Halides tetrameric

The complexity of the substitution reaction pathway intensifies in the replacement reactions of the tetrameric halides N4P4X8. A total of 33 isomers is possible (17,18). 

Reactions of Trimeric and Tetrameric Halides with Hydroxy and... 

Hawthorne and co-workers have also produced a series of macrocyclic Lewis acid hosts called mercuracarborands (156, 157, and 158) (Fig. 84) with structures incorporating electron-withdrawing icosahedral carboranes and electrophilic mercury centers. They were synthesized by a kinetic halide ion template effect that afforded tetrameric cycles or cyclic trimers in the presence or absence of halide ion templates, respectively.163 These complexes, which can bind a variety of electron-rich guests, are ideal for catalytic and ion-sensing applications, as well as for the assembly of supramolecular architectures. 

Figure 8 A formal disintegration of the cubane-like tetrameric chalcogen(IV) halides exemplified by the formation of Te3Cl13, Te2Clw2, and TeCl62 from Te4Cl16...

Experimentally, x values for gaseous lithium halides were determined as early as 1949 by molecular beam resonance experiments In solution, the quadrupolar interaction of ethyUithium and of t-butyllithium were investigated in 1964 . It was found that tetrameric and hexameric aggregates have different interactions. In the solid state x of tetrameric methyl- and ethyUithium was determined in 1965 and 1966 , and for lithium formate in 1972 . However, it was not untU Jackman started his investigations of lithium enolates and phenoxides in solution that the quadrupolar interaction was used in a systematic fashion to obtain structural information . 

Phosphonitrilic halides (continued) primary amines and, 1 360-362 secondary amines and, 1 350-362 tertiaiy amines and, 1 362-363 structural theory further aspects of, 1 375 structure, 1 365-366 high polymer and, 1 372 medium polymers and, 1 368-372 spectroscopic data and, 1 369-372 structural theory and, 1 372-375 tetrameric compounds and, 1 367-368 trimeric compounds and, 1 366-367 Phosphonium cations, 9 243-250 halogenated, 9 243-249 salts... 

For the 1 1 complexes with X = halide, a number of crystal structure determinations have shown that tetrameric [AgXPR3]4 units (R = Et or Ph) are formed where the arrangement could be either cubane-like or a chair form (18a and 18b). Some relevant bond distances are summarized in Table 25.170-177... 

Neutral adducts of silver halides with phosphines have been discussed earlier under Section 54.1.3.1. 1 1 adducts were found to be tetrameric and adopted either a (pseudo)- cubane or chair ( step ) type structure. 

Until recently, only two reports existed for 1 1 adducts of silver halides with amines, namely AgT piperidine57 and Agl-morpholine.381 The first had a tetrameric cubane structure whilst the second was described as a stair polymer adduct. The range has now been extended to include 2-and 3-methylpyridine, quinoline and triethylamine.382 In each case the adduct was obtained by recrystallization of silver(I) iodide from neat base. The colourless crystals were found to lose base readily on exposure to the atmosphere and structural data were collected from crystals mounted in argon-filled capillaries, containing mother liquor. 

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