ortho-Metallation products of phenol and aniline with dodecacarbonyl-triosmium. X-Ray crystal structure of [Os3H2(CO)9(NHC6H3F)]

Abstract

Comparisons have been made between ¹H and ¹³C n.m.r. data for complexes [Os₃H₂(CO)₉(C₆H₄X)](X = O or NH) derived from [Os₃(CO)₁₂] and phenol and aniline respectively, and substituted derivatives of these. These comparisons show that the substituted phenol derivatives all form an isostructural series containing cyclohexadienone ligands as in the previously determined X-ray structure of the 2-benzylphenol derivative. In contrast, the aniline derivatives form another isostructural series which contains aromatic ligands. This was confirmed by a single-crystal X-ray structure determination for the title compound [Os₃H₂(CO)₉(NHC₆H₃F)] formed from 4-fluoro-aniline. The crystals are monoclinic, space group P2₁/c, a= 8.630(3), b= 8.957(1), c= 26.070(3)Å, β= 97.99(2)°, and Z= 4. The structure was refined to R= 0.055 for 4 003 observed reflections. The ligand NHC₆H₃F bridges two osmium atoms by an amido-group and is bound to the third osmium atom by a σ-Os–C bond at the ortho-position; overall it is a four-electron donor. As well as [Os₃H₂(CO)₉{C₆H₃(OH)O-p}], quinol gave the compound [Os₆H₃(CO)₁₉(C₆H₃O₂)] which contains two triangular Os₃ clusters linked by the organic ligand through the oxygen atoms.