Studies on novel coordination chemistry of main group elements

Abstract

The studies described are mainly concerned with phosphorus coordination chemistry, and coordination chemistry of main group elements with bulky electron-withdrawing ligand. They may be divided into three parts. Part 1. Identification of new phosphorus specie This project continued the work that had been done in previous student projects, by carrying out a series of reactions of phosphoms(III) halides (X= CI, Br, I) with thiophosphorus(V) halides (X= CI, Br) and zinc dust present, to form several new products. Heating was generally used to increase the rate of reaction. The new phosphorus species can be classed into four kinds. A: Mixed valence phosphorus(III) -thiopho'sphorus(V) halides. B: New dithiophosphorus(V) halides. C: the new triphosphorus(III) halide PI(_2)PIPI(_2). (the first report of this compound). D: Mixed valence phosphorus(III) - dithiophosphorus(V) halides. (^31)P NMR studies have been used extensively throughout the project to identify the products. Part 2. Studies on main group elements compounds containing bulky electron-withdrawing substituents This project has involved reacting ArLi or Ar'Li, Ar"Li(Ar=2,4,6-(CF(_3))(_3)C(_6)H(_2); Ar'=2,6-(CF(_3))(_2)C(_6)H(_3); Ar"=2, 4-(CF(_3))(_2)C(_6)H(_3)) with ECI(_3), (E= As or P) or E'Cl(_4) (E'= Sn, Ge or Si) to synthesise new compounds, SiR(_2)Cl(_2), GeR(_2)Cl(_2). GeArCls, SnR(_2)Cl(_2). ASR(_2)CI, AsArCl(_2) and the previously described PRCl(_2) (R= Ar , Ar' or Ar"). All these new compounds have been characterised by elemental analysis and (^19)F NMR; the molecular structures of SnAr(_2)Cl(_2), SnAr'(_2)Cl(_2). GeAr"(_2)Cl(_2). GeArCb and SiAr"(_2)Cl(_2) have been elucidated by X-ray diffraction. Part 3. Attempt to synthesise phosphaalkynes with bulky electron-withdrawing substituents Attempts have been made to synthesise the first phosphaalkynes containing a bulky electi-on-withdrawing ligand; this involves a series of reactions, the first being the preparation of die phosphaalkene RP=CCl(_2). A few methods have been tested, but due to limit of time and other factors, the compounds could not be synthesized successfully so far.