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

Three thioether functionalized formamidines RNHC(H)NR (R=2‐SMe‐C 6 H 4 , 2‐S t Bu‐C 6 H 4 , 2‐SPh‐C 6 H 4 ) were prepared from the corresponding amines RNH 2 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‐S t Bu 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 theS 1 1 ${{S}_{1}^{1}}$ (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‐S t Bu‐C 6 H 4 N) 2 CH} 2 (THF) 2 ] to the trimeric compound [Li 3 {(2‐SMe‐C 6 H 4 N) 2 CH} 3 ].