Ring and Cage Compounds

The unusual three-membered ring compound (9.50) can be made by the reaction shown [17]. 

A butterfly-shaped double three-membered ring compound has been prepared by photolysis of a dimeric boraphosphetane (9.51) and a cage compound involving 3-coordinate B and P atoms is obtained by reaction (9.52) [18,19]. 

Folded V-ring phosphetanes of type (9.56) have been made [23] as well as derivatives such as (9.57a,b) and six-membered ring compounds (9.57c). 

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Thermal condensation reactions which produce polyphosphates are of great industrial importance. These involve the heating of solid acid phosphate salts whereby P-O-P linkages are formed with the elimination of water (3.101). Numerous long-chain, ring and cage compounds can be produced by reactions of this kind (Chapter 5.4). 

Another adamantane-type compound is obtained by reaction (9.242). The reactions of methyl-chlorosilanes with LiPH2 and Li2PH lead to a whole series of ring and cage compounds built from P-8i linkages [32]. 

AIN, GaN, and InN are attractive materials for applications such as blue lasers and field emitters single-source precursors for these of formula [R2MNR 2]2 (R = alkyl, R = alkyl or H) have been reported.236 The reaction of alkylamines with group 13 trialkyl metal compounds affords oligomeric or polymeric ring and cage structures of metal amides and imides (see section on nitrides). 

Several books and general reviews are already available on phosphorus ring and cage systems (16). This one will focus more specifically on the coordination chemistry of molecular tetraphos-phorus-based doso-compounds, including itself and closely related analogs, and will also include structural data on both free and coordinated species. The questions of the transmission of electronic and structural effects through the molecular frame, and of the extent oftt-bonding, will be critically considered. 

Principally, members of both of the above mentioned classes of compounds (oxidation of the molecule back-bone ring and cage strain) can be exothermic or endothermic compounds. An example of the former is TNT with A H° = -295.5 kj kg-1, while RDX shows a positive standard enthalpy of formation of A H° = +299.7 kj kg"1. 

Sulfur-nitrogen rings and cages are discussed in Sulfur-Nitrogen Compounds. There are several boron-sulfur and silicon- sulfur rings and examples are given in Figure 51. 

N NMR spectroscopy has been applied to the identification of complex mixtures of S N rings and cages formed from the air oxidation of S3 Ns in acetonitrile and to investigations of the dynamic behavior of the bicyclic compound PhCNsSs (11), which undergoes 1,3-nitrogen shifts. ... 

Bonding of the 3jt p(P)-2jt p(C) type is now generally believed to be present in the trivalent phosphorus compounds indicated in Table 6.13. Such compounds have proved invaluable in the synthesis of organophosphorus ring and cage derivatives. It is believed that the chemical behaviour of P=C bonds mimics that of alkenes very closely [15]. 

Some alkyl or phenylstannyl phosphines can be prepared from the appropriate phosphine and alkyl or phenyl tin compound. Many are ring or cage compounds and they are structural analogues... 

Main group elements form a wide variety of neutral, cationic, and anionic compounds having chain, ring, and cage structures (e.g. Zintl anions). [366] All of these may be useful starting materials to be combined with mono- and polynuclear transition metal moieties to generate molecules with novel and exciting structural features. This alternative type of synthetic approach has been used for the synthesis of all the other derivatives included in Table 3-11. For example, as shown in Scheme 3-12, the reaction of either Se4 or Te4 with such mononuclear metal carbonyls as [Fe(CO)s] and [W(CO)6] can yield cluster compounds... 

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