Ikuhiko Ueda

Synthesis and crystal structure of 1:2 molecular complexes of bis(N-alkyl-2-oxy-1-napthylideneaminato)copper(II) and -nickel(II) with 7,7′,8,8′-tetracyanoquinodimethane

Abstract The 1:2 molecular complexes of bis(N-alkyl-2-oxy-1-napthylideneaminato)copper(II) and -nickel(II) with 7,7 , 8,8 - tetracyanoquinodimethane (TCNQ) have been prepared and characterized, where N-alkyl group = CH 3 , C 2 H 5 , n-C 3 H 7 , iso-C 3 H 7 . The crystal structures of bis(N-isopropyl-2-oxy-naphthydeneaminato)copper(II) [I] and its 1:2 molecular complex with TCNQ [II] have been determined by the single-crystal X-ray diffraction method and refined by the block-diagonal least-squares method to give R = 3.55 and 3.71% for [I] and [II], respectively. The copper atom of compound [I] has a coordination geometry intermediate between square planar and tetrahedron, where the dihedral angle between CuNO planes is 38.6°. The crystal structure of compound [II] shows a typical π-π type molecular complex structure of alternately stacked donor (naphthalene moieties of metal complex) and acceptor (TCNQ) molecules where the copper atom assumes a square planar coordination geometry with a markedly stepped chair-like shape. ESR measurements have been revealed that the A ∥ values of the component copper(II) complexes are decresed and the g ∥ values are increased in the order of increasing bulkiness of the alkyl groups. On the other hand, the A ∥ and g ∥ values of the molecular complexes are less influenced by the bulkiness of the alkyl groups. The above results were discussed in relation to the coordination geometry around the copper atom.

Copper(II) and nickel(II) complexes of N,N′,N″,Nâ—-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclotetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh). Crystal structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3

New octaamine dinucleating ligands, N,N′,N″,N‴-tetrakis(2-aminoethyl)-1,4,7,11-tetra-azacyclo-tetradecane (taei), -1,4,8,12-tetra-azacyclopentadecane (taep), and -1,5,9,13-tetra-azacyclohexadecane (taeh) and their complexes with CuII and NiII were synthesized. Of the 19 complexes isolated, the structures of [Cu2(taep)][ClO4]4, [Cu2(taeh)][ClO4]4, and [Cu2(N3)(taeh)][ClO4]3 were determined by X-ray crystal analysis. In all these complexes each copper is co-ordinated by two ring nitrogens and two pendant amino nitrogens, and the two CuN4 co-ordination sets face each other. In the azido complex the N3– is bonded to both coppers in an end-to-end fashion. The dinuclear complexes [Cu2L][ClO4]4(L = taei or taep) further incorporate various anions between the two coppers to form [Cu2X(L)][ClO4]3. However, only the azido complex was obtained with taeh. The results are discussed in terms of the ring-size effect.

A new class of ergostane glycosides from tubocapsicum anomalum

Abstract The structures of two new C 28 steroidal lactone glycosides have been established; Spectroscopic and X-ray diffraction analyses of tubocapsigenin A diacetate, one of sapogenol derivative of these glycosides, have presented a new class of steroidal lactone structure.

Syntheses and molecular structure of bis(1-substituted, 2.4-dithiobiuretato)- nickel(II) complexes

Abstract Bis(1-substituted, 2.4-dithiobiuretato)nickel(II) complexes, where 1-substituted groups = C 2 H 5 , n-C 3 H 7 , iso-C 3 H 7 , o -tolyl and p -anisidine, have been prepared and characterized on the basis of elemental analyses, magnetic moments at room temperature and electronic spectra. The crystal structure of bis(1-isopropyl-2,4-dithiobiuretato)nickel(II)·2(dimethylformamide) has been determined from 1446 X-ray diffraction data. The crystals are monoclinic, space group P2 1 /c, with two formula units in a unit cell of dimensions a = 8.008(2), b = 14.460(5), c = 12.059(5) A and β = 106.45(3)°. The structure was solved by conventional Patterson and Fourier methods, and block-diagonal least-squares refinements led to a final discrepancy index 0.038. The structure consists of discrete bis(1-isopropyl-2,4-dithiobuiretato)nickel(II) and dimethylformamide molecules, and the former molecule is centrosymmetric with the two bidentate ligands of isopropyl- 2,4-ditiobuiretato chelating to the central nickel atom through the two sulfur atoms. Examination of the bond distances and the planarity of the molecule revealed that the π-conjugation system extends over the 2,4-dithiobiuretato moiety.

A novel cholestane derivative as root growth inhibitor from Heloniopsis japonica

Abstract A novel cholestane glycoside, helojaposide ( 1 ), was obtained from Heloniopsis japonica. 1 exhibits an inhibitory activity for the root growth of rice.

A novel photochemical transformation of methyl 6-chloro-3,4-dihydro-4-methyl-3-oxo-2H-1,4-benzoxazine-8-carboxylate to β-lactams

Abstract A unique photoreaction of methyl 6-chloro-3,4-dihydro-4-methyl-3-oxo-2 H -1,4-benzoxazine-8-carboxylate in methanol gives four β -lactam compounds, methyl 6-chloro-2,9-dioxo-1-methyl-1-azaspiro[3.5]nona-5,7-diene-8-carboxylate and three stereoisomers of dimethyl 3-chloro-4-(1′-methyl-2′-oxoazetidin-4′-ylidene)-2-butene-1,1-dicarboxylate.