Hexaco-ordinated Phosphorus Compounds

Report of the Xlllth International Conference on Phosphorus Chemistry, Jerusalem, 1995 Phosphorus, Sulfur and Silicon, 1996,109-111. 

Melnicky, I. Neda, and R. Schmutzler, Phosphorus, Sulfur and Silicon, 1995,106, 65. 

Melnicky, A. Vollbrecht, A. Fischer, P.G. Jones, A. Martens-von Salzen R. Schmutzler, U. Niemeyer B. Kutscher, and J. Engel, Phosphorus, Sulfur and Silicon, 1996,109-110, 629. 

The proceedings of the 13th International Conference on Phosphorus Chemistry, Jerusalem 1995, have appeared. The reports therein on tervalent phosphorus acid derivatives will not be covered here. The final volume of the chemistry of organophosphorus compoxmds in the Patai series, the chemistry of functional groups, contains a chapter on the preparation and properties of tervalent phosphorus acid derivatives. A new twelve volume work. Comprehensive Heterocyclic Chemistry II, contains several chapters on phosphorus-containing heterocycles, many of which are tervalent phosphorus acid derivatives.  

Finally a new departure in an unusual aspect of hypervalent phosphorus chemistry has been provided by the synthesis of water-stable dialkoxy phosphorus(V)-tetraphenylporphyrins (125) from (124). The six-co-ordinate phosphorus porphyrin (125) with R=Et, has 

8 1 = -180.1, which suggests that the ethoxy groups are attached to the central phosphorus at the fifth and sixth co-ordination sites.The bis-hydroxymethyl derivative (R = HOCH2) is water soluble and very stable even under acidic and basic aqueous conditions, a property which may be useful in phototcdox catalysis.  

Interest in hypervalent phosphorus chemistry has been maintained especially with regard to structural studies and the synthetic utility of pentaco-ordinate phosphorus compounds. Conformational effects of ring fusion and heteroatom substitution in six-membered rings of spirocyclic oxyphosphoranes have received further attention and hence added fuel to the debate over the occurence of diequatorial six-membered ring orientations as tbp models for enzymatic action on c-AMP. Finally, a novel departure has occurred in the area of hexaco-ordinate phosphorus chemistry with the preparation of further derivatives of the porphyrin ring system containing hypervalent phosphoras coordinated by the tetnqiyrrole unit 

Prichard, and (the late) S.M. Watson, J. Chem. Soc., Chem. Commun., 1991, 1447. 

Hexaco-ordinated Phosnhorus Compounds- The first examples of diazadiphosphetidines (128) with phosphonium and 6-coordinate phosphate centres without halogen atoms on phosphorus were formed from the reaction of 

Robinet, M. Barthelat, V.Gasmi and J. Devillers, J.Chem.Soc., Chem.Commun., 1989, 1103. 

Murray, A. Pautard-Cooper, N.A.Eskew and S.A.Evans Jr., Phosphorus, Sulfur and SUicon, 1990,48i 0,101. 

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Hexaco-ordinated Phosphorus Compounds. - The reaction of PCt with alkylammonium fluorides in the presence of secondary amines gives PF5-amine adducts (132)60. The additional presence of alcohols or phenols leads to the formation of alkoxy- or aroxypenta-f luorophosphates, ROPF -. The PF -amine adducts may also be converted into ROPF - by treatment with alcohols or into ArNHPF -by treatment with primary arylamines. 

Cavell et al. have synthesised and characterised a series of neutral, hexaco-ordinate phosphorus compounds containing divalent, tridentate diphenol imine, azo and thio ligands. For example, the reaction of silylated Schiff base ligands e.g. 112) with PCI5 gave the neutral, hexacoordinate compound 113 by... 

Several reports of the synthesis of hexaco-ordinate phosphorus compounds [e.. (81)] from tervalent phosphorus have appeared (see Chapter 2). P N.m.r. studies... 

Hexaco-ordinate Phosphorus Compounds - A series of heterocyclic phosphorates (133) with a P-C Bond in the ring have been prepared by the reaction of phosphonates... 

A number of important review articles have appeared in the area of pentaco-ordinate and hexaco-ordinate phosphorus chemistry. Robert Holmes has provided an extremely informative comparison of the hypervalency, stereochemistry and reactivity of silicon and phosphorus including the application of the latter to enzyme systems. The coordination chemistry of hydrophosphoranes including the formation of complexes from bicyclic-, tricyclic- and tetracyclic hydrophosphoranes has also been the subject of a comprehensive review with literature coverage to 1995. Numerous metal complexes are mentioned including Rh, Ru, Pd, Co, Fe, Mo, and W and the relevance to asymmetric catalysis is discussed. Neutral six-coordinate compounds of phosphorus, including mono-, di-, tri-, and tetracyclic examples, have also been reviewed. 

Phosphines and Phosphonium Salts Pentaco-ordinated and Hexaco-ordinated Compounds Phosphine Oxide and Related Compounds Tervalent Phosphorus Acids Quinquevalent Phosphorus Acids Nucleotides and Nucleic Acids Ylides and Related Compounds Phosphazenes. 

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