Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 3. Reactivity Studies of the Bis(butadiene) Complex [CpMo( s-cis-supine -η-C 4 H 6 )( s-trans -η-C 4 H 6 )][BF 4 ] † - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Organometallics Année : 1998

Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 3. Reactivity Studies of the Bis(butadiene) Complex [CpMo( s-cis-supine -η-C 4 H 6 )( s-trans -η-C 4 H 6 )][BF 4 ] †

Résumé

The compound [CpMo(s-cis-supine-C4H6)(s-trans-C4H6)]BF4 (2) reacts with a variety of nucleophilic reagents to afford either substitution of the s-trans-butadiene ligand or regioselective nucleophilic addition to the endo terminal carbon of the s-trans butadiene ligand. The reaction with tBuNC affords the substitution product [CpMo(s-cis-supine-C4H6)(tBuNC)2]BF4 (3). Nucleophilic addition of PMe3 leads to [CpMo(s-cis-supine-C4H6)(syn-prone-C3H4-1-CH2PMe3)]BF4 (4), which has been characterized also by X-ray crystallography. Nucleophilic addition of methyllithium or allylmagnesium bromide affords [CpMo(s-cis-supine-C4H6)(syn-prone-C3H4-1-CH2R)]BF4 (R = Me, (5), CH2CHCH2 (6)). The Grignard reaction, however, also affords the substitution product CpMo(s-cis-supine-C4H6)(prone-C3H5). Compound 5 is oxidized by ferrocenium to [5]+, which rapidly and extensively isomerizes to [CpMo(s-cis-supine-C4H6)(syn-supine-C3H4-1-Et)]+ ([7]+). Reduction of the latter by cobaltocene affords CpMo(s-cis-supine-C4H6)(syn-supine-C3H4-1-Et) (7), which isomerizes slowly (t1/2 = 95 min at room temperature) to 5. A cyclic voltammetric investigation of 5 and [7]+ is consistent with the chemical redox experiments and yields kinetic and thermodynamic information on the interconversion between [5]+ and [7]+. Theoretical calculations rationalize the higher reactivity at the s-trans diene endo position for compound 2 as the result of a greater participation of the orbitals of this atom to the LUMO.
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hal-03312493 , version 1 (06-10-2021)

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Li-Sheng Wang, James Fettinger, Rinaldo Poli, Rita Meunier-Prest. Cyclopentadienylmolybdenum(II) and -(III) Complexes Containing Diene and Allyl Ligands. 3. Reactivity Studies of the Bis(butadiene) Complex [CpMo( s-cis-supine -η-C 4 H 6 )( s-trans -η-C 4 H 6 )][BF 4 ] †. Organometallics, 1998, 17 (13), pp.2692-2701. ⟨10.1021/om971079s⟩. ⟨hal-03312493⟩
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