Synthesis and Crystal Structures of Three Thioether Functionalized Formamidines and Their Corresponding Lithium Formamidinates

Abstract

Three thioether functionalized formamidines RNHC(H)NR (R=2‐SMe‐C6H4, 2‐StBu‐C6H4, 2‐SPh‐C6H4) were prepared from the corresponding amines RNH2 and triethyl orthoformate. X‐ray crystal structure determinations revealed the typical E configuration about the amidine C=N bond for all three compounds. The 2‐SMe and 2‐StBu derivatives exhibit the most frequently observed anti orientation of the RNH group while the 2‐SPh derivative displays the much more rarely encountered syn arrangement. All three compounds exhibit weak intramolecular N−H…S hydrogen bridges of the S11 (5) type. Treatment of the amidines with n‐BuLi led to the formation of the corresponding lithium amidinates. X‐ray crystal structure determinations of the lithium amidinates revealed several molecular patterns ranging from the mononuclear complex [Li{2‐StBu‐C6H4N)2CH}2(THF)2] to the trimeric compound [Li3{(2‐SMe‐C6H4N)2CH}3].