiff-base macrocycles (LPr)4− and (LBu)4− are isolated as dimetallic complexes 10–13 by the [2+2] condensation of 5,5-dimethyl-1,9-diformyldipyrromethane (9) and 1,3-diaminopropane or 1,4-diaminobutane, respectively, using Cu2+ or Ni2+ template ions. Single crystal X-ray structure determinations carried out on 10–13 show that each metal atom is in a square planar N4 geometry, being bound to two deprotonated pyrrole nitrogen atoms of one dipyrromethane unit and to the two adjacent imine nitrogen atoms. NMR spectra obtained for the two dinickel(II) complexes 12 and 13 show that in CDCl3 solution they are highly symmetrical and diamagnetic.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The electronic structure of the dimeric iron complex [Fe2(bbpo)Cl4] n− with the tetranionic ligand 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenyl)oxamide was studied in two different oxidation states. Combined Mössbauer and EPR investigations in conjunction with magnetic susceptibility measurements are used to demonstrate the complementarity of the techniques. The dianion [Fe2(bbpo)Cl4]2−(2) is a high-spin iron(III) compound with magnetic properties resulting from competing exchange and zero-field interactions of the iron sites. Unusual integer-spin EPR spectra could be recorded from an excited spin septet, S t=3, of the coupled system. Electrochemical oxidation yields the monoanion [Fe2(bbpoox1)Cl4]− (2 ox ) which also is an iron(III) compound; the ligand is redox non-innocent and forms a π radical that is bound to one of the iron centers and the total spin S t=1/2 ground states of the molecule originates from exchange coupling of the three paramagnetic centers. A simplified spin coupling scheme assuming infinitively strong radical-iron(III) interaction yields a reasonable and rational interpretation of the magnetic and electronic properties of 2 ox .

The new triazolate-containing Schiff-base macrocyclic ligand L22− has been synthesised as [PbII2(L2)](ClO4)2, 1, by the [2 + 2] cyclisation reaction of 3,5-diacetyl-1H-1,2,4-triazole and 1,3-diaminopropane using lead(II) template ions. The macrocycle provides four nitrogen atoms, two imine and two triazolate donors, as equatorial donor atoms to each of the two metal ions in the macrocycle. A series of copper(II) complexes of the L22− macrocycle has been produced with a variety of axial donors. Each copper complex has been structurally characterised by X-ray diffraction and three different structural types can be distinguished: monomeric, trimeric and polymeric. These different types arise from adding a different ratio of thiocyanate ions to the copper(II) transmetallation reaction of [PbII2(L2)](ClO4)2 (1). The monomeric dicopper(II) macrocyclic complexes include [CuII2(L2)(NCMe)2](ClO4)2 (2) and [CuII2(L2)(NCS)2] (3). The trimeric complex {[CuII2(L2)]3(NCS)2}(ClO4)4 (4) consists of three dicopper(II) macrocyclic complexes bridged by two thiocyanate ions. The thiocyanate-bridged polymeric complex {[CuII2(L2)(NCS)][CuII2(L2)(SCN)](ClO4)2}x (5) comprises two types of macrocyclic units in the repeating unit. A second polymeric isomer {[CuII2(L2)(NCS)](ClO4)}x (6), incorporating a more symmetrical thiocyanate-bridging mode that has only one type of macrocyclic unit in the repeating unit, is also reported.

A new Schiff-base macrocycle is obtained by the lead(II) ion templated [2+2] condensation of 3,5-diacetyl-1H-1,2,4-triazole and 1,4-diaminobutane in the presence of sodium hydroxide. Transmetallation of the resulting dilead complex, Pb2(L2)(ClO4)21, in acetonitrile with two equivalents of CoCl2·6H2O leads to the isolation of an orange, six-coordinate complex, [CoII2(L2)(OH2)3(NCCH3)](ClO4)2·H2O·2CH3CN 2. Subsequent reaction of 2 with two equivalents of NaOCN or NEt4Cl yielded red–purple five-coordinate [CoII2(L2)(NCO)2] 3 and red five-coordinate [CoII2(L2)(Cl)2]·1.5CH3CN 4, respectively. In all three air-stable dicobalt complexes the macrocycles contain two high-spin cobalt(II) centers which are weakly antiferromagnetically coupled (2J = −3.0, −0.4, −3.5 cm−1 for 2, 3 and 4, respectively). Complexes 2–4 have been characterized by X-ray diffraction and are the first structurally characterised complexes of a triazolate-containing macrocycle to date.

Structurally characterised cobalt(II) complexes containing pyridazine, triazole or triazolate ligands are the subject of this review. Firstly a brief introduction to Schiff-base macrocyclic chemistry is given and then the crystal structures and magnetic properties of pyridazine-containing cobalt(II) complexes are discussed, focussing on macrocyclic complexes. There follows a discussion of the crystal structures, as well as the magnetic behaviour where known, of cobalt(II) complexes containing the triazole moiety in a N1,N2-bridging fashion. Finally an overview of reported complexes where the triazole unit has been incorporated into a Schiff-base macrocyclic framework is provided. None of these triazole-containing macrocyclic complexes has been structurally characterised.

The dinucleating ligand 1,2-bis(3,5-di-tert-butyl-2-hydroxyphenyl)oxamide [H-4(bbpo)] has been synthesized. From its reaction with GaCl3 or FeCl3 in CH3OH/NaOH the salts [N(nBu)(4)](2)[M-2(111)(bbpo)Cl-4] [M = Ga (1), Fe (2)] have been isolated as crystalline solids upon addition of [N(nBu)4]Cl. Complexes 1 and 2 have been characterized by single-crystal X-ray crystallography. Cyclic voltammetry established that both species undergo two successive, reversible one-electron oxidations in CH2O2 {0.10 m [N(nBu)(4)]PF6} which are shown to be ligand-centered: one and then two N,O-coordinated o-iminobenzosemiquinonate pi-radicals form which couple antiferromagnetically with the high-spin ferric ions in 2. Thus, the monoanion of 2 has an S-t = 1/2 ground state. The complexes have been characterized by Mossbauer, UV/Vis, and EPR spectroscopy. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).