Phirtu Singh

MOLECULES OF COPPER(II) l-SPARTEINE DINITRATE ARE MIXED FOUR- AND FIVE-COORDINATE IN ONE CRYSTALLINE PHASE AND ONLY FOUR-COORDINATE IN ANOTHER

Abstract A neutral complex of Cu(II) with the chiral bidentate nitrogen-chelating alkaloid (−)-sparteine, with nitrate groups occupying the remaining coordination sites, has been prepared and characterized. Solution conductivity measurements indicate that both nitrate groups are coordinated to copper to give a neutral molecule. Optical and electron-spin-resonance spectra in toluene/CHCl3, did not show a clear picture of the coordination geometry. A frozen-glass ESR spectrum showed the same evidence for mixed species, with the predominant species characterized by a very low A11 value of 118 G. Crystals 1 and 2 of Cu(C15H26N2)(NO3)2 were grown by two methods: 1 at 25°C from saturated acetonitrile, and 2 at 5°C from ethanol/dichloromethane under CCl4 vapor. Their structures were determined by X-ray crystallography. Crystals 1 were monoclinic, space group P21, with a = 7.851(6), b = 14.408(10), c = 16.079(10) A, β = 97.93(6)°, V = 1801(2) A and Z = 4. Crystals 2 were orthorhombic, space group P212121, with a ...

X-ray crystal structure of disperse red 167

Abstract X-ray diffractometer data have been used to determine the crystal structure of CI Disperse Red 167, an important automotive disperse dye. The structure was solved by direct methods and refined by least squares to R = 0.0442 for 1115 independent reflections. This monoazo dye possesses a planar azobenzene skeleton, as the dihedral angle between the planes made by the two aromatic rings is 1.5°. The non-bonding distance between the hydrogen atom of the acetamido group and azo nitrogen N(1) is well within the expected distance for intramolecular hydrogen bonding. Interestingly, the chloro and acetamido groups lie on the same side of the azo bond, and each unit cell of this dye contains 8 molecules.

Synthesis and characterization of tetraalkylammonium salts of bis(5,6-dihydro-1,4-dithiin-2,3-dithiolato)cobaltate(III). Crystal structure of [(C4H9)4N]2[Co(DDDT)2]2

Abstract The reaction between CoCl2·6H2O and K2DDDT (the potassium salt of 1,2-dithiolene 5,6-dihydro-1,4- dithiin-2,3-dithiolate) under an argon atmosphere yields a dimeric dianion which can be isolated as a tetraalkylammonium salt. Constant potential electrolysis of the formally Co(III) product yields a Co(II) species. Both complexes are extremely sensitive to air in solution. The solid Co(III) product, however, is sufficiently air stable to allow a structural analysis of the tetrabutylammonium salt. The crystal belongs to the monoclinic space group C2/c with unit cell dimensions of a=23.626(3), b=16.915(3), c= 16.294(2) A, β=101.62(1)°, Z=8. The coordination around the cobalt atom is best described as square pyramid with an average basal CoS bond length of 2.197(1) A and an apical CoS distance of 2.328(1) A. The dimeric structure allows for S…S contacts in the crystal lattice as short as 3.22 A. The structure refined to R=0.037 and Rw=0.053. The frozen glass ESR spectrum of the Co(II) complex exhibits three sets of eight lines with g1=1.933, g2=2.067 and g3=2.860. A cyclic voltammogram contains a two-electron reversible wave, a quasi-reversible one- electron wave and a reversible one-electron wave indicating a four-member electrochemical series: [Co- (DDDT)2]2o[Co(DDDT)2]2− ⇄[Co(DDDT)2]22−⇄2Co(DDDT)22−. The solid-state 13C NMR spectrum shows different resonances for carbons in the double bonds of the ligand, consistent with splitting of the C=C stretch in the IR spectrum.

Effect of cation on the structures, magnetic properties and specific heats of salts of bis(5,6-dihydro-1,4-dithiin-2,3-dithiolato)nickelate(III): the crystal structure of[(CH-3)4N] [Ni(DDDT)2]

Abstract The structure of the tetramethylammonium salt of Ni(DDDT)2- (DDDT2-=5,6-lihydro-l,4-dithiin-2,3-dithiolate) has been determined by X-ray crystallography. The crystal belongs to the orthorhombic space group Pbca with unit cell dimensions a=0.543(2), b=13.937(5), c=27.518(7) A, Z=8. The NiS4 core exhibits square planar coordination with an average NiS bond length 2.146(2) A. The crystal packing can be described as interlocking colums consisting of alternating cations and anions. The columns form a zigzag pattern when viewed down the y axis. The shortest S···S contact is 3.57 A with a total of four contacts less than 3.8 A. The X-ray powder diffraction spectrum of this salt showed the presence of only one crystallographic species, while that of the tetrabutylammonium salt indicated the possibility of a third polymorph. Magnetic susceptibility data for [(CH3)4N] [Ni(DDDT)2] were fit to the Curie-Weiss law by expanding the Weiss constant as an infinite series. The specific heats of the [(CH3)4N]+, [(C2H5)4N]+ and [(C4H9)4N]+ salts of Ni(DDDT)2− were measured between 1 and 25 K. Similar specific heats were observed above 4 K but the values differed significantly below this temperature.

X-ray crystal structure of disazo dyes. Part 1: C.I. Disperse Orange 29

Abstract Crystals of C.I. Disperse Orange 29, a disazo dye, were grown from a methanol solution and the X-ray structure was solved from 2484 independent reflections to R = 0.0497. Results showed that the crystal examined exists in the triclinic space group P1. Interestingly, the structure generated possessed a syn conformation, unlike 4-phenylazoazobenzene which is known to exist in the anti conformation.

The first example of a stacked structure containing the 5,6-dihydro-1,4-dithiin-2,3-dithiolate ligand: the crystal structure of [(C2H5)4N][Pt(DDDT)2]

The crystal structure of [(C 2 H 5 ) 4 N][Pt(DDDT) 2 ] where DDDT 2− =5,6-dihydro-1,4-dithiin-2,3-dithiolate belongs to the monoclinic space group C 2/ c with unit cell dimensions a =22.199(6), b =8.206(2), c = 17.698(4) A, β=130.87(1)°, Z =4. The Pt and N atoms lie on an inversion center and a two-fold axis, respectively. The PtS 4 core exhibits square planar coordination with an average PtS bond length of 2.270(6) A. This structure represents the first transition metal complex of the DDDT 2− ligand containing stacks of planar anions. The stacks interlock to form a layer. The molecular packing diagram shows alternating cation and anion layers.

X-ray crystal structure of disazo dyes. Part 2: Derivatives of C.I. Disperse Yellow 23 and C.I. Disperse Orange 29

Abstract Crystals of the 2,6-dichlorobenzoyl ester of C.I. Disperse Yellow 23 and C.I. Disperse Orange 29 were grown from chloroform, and cell dimensions were determined by a least-squares fit. Crystals of both esters were found to exist in the monoclinic space group P2 1 /C. The structures of these dyes possessed the anti conformation, unlike that of underivatized C.I. Disperse Orange 29, but the same as that reported for 4-phenylazoazobenzene.

X-ray crystal structure of C.I. Disperse Yellow 86

Abstract In conjunction with studies pertaining to the design of lightfast dyes for PET, the X-ray crystal structure of C.I. Disperse Yellow 86 has been solved to R=0.067 using 1999 independent reflections of MoKα radiation, collected by the ω-scan method at a variable speed. Results showed that C.I. Disperse Yellow 86 is non-planar, with a dihedral angle of 35.3° between the phenyl rings. In addition, the ortho-nitroanilino moiety of this dye is planar, due to a hydrogen bond between the nitro group and the adjacent amino hydrogen atom. ©

1,2-diaminobenzene adducts of nickel(II) 1,3-diketonates: Their role in dibenzotetraaza[14]annulence macrocycle formation

Abstract The attempted preparation of the macrocyclic ligand,6,8,15,17-tetraphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine from 1,2-diaminobenzene, 1,3-diphenyl-1,3-propanedione, and nickel(II)acetate via a template condensation is unsuccessful because of severe steric interactions in the desired product. The product isolated from this reaction, in high yield, is the bis(1,2-diaminobenzene) adduct of bis(1,3-diphenyl-1,3-propanedionato) nickel(II). Crystals of the adduct are monoclinic with a = 7.425(1), b = 12.221(3), c = 19.194(3) A, β = 97.01°, Z = 2, V = 1728.7 A 3 , and space group P 2 1 / n . The structure was solved by the heavy atom method and difference Fourier techniques, and refined by the block-diagonal least-squares method to a final R of 0.0379 for 2218 reflections with I >2σ( I ). An empirical absorption correction was made via ψ-scan of 5 reflections with 2θ-values between 5 and 90°, and χ close to 90°. The compound consists of a square planar Ni(II)O 4 array with two molecules of axially coordinated diamine. The monodentate trans arrangement of a diamine molecules gives the compound the overall pseudo-octahedral geometry that is common to adducts of metal 1,3-diketonates. The 6,8,15,17-tetramethyl macrocycle is readily formed via template condensation when the diketone employed is 2,4-pentanedione. The bis(1,2-diaminobenzene) adduct of bis(2,4-pentanedionato)nickel(II) has also been prepared. A small amount of macrocycle can be detected by refluxing this latter adduct in alcohol. The principal product is (1,2-diaminobenzene) tetrakis(2,4-pentanedionato)dinickel(II).

X-Ray crystal structure of the dye 4-(N,N-bis-(β-hydroxyethyl) amino) azobenzene

Abstract The crystal structure of 4-( N , N -bis-(β-hydroxyethyl)amino)azobenzene was determined through the use of X-ray diffractometer data. The structure was solved via direct methods and refined by least squares to R = 0.0594 for a data set consisting of 1610 unique reflections. The azobenzene skeleton of the dye is essentially planar, with a dihedral angle of 10.3° between the planes defined by the two aromatic rings. The geometry about the azo linkage, and some key bond lengths of this dye, are compared to the corresponding values for some previously reported azobenzenes.