I+-abstraction versus I--displacement in the reactions of diiodoacetylene with metal carbonyl anions: X-ray structure of CMn(CO)5>

Article abstract of DOI:10.1016/0022-328X(91)80023-D

Solid diiodoacetylene IC<*>CI, reacts with THF solutions of the highly basic, third row, metal carbonyl anion, Re(CO)5^-, exclusively by a formal I⁺-abstraction process producing ReI(CO)5 and Re2I2(CO)8.Under the same conditions, the less basic, first row, metal carbonyl anion, Mn(CO)5^- reacts to produce not only Mn2I2(CO)8 by formal I⁺-abstraction but also (OC)5MnC<*>CMn(CO)5 by I^--displacement.These results may be rationalized by HSAB arguments and consideration of charge distribution in the substrate as indicated by molecular orbital calculations.The X-ray structure of (OC)5MnC<*>CMn(CO)5 is reported.Crystals are triclinic, space group P<*>1, with Z = 1 in a unit cell of dimensions a 6.421(2), b 6.425(2), c 9.520(2) Angstroem, α 81.86(2), β 88.55(2), γ 82.06(2) deg, and D_calc 1.79 g cm^-3.The structure was solved by the Patterson and Fourier methods and refined by full-matrix least squares to R = 0.024, R_w = 0.033 for 1372 observed reflections with F_o² > 3.0?(F_o²).The complex is centrosymmetric and thus exhibits an eclipsed geometry in the solid state.