Chalcogen amides

Hence, chalcogenoamidophosphinic acids of general formula R2P(E)NHR (27) can be considered as dichalcogenophosphinic acids with one of the chalcogen atoms replaced by an amido group. These amido species are still normally referred to as acids due to their acidic amide protons. They are accessible from reaction of thiophosphinic chlorides and primary amines (Equation 43) or from reaction of aminophosphines with elemental chalcogen... 

The ligands that have been used in the preparation of metal nitride complexes are quite varied. They include halides, carbogenic groups (alkyl moiety and Cp ), pnic-togens (amine, amide, imide, phosphine, and arsine), and chalcogens (ether, alkox-ide, oxo, thioalkoxide, and selenides). Chart 1 provides a listing of the various ligands and the associated nitrido metal complexes. 

Pnictogen or chalcogen oxides, ethers or amides form O-bonded adducts with both SbCl3 and SbCls. Typical examples that have been characterized include [SbClsL] (L = PyNO, MesNO, (R0)3P0, The structure of [SbClsCDMSO)]... 

The coupling of phosphoryl or phosphinyl amides with phosphoryl or phosphinyl halides is an excellent method for the preparation of unsymmetrical ligands, and affords the synthesis of compounds with both organic groups and chalcogens differing. 

Despite statements made in Chapter 2 about the unpopularity of this procedure for the preparation of phosphonic and phosphinic esters from those of phosphonous and phos-phinous acids by the addition of oxygen, partly because of the lack of availability of the phosphorus(III) esters, but also because of the high reactivity exhibited by those esters towards oxidizing agents, the reduced reactivity shown towards the higher chalcogens by phosphonous and phosphinous halides (dihalo- and monohalo-phosphines), and even by some of the more reactive phosphorus(III) species, e.g. amides, makes such addition reactions feasible propositions. 

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