(η6-Phenyl)Cr(CO)3- and (η6-Phenyl)Co4(CO)90substituted metallocenylcarbinols of the iron subgroup: synthesis, structure and hydrogen bonding

The synthesis of α-metallocenylcarbinols (M = Fe, Ru, Os) with bulky organometallic substituents R in the carbinol group (R 1 = (η 6 -Phenyl)Cr(CO) 3 , R 2 = (η 6 -Phenyl)Co 4 (CO) 9 ) is reported. The steric hindrances caused by these R are shown to prevent the usual association of carbinols via intermolecular hydrogen bonds of the OH⋯O type. In the crystal, chelate cycles with intramolecular hydrogen bonds of the OH⋯M type are formed. The results of an X-ray diffraction study are in good agreement with the IR spectoscopic data, providing evidence of an additional weak OH⋯OC interaction present in R 1 -substituted carbinols. In solution, no molecules with free (i.e. not bonded via intramolecular hydrogen bonds) OH groups are found. The relative stability of such chelate cycles is discussed.