TY - JOUR
T1 - 13C and 31P NMR studies on geometrical non-rigidity in heterobinuclear complexes [WM(CO)3(PPh3)2(η5-C5H5)] (M Rh, Cu)
AU - Lindsell, W. Edward
AU - Tomb, Peter J.
PY - 1989/12/5
Y1 - 1989/12/5
N2 - 13C NMR studies on [W2(CO)6Cp2] (Cp = ?5-C5H5), including a 2D EXSY study, confirm that simple rotation about the WW bond is responsible for the isomerisation in solution. Variable temperature 31P{1H} and 13C{1H} NMR spectra of [WRh(µ-CO)2(CO)(PPh3)2Cp] establish that a pseudo-rotational process, with ?G 27.9 ± 0.8 kJ mol-1 at -108 ± 8°C, results in interchange of the inequivalent PPh3 groups and all the CO ligands. The mechanism of this facile fluxional process is discussed in relation to that of [W2(CO)6Cp2], and an intermediate (or transition state) of the type [WRh(µ-CO)3(PPh3)2Cp] is proposed. Variable temperature 31P{1H} and 13C{1H} NMR spectra of [WCu(CO)3(PPh3)2Cp] in solvents of various polarities establish a related geometrical non-rigidity for this complex, but with ?G ca. 39-41 kJ mol-1, in the range -57 to -69°C; this result, considered along with the very low electrical conductivity in acetone, suggests that an intramolecular mechanism also operates for this interchange. © 1989.
AB - 13C NMR studies on [W2(CO)6Cp2] (Cp = ?5-C5H5), including a 2D EXSY study, confirm that simple rotation about the WW bond is responsible for the isomerisation in solution. Variable temperature 31P{1H} and 13C{1H} NMR spectra of [WRh(µ-CO)2(CO)(PPh3)2Cp] establish that a pseudo-rotational process, with ?G 27.9 ± 0.8 kJ mol-1 at -108 ± 8°C, results in interchange of the inequivalent PPh3 groups and all the CO ligands. The mechanism of this facile fluxional process is discussed in relation to that of [W2(CO)6Cp2], and an intermediate (or transition state) of the type [WRh(µ-CO)3(PPh3)2Cp] is proposed. Variable temperature 31P{1H} and 13C{1H} NMR spectra of [WCu(CO)3(PPh3)2Cp] in solvents of various polarities establish a related geometrical non-rigidity for this complex, but with ?G ca. 39-41 kJ mol-1, in the range -57 to -69°C; this result, considered along with the very low electrical conductivity in acetone, suggests that an intramolecular mechanism also operates for this interchange. © 1989.
UR - http://www.scopus.com/inward/record.url?scp=0347103880&partnerID=8YFLogxK
M3 - Article
SN - 0022-328X
VL - 378
SP - 245
EP - 253
JO - Journal of Organometallic Chemistry
JF - Journal of Organometallic Chemistry
IS - 2
ER -