Xiaolan Kou

SYNTHESES, CRYSTAL STRUCTURES AND COORDINATION COMPOUNDS OF SOME 2-HETARYLCYANOXIMES

Abstract 2-hetarylcyanoximes which have the general formula HO–NC(CN)–R, where R is a heterocyclic group such as 2-pyridyl, 2-quinolyl, 2-benzthiazolyl etc., have been found to be good multidentate ligands for coordination chemistry. They form intensely colored complexes with iron(II) and bis-compounds with copper(I), which are used in analytical chemistry. Stability constants for anionic Fe2+ tris-cyanoximates were determined. The detailed syntheses and crystal structures of 2-pyridilcyanoxime (HPCO), 2-quinolylcyanoxime (HQCO) and 2-thiazolylcyanoxime (HTLCO) are reported. Molecules of HPCO in the crystal state adopt a non-planar cis–anti conformation. HQCO crystallizes as a monohydrate and this cyanoxime has a trans–anti non-planar conformation in the solid state. Molecules of HTLCO showed a trans–syn planar conformation in the solid state. Crystal structures of other known cyanoxime ligands are reviewed, as well as syntheses and the coordination modes for 2-hetarylcyanoximes in various complexes with s-, p- and d-metals.

Azacrown ethers containing oximic and Schiff base sidearms - potential heteronuclear metal ion receptors

Abstract A simple synthetic pathway for the preparation of oxime- and Schiff base-containing aza- and diazacrown ethers is reported. N-Methoxymethyl-substituted aza-15-crown-5 and aza-18-crown-6 as well as N,N′-bis(methoxymethyl)-substituted diaza-18-crown-6 were treated with 5-bromosalicylaldehyde to produce the N-(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted aza-15-crown-5 (8), aza-18-crown-6 (9) and N,N′-bis(2′-hydroxy-3′-carbonyl-5′-bromobenzyl)-substituted diaza-18-crown-6 (10) compounds. Compounds 8 and 10 were treated with hydroxylamine to give oxime-substituted ligands 12 and 13. A series of bis-Schiff base-containing diaza-18-crown-6 ligands were prepared by reacting 10 with 2-hydroxyaniline (to form 14), 5-nitro-2-hydroxyaniline (15), 2-aminopyridine (16), 2-hydrazinopyridine (17) and N-aminomorpholine (18). Compounds 12–18 are potential complexing agents for simultaneous binding of soft transition and hard alkali or alkaline earth metal ions in one molecule. These new oxime- and Schiff base-containing ligands interacted strongly with Na+ and K+ in methanol. The interaction of the aromatic portions of 9, 10, and 12–15 with transition metal ions was shown by the UV spectra of the metal ion complexes in 50% aqueous DMF. The X-ray structure of 10 is reported.

The double helical binuclear cooper complex of 6,6⁗ dimethyl-4′, 4‴ diphenyl-quinquepyridine and monohelical cadmium complex of 6,6⁗-dimethylquinquepyridine. Syntheses, crystal and molecular structure of [Cu2 (L2)2] [ClO4]3 · 2CH3CN and [CdL1] [ClO4]2

Abstract The binuclear copper complex of 6,6⁗-dimethyl-4′,4‴-diphenylquinquepyridine L2 and the mononuclear cadmium complex of 6,6⁗-dimethyl-quinquepyridine L1 have been prepared by the reaction of L2 with Cu(ClO4)2 · 6H2O and L1 with Cd(ClO4)2 · 2H2O, respectively. These complexes were characterized by elemental analysis, IR, 1H NMR and fast atom bombardment MS spectra. X-ray crystallographic measurement reveals that a Cu1 CuII mixed valence state copper complex is obtained, in which two ligand molecules self-organized around the CuI and CuII ions to form a double helical configuration. The cadmium complex is mononuclear, has a highly symmetrical configuration and may be regarded as a monohelical compound.

A novel cyclophane–anthracene complex

Abstract A cyclophane host formed by connecting the oxygen atoms of two α,α′-di-(4-hydroxyphenyl)-1,4-diisopropylbenzene units with two pentamethylene spacers forms a unique solid-state complex with anthracene.

One- and two-step metal ion templated syntheses of the cryptands

Abstract New cryptands [3.2.1], [4.2.1] and [4.2.2] were prepared in good yields by treating the appropriate diazacrown with the ditosylate esters of triethylene, tetraethylene or pentaethylene glycol as required. Treatment of 4,10-diaza-15-crown-5 with α , α ′-dibromo- m -xylene gave a mixture of the cryptand (1:1 cyclization) and the tricyclic bisdiaza-15-crown-5 connected by two m -xylylene units (2:2 cyclization) when K 2 CO 3 was used as the base. When Li 2 CO 3 was used, the same reaction gave only the 1:1 cyclization. An 1 H NMR spectrum of the m -xylylene-containing cryptand exhibited a peak at δ 8.85 which suggests that the proton on benzene position 2 is close to the diaza-15-crown-5 cavity. The X-ray crystal structure of that compound showed that to be the case. A metal ion template effect was also observed in the preparation of [3.3.3] from 3,6,9-trioxa-1,11-diiodoundecane and its diamine analog. Only [3.3.3] was observed with K 2 CO 3 . When Cs 2 CO 3 was used, mainly a bis(aza-12-crown-4) was isolated. When the diiodide was changed to the corresponding ditosylate, both [3.3.3] and the bis(aza-12-crown-4) were isolated.

Synthesis of a New Cyclophane Host and Crystal Structures of Its Compounds with Neutral Guests

A new cyclophane host molecule 3 is prepared by connecting the oxygenatoms of twoα,α′-di(4-hydroxyphenyl)-1,4-diisopropylbenzene units withtwo trimethylene spacers. Solid-state structures are determined forcompounds of 3 with dichloromethane and p-xylene guests. The crystals of thetwo host-guest compounds are isomorphous.

Synthesis, spectra and crystal structures of complexes of ambidentate C6H5C(O)C(NO)CN–

Compounds of NiII, CuII, PbII, AgI, TlI, SnIV and SbV with the oxime C6H5C(O)C(NOH)CN (HL) were obtained from water, alcohol or acetonitrile solutions. The copper(II) complexes have been prepared in high yields using metallic copper powder. The compounds were characterized by IR, UV/VIS spectroscopy, magnetochemistry and X-ray analysis. The crystal and molecular structures of [CuL2(H2O)] and [CuL2(4-mpy)2](4-mpy = 4-methylpyridine) have been determined. In both complexes the anions adopt a cis-anti conformation, and the CuII is five-co-ordinated. The wide variety of co-ordination modes exhibited by the oximate are reviewed and discussed.

NEW FERROCENOPHANES CONTAINING A HYDROPHOBIC, AROMATIC POCKET

Five novel ferrocenophanes which incorporate a hydrophobic, aromatic ‘pocket’ derived from α,α′-bis(4-hydroxyphenyl)-1,4-diisopropylbenzene or α,α′-bis(4-aminophenyl)-1,4-diisopropylbenzene are synthesized. CFour of the new ferrocenophanes have been studied by cyclic voltammetry. Solid-state structures of lipophilic ferrocenophane diamide 5, which has an aromatic ‘pocket’, and of the reactant 1,1′-di(hydroxymethyl)ferrocene (13) have been determined by single-crystal X-ray diffraction analysis and are compared with those for other ferrocenophanes and 1,1′-disubstituted ferrocenes respectively. 13 crystallizes in the space group P2l/c with a = 13.395(12) A, b = 7.714(5) A, c = 10.497(11) A, β = 105.76(8)°, V = 1043.9 A3, Z = 4, and R(Rw) = 0.0323 (0.0354) for 999 reflections (F > 4.0σ(F)). 5 crystallizes in the space group P2l/n with a = 10.948(2) A, b = 12.387(2) A, c = 30.425(4) A, β = 90.49(1)°, V = 4126.2 A3, Z = 4, and R(Rw) = 0.0611(0.0723) for 3499 reflections (F > 4.0σ(F)). For 13, the structure consists of chains of molecules connected by hydrogen bonds with ferrocene units on the outside of the chains and a hydrogen-bonded network on the interior.

Revision of the structure of a sesquiterpene from Ligularia sagitta

The structure of a new sesquiterpene from the rhizomes of Ligularia sagitta was revised as benzofuranoeremophil-1-ene by 2D NMR and X-ray diffraction.

Crystal structure of the cryptand [3.33] - potassium iodide complex: A large coordination number for potassium ion

Abstract Cryptand [3.3.3] was prepared by a one-step process from 2 moles of 1,11-diiodo-3,6,9-trioxaundecane and 1 mole of 1,11 -diamino-3,6,9-trioxaundecane in acetonitrile using potassium carbonate as the base. An X-ray crystal study of the KI-[3.3.3] complex shows that all cryptand donor atoms are directed towards the encapsulated K+. The K+ ion is not midway between the two nitrogen atoms, but is 3.15A from one nitrogen and 3.37A from the other. The X-ray structure strongly suggests that potassium is coordinated by eleven donor atoms.