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- Boström, Dan, et al.
(författare)
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CIS-Trans Influences on Square-Planar Platinum(II) Complexes : Structure of CIS-BIS (Dimethyl Sulfoxide) Dinitratoplatinum (II)
- 1991
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Ingår i: Acta Crystallographica Section C. - Copenhagen, Denmark : Munksgaard International Publishers. - 0108-2701 .- 1600-5759. ; 47, s. 2101-2104
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Tidskriftsartikel (refereegranskat)abstract
- cis-[Pt{(CH3)2SO}2(NO3)2], M(r) = 475.36, monoclinic, P2(1)/c, a = 9.006 (1), b = 14.209 (2), c = 10.908 (2) angstrom, beta = 117.88 (1)-degrees, V = 1233.9 (2) angstrom 3, Z = 4, D(x) = 2.559 Mg m-3, lambda(Mo K-alpha)BAR = 0.7107 angstrom, mu = 11.84 mm-1, F(000) = 896, T = 293 K, R = 0.033 for 1763 unique reflections [I > 3-sigma(I)]. The Pt atom coordinates two S atoms from two dimethyl sulfoxide ligands and two O atoms from different nitrate ions in a slightly distorted square-planar geometry (maximal deviation 0.10 angstrom) in a cis arrangement. The compound consists of van der Waals packed molecules appearing in pairs with a Pt-Pt distance of 4.008 (1) angstrom. The acceptor-donor distances observed are: Pt-S = 2.214 (3), 2.220 (3) and Pt-O = 2.040 (9), 2.059 (9) angstrom. These are almost the same as the corresponding ones previously found in tetrakis(dimethyl sulfoxide)platinum(II) bis(trifluoromethanesulfonate) where two dimethyl sulfoxide ligands bond to Pt via their O atoms, also in a cis position. A literature survey of platinum dimethyl sulfoxide compounds shows that the Pt-S distance is significantly affected by both cis and trans influences.
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| 3. |
- Bäckman, B, et al.
(författare)
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The absence of correlations between a clinical classification and ultrastructural findings in amelogenesis imperfecta.
- 1993
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Ingår i: Acta odontologica Scandinavica. - 0001-6357. ; 51:2, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- This study was performed to examine whether a clinical classification of different phenotypes of amelogenesis imperfecta could be discernible at the ultrastructural level. Seventeen primary teeth from 16 children with hypomineralization, hypomaturation, or hypoplastic variants of the disease were collected for histologic studies of the enamel by means of polarized light microscopy, scanning electron microscopy (SEM), and secondary ion mass spectrometry (SIMS). Polarization microscopy showed that the enamel was hypomineralized; in six teeth a wavy configuration of the enamel prisms also appeared. Three histomorphologic main types could be discerned. In 10 of the teeth extensive hypomineralization of the bulk of the enamel was found. One tooth had an unusually thick enamel with only a thin normally mineralized surface layer. SIMS images showed less pronounced signals from Ca2+ and Na+ but with stronger signals from Cl- and CN-, representing the organic component of enamel. The SEM images showed an irregular prism pattern with marked interprismatic areas. Irrespective of the clinical appearance or the hereditary pattern the main findings were hypomineralized enamel with or without wavy bands. Neither of the analytical methods used in this paper distinguishes between the clinical phenotypes of amelogenesis imperfecta.
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