Tungsten-183 NMR study of cis-[W(CO)4(PPh3)(4-RC5H4N)]; effect of varying the σ donor strength of the pyridine

Tungsten‐183 NMR data are reported for the complexes cis‐[W(CO)4(PPh3)(4‐RC5H4N)] (R = H, Me, Ph, COMe, COPh, OMe, NMe2, Cl, NO2). The 183W chemical shift (obtained by indirect detection using 31P) is found to correlate with the Hammett σ function for the group R, with 183W shielding increasing approximately linearly with the donor strength of the pyridine over a range of 93 ppm. The X‐ray structures of cis‐[W(CO)4(PPh3)(4‐MeOC5H4N)] and cis‐[W(CO)4(PPh3)(4‐PhCOC5H4N)] are also reported. Copyright © 2013 John Wiley & Sons, Ltd. Tungsten‐183 chemical shifts for complexes with R = H, Me, Ph, COMe, COPh, OMe, NMe2, Cl, NO2 show a good correlation with Hammett σp for R.