Bridging, intermolecular

Fused versus bridged (intermolecular I J-diyl trapping)... 

In dimethyltin diformate, however, the two carbonyl groups bridge intermolecularly, to form infinite sheets similar to those in dimethyltin difluoride or dimethyltin di(fluorosulfonate).29 If the linearly polymeric diorganotin carboxylates are dissolved in chloroform, the 119Sn NMR chemical shift moves downfield by 50 to 100 ppm, and is then almost independent of concentration, showing that the compounds are monomeric in solution.23-30 Dibutyltin glutarate is a linear polymer as shown in 13-9.31... 

With the exception of H bridges, intermolecular forces are all of the same order of magnitude, so localized vibrations are not to be expected, but since the forces are weak, their influence extends over long distances, which makes collective excitations (phonons) possible. To get a feeling for what kind of phonons are possible and how, to observe them, we discuss briefly some special cases. 

Other interesting synthetic applications of the ketone-derived enamine alkylation are found in the monomethylation of steroid enamines (249), extension of the benzylation reaction (250) to a ferrocene derivative (251), the use of a-bromoesters (252) and ketones (252) or their vinylogues (25J), in the syntheses of alantolactone (254-256), isoalantolactone (257), and with a bridged bis-enamine (258). The use of bifunctional alkylating agents is also seen in the introduction of an acetylenic substituent in the synthesis of the characteristic fragrant constituent of jasmine (259), the synthesis of macrocyclic ketolactones (260), the use of butyrolactone (261), and the intermolecular or intramolecular double alkylations of enamines with dihalides (262). 

The resulting derivatives, unlike most organotin carboxylates, are hydrolyzed relatively readily in air. An X-ray crystallographic study 399) showed that trimethyltin glycinate has an intermolecularly associated, polymeric structure, with bridging amino groups. 

Besides such intermolecular stabilized compounds, intramolecular stabilized compounds have also been reported. Rettig et al. described the synthesis of phosphine-stabilized Al—N monomers by using a tripodal ligand [101]. More recently, Raston et al. reported on the synthesis of compounds of the type [H2A1E(H)R]2, containing only weak Al—H bridges [102]. 

A related dinuclear species 77, recently described, constitutes the first dinuclear gold(I) complex with heterobridged phosphor-1,1 -dithiolato moieties and bis(ylide) bridging ligands [ 102]. It is obtained by reaction between [ AuS2PPh2] and the diylide gold complex 74 (R=Me). No intermolecular Au-Au interaction is observed in 77 but the oxidative addition of chlorine to the product leads to a new complex 78 in which a single bond is formed between the two Au(II) centers (Scheme 26). 

In the intermolecular reactions between anthocyaifins and flavonoids mediated by acetaldehyde, new compounds linked by an ethyl bridge are formed. Three new compounds were detected by the reaction of malvidin 3-glucoside and proanthocy-... 

Type 1. Bridging adducts (see Fig. 2), where the dioxygen ligand is bridged between two metal atoms intermolecularly. Here, the metal dioxygen ratio is invariably 2 1. 

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