Synthesis, characterization and crystal structures of novel hafnium porphyrins

Abstract

Dichlorohafnium porphyrin complexes [Hf(por)Cl₂][por = 2,3,7,8,12,13,17,18-octaethylporphyrinate (oep) or 5,10,15,20-tetraphenylporphyrinate (tpp)] which are potentially useful precursors for various hafnium porphyrin complexes, were synthesised and characterized. The structure of [Hf(oep)Cl₂(H₂O)] has been determined by X-ray crystallography; the co-ordination geometry around the Hf atom can be described as a 4 : 3 piano-stool with the square base occupied by the porphyrin N atoms and the legs by the two Cl atoms and a water molecule. Treatment of [Hf(por)Cl₂] with [NBuⁿ₄]₃[P₃O₉] gave [NBuⁿ₄][Hf(por)(P₃O₉)](por = oep and tpp). The crystal structure of the oep complex revealed a seven-co-ordinate Hf atom surrounded by 4 N atoms of the porphyrin and 3 O atoms of the P₃O₉^3– ligand. The N₄ and O₃ planes are almost parallel and the Hf atom is located 1.007 Å above the N₄ plane and 1.476 Å below the O₃ plane. Crystal data for [Hf(oep)Cl₂(H₂O]·C₆H₆; triclinic, space group P, a= 11.977(2), b= 12.261(1), c= 14.677(2)Å, α= 76.74(1), β= 85.41(1), γ= 74.41(1)°, Z= 2; R= 0.081 and R′= 0.092 for 3325 independent reflections with l > 3σ(l). Crystal data for [NBuⁿ₄][Hf(oep)-(P₃O₉)]·2CHCl₃: monoclinic, space group P2₁/n, a= 15.490(2), b= 19.133(1), c= 22.761(4)Å, β= 99.425(7)°, Z= 4; R= 0.036 and R′= 0.037 for 4823 independent reflections with l > 3σ(l).