A-Tris trimethylsilyl Amidines

SUBMITTED BY RENE T. BOERE , ROBIN G. H1CKS, and RICHARD T, OAKLEY  

iV -Tris(trimethylsilyl)ainidines have been used recently as precursors for a number of inorganic heterocycles and metallacycles, some of which are being studied in light of their unusual solid state properties. Boere et al. reported the synthesis of several aryl-substituted persilylated benzamidines and the related compound AT,iV,iV, N ,Ar ,N -hexakis(trimethylsilyl)-l,4-benezenedicarboximidamide (hereafter referred to as HBDA) the present syntheses, which are generally based on the same reaction of an aryl-substituted carbonitrile with lithium bis(trimethylsilyl)amide, offer more facile routes to representative mono- and polyfunctional carboximidamides (i.e., amidines) as well as the prototypal derivative N,JV,Af -tris(trimethyl-silyl)formimidamide. As before, the crystalline diethyl ether adduct of lithium bis(trimethylsilyl)amide is favored over the nonsolvated amide in these syntheses the preparation of the diethyl ether adduct is also described here. 

All reactions are carried out under an atmosphere of dry nitrogen gas unless otherwise stated. Lithium bis(trimethylsilyl)amide (Aldrich), 1,4-dicyanoben-zene (Aldrich), chlorotrimethylsilane (Aldrich), and 1,3,5-triazine (Aldrich) are used as received. Benzonitrile (Fisher) is vacuum distilled from P2OS prior to use. Solvents are purified by distillation as follows hexane, over calcium hydride diethyl ether, over LiAIH4 ( Caution. Reacts violently with water)-, toluene, over sodium acetonitrile, over P2O5. 

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