Tetrahedral diphosphine complexes

Several low-spin cobalt(II) cyanide complexes containing tertiary or secondary phosphine ligands, and corresponding to the general formula [Co(CN)2P3] have been prepared by halide-cyanide exchange (CN -form anion resin) from tetrahedral [C0X2P2] complexes (X = Cl, Br) and an excess of phosphine (Table With ditertiary phosphines the reaction gives either diphosphine-... 

Four- and five-coordinated aluminium is present in such phosphine complexes as in Equation 9.131. An interesting comparison can be made between the diphosphine complexes[Cy2PCH2CH2PCy2l [A1H312 and [PPr 2CH2CH2PPr 2]AlH3 . The cyclohexyl complex is monomeric with approximately tetrahedrally coordinated Al (b), but in the isopropyl complex the coordination is trigonal bipyrami-dal (c) and this is reflected in a difference in the Al-P bond length in the two compounds [5]. 

Fig. 7. Structures of some possible Au(f) diphosphine complexes (1) bridged digold, (IT) annular, (III) tetrahedral, (IV) chelated 3-coordinate complex...

It is possible that the tetrahedral, bis-chelated Cu(I), Ag(I) or Au(I) diphosphine complexes (especially those with phenyl substituents) are recognised by cells in a similar manner to the phenyl phosphonium salts discussed above as lipophilic cations which distribute according to membrane potentials. Indeed, Mirabelli and coworkers (unpublished results) have found preliminary evidence for extensive specific damage to mitochondria by [Au(dppe)2] in hepatocytes. It is also notable that positively-charged... 

Berners-Price SJ, Sadler PJ and Brevard C (1990) Tetrahedral, chelated, silver(I) diphosphine complexes. Rapid measurements of chemical shifts and couplings by two-dimensional P- ° Ag NMR spectroscopy. Magnetic Resonance in Chemistry 28 145-148. 

The reaction of mercuric iodide with the chelating diphosphine bis(diphenyl-phosphinoethyl)sulphide gives the complex [(Ph2PC2H4)2S]HgI2.184 Structural analysis shows the mercury to be in a distorted tetrahedral co-ordination, with formation of an eight-membered puckered chelate ring. 

However, even a large-pore zeolite such as zeolite Y, whose structure consists of almost spherical 13 A supercages interconnected tetrahedrally through smaller apertures of 7.4 A in diameter, is limited regarding the size of guest molecules by the space available in these. Indeed, organometallic complexes as they are widely used for stereo controlled reactions in the production of fine chemical production are often too spacious to enter those pores. This was previously demonstrated for Rhodium diphosphine or Cobalt salen complexes12-13. 

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