TY - JOUR
T1 - Synthesis, reactions, and dynamic nuclear magnetic resonance studies of η2-vinyl complexes of molybdenum and tungsten, [m{η3-C(CF3)C(CF3)(L-L)}(CF 3C=CCF3)(η5-C5H5)] (L-L = MeCO2-...
AU - Davidson, Jack L.
PY - 1987
Y1 - 1987
N2 - full title:Synthesis, reactions, and dynamic nuclear magnetic resonance studies of ?2-vinyl complexes of molybdenum and tungsten, [m{?3-C(CF3)C(CF3)(L-L)}(CF 3C=CCF3)(?5-C5H5)] (L-L = MeCO2-, Me2PS2-, Et2NCS2-, or Me2NCS2-) Reactions of bis(hexafluorobut-2-yne) complexes [MCl(CF3C=CCF3)2(?5-C 5H5)] (M = Mo or W) with anions L-L = MeCO2-, Me2PS2-, and R2NCS2- (R = Me or Et) give adducts [M(L-L)(CF3C2CF3)2(? 5-C5H5)] which exhibit a bis(alkyne) structure containing a monodentate ligand L-L and/or an isomeric ?2-vinyl structure in which the ligand L-L forms a bridge between the metal and the ?2-vinyl ligand. In the cases M = Mo or W, L-L = R2NCS2 (R = Me or Et) the ?2-vinyl structure is stereochemically rigid whereas with M = Mo, L-L = MeCO2- or Me2PS2-; M = W, L-L = Me2PS2-, 19F n.m.r. studies reveal fluxional behaviour attributed to reversible cleavage of the (L-L)-?2-vinyl linkage which regenerates the bis(alkyne) structure. Thermolysis of ?2-vinyl complexes [Mo{?3-C(CF3)C(CF3)(L-L)}(CF 3C=CCF3)(?5-C5H 5)] gives tetrakis(trifluoromethyl)cyclobutadiene derivatives [Mo(L-L){?4-C4(CF3)4}(? 5-C5H5)] (L-L = S2CNR2) in which the cyclobutadiene ring exhibits high barriers to rotation about the metal-ligand axis. Complexes of this type can also be obtained from the metathetical reactions of [MoI(CO){?4-C4(CF3)4}(? 5-C5H5)] with metal salts of (L-L)- (S2CNMe2 or pyridine-2-thiolate). Thermolysis of [Mo{?3-C(CF3)C(CF3)S2CNR 2}(CF3C=CCF3)(?5-C 5H5)] also gives small quantities of the ?2-vinyl complex [Mo{?3-C(CF3)C(CF3)C(CF 3)=C(CF3)S}(?2-R2NCS)(? 5-C5H5)] resulting from condensation of the two fluorocarbon units and fragmentation of the R2NCS2 moiety. This type of complex is the major product when the ?2-vinyl complex [Mo{?3-C(CF3)C(CF3)S2CNR 2}(CF3C=CCF3)(?5-C 5H5)] is photolysed in solution.
AB - full title:Synthesis, reactions, and dynamic nuclear magnetic resonance studies of ?2-vinyl complexes of molybdenum and tungsten, [m{?3-C(CF3)C(CF3)(L-L)}(CF 3C=CCF3)(?5-C5H5)] (L-L = MeCO2-, Me2PS2-, Et2NCS2-, or Me2NCS2-) Reactions of bis(hexafluorobut-2-yne) complexes [MCl(CF3C=CCF3)2(?5-C 5H5)] (M = Mo or W) with anions L-L = MeCO2-, Me2PS2-, and R2NCS2- (R = Me or Et) give adducts [M(L-L)(CF3C2CF3)2(? 5-C5H5)] which exhibit a bis(alkyne) structure containing a monodentate ligand L-L and/or an isomeric ?2-vinyl structure in which the ligand L-L forms a bridge between the metal and the ?2-vinyl ligand. In the cases M = Mo or W, L-L = R2NCS2 (R = Me or Et) the ?2-vinyl structure is stereochemically rigid whereas with M = Mo, L-L = MeCO2- or Me2PS2-; M = W, L-L = Me2PS2-, 19F n.m.r. studies reveal fluxional behaviour attributed to reversible cleavage of the (L-L)-?2-vinyl linkage which regenerates the bis(alkyne) structure. Thermolysis of ?2-vinyl complexes [Mo{?3-C(CF3)C(CF3)(L-L)}(CF 3C=CCF3)(?5-C5H 5)] gives tetrakis(trifluoromethyl)cyclobutadiene derivatives [Mo(L-L){?4-C4(CF3)4}(? 5-C5H5)] (L-L = S2CNR2) in which the cyclobutadiene ring exhibits high barriers to rotation about the metal-ligand axis. Complexes of this type can also be obtained from the metathetical reactions of [MoI(CO){?4-C4(CF3)4}(? 5-C5H5)] with metal salts of (L-L)- (S2CNMe2 or pyridine-2-thiolate). Thermolysis of [Mo{?3-C(CF3)C(CF3)S2CNR 2}(CF3C=CCF3)(?5-C 5H5)] also gives small quantities of the ?2-vinyl complex [Mo{?3-C(CF3)C(CF3)C(CF 3)=C(CF3)S}(?2-R2NCS)(? 5-C5H5)] resulting from condensation of the two fluorocarbon units and fragmentation of the R2NCS2 moiety. This type of complex is the major product when the ?2-vinyl complex [Mo{?3-C(CF3)C(CF3)S2CNR 2}(CF3C=CCF3)(?5-C 5H5)] is photolysed in solution.
UR - http://www.scopus.com/inward/record.url?scp=51149217021&partnerID=8YFLogxK
U2 - 10.1039/DT9870002715
DO - 10.1039/DT9870002715
M3 - Article
SN - 1472-7773
SP - 2715
EP - 2722
JO - Journal of the Chemical Society, Dalton Transactions
JF - Journal of the Chemical Society, Dalton Transactions
IS - 11
ER -