Tin-nitrogen rings

SILICON-, GERMANIUM- AND TIN-NITROGEN RINGS 10.3.1 Saturated Systems... 

A novel cyclophosphazene-substituted tin-nitrogen ring compound (33) has been identified from the reaction ... 

In this section, syntheses of a variety of inorganic nitrogen compounds are described. The syntheses include those of triazanium chlorides alkylamino derivatives of boron, arsenic, and tin and trimeric and tetrameric boron-nitrogen ring structures as exemplified by borazine (HNBH)3. 

The reactivity of the tin-nitrogen bond in eyelostannazanes towards orga-noelement halides may be used to prepare other inorganie heteroeyeles, e.g. B2N2 rings [eqn (10.23)]. ... 

Figure 8.12 An illustration of the planar (TIN)2 ring in the compound [(TI N(SiMe3)2 )2]. Thallium, nitrogen and silicon atoms are shown as black spheres and carbon atoms are white. Selected bond lengths TI1-N1 2.581(7), TI1-N2 2.576(7) A...

Each of these tin atoms acts as a Lewis acid, with two neighboring nitrogen atoms functioning as electron donors. The ten-membered ring folds up to generate a four-membered cycle bridged at the 1,3- and 2,4-positions. The structure, which can easily be deduced from high-resolution NMR spectra, is displayed in Fig. 14. 

The structure of this adduct is displayed in Fig. 17 177>. As should be expected (see Chapters 3 and 4) the nitrogen atom of t-butylamine is coordinated with the tin atom at nearly right angles with respect to the four-membered ring. 

Bicyclic alkaloids. Nagao et al. have developed a general synthesis of chiral bicyclic alkaloids with a nitrogen atom at the ring juncture, such as pyrrolizidines [5.5], quinolizidines [6.6], and indolizidines [6.5], based on a highly diastereose-lective alkylation of 3-a>-chloroacyl-(4S)-isopropyl-l,3-thiazolidine-2-thiones (1, m = 1,2) with 5-acetoxy-2-pyrrolidinone (2, n = 1) or 6-acetoxy-2-piperidinone (2, n = 2). Thus the tin enolate of 1 (m = 1), prepared with Sn(OTf) and N-... 

An elegant solution to the problem has been provided by tin measurement of the nuclear magnetic resonance spectra, which permits a direct determination of the inversion frequency. The spectra of A -subetituted aziridines such ns (VIH), (IX), and (X) showed that Hie substituent on the nitrogen docs not lie in tho piano of the ring. However, the inversion frequency is so high that resolution of such molecules in the most favorable ease is likely to be possible only at tem fiora-turee below -500.". "... 

Phenyl ethylenesulfonate, 241 Tin(IV) chloride, 300 Containing one sulfur 2,4-Bis(4-me thoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide, 38 Titanium(IV) chloride-Zinc, 310 Other five-membered heterocycles Carbon dioxide, 65 Methanesulfonyl chloride, 176 Six-membered rings Containing one nitrogen—piperidines Dichlorotris(triphenylphosphine)-ruthenium(II), 107 Mercury(II) trifluoroacetate, 175 Tetrakis(triphenylphosphine)-palladium(O), 289... 

The one-dimensional coordination polymer 158 with hexacoordinated tin atoms resulted from the reaction of diphenyltin dibromide with bis(l,2,4-triazol-l-yl)methane347. The bis(triazol-l-yl)methane coordinates to the tin atom in a bidentate bridging fashion through the nitrogen atoms at the 4-position of the triazole rings with intermolecular Sn—N distances of 2.454(7) A. 

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