(1S,2R,2′S)‐ and (1S,2S,2′S)‐1‐phenyl‐2‐phenyl­thio‐2‐(tetra­hydro­pyran‐2′‐yl­thio)­ethanol diastereoisomers at 193 K

In the synthesis of 1‐phenyl‐2‐phenyl­thio‐2‐(tetra­hydro­pyran‐2‐yl­thio)­ethanol, C₁₉H₂₂O₂S₂, four diastereoisomers are formed. Two non‐centrosymmetric enantiomeric forms which crystallize in space groups P2₁2₁2₁ and Pna2₁ are presented. The former has an intramolecular hydrogen bond between the hydroxyl group and the O atom of the tetra­hydro­pyran ring. In the latter isomer, the hydroxyl group forms an intermolecular hydrogen bond to the O atom of the tetra­hydro­pyran­yl group of a neighbouring mol­ecule, joining the mol­ecules into chains in the c‐axis direction; the O?O distances are 2.962 (4) and 2.764 (3) Å, respectively. The tetra­hydro­pyran rings are in chair conformations in both isomers and the S side chain has an equatorial orientation in the former, but an axial orientation in the latter mol­ecule.     

An anthracene dimer with a fused 1,3‐dithiole ring at 193 K

The first butterfly‐shaped anthracene dimer including S atoms,8,9‐di­hydro‐3a,8[1′,2′]:9,13b[1′′,2′′]­di­benzeno­dibenzo­[3,4:7,8]cyclo­octa­[1,2‐d]‐1,3‐di­thiole, C₂₉H₂₀S₂, contains an exceptionally long Csp³—Csp³ bond of 1.672 (2) Å in the fused 1,3‐di­thiole ring. The length of the other bond bridging the anthracene moieties is 1.604 (3) Å.     

The optimization of on-wafer shield-based test fixture layout

The effect of layout design on shield-based test fixture parasitic components is studied in this paper. As a result, guidelines for shield-based test fixture layout design are given. The novel test fixture layout details studied in this paper are a slotted ground plane with different slot orientation, the use of ground-bar extensions in a ground-shielded test fixture, and the upgrade of a ground-shielded test fixture to a fully shielded structure with a common ground. It was found that a slotted ground plane does not increase the ground lead impedance significantly. Thus, successful ground-shielded test fixture processing can be ensured by obeying process stress release design rules. Furthermore, the additional ground bar extensions had a negligible effect on reducing the ground-shielded test fixture ground lead impedance. However, upgrading the ground-shielded test fixture structure to fully shielded reduced the ground lead impedance. Therefore, fully shielded test fixtures are proposed for use with two-port cascade-based deembedding methods, which commonly are incapable of taking into account ground lead parasitic components.     

Two 9‐alkylthiophenanthrenes at 193 K (alkyl = dodecyl and tetradecyl)

Two isostructural 9‐thiophenanthrene derivatives, 9‐dodec­ylthiophenanthrene, C₂₆H₃₄S, (I), and 9‐tetradecylthiophen­anthrene, C₂₈H₃₈S, (II), are reported. They crystallize in the monoclinic space group P2₁/c with four molecules in a unit cell. The S—C_phenanthrene bonds are 1.767 (2) and 1.772 (4) Å and S—C_alkyl bonds are 1.809 (2) and 1.804 (4) Å for (I) and (II), respectively. The bond angles at S are 104.04 (11) and 104.0 (2)° for (I) and (II), respectively.     

Di‐9‐anthryl disulfide at 193 K

The title compound, C₂₈H₁₈S₂, crystallizes in the monoclinic space group P2₁/n and the structure shows pseudosymmetry close to the space group C2/c. At 193 K the compound has a long S—S bond of 2.1089 (12) Å and the S atom to anthracene bond distances are 1.776 (3) and 1.770 (2) Å. The C—S—S—C torsion angle is 76.06 (13)°.     

An experimental study of scalability in shield-based on-wafer CMOS test fixtures

In this paper, the possibilities of employing full scalability to on-wafer complementary metal-oxide-semiconductor (CMOS) test fixtures is studied experimentally. Several test fixtures and in-fixture sets were fabricated and measured in order to find the significant parasitic components in shield-based fixtures. An improved method for applying bi-directional scaling to on-wafer shield-based test fixtures is proposed. This method takes into account the parasitic series resistance, series inductance, and parallel capacitance that are present in the test fixture. The proposed method can be used successfully in commonly known deembedding methods. This is verified through measurements. The test fixtures were fabricated on top of a lossy substrate using double-poly, three-metal-layer 0.35-/spl mu/m CMOS technology.     

Strong Axial Preference of 2-S Substituents in 3,4-Dihydro-2 H -1-Benzopyrans

The synthesis and crystal structure of a O,S,S-acetal derivative (1 R *,2 R *,2' S *)-1-(3,4-dihydro-2 H -1-benzopyran-2-ylthio)-2-phenyl-1-phenylthiopropan-2-ol 4 are reported. The 2-S-sidechain orientation in solution determined by OCHS signals in 1 H NMR spectra is mainly axial in all the 3,4-dihydro-2 H -1-benzopyran derivatives. Compound 4 crystallizes in the triclinic space group P 1 with an axial 2-S-sidechain and an intramolecular hydrogen bond between the OH and the ether oxygen with the O;;;O distance of 2.799(3) Å.