Choudhury M. Zakaria

The redox behaviour of some bis-ferrocenyl compounds: crystal and molecular structures of diferrocenylmethane and diferrocenylmethanol☆

Abstract 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) A. 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 R22(4). The crystal structure of diferrocenylmethane 1 contains isolated molecules having almost the same conformation and molecular volume as 3.

Hydrogen bonding in diphenylmethanols, RCPh2OH: structures of monomeric (4-biphenyl)diphenylmethanol and diphenyl(2-pyridyl)methanol, dimeric 1,1,3-triphenylpropyn-1-ol, trimeric 2-methyl-1,1-diphenylpropan-1-ol, tetrameric diphenyl(2-thienyl)methanol, hexameric bis(pentafluorophenyl)methanol (at 293 and 173 K) and polymeric diphenylmethanol

(4-Biphenyl)diphenylmethanol (1), C 25 H 20 O, orthorhombic, P2 1 2 1 2 1 , a = 8.3580 (11), b = 13.8976(17), c = 15.5915 (12) A, Z = 4, R = 0.032 for 1146 observations [I > 3σ(I)] : the structure contains isolated monomers with no hydrogen bonding. Diphenyl(2-pyridyl)methanol (2), C 18 H 15 NO, monoclinic, P2 1 /c, a = 8.1899 (8), b = 14.855 (2), c = 11.6069 (15) A, β = 96.344(8)°, Z = 4, R = 0.049 for 879 observations [I > 3σ(I)] : the structure consists of isolated monomers in which the intramolecular O-H...N hydrogen-bond motif has graph set S(5). 1,1,3-Triphenylpropyn-1-ol (3), C 21 H 16 O, monoclinic, P2 1 /c, a = 5.9794(12), b = 9.953 (3), c = 26.420 (3) A, β = 91.365 (12)°, Z = 4, R = 0.039 for 971 observations [I > 2σ(I)] : the structure contains centrosymmetric dimers held together by O-H...π(arene) hydrogen bonds involving one of the phenyl groups, rather than the propargyl group. 2-Methyl-1,1-diphenylpropan-1-ol (4), C 16 H 18 O, trigonal, P31c, a = 13.9232(17), c = 12.0200(19) A, Z = 6, R = 0.031 for 763 observations [I > 3σ(I)] : the structure consists of cyclic hydrogen-bonded trimers with crystallographic threefold symmetry and disordered hydroxyl H atoms in a motif with graph set R 3 3 (6) : the O...O distance in the trimers is 2.864 (7) A. Diphenyl(2-thienyl)methanol (5), C 17 H 14 OS, rhombohedral, R3, a = 19.20(1), c = 26.48(1)A, Z = 24 : this compound is isomorphous and isostructural with triphenylmethanol, Ph 3 COH, and forms hydrogen-bonded tetrahedral tetramers. Bis(pentafluorophenyl)methanol (6), C 13 H 2 F 10 O, rhombohedral, R3, a = 26.113(3), c = 9.788 (3) A (at 293K), R = 0.068 for 1214 observations [I > 2σ(I)] ; a = 26.006 (4), c = 9.5941(11) A (at 173 K), R = 0.072 for 1889 observations [I > 2σ(I)], Z = 18 ; the structure consists of coaxial stacks of cyclic hydrogen-bonded hexamers, each of 3 symmetry, and with a hydrogen-bond motif of graph set R 6 6 (12). Within the hexamers, the molecules are disordered over two orientations in the ratio 0.779 (3) :0.221 (3) at 293 K and 0.776 (2) :0.224 (2) at 173 K : the O...O distance is 2.702 (4) A at 293 K and 2.683(4)A at 173K. Diphenylmethanol (7), C 13 H 12 O, orthorhombic, P22 1 2 1 , a = 5.1300(10), b = 18.650(5), c = 21.168 (6) A, Z = 8, R = 0.035 for 1487 observations [I >3σ(I)] : there are two molecules in the asymmetric unit and the molecules are linked by hydrogen bonds into spiral chains having graph set C(4) and lying parallel to the a-axis ; the O...O distances within the chains are 2.826(3) and 2.878 (3) A.

Ferrocenyl salts as synthons: new ferrocenyl-1,3-dikentones

Abstract Reaction of (ferrocenylmethyl)trimethylammonium iodide with the mono-sodium salts of a range of acyclic 1,3-diketones leads smoothly to 2-(ferrocenylmethyl)-1,3-diketones [(C 5 H 5 )Fe(C 5 H 4 )CH 2 ]CH(COR 1 )(COR 2 ), but with the corresponding tetrabutylammonium salts deacylation occurs. With the sodium salt of cyclohexane-1,3-dione, disubstitution occurs to give (2,6-dioxocyclohexane-1,1-diyl)bismethyleneferrocene, [(C 5 H 5 )Fe(C 5 H 4 CH 2 )] 2 C[(CO) 2 (CH 2 ) 3 ]. The lithium salt of acetylferrocene reacts with a range of monocarboxylic esters to provide 1-ferrocenyl-1,3-diketones [(C 5 H 5 )Fe(C 5 H 4 )]COCH 2 COR, but simple esters of dicarboxylic acids either do not react, or undergo only monosubstitution.

Hydrogen bonding in α-ferrocenyl alcohols: structures of 1-ferrocenylethanol, 1-ferrocenyl-2-phenylethanol, 1-ferrocenyl-1-phenylpropan-1-ol, 1-ferrocenyl-1-phenyl-2-methylpropan-1-ol, 1-ferrocenyl-1-phenyl-2,2-dimethylpropan-1-ol, 1-ferrocenyl-1,2-diphenylethanol and diferrocenyl(phenyl)methanol

The structure of 1-ferrocenylethanol (1a), C 12 H 14 FeO, tetragonal, I4 1 cd, a = 23.3334(18), c = 7.7186(11)A, Z = 16, R = 0.025 for 850 observations [I > 3σ(I)], contains spiral chains generated by a 4 1 axis, in which the molecules are connected by O-H...O hydrogen bonds in a motif with graph set C(2) with an O...O distance of 2.724(3)A. 1-Ferrocenyl-2-phenylethanol (1f), C 15 H 18 FeO, orthorhombic, Pnaa, a = 9.8589(7), b = 15.2800(17), c = 19.1399(17) A, Z = 8, R = 0.036 for 1508 observations [I >3σ(I)], crystallizes as dimeric aggregates lying across a crystallographic twofold axis and held together by O-H...O hydrogen bonds in a motif with graph set R 2 2 (4) with an O...O distance of 2.868(8)A ; there are also intramolecular O-H...π(C 5 H 5 ) interactions. 1-Ferrocenyl-1-phenyl-propan-1-ol (2b), C 19 H 20 FeO, monoclinic, P2 1 /c, a = 10.2443 (13), b = 10.5811 (17), c = 14.2487(12)A, β = 100.190(9)°, Z = 4, R = 0.029 for 2289 observations [I >3σ(I)], crystallizes as isolated molecules containing O-H...π(C 5 H 5 ) interactions. In 1-ferrocenyl-1-phenyl-2-methylpropan-1-ol (2c), C 20 H 22 FeO, monoclinic, Cc, a = 25.387(4), b = 7.6825 (6), c = 17.803 (3) A, β = 108.217 (17)°, Z = 8, R = 0.022 for 3286 observations [I > 3σ(I)], there are two molecules in the asymmetric unit, but the structure consists of isolated molecules containing O-H...π(C 5 H 5 ) interactions. 1-Ferrocenyl-1-phenyl-2,2-dimethylpropan-1-ol (2d), C 21 H 24 FeO, monoclinic, P2 1 /n, a = 8.007(4), b = 13.002(2), c = 66.24 (1) A, β = 91.96(3)°, Z = 16, R = 0.072 for 4130 observations [I > 3σ(I)], has four molecules in the asymmetric unit, but there is no intermolecular hydrogen bonding. The structure of 1-ferrocenyl-1,2-diphenylethanol (2f), C 24 H 22 FeO, monoclinic, C2/c, a = 26.229 (2), b = 5.889(2), c = 24.553(2) A, β = 104.114 (11)°, Z = 8, R = 0.036 for 1733 observations [I > 2.5σ(I)], consists of isolated molecules in which the hydroxyl H atom is disordered unequally over three sites, each of which is trans to one of the C-C bonds involving C1 ; H atoms in two of these sites are involved in intramolecular O-H... π(C 5 H 5 ) interactions and the H atom in the third is involved in an O-H...π(arene) interaction. The structure of diferrocenyl(phenyl)methanol (2g), C 27 H 24 Fe 2 O, triclinic, P1, a = 9.3999(11), b = 11.1988(16), c = 11.9720(16)A, a =117.844(11), β = 98.890(10), γ = 102.362 (11)°, Z = 2, R = 0.031 for 3435 observations [I > 2.5σ(I)], consists of centrosymmetric dimers held together by O-H...O hydrogen bonds in a motif with graph set R 2 2 (4) with an O...O distance of 2.926(4)A ; there are also intramolecular O-H...η(C 5 H 5 ) interactions. Closed dimers containing the R 2 2 (4) (OH) 2 hydrogen-bonding motif, while unknown for purely organic alcohols, are a common occurrence in α-ferrocenyl alcohols (five examples from 13 known structures).

Hydrogen bonding in ferrocene derivatives: Crystal structure of racemic ferrocenyl(phenyl)methanol

Abstract A single-crystal X-ray diffraction study has been carried out on racemic ferrocenyl(phenyl)methanol. There are two independent chiral molecules A and B in the asymmetric unit, and the molecules are linked by OH⋯O hydrogen bonds into zigzag chains characterized by the motif  S (A) R (B) R (A) S (B); within these chains the two independent hydrogen-bonded O⋯O distances are 3.059(2) and 3.150 A.

O–H⋯π(arene) intermolecular hydrogen bonding in the structure of 1,1,2-triphenylethanol

The 1,1,2-triphenylethanol molecule, Ph2(PhCH2)COH (I), forms centrosymmetric dimers in the solid state. The shortest O-..O separation, 5.837 (3)A,, is too long for any O--H..-O hydrogen-bond formation. Instead, there are O--H~..π(arene) interactions between the hydroxyl group of one molecule and a phenyl group of a centrosymmetrically related molecule. The O...C and H-..C distances between the hydroxyl group and the closest phenyl-ring C atom are 3.525 (4) and 2.73 (4)~,, respectively. These intermolecular contacts are the only driving force towards dimer formation in the solid state.

Structures of 1-ferrocenyl-1-phenylethanol, ferrocenyl(diphenyl)methanol and ferrocene-1,1'-diylbis(diphenylmethanol)

Racemic 1-ferrocenyl- 1-phenylethanol, [(CsHs)Fe- (CsHa)]CPhMeOH (I), crystallizes as discrete molecules which are not involved in hydrogen bondinog; the shortest intermolecular O-..O contact is 3.768(3) A and the hydroxyl H atom is orientated towards the unsubstituted cyclopentadienyl ring. Ferrocenyl(diphenyl)methanol, [(CsHs)Fe(CsHa)]CPh2OH (II) is hydrogen bonded to form centrosynunetric dimers with O...O 2.816(1) and H...O 2.52 ]k. Ferrocene-l,l~-diylbis(diphenylmeth - anol), Fe[(CsHa)C(Ph)2COH]2 (III) crystallizes as a dimeric aggregate with the Fe atoms on twofold crystallographic symmetry axes and the four O atoms defining a folded trapezium with O...O 2.762(2), 2.714(2) and 2.865(2) A,. The four hydroxyl groups are disordered equally over two orientations such that there are two halfoccupancy H-atom sites between each hydrogen-bonded oxygen pair.

The redox behaviour of ferrocenyl alcohols and ferrocenediyl-diols: crystal and molecular structure of ferrocenyl(2-furyl) phenylmethanol☆

Abstract Cyclic voltammetry and controlled-potential coulometry show that ferrocenyl alcohols of type (C5H5)Fe(C5H4)C(OH)RR′ and ferrocenediols of type Fe[(C5H4)CCR′(OH)]2 undergo quantitative and reversible one-electron oxidation at the metal centre, and that the redox potentials are controlled predominantly by the inductive effects of the substituents at the α-carbon. The crystal structure of the new alcohol ferrocenyl(2-furyl)phenylmethanol not only confirms its molecular constitution, but also demonstrates that in the solid state it forms centrosymmetric hydrogen-bonded dimers involving cyclic (OH)2 bridge without any participation of the furan oxygen atom in the hydrogen bonding.

Hydrogen-bonded adducts of ferrocene-1,1′-diylbis-(diphenylmethanol): crystal and molecular structures of adducts with methanol (1 : 1) and pyridine (1 : 2)

Ferrocene-1,1′-diylbis(diphenylmethanol), [Fe(C5H4CPh2OH)2], forms hydrogen-bonded host–guest adducts with a wide range of hydrogen-bond donors and acceptors. Adducts with a diol: guest ratio of 1 : 1 were formed by MeOH, EtOH, Me2SO, Me2NCHO, piperazine, and 4,4′-bipyridyl and 1 : 2 adducts by Me2SO, dioxane, pyridine and piperidine. The 1 : 1 adduct with MeOH has been shown to be triclinic, space group P with a= 8.7624(3), b= 12.2797(6), c= 14.8773(8)A, α= 106.572(4), β= 97.879(4), γ= 100.873(4)° with a final R of 0.044 for 4982 observed reflections. The structure consists of a centrosymmetric assembly of two molecules of the host diol and two molecules of the guest MeOH, hydrogen bonded together to form a chair conformation (OH)6 ring. The 1 : 2 adduct with pyridine has been shown to be monoclinic, space group C2/c with a= 16.6252(10), b= 11.1016(9), c= 20.9440(16)A, β= 107.855(6)° with a final R of 0.042 for 3260 observed reflections. In the structure the diol lies on a two-fold rotation axis with its hydroxyl hydrogens disordered and participating in both intramolecular O–H ⋯ O and intermolecular O–H ⋯ N hydrogen bonding with the two pyridine guest molecules.

Hydrogen Bonding in Ferrocene Derivatives: Structure of the 1:1 Adduct of Ferrocenyl(diphenyl)methanol and Dimethyl Sulfoxide

Ferrocenyl(diphenyl)methanol, [(C 5 H 5 )Fe{(C 5 H 4 )C-(Ph 2 )OH}], forms a 1:1 adduct with dimethyl sulfoxide, (CH 3 ) 2 SO. In this adduct, the hydrogen-bonded aggregate consists of one molecule of the ferrocene acting as hydrogen-bond donor and one molecule of DMSO acting as hydrogen-bond acceptor; the hydrogen-bonded O...O distance is 2.796 (2) A