TY - JOUR
T1 - Co-ordinatively unsaturated alkyne complexes of tungsten
T2 - Synthesis and dynamic nuclear magnetic resonance studies of some but-2-yne derivatives
AU - Davidson, Jack L.
AU - Vasapollo, Guiseppe
PY - 1988
Y1 - 1988
N2 - Reactions of [{W(µ-Br)Br(CO) (MeC=CMe)2}2] (1) with one molar equivalent of Na(S2CNMe2), Na(S2PMe2), or Tl(acac) (acac = acetylacetonate) give mononuclear derivatives [WBr(L-L)(CO)(MeC=CMe)2] (2) (L-L = S2CNMe2, S2PMe2, or acac). The 1H and 13C n.m.r. spectra of the acac complex are temperature independent whereas dynamic 1H n.m.r. studies of the S2CNMe2 and S2PMe2 derivatives have been interpreted in terms of a molecular rearrangement involving dechelation of the bidentate ligand which exchanges the alkyne environments and the ends of the dithiolate ligand. The reaction of (1) with two molar equivalents of Na(S2PMe2) gives the bis-alkyne complex [W(S2PMe2)2(MeC=CMe)2] (3) whereas Na[S2P(OMe)2] and TI(acac) give mono-alkyne derivatives [W(L-L)2(CO)(MeC=CMe)] (4) [L-L = S2P(OMe)2 or acac]. 1H N.m.r. studies of (3) suggest fluxional behaviour involving dechelation of S2PMe2 which exchanges both the S2PMe2 methyls and the alkyne methyls without necessarily requiring alkyne propeller rotation. In contrast, fluxional behaviour in (4) [L-L = S2P(OMe)2] clearly involves alkyne propeller rotation in addition to two other processes, one of which exchanges the methyl groups of one S2P(OMe)2 group. However, the only dynamic process observed with (4) (L-L = acac) appears to involve alkyne propeller rotation.
AB - Reactions of [{W(µ-Br)Br(CO) (MeC=CMe)2}2] (1) with one molar equivalent of Na(S2CNMe2), Na(S2PMe2), or Tl(acac) (acac = acetylacetonate) give mononuclear derivatives [WBr(L-L)(CO)(MeC=CMe)2] (2) (L-L = S2CNMe2, S2PMe2, or acac). The 1H and 13C n.m.r. spectra of the acac complex are temperature independent whereas dynamic 1H n.m.r. studies of the S2CNMe2 and S2PMe2 derivatives have been interpreted in terms of a molecular rearrangement involving dechelation of the bidentate ligand which exchanges the alkyne environments and the ends of the dithiolate ligand. The reaction of (1) with two molar equivalents of Na(S2PMe2) gives the bis-alkyne complex [W(S2PMe2)2(MeC=CMe)2] (3) whereas Na[S2P(OMe)2] and TI(acac) give mono-alkyne derivatives [W(L-L)2(CO)(MeC=CMe)] (4) [L-L = S2P(OMe)2 or acac]. 1H N.m.r. studies of (3) suggest fluxional behaviour involving dechelation of S2PMe2 which exchanges both the S2PMe2 methyls and the alkyne methyls without necessarily requiring alkyne propeller rotation. In contrast, fluxional behaviour in (4) [L-L = S2P(OMe)2] clearly involves alkyne propeller rotation in addition to two other processes, one of which exchanges the methyl groups of one S2P(OMe)2 group. However, the only dynamic process observed with (4) (L-L = acac) appears to involve alkyne propeller rotation.
U2 - 10.1039/DT9880002855
DO - 10.1039/DT9880002855
M3 - Article
SN - 1472-7773
SP - 2855
EP - 2863
JO - Journal of the Chemical Society, Dalton Transactions
JF - Journal of the Chemical Society, Dalton Transactions
IS - 11
ER -