The stereoelectronic parameters of phosphites. The quantitative analysis of ligand effects (QALE)

Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

“…The acyl m CO absorptions bands are observed at 1607 and 1597 cm À1 for 2a and 2b, respectively. The complexes 2a [13,25] and 2b [13,25,26] were reported previously, but only m CO absorption bands in cyclohexane were reported (m CO = 1924 for 2a and 1920 for 2b).…”

Transition metal-substituted paraffins: synthesis and properties of some μ-saturated heterobimetallic complexes containing Mo and W or Fe and the crystal structures of [(η5-C5H5)(CO)3W(CH2)3Mo(CO)2(PPh3)(η5-C5H5)] and [(η5-C5H5)(CO)2(PPh3)Mo(CH2)3Fe(CO)2(η5-C5H5)]

“…Some of the W(CO) or Fe(CO) and Mo(CO) peaks overlap, but the peaks between 1830 and 1850 cm À1 can be clearly assigned to Mo(CO) [1,17]. Steric effects of the phosphines are difficult to separate from electronic factors and hence are closely interrelated [23,24]. Since PMe 3 is the most basic phosphine within the group with the lowest p-acceptor properties, its complexes have the strongest M(CO) bonds and hence the lowest frequency infrared bands in the m(CO) region.…”

Pendent group effects, PGEs, in P-donor ligands

“…= aw d + by + cE ar + dp p + e (2) whatever complex they are in, or whatever measurement is being made, only the coefficients a and d changing from case to case. 9, deviations of ca. E ar was a ''parameter'' that had been derived 12 by noting deviations from expected behaviour that were observed when aryl groups were attached to the P-donor atom (see below).…”