Superamidines 2. Synthesis of the bulky ligand N,N'-bis-(2,6-diisopropylphenyl)-trifluoroacetamidine and its molybdenum carbonyl complex

N,N'-bis-(2,6-diisopropylphenyl)trifluoroacetamidine has been prepared for the first time from 2,6-diisopropylaniline and the trifluoroacylation reagent TFAP via the imidoylchloride. The crystal structure of the amidine was determined, indicating that it crystallizes in the Z-anti tautomer, in contrast to the nonfluorinated analogue, which is E-anti in the solid state. In solution, as indicated by NMR spectroscopy, it exists in two isomeric forms. The amidine reacts with Mo[(CO).sub.6] to produce a coordination complex with Mo[(CO).sub.3] in which the ligand is also in the Z-anti geometry, the metal is [[eta].sup.6]-coordinated to the imino-2,6-diisopropylphenyl ring, and the amino N-H unit is directed towards the metal, as determined by a single-crystal X-ray structure. Unlike the analogous nonfluorinated acetamidine, there is no indication of an intermediate in which the neutral amidine is coordinated in a monodentate fashion to an Mo[(CO).sub.5] unit, which we now attribute to the predominant geometry of the ligand, both in the solid state and in solution, being Z-anti. The high steric bulk of this superamidine ligand apparently prevents the formation of a metal-metal bonded [Mo.sub.2][(amidinate).sub.4] as observed previously in a redox reaction between N,N'diphenylbenzamidine and Mo[(CO).sub.6] under similar thermal reaction conditions. Key words: trifluoromethyl, superamidine, amidine, molybdenum, carbonyl, coordination.