Bis{2,6-bis­[(2-hy­droxy-5-methyl­phen­yl)imino­meth­yl]pyridine} monohydrate

The title compound, 2C21H19N3O2·H2O, was synthesized by a Schiff base condensation of 2,6-diformyl­pyridine with 2-amino-4-methyl­phenol in ethanol. In the crystal, two mol­ecules of 2,6-bis­[(2-hy­droxy-5-methyl­phen­yl)imino­meth­yl]pyridine dimer­ize via hydrogen bonding to a water mol­ecule, which lies on a twofold axis. There are also intra­molecular phenol–imine hydrogen bonds. The dimers are further linked via π–π (phen­yl–pyridine) [centroid–centroid distance = 3.707 (2) Å] and π–π edge-to-edge [3.392 (2) Å] inter­actions. The dihedral angles between the central ring and the two pendant rings are 11.46 (8) and 2.06 (8)° while the pendant rings make a dihedral angle of 10.14 (8)°

Bis{tris[2-(2-oxidobenzylideneazaniumyl)ethyl]amine-κ3 O,O′,O′′}calcium bis(perchlorate) acetonitrile disolvate

The title complex, [Ca(C27H30N4O3)2](ClO4)2·2CH3CN, is composed of centrosymmetric (CaL2)2+ cations [L = tris­(2-hy­droxy­benzoyl­amino­eth­yl)amine = H3saltren], uncoordin­ated perchlorate anions and acetonitrile solvent mol­ecules. The calcium ion is six-coordinated and is bonded to all phen­oxy O atoms from both zwitterionic saltren mol­ecules. There are strong intra­molecular N—H⋯O hydrogen bonds. The cations are linked into chains via weak inter­molecular C—H⋯O hydrogen bonds and C—H⋯π and π–π stacking inter­actions [centroid–centroid distances = 3.306 (3) and 3.415 (3) Å]

Spirobicyclic Diamines. Part 3: Synthesis and Metal Complexation of Proline-Derived [4,4]-Spirodiamines.

The syntheses of racemic and homochiral [4.4]-spirolactams, starting from L-proline, in good yields are described. Reduction of the lactam carbonyl group of spirolactams, containing chiral substituents on the lactam nitrogen, with lithium aluminium hydride, gives a series of homochiral [4.4]-spirodiamines. The crystal structure of one of these spirodiamines on complexation with zinc chloride was obtained. Interestingly it showed a hydrogen-bonded dimeric structure, where the monomers are diastereoisomeric diamines

A coordinatively flexible hexadentate ligand gives structurally isomeric complexes M-2(L)X-3 (M = Cu, Zn; X = Br, Cl)

Polypyridyl multidentate ligands based on ethylenediamine backbones are important metal-binding agents with applications in biomimetics and homogeneous catalysis. The seemingly hexadentate tpena ligand [systematic name: N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetate] reacts with zinc chloride and zinc bromide to form trichlorido[mu-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dizinc(II), [Zn-2(C22H24N5O2)Cl-3], and tribromido[mu-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dizinc(II), [Zn2Br3(C22H24N5O2)]. One Zn-II ion shows the anticipated N5O coordination in an irregular six-coordinate site and is linked by an anti carboxylate bridge to a tetrahedral ZnX3 (X = Cl or Br) unit. In contrast, the Cu-II ions in aquatribromido[mu-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dicopper(II)-tribromido[mu-N,N,N'-tris(pyridin-2-ylmethyl)ethylenediamine-N'-acetato]dicopper(II)-water (1/1/6.5) [Cu2Br3(C22H24N5O2)][Cu2Br3(C22H24N5O2)(H2O)]center dot 6.5H(2)O, occupy two tpena-chelated sites, one a trigonal bipyramidal N3Cl2 site and the other a square-planar N2OCl site. In all three cases, electrospray ionization mass spectra were dominated by a misleading ion assignable to [M(tpena)](+) (M = Zn2+ and Cu2+)

Structure-Reactivity Relationships of L-Proline Derived Spirolactams and a-Methyl Prolinamide Organocatalysts in the Asymmetric Michael Addition Reaction of Aldehydes to Nitroolefins.

L-Proline derived spirolactams and a-methyl prolinamides act as organocatalysts for the asymmetric conjugate addition of aldehydes to nitroolefins in excellent yields, with good diastereoselectivity and enantioselectivity. Furthermore, low catalyst loadings (5 mol%) and a low aldehyde molar excess (1.5 molar equivalents) were achieved

Comparison of copper imine and amine podates: geometric consequences of podand size and donor type

The imine podands tris[(2-nitrobenzylidene)aminoethyl]amine and tris[(2-nitrobenzylidene)aminopropyl]amine both stabilize copper(I), forming {tris[(2-nitrobenzylidene)aminoethyl]amine-κ4 N}copper(I) perchlorate aceto-nitrile disolvate, [Cu(C27H27N7O6)]ClO4.2CH3CN, (II), and {tris[(2-nitrobenzylidene)aminopropyl]amine-κ4 N}copper(I) perchlorate, [Cu(C30H33N7O6)]ClO4, (VI), respectively. The larger propyl-based ligand is a poorer fit for the CuI ion. The reduced amine podand tris[(2-nitrobenzyl)aminoethyl]amine binds CuII and the resulting compound, chloro{tris[(2-nitrobenzyl)aminoethyl]amine-κ4 N}copper(II) chloride ethanol solvate, [Cu(C27H33N7O6)Cl]Cl.C2H5OH, (IV), shows both intra- and inter-molecular hydrogen bonding, which gives rise to RRS or SSR conformations in the podand strands rather than the expected pseudo-threefold symmetry

Structure-reactivity Studies of Simple 4-hydroxyprolinamide Organocatalysts in the Asymmetric Michael Addition Reaction of Aldehydes to Nitroolefins

A series of simple 4-hydroxyprolinamides was synthesised and they were found to act as organocatalysts for the asymmetric conjugate addition of aldehydes to nitroolefins in excellent yields (98%), with complete diastereoselectivity (99:1, syn:anti) and enantioselectivity (98% e.e. for syn). Furthermore, the use of low catalyst loadings (5 mol%) and a low aldehyde molar excess (1.5 equivalents) were achieved

Mixtures obtained by reacting trans-(�)-1,2diaminocyclohexane with acetylacetone in the presence of simple cobalt(II) salts.

In the absence of a metal ion, racemic trans-1,2-diaminocyclohexane (trans-(�)DCH) reacts with acetylacetone (acacH) (1:2.5 mole ratio) to form the bisoxoenamine condensation product, boe (1). CoCl2·6H2O and Co(ClO4)2·6H2O each react with trans-(�)DCH in air to give complexes containing the oxidised Co(III) ion, [Co((�)DCH)3]3+, which does not subsequently react with added acacH to give a Schiff base complex. Mixtures of complexes are obtained from one-pot reactions involving trans-(�)DCH, a simple Co(II) salt and acacH (1:1:2.5 mole ratio). When CoCl2·6H2O is used, the mixed-ligand Co(II) complex [Co((�)DCH)Cl2] (4) precipitates first and, after a period of weeks, the Co(II) complex (diazH)2[CoCl4] (5) (diazH+ is a diazepinium cation), the Co(II) complex [Co(boe)Cl2]n (6) and the Co(III) complex [Co(acac)3] (7), co-crystallise from the mother liquor. Using Co(ClO4)2·6H2O in the reaction with trans-(�)DCH and acacH also gives a mixture of products. Complexes 7, the Co(II) complex [Co2(acac)4(H2O)2][Co(acac)(H2O)4]ClO4·EtOH (8) and the Co(III) complex [Co(acac)2(�)DCH]ClO4 (9) co-crystallise. Complexes 1, 5, 7, 8 and 9 were characterised using X-ray crystallography. The major difference between using CoCl2·6H2O and Co(ClO4)2·6H2O in reactions involving (�)DCH and acacH is that no DCH/acacH condensation products are identified in the product mixtures when the perchlorate salt is employed

Ethyl 5-acetyl-2-amino-4-methyl­thio­phene-3-carboxyl­ate

In the title compound, C10H13NO3S, prepared in a one-pot reaction, the mol­ecular conformation is stabilized by an intra­molecular N—H⋯O hydrogen bond. The packing is consolidated by further N—H⋯O links. The H atoms of two of the methyl groups are disordered over two sets of sites with equal occupancies

Synthesis and Characterisation of Macrocycles Containing both Tetrazole and Pyridine Functionalities

The syntheses of tetra-tetrazole macrocycles containing at least one 2,6-bis(tetrazole)pyridine unit, linked by a variety of n-alkyl (n = 3, 5, 7 or 9 carbon atoms) chain lengths, are described. There has been no previous incorporation of the pyridine moiety into a tetra-tetrazolophane macrocycle. The crystal structure of one such tetra-tetrazole macrocycle has also been structurally characterised and revealed a bowl-shaped conformation