Metal/phosphorus displacement

Nitrogen Displaces the Metal Phosphorus Displaces the Metal Oxygen Displaces the Metal Sulfur Displaces the Metal Fluorine Displaces the Metal Chlorine Displaces the Metal Bromine Displaces the Metal Iodine Displaces the Metal... 

Selenium monochloride behaves as a strong chlorinating agent towards metals, metallic selenides and hydrocarbons.3 Phosphorus displaces selenium from the chloride with formation of phosphorus trichloride.4 Chlorine converts it into the tetrachloride. 

For the halogen-metal exchange reaction of bulkier halopyrimidines, steric hindrance retards the nucleophilic attack at the azomethine bond. As a consequence, halogen-metal exchange of 5-bromo-2,4-di-r-butoxypyrimidine (43) with n-BuLi could be carried out at -75 °C [20]. The resulting lithiated pyrimidine was then treated with n-butylborate followed by basic hydrolysis and acidification to provide 2,4-di-f-butoxy-5-pyrimidineboronic acid (44). 5-Bromopyrimidine 43 was prepared from 5-bromouracil in two steps consisting of a dehydroxy-halogenation with phosphorus oxychloride and an SnAt displacement with sodium r-butoxide. 

The two-coordinate phosphorus atom of a phosphonio-phospholide moiety is generally a weaker Lewis-base than a tertiary phosphine as a consequence, the complexes are thermally less stable (this holds in particular for metal fragments with low back donation capability, e.g. Mn(CO)4Cl) [35, 43], benzophospholide ligands are easily displaced by tertiary phosphines such as PhsP [27, 44], and bidentate ligands comprising a phosphonio-ben-zophospholide and a phosphine site react with transition metal fragments preferentially at the phosphine site coordination of both phosphorus atoms is only observed if the substrate offers two vacant coordination sites [27, 47]. 

In the latter, the valency angles must be about 100°, so the layers cannot be flat. Their shape is obtained if, in Figure 38, the atoms shown with the clear circles are displaced somewhat below the plane of the paper and the shaded ones similarly, above it. If the layers formed in this way are then arranged on top of one another, the crystal structure of the elements arsenic, antimony and bismuth are obtained in their normal forms in which they have metallic properties. There also exists a modification of phosphorus with a similar structure. In addition, there are other forms of arsenic and antimony, the properties of which correspond to those of yellow phosphorus these forms contain molecules p As4 and Sb4. 

Numerous examples of the displacement of the alkali metal ions by heavier metal ions and by non-metals, such as boron, silicon and phosphorus, have been reported <72HC(25-2)127, B-74MI30502, B-77MI30502). 

Methylene phosphines,296 RP=CR2, can form o (t/1) and n (tj2) complexes, or both, with transition metals (54-56). The o (ij1 ) complexes cis-M(CO)4(mesP=CPh2)2 (M = Cr, Mo, W) have been synthesized, e.g. by displacing norbomadiene from Mo(CO)4(C7H8). MO calculations indicate that the HOMO in CH2—PH is n type, the phosphorus lone pair o orbital slightly more stable and... 

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