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Showing papers by "George M. Sheldrick published in 1991"


Journal ArticleDOI
TL;DR: In this paper, the crystal structure of 1 exhibits a three-legged stool monomer of composition (C5Me5Na · 3py), whereas 2 has a linear zig-zag chain structure of composition.

78 citations


Journal ArticleDOI
TL;DR: In this article, the reactions of BiCl3 with 2,4,6-tris(trifluoromethyl)phenyl lithium (LiRf) in ether solution in 1 : 2 and 1 : 3 ratios have led to the isolation of BiRf2Cl (I) and Bi(Rf3 (II).

68 citations


Journal ArticleDOI
TL;DR: In this paper, the reaction of appropriate combinations of 2,4,6-tris(trifluoromethyl)phenol (ROH) or ROH with NaH or KH with ROH was shown to form compounds 1-4 with NMR spectrosccpy and single crystal X-ray structure analysis.
Abstract: [Na(OR)(thf)2]21, [K(OR)(thf)2(µ-thf)]22, [Na(SR)(thf)2·0.25thf]x3 and [K(SR)-(thf)]x4 were formed by the reaction of the appropriate combinations of 2,4,6-tris(trifluoromethyl)phenol (ROH) or 2,4,6-tris(trifluorornethyl)benzenethiol (RSH) with NaH or KH; compounds 1-4 have been characterised by NMR spectrosccpy and single crystal X-ray structure analysis, both phenoxides being dimeric whereas two distinct polymeric structural types are observed for the thiolates.

44 citations


Journal ArticleDOI
TL;DR: The first solid-state X-ray analysis of a four-membered [LiN]2 heterocycle with two solvent-free two-coordinate Li centers was performed in this paper.
Abstract: [LiN(SiMe3)Ar]2 (1, Ar = 2,6-iPr2C6H3) is prepared by the reaction of HN(SiMe3)Ar with nBuLi in n-hexane. This compound with an unusual structure contains a four-membered [LiN]2 heterocycle with two solvent-free two-coordinate Li centers. Its molecular structure represents the first solid-state X-ray analysis of an uncomplexed [LiN]2 dimer.

42 citations


Journal ArticleDOI
TL;DR: In this paper, three new germaimines have been synthesized and two of them characterized by X-ray diffraction; the GeN bond lengths agree well with an ab initio prediction for H2GeNH.
Abstract: Three new germaimines have been synthesized and two of them characterized by X-ray diffraction; the GeN bond lengths agree well with an ab initio prediction for H2GeNH.

36 citations



Journal ArticleDOI
TL;DR: A single X-ray structural analysis shows a folded polymeric structure for thallium(I) 2,4,6-tris(trifluoromethyl)thiophenolate as mentioned in this paper.
Abstract: Preparation and Structure of Thallium(I) 2,4,6-Tris(trifluoromethyl thiophenolate, a Compound with a Folded Polymeric Structure The title compound, thallium(I) 2,4,6-tris(trifluoromethyl)thiophenolate (1) has been prepared by using either TlOEt and (CF3)3C6H2SH or Tl2CO3 and (CF3)3C6H2SNa. A single X-ray structural analysis shows a folded polymeric structure for 1; the crystal lattice incorporates half of a 1,4-dioxane molecule per Tl atom. This compound has a surprisingly high kinetic stability compared to known thallium(I) thiolates.

18 citations



Journal ArticleDOI
TL;DR: In this paper, the properties of 1,2,4,3-thiadiazaboretidines have been discussed and the 11B chemical shifts have been calculated for 3-phenyl by the IGLO method and correlate acceptably with the experimental values.
Abstract: Synthesis and Properties of 1,2,4,3-Thiadiazaboretidines. Crystal Structure of 2,4-Di-tert-butyl-3-phenyl-1,2,4,3-thiadiazaboretidine Reaction of sulfur diimides with alkyl(aryl)bis(methylthio)boranes leads to reductive 1,3-cycloaddition of the NSN sequence with formation of the 1,2,4,3-thiadiazaboretidines 2a-g. NMR (1H, 11B, 13C, 15N, 29Si), mass spectra and the results of the X-ray analysis of 21 are reported and discussed. The 11B chemical shifts have been calculated for 3-phenyl-1,2,4,3-thiadiazaboretidine and some related model compounds by the IGLO method and correlate acceptably with the experimental values.

15 citations


Journal ArticleDOI
TL;DR: In this article, a condensation product with three ORf functions coupled with the elimination of three fluorine atoms has been characterized spectroscopically and by X-ray crystallography.

13 citations


Journal ArticleDOI
TL;DR: In this article, an improved synthesis of the aminoiminophosphorane 1 is described, where the compound TiCl4 reacts with Me3SiOPPh2NSiMe3 unexpectedly with elimination of all Me 3Si groups to yield the eight-membered heterocycle [{TiCl2(OPPh 2N)}2].
Abstract: The reaction of ZrCl4 with (Me3Si)2NPPh2NSiMe31 yields the four-membered heterocycle [[graphic omitted]SiMe3)]. An improved synthesis of the aminoiminophosphorane 1 is described. The compound TiCl4 reacts with Me3SiOPPh2NSiMe3 unexpectedly with elimination of all Me3Si groups to yield the eight-membered heterocycle [{TiCl2(OPPh2N)}2]. A vanadium-containing dimetallacyclophosphazene [{VCl2(NPPh2N)}2] has been synthesised from [VCl3(NSiMe3)] and CiPPh2NSiMe3. The X-ray structures of [[graphic omitted]SiMe3)]·MeCN and [{TiCl2(OPPh2N)}2]·4MeCN have been determined. While the cyclic Zr–N distances in the former have to be considered as single bonds, the short Ti–N of the latter (almost planar) suggest double-bond character.

Journal ArticleDOI
TL;DR: In this article, the structure of (Perfluoroalkyl)(dimethylamino)sulfonium hexafluoroarsenates was elucidated by X-ray analyses, and the influence of the substituents on the bonding was discussed.
Abstract: (Perfluoroalkyl)(dimethylamino)sulfonium Hexafluoroarsenates MeN = S(CF3)2 (5) is alkylated by Me3O⊕ AsF⊖6 to Me2N-S(CF3)⊕2 AsF⊖6 (4). From 5 and MeOSO⊕ AsF⊖6 (6) MeOS(O)-N(Me)S(CF3)⊕2 AsF⊖6 (7) is formed as a relatively stable primary product. Decomposition of 7 gives the expected 4 only in poor yield. Nucleophilic substitution of the sulfur-bonded fluorine in CF3SF⊕2 AsF⊖6 (8) by Me3SiNMe2 yields CF3S(NMe2)⊕2 AsF⊖6 (9). Similarly, (CF3)2CFSF⊕2 AsF⊖6 (10) reacts with dimethyl(trimethylsilyl)amine to give (CF3)2CFS(NMe2)⊕2 AsF⊖6 (11). The structures of 4 and 9 are elucidated by X-ray analyses, and the influence of the substituents on the bonding is discussed.

Journal ArticleDOI
TL;DR: The reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4-disubstituted benzene derivatives leads to products which contain two diisoalkylaminoboradiyl units and two remaining double bonds which are located on the substituted C atoms.
Abstract: Twofold Borylation of Benzene Derivatives with (Diisoalkylamino)boradiyl Units The reaction of subvalent boron species generated by the defluorination of difluoro(diorganylamino)borane with Na/K alloy in the presence of 1,4-disubstituted benzene derivatives leads to products which contain two (diorganylamino)boradiyl units and two remaining double bonds which are located on the substituted C atoms. Compounds 5 to 8 exhibit structures based on a 2,8-diborabicyclo[3,2,1]octa-3,6-diene skeleton while 9 shows a skeleton with a 1,3a,4,6a-tetrahydroborolo[3,2-b]borole structure. The latter structure corresponds to that of 1 obtained in the same reaction with benzene. The compounds are characterized by elemental analyses and spectroscopically [MS, NMR (1H, 11B, 13C, 15N, 19F, 29Si)]. X-ray structure analyses are presented for 1, 6, 7, 8, and 9.

Journal ArticleDOI
TL;DR: Aza-Rhenium (VII) compound 2 as mentioned in this paper reacts with three equivalents of 2,6-diisopropylphenyl isocyanate with evolution of CO2 to give the title compound 2.
Abstract: Synthesis and Structure of Ph3PNRe(NC6H3iPr2;-2,6)3 - An Aza-Rhenium (VII) Compound. Ph3PNReO3 (1) reacts with three equivalents of 2,6-diisopropylphenyl isocyanate with evolution of CO2 to give the title compound 2. The X-ray single crystal structure of 2 exhibits a rhenium atom tetrahedrally coordinated to four nitrogen atoms (space group P 3).

Journal ArticleDOI
TL;DR: The products of RC6H,*5BNR, with monoalkylbenzenes, are the highest borylated species to be formed in reactions between dehalogenation products of F,BN(i-Pr),.

Journal ArticleDOI
TL;DR: The lithium derivative of tert-butyl(di-tert-butylfluorosilyl)-amine (1) reacts with sulfur or selenium to give the bis[fluorosily l)-amino]di- and -trisulfanes 2, 3 and -selane 4, respectively.
Abstract: 1,3-Bis[tert-butyl(di-tert-butylfluorosilyl)amino]trisulfane – a Compound with FSiNSSSNSiF Helix The lithium derivative of tert-butyl(di-tert-butylfluorosilyl)-amine (1) reacts with sulfur or selenium to give the bis[(fluorosilyl)-amino]di- and -trisulfanes 2, 3 and -selane 4, respectively. The trisulfane 3 crystallizes from n-hexane and exhibits a helical structure (X-ray analysis).





Book ChapterDOI
01 Jan 1991
TL;DR: In this article, the authors consider some elementary applications along the lines described by S.R. Hall at the 1970 Advanced Study Institute on Direct and Patterson Methods at Parma, and propose a general method of incorporating space group symmetry into crystallographic programs.
Abstract: Structure factor algebra (Bertaut, 1956) provides a general method of incorporating space group symmetry into crystallographic programs. We shall consider some elementary applications, along the lines described by S.R. Hall at the 1970 Advanced Study Institute on Direct and Patterson Methods at Parma.

Journal ArticleDOI
TL;DR: In this article, the new compounds Se[N(SiMe 3 ) 2 ] 2 and Te[NMe 3 ] 2 were prepared in relatively good yields and their crystal structures determined by X-ray crystallography at low temperature.
Abstract: The new compounds Se[N(SiMe 3 ) 2 ] 2 and Te[N(SiMe 3 ) 2 ] 2 have been prepared in relatively good yields and their crystal structures determined by X-ray crystallography at low temperature. The Se compound crystallizes in the monoclinic system, space group C2/c. The Te compound crystallizes in the triclinic system, space group P1