Cage structures phosphorus-containing

As we shall see in the following Sections, phosphorus also forms a number of cage structures based on expansion of the P4 tetrahedron, containing three- or four-coordinate phosphorus. It has also been found to form ring or chain structures from linked tetrahedra, with oxygen or nitrogen substituents on phosphorus. 

Further products of the hydrolysis of calcium phosphide are P2H4, P3H5 and other hydrides, all of which contain P—P bonds. These are very sensitive to air and also are very unstable, tending to decompose to PH3 and phosphorus-rich polymers. The most stable is P7H3, which has the cage structure shown in Figure 11.16. Its stability is due to the wide separation of the hydrogen atoms, so that PH3 is not lost readily. 

Abstract The syntheses, structural properties, and reactivities are reviewed for phosphine-acetylenic macrocycles and cages. These compounds are of current interest for their phosphorus-containing 7c-conjugated molecular frameworks. A distinction is made between organic compounds, in which the building blocks are assembled by consecutive transformations, and organometallic structures, in which the coordinative ability of phosphorus is employed to assemble the monomeric building blocks. 

Cage-like structures containing phosphorus have been assigned on the basis of NMR spectra. For instance, in B10H10CHP, identified as a... 

We have discussed the structure of crystalline N2 in Section 4.4.1. Several allotropes of phosphorus are well known. In the gas phase there are P4 tetrahedral molecules, and this condenses as white (also described as yellow) P containing P4 molecules in the solid. There are two forms of white P, but the detailed structures are not known. There are inconsistencies in the structural reports. A monoclinic form of P contains cage-like P,s and P9 groups linked by pairs of P atoms to form... 

In Figure 2.6, we show the 3D model of white phosphorus (P4). It is a beautiful cage molecule White phosphorus is the most common structure of the element in nature. Since P is a triple connector, it can make many other molecules which contain only P atoms. Thus, we have also red and black phosphorus, which are much more complex molecules than P4. 

Since the phosphorus atoms of these macrocycles are all included in phosphole rings, they readily invert close to room temperature. The macrocycles 195-197 can therefore adopt their conformations to the stereochemical requirements of the complexed metals. Macrocycles 195 and 196 can chelate either one (198) (M = Mo(CO)4 [166], PdCb [167]) or two (199-200) (M = Mo(CO)4 [166]) metal-containing units via their diagonal phosphorus atoms. The structure of the cage complex 200 shows a Mo-Mo distance of 5.883 A [166]. Life-times of the palladium catalyst based on the cyclophane ligand 195 in Stille cross-coupling and Heck reactions demonstrate extraordinary resistance of the catalyst towards degradation [167]. 

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