Spiro-λ4-sulfanes with O-ligands of different electronegativity in axial positions. A comparison of CH2O–SIV–OCO and CH2O–S+IV · ·  · OC bond systems

CCD Charge Density Study on Crystals with Large Unit Cell Parameters: The Case of Hexagonall-Cystine

“…The two negative (λ 1 , λ 2 ) curvatures at the CP are of equal magnitudes and the ratio |λ 3 /λ 1 | close to 1 indicates that the S−C1 bond has a cylindrical symmetry. Very close experimental values of the Laplacian and of the electron density at the CP were obtained in other compounds containing S−C bonds: [−2.39 e Å -5 , 1.34 e Å -3 ] and [−3.10 e Å -5 , 1.31 e Å -3 ] in the BTDMTTF−TCNQ complex, [−6.82 e Å -5 , 1.33 e Å -3 ] in 3,3,6,6-tetramethyl- S -tetrathiane, [−2.60 e Å -5 , 1.36 e Å -3 ] and [−2.00 e Å -5 , 1.39 e Å -3 ] in diaryl(alkoxy)acyloxy)spiro-λ 4 -sulfane compared to +2.58 e Å -5 and 0.89 e Å -5 for noninteracting atoms. The two latter cases correspond to a methyl-substituted six-membered ring containing four sulfur atoms, one adopting a twist-boat conformation, and the other with an hypervalent bond.…”

Recent advances in spirochalcogenurane stereochemistry—A mini review

“…25 The structure determination of these unsymmetrical spirosulfuranes gave interesting information insofar as the lengths of the axial bonds were found to be quite unequal as also found for the corresponding racemates. 61 Thus, the SÀ ÀOÀ À(alkyl) bond lengths in 4 and 5 were found to be 1.707 and 1.661 Å , respectively, whereas the lengths of the corresponding SÀ ÀOÀ À(acyl) bonds were as much as 2.052 and 2.129 Å . The OÀ ÀSÀ ÀO arrangement was found to be almost linear in both cases (angle 1808 and 1738, respectively), demonstrating the trigonal bipyramidal geometry.…”

Synthesis and hydrolysis of optically active naphthyl-phenyl-bis(acyloxy)spiro-λ4-sulfane: absolute configurations of spiro-λ4-sulfanes, related sulfonium salts and naphthyl phenyl sulfoxides determined by CD spectroscopy using exciton chirality and empirical rules

“…In other experiments optically active spiro-l 4 -sulfanes 1 and sulfoxide carboxylic acids 1a were methylated to obtain sulfonium salts 1b and sulfoxide carboxylic acid methyl esters 1c, respectively 3,5,6 without loss of the optical activity. XRay crystallographic investigations proved that spirol 4 -sulfanes (1) and their sulfonium salt derivatives 1b possess trigonal bipyramidal structure, [7][8][9][10][11][12][13][14] and the geometry of the sulfonium salts is stabilized by an S···O close contact. Methods for syntheses of diaryl spiro-l 4 -sulfanes 1, sulfonium salts 1b and sulfoxide carboxylic acid methyl esters 1c from sulfoxide carboxylic acids 1a are shown in Scheme 1 (Z-Y=CH 2 -O, CO-NMe or CO-O; Ar=phenyl or naphthyl ring).…”