Lithium Fluoroarylamidinates: Syntheses, Structures, and Reactions

Lithium fluoroarylamidinates [(ArFC(NSiMe3)2Li)n·xD] (ArF = 4-CF3C6H4, n = 2, D = OEt2, x = 1 (2a); n = 1, D
= TMEDA, x = 1 (4a); ArF = 2-FC6H4, n = 2, D = OEt2, x = 1 (2b); ArF = 4-FC6H4, n = 2, D = OEt2, x =
2 (2c); ArF = 2,6-F2C6H3, n = 2, D = OEt2, x = 1 (2d); n = 2, D = 2,6-F2C6H3CN, x = 2 (3d); ArF = C6F5, n
= 2, D = OEt2, x = 1 (2e), n = 1, D = TMEDA, x = 1 (4e); n = 1, x = 2, D = OEt2 (5e); D = THF (6e)) were
prepared by the well-known method from LiN(SiMe3)2 and the corresponding nitrile in diethyl ether or by addition
of the appropriate donor D to the respective diethyl ether complexes. Depending on the substituents at the aryl
group and on the donors D, three different types of structures were confirmed by X-ray crystallography. Hydrolysis
of 2e gave C6F5C(NSiMe3)N(H)SiMe3 (7e) and C6F5C(NH)N(H)SiMe3 (8e). The lithium fluoroarylamidinates 2a−2d
react with Me3SiCl to give the corresponding tris(trimethylsilyl)fluoroarylamidines ArFC(NSiMe3)N(SiMe3)2 (9a−9d).
Attempts to prepare C6F5C(NSiMe3)N(SiMe3)2 from 2e and Me3SiCl failed; however, the unprecedented cage
{[C6F5C(NSiMe3)2Li]4LiF} (10e) in which a fluoride center is surrounded by a distorted trigonal bipyramid of five Li
atoms was obtained from this reaction.