77965-00-5Relevant articles and documents
DIENE-METAL ? BONDING. SOME UNEXPECTED EFFECTS OF GROUP 5 DONOR LIGANDS ON CARBON-13 NUCLEAR MAGNETIC RESONANCE PARAMETERS AND X-RAY CRYSTAL STRUCTURES
Pearson, Anthony J.,Raithby, Paul R.
, p. 884 - 891 (1981)
A number of η4-cyclohexadiene-Fe(CO)2L and η4-2-methoxycyclohexadiene-Fe(CO)2L complexes have been prepared and their 13C n.m.r. spectra recorded.Methoxy-substituent effects suggest a depopulation rather than the expected enhanced population of the diene l.u.m.o. (lowest unoccupied molecular orbital) as the ?-acceptor strength of L decreases.X-Ray crystal-structure determinations for L = PPh3 were in agreement, and an explanation is proposed.Complexes (7) and (8) both crystallise in the monoclinic space group P21/c with Z = 4.The cell parameters are a = 10.289(4), b =24.651(10), c = 9.282(4) Angstroem, and β = 109.37(3)deg for (7) and a = 14.444(7), b =18.052(10), c = 9.229.(4) Angstroem and β = 100.57(4)deg for (8).The structures were solved by a combination of Patterson and Fourier-difference techniques, and refined by blocked-cascade least squares to R = 0.053 for 3 325 unique observed reflections (7) and to R = 0.062 for 2 952 reflections (8).
