Elmer O. Schlemper

Crystal structure of oxo(diperoxo)bipyridylmolybdenum(VI)

Abstract Yellow oxo(diperoxo)bipyridylmolybdenum(VI), C10H8MoN2O5, Mr = 332.1 crystallizes in the monoclinic space group P21/n, a = 6.261(3), b = 12.726(1) c = 13.752(3)A, β = 91.84(2)°, V = 1095.2(5)A3, Z = 4, Dc = 2.014(1) g/cm3, MoKα(λ = 0.7107A), μ = 11.8 cm−1, T = 22(1)°C, R = 0.034, ωR = 0.040, number of reflections in least squares (F0 > 2σ(F0)) = 1125. The molybdenum coordination (distorted trigonal bipyramidal) is as in the corresponding chromium complex, C10H8CrN2O5 which has closely similar bond angles but is not isomorphous. The difference in MoNapex and MoNeq bond distances (2.312(5) and 2.199(5)A) is similar to that in the CrNapex and CrNeq distances (2.23(2) and 2.11(2)A). The MO distances for each peroxo ligand (ave. 1.910(2) and 1.950(2)A) are significantly different and slightly longer than those in the chromium complex as is the OO distance of 1.459(6)A. The latter is indicative of greater negative charge on the O2 ligands, approaching that of O2−2 in the molybdenum complex.

The crystal and molecular structure of dichiorobis(2,4-pentanedionato)tin(IV)

Abstract Dichlorobis(2,4-pentanedionato)tin(IV), SnCl 2 (C 5 H 7 O 2 ) 2 , crystallizes in the monoclinic space group C2/c with a = 13.937(4), b = 7.864(2), c = 13.746(4) A , β = 107. 75((1),°, Z = 4, D c = 1. 796(1) g/cc, and D m = 1.78 g/cc. The crystal structure was solved by conventional Patterson and Fourier methods using 2053 independent reflection intensities measured by the θ–2θ scan method with a scintillation counter. Refinement by the full-matrix least squares method gave a final agreement factor R(F) of O.036. The structure consists of discrete molecules with the tin atom in a distorted octahedral configuration. The chloro ligands are in cis position and are related by a crystallographic two-fold axis. The important average bond distances are SnCl (2.345(1) A ), SnO (2.058(7) A ), CO (1.282(8) A , CC (conjugated) (1.386(12) A ), and CC(sp 3 ) (1.488(5) A ). The ClSnCl angle is 96.86(5)°.

The crystal and molecular structures of [Co(NH3)6][CuCl5] as determined from single crystal X-ray and neutron diffraction data

Abstract The crystal structure of the title compound was determined at room temperature (ca. 21°C) using single crystal X-ray and neutron diffraction data. The substance crystallizes in the cubic space group Oh8-Fd3c in a unit cell whose edge is a = 21.992(3)A. The X-ray data were refined to R(F0) = 0.026 and Rw(F0) = 0.027, while the neutron data refined to R(F0) = 0.055. The two sets of coordinates obtained agree remarkably well even for the hydrogen atoms but, since the neutron results are more reliable for the hydrogen atom positions, our discussion is based on these. The Co-N and distances are, respectively, 1.968(2)A and 0.953(5)A. The most important result, namely the Cu-Cl(axial)Cu-Cl(equat.) ratio, is 0.955; the individual values of these quantities being Cu-Cl(ax) = 2.301 and Cu-Cl(equat.) = 2.409. Thus, the CuCl53− anion is axially compressed by a substantial amount and, in this respect, resembles its octahedral CuF64− relative.

The Phenomenon of Conglomerate Crystallization. V. Clavic Dissymmetry in Coordination Compounds. IV. A Neutron Diffraction Study of K[trans-Co(NH3)2(NO2)4]

Abstract The structure of K[ trans -Co(NH 3 ) 2 (NO 2 ) 4 ] has been determined by neutron diffraction data collected at room temperature ( ca. 21 °C). The substance crystallizes as a conglomerate of antipodal crystals, many large enough for neutron diffraction work. The space group and cell constants are: P 2 1 2 1 2 1 ; a = 11.275(3), b = 12.806(5) and c = 6.696(3) A. The cell volume is 966.82 A 3 and given the M r of 316.12 g mol −1 , the D (calc; Z = 4) is 2.170 g cm −3 . The data (1553 unique reflections) were corrected for absorption (μ = 79.533 cm −1 ) and there was no decay during data collection, as expected from the X-ray study. All heavy atoms were initially placed at the positions found with X-rays, refined isotropically and, after locating the hydrogens in a difference map, all atoms were refined isotropically. Conversion to anisotropic motion was followed by 12 cycles of least-squares fitting (200 variables), at which point the structural refinement converged to its final R and R w factors of 0.056 and 0.056, respectively. The goodness of fit was 1.133. The positional parameters of the two studies are in close agreement, as expected. For example, the average value of the CoN(NH 3 ) bonds in the X-ray and neutron studies are, respectively, 1.958(3) A and 1.949(9) A. The average value of the CoN(NO 2 ) distances for the X-ray and neutron studies are 1.956(3) A and 1.948(9) A, while the average NO distances are 1.230(4) and 1.222(6) A for the former and latter, respectively. The most important result derived from this study is the accurate location of the hydrogens of the −NH3 ligands which had caused problems in two previous X-ray studies of salts of this anion. In this analysis, we found that −N1(NH 3 ) is well behaved thermally while −N2(NH 3 ) is much less so, the reason being that the three hydrogens of the amines attempt to form hydrogen bonds with the adjacent oxygens of the basal plane −NO 2 ligands — which is impossible while satisfying all of them equally well. One of the two amino ligands manages better than the other one, as we shall demonstrate below.

An Rh-105 complex of tetrathiacyclohexadecane diol with potential for formulating bifunctional chelates☆

1,5,9,13-Tetrathiacyclohexane-3,11-diol (16S4-diol), a sulfur crown ether analog, was studied as a potential chelating agent to complex no-carrier-added (NCA) grade 105Rh(III) in high yield at low ligand concentrations. trans-[RhCl2(16S4-diol)]chi (chi = Cl, PF6) was prepared using nonradioactive RhCl3.3H2O and characterized by UV-Vis, nuclear magnetic resonance (NMR) and X-ray crystallography. It was shown to have a +1 charge with the Rh(III) metal center coordinated to the four S atoms equatorially and two Cl atoms in trans axial positions. The 105Rh-16S4-diol complex prepared with NCA 105Rh(III)-chloride reagent was found to exhibit identical chromatographic properties as trans-[Rh(III)Cl2(16S4-diol)]+ (including silica and C-18 thin-layer chromatography [TLC] and electrophoresis). The preparation of 105Rh-16S4-diol complex formation optimized for conditions of pH, temperature, time, % ethanol and quantity of 16S4-diol resulted in yields > 90%. Very low quantities of 16S4-diol (3 nmol) complex NCA 105Rh(III) under relatively mild reaction conditions (heating at 64 degrees C for 90 min) in the presence of ethanol (10%), yielded the high specific activity 105Rh-16S4-diol complex as a single cationic species. The 105Rh-16S4-diol complex was shown to be stable for > or = 4 days in physiological buffers at room temperature and in human serum at 37 degrees C.

Intramolecular hydrogen bonding: synthesis and crystal structure of nickel(II) and copper(II) complexes of a tetradentate amine oxime

Abstract In the reaction of the tetradentate ligand 3,3′-(1,4- butanediyldiamino) bis (3-methyl-2-butanone)-dioxime (BnAO) with nickel(II) and copper(II), the monomeric [Ni(BnAO-H)]I·H2O and a mixed monomer/dimer salt [Cu(BnAO-H)H2O]2[(Cu(BnAO-H))2](ClO4)4, respectively, are formed, and all complexes have an intramolecular hydrogen bond between cis oxime groups. The OHO bonds give the characteristic infrared absorptions as well as the downfield proton-NMR signal (Ni complex). [Ni(BnAO-H)]I·H2O crystallizes in space group P21/a with a=13.511(2), b=10.599(2), c=14.096(2) A, β=97.52°, Z=4 and Dc=1.623 g/cm3. The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to a final R of 0.021 for 2124 reflections with I 2σ(I). The nickel(II) atom in the complex has slightly distorted square planar geometry with an intramolecular O···O contact of 2.417(7) A. The copper(II) complex crystallizes in space group P21/c with a =13.425(2), b=21.446(3), c=14.349(4) A, β= 104.4(5)°, Z=8 (monomers) and Dc=1.485 g/cm3. The final R value for this complex was 0.053 for 3033 reflections with I 2σ(I). This structure contains a monomeric [Cu(BnAO-H)H2O]+ ion and a dimeric [(Cu(BnAO-H))2]2+ ion, having intramolecular O···O hydrogen bonds of 2.421(5) and 2.531(5) A, respectively. The copper(II) ions have square-pyramidal coordination with the axial positions occupied by an oxygen of the water of hydration in the monomer and by an oxime oxygen atom in the dimer. A center of symmetry relates the two halves of the dimer. The copper atom in each case is out of the plane of the four nitrogen atoms toward the axial site. The copper(II) complex is unusual in that the crystal contains both a monomer and a dimer.

Lewis acid mediated reactions of N-phenyl-(4-methylphenyl)-sulfoximidoyl chloride with alkynes. A novel route to benzothiazines

Abstract A general route to benzothiazines has been developed. Treatment of 1 with a Lewis acid in the presence of an alkyne leads to benzothiazines, often in high yields.

Rhodium complexes of two bidentate secondary amine oxime ligands and application to the labelling of proteins

The syntheses of a new, bifunctional ligand, 3-[N-(4-aminobenzyl)]amino-3- methyl-2-butanone oxime, ligand I , and a non-bifunctional analogue 3-benzylamino-3- methyl-2-butanone oxime, ligand II , the former for labelling proteins with 105 Rh complexes for internal radiotherapy applications are reported. The rhodium complex of ligand II was isolated and characterized by 1 H NMR, IR spectroscopy and X-ray crystallography. The crystal structure consists of discrete mononuclear, neutral and slightly distorted octahedral molecules. The octahedron around rhodium consists of two trans -chlorine atoms and four nitrogen atoms from the two bidentate amine oxime ligands. The complex formed in situ with the bifunctional ligand I gives up to 95% yield with 105 Rh in pH 9 bicarbonate buffer. This complex was converted to the isothiocyanate derivative with thiophosgene and extracted into CHCl 3 (91%). Conjugation yields of greater than 90% could be obtained with human γ-globulin. The protein conjugation method described is suitable for the preparation of 105 Rh labelled antibodies with specific activities of 1.6–9.3 mCi mg −1 .

Crystal and molecular structures of tin(IV) dithiocarbamates: II. Tris (N,N-diethyldithiocarbamato) methyltin(IV), a seven-coordinated pentagonal bipyramidal complex

The crystal structure of the title compound has been determined from 2919 independent reflections measured by scintillation methods. The crystals are monoclinic, space groupP21/n, with cell parametersa = 10.041(3),b = 10.712(4),c = 24.295(7) Å, β = 93.17(5), andZ = 4. The structure was solved by Patterson and Fourier techniques, and refined by full-matrix least-squares methods toR = 0.058. The crystal structure consists of discrete, neutral, mononuclear, seven coordinated tin complexes. The geometry around the tin is a distorted pentagonal bipyramid with the methyl group axial, two dithiocarbamate ligands equatorial, and one dithiocarbamate bridging axial-equitorial. For the equatorial dithiocarbamates, each ligand has a short Sn-S distance [2.618(2) Å] and a longer Sn-S distance [2.761(12) Å]. For the other dithiocarbamate ligand there is a short axial Sn-S distance [2.481(2) Å] and a long equatorial Sn-S distance[2.817(2) Å]. The Sn-C distance has a rather normal value of 2.148(8) Å.

Rhodium(III) complexes of new N-substituted α-amine oxime ligands : synthesis and crystal structures of [Rh(phenao)2Cl2], [Rh(Phetao)2Cl2], [Rh(acetanilidoao)2Cl2] and [Rh(N-methyl acetanilidoao)2Cl2]

Abstract Four new bidentate, α-amino substituted α-amine oxime ligands and their rhodium(III) complexes are reported. Characterization of the ligands and the complexes by proton NMR is included. The ligands are 3-(N-phenylamino)-3-methyl-2-butanone oxime (PhenAO), 3-[N-(2-phenylethyl)amino]-3-methyl-2-butanone oxime (PhetAO), 3-[N-(4-acetanilido)amino]-3-methyl-2-butanone oxime (acetanilidoAO) and 3-[N-(4-(N-methyl)acetanilido)amino]-3-methyl-2-butanone oxime (N-methyl acetanilidoAO). The rhodium complexes, [Rh(PhenAO) 2 Cl 2 ], [Rh(PhetAO) 2 Cl 2 ], [Rh(acetanilidoAO) 2 Cl 2 ] and [Rh(N-methyl acetanilidoAO) 2 Cl 2 ], were also characterized by single-crystal X-ray diffraction. The complexes are neutral and octahedral with coordination of two bidentate amine oxime ligands through the oxime and amine nitrogen atoms and two trans -chloride ligands. The cis -oximes in each case lose one proton and the remaining proton is involved in a strong OHO hydrogen bond. Bond distances and angles in the complexes are normal. Details of the structures (including two modifications of the first two complexes) are presented.