Synthesis and Properties of [CoCp*(2,5-PC4tBu2H2)]: The First Monophosphacobaltocene

✍ Scribed by Claire Burney; Duncan Carmichael; Kareen Forissier; Jennifer C. Green; François Mathey; Louis Ricard

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 183 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200204421

✦ Synopsis

Abstract

The reduction of the phosphacobaltocenium salt [CoCp*(2,5‐PC~4~__t__Bu~2~H~2~)]^+^[BPh~4~]^−^ (3; Cp*=pentamethylcyclopentadienyl) by magnesium in tetrahydrofuran (THF) furnishes the stable air‐sensitive phosphacobaltocene [CoCp*(2,5‐PC~4~__t__Bu~2~H~2~)] (4) in yields of up to 80 %. The crystal structure of 4 shows long CoC~α~ and short C~α~C~β~bonds in the phospholyl ligand, consistent with a semi‐occupied molecular orbital (SOMO) having a″ symmetry. A combined Amsterdam density functional (ADF)/photoelectron spectroscopic study, which confirms this assignment, gives ionisation energies (IE) of 5.02 eV from the SOMO and 8.89 eV from the phosphorus “lone pair”. A comparison of cyclovoltammograms for 3 and the corresponding cyclopentadienyl complex [CoCp*(1,3‐C~5~__t__Bu~2~H~3~)]^+^ [BPh~4~]^−^ (5) shows that replacing a CH group by an sp^2^ phosphorus atom results in an anodic first reduction potential shift of 0.29 V.