Remote C-F-metal interactions in late-transition-metal complexes

Article abstract of DOI:10.1021/om100261e

A series of phosphorus ligands containing the 5,6,7,8- tetrafluoronaphthalen-1-yl group (NpF₄) has been prepared, starting from 1-bromo-5,6,7,8-tetrafluoronaphthalene. The coordination chemistry of diphenyl(5,6,7,8-tetrafluoronaphthalen-1-yl)phosphine (1) with Ir(III), Pd(II), Pt(II), Rh(I), Ir(I), and Au(I) has been investigated, focusing on a possible remote interaction of the fluorine atom at position 8 of the naphthyl group (F¹) with the metal center. The Ir(III) complex [IrCp*Cl ₂(1)] (12) displays a weak J(P,F¹) coupling constant of 8 Hz and no Ir-F¹ interaction. A cationic derivative, the formally coordinatively unsaturated [IrCp*Cl(1)]SbF₆ (13), is generated upon chloride abstraction. For this complex J(P,F¹) is 80 Hz and the Ir-F¹ distance is 2.956(2) A. [MCl(η³-allyl)(1)] complexes (14, M = Pt; 15, M = Pd) display what is interpreted as a weaker M-F¹ interaction despite corresponding J(P,F¹) values of 67 and 98 Hz and M-F¹ distances of 3.069(2) and 2.995(2) A, respectively. Similar considerations apply to the analogous Rh(I) and Ir(I) complexes [IrCl(COD)(1)] (18) and [RhCl(COD)(1)] (19) (J(P,F¹) = 62 and 75 Hz and M-F¹ = 3.0744(14) and 3.0997(8) A, respectively). With the chiral enantiopure ligand (11bS)-4-(5,6,7,8-tetrafluoronaphthalen-1- yl)dinaphtho[2,1-d:1′,2′-f][1,3,2]dioxaphosphepine (10) analogous complexes were prepared. Ligand 10 is formally a derivative of 1 where the two phenyl groups have been replaced by a BINOL unit. In the case of [PtCl(η³-allyl)(10)] (16) and [RhCl(COD)(10)] (21) the coupling between F¹ and the NMR-active nuclei ¹⁹⁵Pt and ¹⁰³Rh, respectively, was detected in 2D NMR heteronuclear correlation experiments.