117467-87-5Relevant articles and documents
Synthesis and reactivity of benzyne derivatives of rhenium formed by facile ortho-hydrogen abstraction in a homoleptic rhenium aryl. X-ray structure of the cationic benzyne [Re(η2-2-MeC6H3)(2-MeC6H 4)2(PMe3)2][I5]
Arnold, John,Wilkinson, Geoffrey,Hussain, Bilquis,Hursthouse, Michael B.
, p. 415 - 420 (1989)
The paramagnetic benzyne complexes Re(η2-2-MeC6H3)(2-MeC6H 4)2(PMe2R)2 (R = Me, 2a; R = Ph, 2b) are formed at low temperature via ligand-induced ortho-hydrogen abstraction on addition of phosphine to the homoleptic aryl Re(2-MeC6H4)4 (1). Complexes 2 are oxidized under mild conditions to the benzyne cations [2][X] (X = PF6-, BPh4-, OTf-, Co(CO)4-, I5-) with E1,2 = -0.90 V (relative to Cp2Fe at 0.00 V). The cations are reduced by strong nucleophiles, e.g., LiBEt3H, Me3SiCH2MgCl, in THF, back to the neutral species. NMR data for [2][X] are in agreement with the solid-state structure, determined for [2a][I5] by X-ray crystallography. Crystals are orthorhombic, space group Pna21. with a = 18.735 (2), b = 13.954 (5), c = 14.193 (2) A?, Z = 4, Dcalcd = 2.23 g cm-3. The geometry of the cation can be described as distorted trigonal bipyramidal with the benzyne symmetrically η2-bound at an equatorial site (Re-C(benzyne) = 2.02 (2) A?) and with axial phosphines (Re-P = 2.421 (5) and 2.435 (51 A?); the equatorial Re-C(2-MeC6H4) distances are 2.09 (1) A?.