The redox behaviour of ferrocene molecules .12. The redox behaviour of some bis-ferrocenyl compounds: Crystal and molecular structures of diferrocenylmethane and diferrocenylmethanol

Electrochemistry of diferrocenylmethane (1), diferrocenylketone (2), diferrocenylmethanol (3), diferrocenyl(phenyl)methanol (4), bis(1-ferrocenylpropyl) ether (5), 3,3-bis(ferrocenylmethyl)pentane-2,4-dione (6), 2,2-bis(ferrocenylmethyl)cyclohexane-1,3-dione (7) and trans-1,2-diferrocenylethene (8) shows that one-electron oxidation of the individual ferrocenyl sub-units takes place through: (i) separated charge transfers for 2 and 4; (ii) nearly overlapping steps for 1, 3 and 8; and (iii) single steps for each of 5, 6 and 7. This reflects the extent of electronic communication between the two redox centres, which is relatively high in the first case, decreases for the second series and is negligible for the third series. The crystal structure of diferrocenylmethanol 3 demonstrates that in the solid state the molecules are aggregated into centrosymmetric pairs with an O ... O distance of 3.020(3) Angstrom. The hydroxyl hydrogen atoms are disordered, but one pattern of site occupancy gives rise to a closed (OH)(2) dimer with hydrogen-bonding graph set R(2)(2)(4). The crystal structure of diferrocenylmethane 1 contains isolated molecules having almost the same conformation and molecular volume as 3.