Chuanjiang Hu

Synthesis, crystal structure and magnetic properties of A[Ni(mnt)2] complexes [A = 1-(4-nitrobenzyl)quinolinium or 1-benzylpyridinium; mnt2− = maleonitriledithiolate]

Two new ion-pair complexes A[Ni(mnt)2], [A = 1-(4-nitrobenzyl)quinolinium (1), and 1-benzylpyridinium (2)] have been prepared and characterized. The crystal structure of (1) has been determined by X-ray diffraction analysis. In the solid state, anions and cations of (1) form completely segregated stacking columns, with the Ni···Ni distances alternating between 3.890(4) and 4.965(5) Å in the [Ni(mnt)2]− stacking column. The variable temperature magnetic susceptibilities of (1) and (2) have been measured over the 77–300 K range and the results reveal that (1) is diamagnetic and that (2) shows a weak antiferromagnetic spin exchange interaction between the metal ions. The e.p.r. spectra of (1) and (2) in MeCN at room temperature were similar, the g-values being almost identical.

Racemic titanium(IV) complexes of salicylideneamino acids

New racemic complexes of titanium with Schiff bases derived from condensation of salicylaldehyde with dl-alanine (H2Sal-dl-Ala) and dl-valine (H2Sal-dl-Val) have been prepared. The crystal structure of [(Sal-dl-Val)2Ti·CH2Cl2 bis(N-salicylidenevalinato)titanate(IV) CH2Cl2] has been solved by single-crystal X-ray diffraction methods; the crystal is a racemate consisting of a pair of enantiomers (Sal-d-Val)2Ti and (Sal-l-Val)2Ti. The Schiff-base ligand acts as a double negatively-charged tridentate ONO chelate, coordinated to the titanium atom. The geometry around titanium is a distorted octahedron. The i.r. and u.v.–vis. spectra of the complexes have been evaluated.

Synthesis, crystal structure, and properties of [Cu(LH)]2[M(mnt)2] [M = Ni or Cu; H2L = 3,3′-(1,3-propanediyldinitrilo)-bis(2-butanone oxime); mnt2− = maleonitriledithiolate] complexes containing bridging cyano groups

Interesting complexes containing a mnt2− bridge, based on the reaction of [M(mnt)2]2− [M = Ni or Cu] with [Cu(LH)]+, have been prepared and characterized by e.s.m.s., i.r and u.v–vis. spectroscopic techniques and by electrochemistry. The complexes show weak antiferromagnetic interactions between magnetic centers. The X-ray analysis of the molecular structure of [Cu(LH)]2[Ni(mnt)2] has been completed. It structurally features the CN group of mnt2− which can act as a bridging ligand between two transition metals.

Synthesis, spectroscopic characterization and X-ray crystal structure of vanadylpolymolybdophosphates with monocapped Keggin polyanion [PMo5V7O40(VO)]7−

Abstract The preparation of the heteropolyoxometalates K6[HPMo5V7O40(VO)]·16H2O (1), (n-Bu4N)4[H3PMo5V7O40(VO)] (2) and (CN3H6)6[HPMo5V7O40(VO)]·4H2O (3) is described. Compounds 2 and 3 have been characterized by X-ray diffraction methods. Both compounds contain a monocapped Keggin anion. For compound 2 the capping VO group is disordered in six sites, while there are two types of sites for the capping VO group for compound 3. The IR spectra have been investigated.

Synthesis, structure, spectral and magnetic properties of a dinuclear copper(II)/nickel(II) complex bridged by glyoximate groups

Abstract A new dinuclear complex of formula [(tmen)(H2O)2Ni(Hdmg)(dmg)Cu]·ClO4 (H2dmg=dimethylglyoxime, tmen=tetramethylenediamine) has been synthesized. The crystal structure of the complex has been solved by a single-crystal X-ray diffraction method. The structure consists of one cationic dinuclear complex, [(tmen)(H2O)2Ni(Hdmg)(dmg)Cu]+, and one anion, ClO4−. In the dinuclear cationic complex the copper(II) ion and the nickel(II) ion are bridged by two oximate groups, one through the nitrogen and oxygen atoms and the other only through the oxygen atom. The intramolecular Cu⋯Ni distance is 3.424 A. The geometry around the copper atom is a distorted square pyramid, and the geometry around the nickel atom is a distorted octahedron. Variable-temperature magnetic susceptibility measurements (75–300 K) on the title complex revealed the occurrence of an intramolecular antiferromagnetic interaction through the oximate bridges. The IR and UV–Vis spectra have also been investigated.

The Inclusion Complex of Ferrocene with a Dithiolene Functionalized β-Cyclodextrin

A new βcyclodextrin derivative with the anion side-arm, mono[6-deoxy-6-(2-sodium thio-1,2-dicyane ethylenylthio)]-βcyclodextrin (6-mnt-βCD), and its inclusion complex with ferrocene (6-mnt-βCD/Fc), have been prepared and characterized by elemental analysis, IR spectroscopy, UV spectroscopy, mass spectrometry, 13C-NMR spectroscopy, thermogravimetry, and cyclic voltammetry (CV). Thermogravimetry analysis of the compound shows that the thermal stabilities of both the host and the guest in the inclusion complex have been greatly improved due to an additional interaction between the side-arm of the host and the guest. The interplay between the guest and the host with side-arm in the complex resulted in smaller positive potential shifts in CV compared to that in the inclusion complex βCD/Fc.

Synthesis, crystal structure and magnetic studies of cis-configuration copper(II)—M(II) (M = Ba, Ca) complexes of novel Schiff bases derived from salicylaldehyde and dipeptides

The novel heteronuclear complexes [M(CuL)2]2 · nH2O [M = Ba (1), Ca (2); H2L = N-salicylideneglycylglycine] were synthesized and characterized, and the crystal structure of complex (1) was determined by X-ray diffraction. The entire structure is held together by an extensive network of H-bonds and π–π interactions. Variable-temperature magnetic susceptibility measurements (75–300 K) revealed the occurrence of an intramolecular antiferromagnetic interaction in (1) and (2).

Intramolecular photo-substitution in the inclusion compound of mono[6-deoxy-6-(2-butenedinitrile-2,3-dimercapto sodium salt)]–β-cyclodextrin with cyclopentadienyl manganese tricarbonyl in DMF solution

A novel β-CD derivative, mono[6-deoxy-6-(2-butenedinitrile-2,3-dimercapto sodium salt)]–β-CD 1, and its inclusion compound 2 with CpMnI(CO)3 have been prepared and characterized by spectroscopic methods. The inclusion complexation significantly stabilized both the host and guest. Upon irradiation of inclusion compound 2 in DMF solution, an interesting intramolecular photo-substitution resulting in the formation of a self-stabilized compound mono[6-deoxy-6-(2-butenedinitrile-2,3-dimercapto sodium salt)]–β-CD–MnII(DMF)2Cp 5 was observed. Based upon a double-recognition between the host and the organometallic guest, compound 5 became very stable in DMF solution.

Synthesis, electrochemical and magnetic properties of Cu3complexes of a series of new compartmental trinucleating ligandsH4L

A series of linear trinuclear copper(II) complexes [Cu 3 L(dmso) 5 (H 2 O)][ClO 4 ] 2 ·H 2 O {H 4 L = 2,6-bis[(5-substituted salicylidene)hydrazinocarbonyl]pyridine; L = L 1 , R = H; L = L 2 , R = Me 3 ; L = L 3 , R = Bu t ; L = L 4 , R = OMe 3 ; L = L 5 , R = Cl; L = L 6 , R = Br; dmso = dimethyl sulfoxide} have been synthesized and characterized on the basis of infrared and electronic spectra, electrochemical and variable-temperature (80–300 K) magnetic measurements. The crystal and molecular structure of [Cu 3 L 1 (dmso) 5 (H 2 O)][ClO 4 ] 2 ·H 2 O has been established by X-ray diffraction. The structure consists of a Cu II Cu II Cu II trinuclear cation, unco-ordinated perchlorate anions, and a water molecule of crystallization. Each copper ion is in a square-pyramidal environment. The compartmental ligand L 1 co-ordinates in two different modes: (i) as tridentate in the terminal compartment defined by the hydrazonic carbonyl, hydrazonic nitrogen and phenolic oxygen; (ii) tridentate in the central chamber defined by the pyridyl nitrogen and two hydrazonic nitrogens. Cryomagnetic investigations reveal a moderately strong antiferromagnetic spin exchange among adjacent copper(II) ions in each complex (J = -40 to -65 cm -1 ), showing that the compartmental ligands of the Cu II Cu II Cu II are good mediators for spin-exchange interactions. Cyclic voltammetry of complex 1 showed one oxidation wave attributed to Cu II Cu II Cu II →& -e - Cu II Cu III Cu II , a one-electron transfer reduction peak due to Cu II Cu II Cu II →& +e - Cu II Cu I Cu II and a two-electron transfer wave established as Cu II Cu I Cu II →+2e - Cu I Cu I Cu I .

Synthesis, structure and the e.s.r. spectrum of the mixed-valence molybdovandate Na2(NH4)4[(VIVVV8Mo)O28] · 10H2O

The mixed-valence molybdovanadate compound Na2(NH4)4[VIVVV8Mo)O28] · 10H2O [Vanadata(6-)tetradeca-μ-oxotetra-μ3-oxodi-μ6-oxoheptaoxo(oxomolybdate) nonatetrammonium disodium, decahydrate] has been synthesized from sodium molybdate(VI) dihydrate and sodium metavanadate dihydrate in aqueous solution by adding NH2OH · HCl. The molecular structure has been determined by X-ray diffraction and is based on the isopolydecavanadate structure. The molybdate atom is crystallographically disordered over 6MO6 octahedral sites. The e.s.r. spectrum clearly indicates that one vanadium atom has the oxidation number +4.