Synthesis of New Bulky Bis(amidine) with the Conformationally Rigid meta-Phenylene Bridge and Its Dilithium Derivative [1,3-C6H4{NC(Ph)N(2,6-iso-Pr2C6H3)}2]Li2(TMEDA)2

Abstract

The reaction of 2,6-diisopropylaniline with m-phenylenedibenzimidoyl chloride 1,3-C₆H₄{N=C(Ph)Cl}₂ in the presence of triethylamine in a toluene solution affords bis(amidine) 1,3-C₆H₄{NC(Ph)NH(2,6-iso-Pr₂C₆H₃)}₂ (H₂L) in which two amidinate fragments are bound by the conformationally rigid m-phenylene linker. The metallation of bis(amidine) by n-butyllithium in the presence of tetramethylethylenediamine (TMEDA) occurs readily in a tetrahydrofuran solution at –70°С to form the corresponding lithium amidinate complex 1,3-C₆H₄{NC(Ph)N(2,6-iso-Pr₂C₆H₃)}₂Li₂(TMEDA)₂ (I). The X-ray structure analysis shows that complex I is monomeric (CIF file CCDC no. 1873201). Each amidinate fragment NCN is bound to one lithium atom via the κ²-N,N chelating mode.