ortho‐Directed Metathetical Fluoride/Amide Exchange in (Pentafluorophenyl)amides

Abstract

The indium tris(amide)s [(Et2N)3–nIn{N(C6F5)(2‐C5H4N)}n] [n = 1 (15), 2 (16) or 3 (9)] have been prepared by treatment of [In(NEt2)3]2 (3) with a stoichiometric amount of (2‐C5H4N)(C6F5)NH (1). The analogous reaction of Bi(NMe2)3 (2) with 3 equiv. of amine 1 and the treatment of BiCl3 (5) with a stoichiometric amount of (2‐C5H4N)(C6F5)NLi (4) both lead to [Bi{N(C6F5)(2‐C5H4N)}3] (10). In contrast, only the difluoride 11 or the monofluoride 12, which are the products of intramolecular ortho‐directed exchange of NMe2 and F substituents, are obtained from the reaction of 2 with 1 or 2 equiv. of 1, respectively. The reaction between Me3Sb(Hal)2 [Hal = Br (7) Cl, (8)] and 1 or 2 equiv. of lithium salt 4 gives the corresponding stable monoamides [Me3(Hal)Sb{N(C6F5)(2‐C5H4N)}] [Hal = Br (17), Cl (18)] or bis(amide) [Me3Sb{N(C6F5)(2‐C5H4N)}2] (19), respectively. The structure of 9 has been confirmed by an X‐ray structure analysis, and density functional calculations data have been used to explain the possible reaction pathway of the ortho‐directed metathetical fluoride/amide exchange.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Intramolecular nucleophilic substitution in C6F5 moiety. The fluoride–dialkylamino exchange in decafluorodiphenlamino moiety

“…It has to be mentioned, that the plausible metal containing side products Sb(OH)F 2 and BiF 3 have not been isolated and characterized. These data confirm the trend previously observed for related pyridine based amides, that the rate of nucleophilic substitution of the ortho-fluorine atom in the C 6 F 5 moiety by an NAlk 2 group decreases in the order Bi > Sb ) In (no reaction) [5,6].…”

“…Refluxing this mixture in toluene for three days affords pure 4. The possible mechanism of such reactions was discussed in our previous reports [5,6]. Hydrolysis of 4 gives free amine 5 in moderate yield.…”

“…These ligand properties qualify fluoroamides as ligands for the design of Lewis acids, however the ligand stability is one aspect that has to be addressed. Recently we have found the novel rearrangement which takes place in amides of antimony and bismuth containing the (C 6 F 5 )(2-pyridyl)N amido ligand [5,6]. During this process an ortho-fluorine atom of the C 6 F 5 moiety is metathetically substituted by a nucleophilic NAlk 2 group, which was transferred from Sb and Bi central atoms.…”

“…Interestingly, relatively few reports deal with organofluorine metal amides MðNR f 2 Þ n of group 3 and 15 metals [4][5][6]. Such fluoroamides tend to have a lower donor strength and a higher group electronegativity than their C-H counterparts [1-3].…”