摘要:

AbstractAttempted preparation of phosphorane9with a 1,3,2‐dioxaphosphorinane ring attached diequatorially to phosphorus led to a mixture of products from which was isolated 12‐membered ring phosphorane10, formally the dimer of9, in low yield (22%). An X‐ray crystal structure of10revealed a highly symmetrical molecule with trigonal bipyramidal geometry at both phosphorus atoms. The 12‐membered ring is attached to phosphorus diequatorially. The ring is strongly puckered about phosphorus with an equatorial O‐P‐O angle of 110°. The chemical shift equivalence of the CH2O resonances in the1H NMR spectrum of10shows the 12‐membered ring to be highly mobile at ambient probe temperature. At −89°C, these resonances are fully decoalesced. The value of ΔG‡for the process that averages these peaks was found to be 10.1 kcal/mol at c

ISSN:1042-7163    

DOI:10.1002/hc.520040223

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

Abstract1,3‐Bis(2,4,6‐tri‐t‐butylphenyl)‐1,3‐diphosphaallene (1) reacted with elemental sulfur under wet reaction conditions to give cis‐ and trans‐2,4‐bis(2,4,6‐tri‐t‐butylphenyl)‐1,2,4‐thiadiphosphetane 2,4‐disulfide (cis‐2and trans‐2) and cis‐2,4‐bis(2,4,6‐tri‐t‐butylphenyl)‐1,2,4‐oxadiphosphetane 2,4‐disulfide (cis‐3). The structure of cis‐3was determined by X‐ray crystall

ISSN:1042-7163    

DOI:10.1002/hc.520040224

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe crystal structures of two pentavalent silicon anions are discussed. The structure of [SiMe3F2]−1shows a trigonal bipyramidal structure with the fluorines in apical positions. The SiF bond distances are the longest known of this type. The crystal structure of fluorosilicate2(1,1‐diphenyl‐1‐fluoro‐3,3‐bis[trifluoromethyl]‐1,3‐dihydro‐2,1‐benzoxasilole[ion 1‐]) is distorted toward a rectangular structure along the Berry pseudorotation coordinate. The lone SiF bond distance in2is much shorter than that in1. The ab initio calculations on a variety of pentavalent fluorinated silicon anions are reported, and good agreement with the experimental data are found. Fluoride affinities for the fluorosilanes are reported and are in reasonable agreement with the experimental values where known. The fluoride affinity of the tetra‐coordinated species is related to the length of the SiF

ISSN:1042-7163    

DOI:10.1002/hc.520040225

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractNovel (E,E)‐dibenzylidene‐N‐phenyl succinimide thioimide1band dithioimide1cderivatives of the photochromic fulgimide1awere synthesized. The thioimide1band dithioimide1cderivatives were found to undergo isomerization as the main photoreaction when irradiated in a variety of organic solvents, as opposed to the reversible electrocyclic ring closure/opening reactions in the case of the fulgimide1a. The X‐ray crystal structures of1band1cwere determined, and the influence of the thiocarbonyl groups on the structural parameters were investigated in comparison to the crystal structure of1a. The1H and13C NMR spectra were recorded for all three compounds1a, 1b, and1cand are discussed in terms of their structural and electronic variations, as is the effect on the photochemical behavior. The twisting of the N‐phenyl ring was found to be a consequence of intramolecular steric interactions and not of intermolecular packing forces. This was substantiated by a series of semiempirical (AMI) calculations. The C(thiocarbonyl) was found to be highly deshielded compared to the corresponding C(carbonyl) carbon atom, and the deshielding effect of the thiocarbonyl group was evident throughout the whole thiocinnamic moiety. Crystal data for monothioimide1b: spacegroup P21/c with a = 8.794(2) Å, b = 9.623(1) Å, c = 22.182(5) Å, β = 91.45(2)°, Rw = 0.038, and R = 0.067. Dithioimide1c: spacegroup Pnna with a = 9.411(2) Å, b = 17.304(2) Å, c = 13.574(2) Å, Rw = 0.0

ISSN:1042-7163    

DOI:10.1002/hc.520040226

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

摘要:

AbstractThe oxidation of 1,5‐dimethyl‐2,4‐bis(diethylamino)‐1,5‐diaza‐2,4‐diphosphorinan‐6‐one5with tetrachloroorthobenzoquinone (TOB) leads to the formation of the spirophosphorane9, which is unstable and undergoes an unusual spontaneous rearrangement into the isomeric methylenephosphinophosphorane11. The sulfuration of9and11gives the stable isomers12and19, exhibiting no tendency of mutual transformation. The mechanism of the isomerization of9into11is discussed. Some chemical properties of9and11have

ISSN:1042-7163    

DOI:10.1002/hc.520040227

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY

ISSN:1042-7163    

DOI:10.1002/hc.520040202

出版商:VCH Publishers, Inc.    

年代:1993

数据来源: WILEY