Synthesis of Tetra-3-butenyl-Substituted Metallocenes and the Application of 1,1‘,3,3‘-Tetrakis(1,1-dimethyl-3-butenyl)ferrocene as Core for the Preparation of Polynuclear Compounds

Abstract

The synthesis of the 1,1′,3,3′-tetrabutenyl-substituted metallocenes [C 5 H 3 (CMe 2 CH 2 CHd CH 2 ) 2 ] 2 M (M ) Fe 1, Co 2, Ni 3), their electrochemical properties, and the solid-state structures of 1 and 3 are presented. Hydrosilylation of 1 with dimethylphenylsilane leads to [C 5 H 3 (CMe 2 (CH 2 ) 3 SiMe 2 Ph) 2 ] 2 Fe, 4. The π-coordination ability of the arene system in 4 has allowed the preparation of the pentanuclear complex [C 5 H 3 (CMe 2 (CH 2 ) 3 SiMe 2 (η 6 -C 6 H 5 -Cr(CO) 3 ) 2 ] 2 Fe, 5, containing a ferrocene core and peripherial η 6 -coordinated Cr(CO) 3 moieties. Electrochemical investigations of 5 show a reversible oxidation of the ferrocene unit as well as an independent, noninteracting irreversible oxidation of the Cr centers.

Axial chiral metallocenes by two-fold ring-closing metathesis

“…We note that similar distortions of the sandwich molecule have been reported for the substrate 1 (e.g. the tilt angle between the Cp planes of 7.2°), 7 thus we conclude that the bridges do not contribute significantly to the observed strain in complex 3. No directional weak intermolecular interactions were observed in the crystal structure.…”

Carbonyl-Substituted Nickelocenes by the Cross-Metathesis Route

“…The side-chains are almost flat and bent upward from the cyclopentadienyl ligand; that is, the plane of the α,β-unsaturated moiety is nearly perpendicular to the ring plane. This feature is reminiscent of the solid-state structure of 1,1′,3,3′-tetrakis(1,1-dimethylbutenyl)nickelocene . We conclude that this arrangement is a consequence of steric repulsion between the substituents.…”

E/ZSwitchable Ring-Closing Metathesis in 1,1′-Bis(but-3-enyl)ferrocenes: Synthesis and Characterization of Axially Chiralansa[6]-Ferrocenes

“…The largest deviation from synclinal eclipsed conformation is observed for compound ( Z )-4e . The Fe–C Cp distances in all studied compounds are in the range from 2.036 to 2.101 Å, which is comparable to the average value in ferrocene (2.05 Å) and substituted ferrocenes …”

“…The same tendency but with more negative values (from −0.175 to −0.196 V) is observed for the series ( E , Z )-4a - ( E , Z )-4d . Since aliphatic substituents in 3a – 3d and ( E , Z )-4a - ( E , Z )-4d have electron-donating properties, the oxidation potentials are lower than the oxidation potential of ferrocene. , The effect of the size of the aliphatic groups follows the rule where the oxidation potential slightly decreases between methyl and ethyl groups. The effect of cyclic substituents on the oxidation potential is rather minor.…”

“…The Fe−C Cp distances in all studied compounds are in the range from 2.036 to 2.101 Å, which is comparable to the average value in ferrocene (2.05 Å) 22 and substituted ferrocenes. 23 Spectroscopic Characterization. The 1 H NMR spectrum of (E,Z)-4a recorded at ambient temperature shows diagnostic olefinic resonances (δ = 5.79, app.…”