The first example of a structurally characterized octahedral hydrotris(pyrazolyl)borate iron methyl complex

• Published in: Journal of organometallic chemistry 2003-03, Vol.669 (1), p.200-206
• Main Authors: Graziani, Olivier, Toupet, Loı̈c, Hamon, Jean-René, Tilset, Mats
• Format: Article
• Language: English
• Subjects: Acyl complex; Alkyl complex; Crystal structure; Iron complex; Photochemical decarbonylation; Tris(pyrazolyl)borate
• ISSN: 0022-328X; 1872-8561
• DOI: 10.1016/S0022-328X(03)00006-8

The one-step synthesis of the known acetyl complex κ 3-TpFe(CO)(PMe 3)(COMe) ( 1, 78% yield) is achieved by reaction of cis, trans-Fe(CO) 2(PMe 3) 2MeI with potassium hydrotris(pyrazolyl)borate (KTp), in CH 2Cl 2 at room temperature. This reaction is specific to the parent Tp ligand. Visible light irradiation of 1 in toluene for 1 h afforded the first octahedral methyl–iron complex featuring the hydrotris(pyrazolyl)borate ligand TpFe(CO)(PMe 3)Me ( 2) in 80% yield. Compound 2 has been fully characterized by elemental analysis, IR, NMR spectroscopies, cyclic voltammetry and by an X-ray diffraction analysis. A comparison of steric and electronic properties is made with those of related cyclopentadienyl (Cp, Cp*, C 5Ph 5) complexes, and suggests that relative donating abilities follow the trend Cp, Cp*, C 5Ph 5>Tp, and structural comparisons indicate that Tp is the most sterically demanding ligand. Visible light photolysis of the one-step prepared acetyl complex κ 3-TpFe(CO)(PMe 3)(COMe) in toluene for 1 h afforded the first octahedral methyl-iron complex featuring the hydrotris(pyrazolyl)borate ligand TpFe(CO)(PMe 3)Me in 80% yield. The latter has been fully characterized by conventional spectroscopies and by an X-ray diffraction analysis.