Synthesis and Structural Characterization of p -Carboranylamidine Derivatives.

In this contribution, the first amidinate and amidine derivatives of p -carborane are described. Double lithiation of p -carborane ( 1 ) with n -butyllithium followed by treatment with 1,3-diorganocarbodiimides, R-N=C=N-R (R = i Pr, Cy (= cyclohexyl)), in DME or THF afforded the new p -carboranylamidinate salts p -C 2 H 10 B 10 [C(N i Pr) 2 Li(DME)] 2 ( 2 ) and p -C 2 H 10 B 10 [C(NCy) 2 Li(THF) 2 ] 2 ( 3 ). Subsequent treatment of 2 and 3 with 2 equiv. of chlorotrimethylsilane (Me 3 SiCl) provided the silylated neutral bis(amidine) derivatives p -C 2 H 10 B 10 [C{ i PrN(SiMe 3 )}(=N i Pr)] 2 ( 4 ) and p -C 2 H 10 B 10 [C{CyN(SiMe 3 )}(=NCy)] 2 ( 5 ). The new compounds 3 and 4 have been structurally characterized by single-crystal X-ray diffraction. The lithium carboranylamidinate 3 comprises a rare trigonal planar coordination geometry around the lithium ions.