Unexpected Outcome of the Reaction of [(COD)2Rh2(μ-OH)2] with TREAT HF or 50% HF. Peculiar Structural Features and Diminished Fluoride Basicity of [(R3P)4Rh2(μ-F)2] (R =i-Pr, Ph)

The reaction of [(COD)Rh(μ-OH)] 2 with TREAT HF (Et 3 N·3HF) or 50% HF in THF unexpectedly produced no Rh fluoride species but rather [Rh 3 (μ-OH) 2 (COD) 2 ]HF 2 ( 1 ), in high yield. Single-crystal and powder X-ray diffraction studies established the structure of 1 and confirmed that the product was homogeneous in bulk. The structure of [( i -Pr 3 P) 4 Rh 2 (μ-F) 2 ] (X-ray) revealed a number of unexpected features pointing to a remarkably diminished basicity of the fluoro ligands.