Synthesis and Reactivity of Fluoro Complexes:  Part 2. Rhodium(I) Fluoro Complexes with Alkene and Phosphine Ligands. Synthesis of the First Isolated Rhodium(I) Bifluoride Complexes. Structure of [Rh33-OH)2(COD)3](HF2) by X-ray Powder Diffraction

The reaction between [Rh(μ-OH)(COD)]2 (COD = 1,5-cyclooctadiene) and 73% HF in THF gives [Rh33-OH)2(COD)3](HF2) (1). Its crystal structure, determined by ab initio X-ray powder diffraction methods (from conventional laboratory data), contains complex trimetallic cations linked together in 1D chains by a μ3-OH···F−H−F···HO-μ3 sequence of strong hydrogen bonds. The complex [Rh(μ-F)(COE)2]2 (COE = cyclooctene; 2), prepared by reacting [Rh(μ-OH)(COE)2]2 with NEt3·3HF (3:2), has been characterized. Complex 1 reacts with PR3 (1:3) to give [RhF(COD)(PR3)] [R = Ph (3), C6H4OMe-4 (4), iPr (5), Cy (6)] that can be prepared directly by reacting [Rh(μ-OH)(COD)]2 with 73% HF and PR3 (1:2:2). The reactions of 1 with PPh3 or Et3P have been studied by NMR spectroscopy at different molar ratios. Complexes [RhF(PEt3)3] (7), [RhF(COD)(PEt3)] (8), and [RhF(PPh3)3] (9) have been detected. The complex [Rh(F)(NBD)(iPr3P)] (NBD = norbornadiene; 10) was prepared by the sequential treatment of [Rh(μ-OMe)(NBD)]2 with 1 equiv of NEt3·3HF and iPr3P. The first isolated bifluoride rhodium(I) complexes [Rh(FHF)(COD)(PR3)] [R = Ph (11), iPr (12), Cy (13)], obtained by reacting fluoro complexes 3, 5, and 6 with NEt3·3HF (3:1), have been characterized. The crystal structures of 3 and 11 have been determined.