Co-ordinatively unsaturated alkyne complexes of molybdenum and tungsten

Reactions and dynamic nuclear magnetic resonance studies of [m(SC6F5)(CO)(CF3C≡CCF 3)(η5-C5H5)] (M = Mo or W) complexes

Jack L. Davidson

Research output: Contribution to journalArticle

Abstract

Variable-temperature 19F n.m.r. studies of the hexafluorobut-2-yne complex [W(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] reveal three distinct phases of fluxional behaviour between -90 and +80°C, attributed to restricted rotation about (a) the S-C6F5 bond, (b) the W-SC6F5 bond, and (c) the CF3CCCF3-W bond ('propeller rotation'), in increasing order of energy. The oxo complex [W(SC6F5)(O)(CF3C=CCF 3)(?5-C5H5)], obtained by air oxidation of the parent carbonyl in diethyl ether, in contrast shows only restricted rotation about the W-SC6F5 bond over the same temperature range. Reactions of the carbonyls [M(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] (M = Mo or W) with tertiary phosphines and phosphites (L) give carbonyl-substitution products [M(SC6F5)(L)(CF3C=CCF 3)(?5-C5H5)] [M = Mo or W, L = P(OMe)3, PMe2Ph, or PEt3; M = Mo, L = PPh3 or PMePh2] under unusually mild conditions which undergo alkyne propeller rotation according to 19F n.m.r. studies. In the case of alkylphosphines, carbonyl substitution was observed to proceed via thermally unstable intermediates, [M(SC6F5)(CO){?2-C(CF3)C(CF 3)L}(?5-C5H5)], isolated and characterised for the case M = W, L = PEt3. N.m.r. data indicate the presence of two isomeric forms containing an ?2-vinyl ligand C(CF3)C(CF3)L resulting from attack of the phosphine at an alkyne carbon atom.

Original languageEnglish
Pages (from-to)2423-2431
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number11
DOIs
Publication statusPublished - 1986

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Tungsten
Alkynes
Molybdenum
Carbon Monoxide
Nuclear magnetic resonance
phosphine
Propellers
Substitution reactions
Phosphines
Phosphites
Ether
Carbon
Ligands
Atoms
Oxidation
Temperature
Air

Cite this

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title = "Co-ordinatively unsaturated alkyne complexes of molybdenum and tungsten: Reactions and dynamic nuclear magnetic resonance studies of [m(SC6F5)(CO)(CF3C≡CCF 3)(η5-C5H5)] (M = Mo or W) complexes",
abstract = "Variable-temperature 19F n.m.r. studies of the hexafluorobut-2-yne complex [W(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] reveal three distinct phases of fluxional behaviour between -90 and +80°C, attributed to restricted rotation about (a) the S-C6F5 bond, (b) the W-SC6F5 bond, and (c) the CF3CCCF3-W bond ('propeller rotation'), in increasing order of energy. The oxo complex [W(SC6F5)(O)(CF3C=CCF 3)(?5-C5H5)], obtained by air oxidation of the parent carbonyl in diethyl ether, in contrast shows only restricted rotation about the W-SC6F5 bond over the same temperature range. Reactions of the carbonyls [M(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] (M = Mo or W) with tertiary phosphines and phosphites (L) give carbonyl-substitution products [M(SC6F5)(L)(CF3C=CCF 3)(?5-C5H5)] [M = Mo or W, L = P(OMe)3, PMe2Ph, or PEt3; M = Mo, L = PPh3 or PMePh2] under unusually mild conditions which undergo alkyne propeller rotation according to 19F n.m.r. studies. In the case of alkylphosphines, carbonyl substitution was observed to proceed via thermally unstable intermediates, [M(SC6F5)(CO){?2-C(CF3)C(CF 3)L}(?5-C5H5)], isolated and characterised for the case M = W, L = PEt3. N.m.r. data indicate the presence of two isomeric forms containing an ?2-vinyl ligand C(CF3)C(CF3)L resulting from attack of the phosphine at an alkyne carbon atom.",
author = "Davidson, {Jack L.}",
year = "1986",
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language = "English",
pages = "2423--2431",
journal = "Journal of the Chemical Society, Dalton Transactions",
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T1 - Co-ordinatively unsaturated alkyne complexes of molybdenum and tungsten

T2 - Reactions and dynamic nuclear magnetic resonance studies of [m(SC6F5)(CO)(CF3C≡CCF 3)(η5-C5H5)] (M = Mo or W) complexes

AU - Davidson, Jack L.

PY - 1986

Y1 - 1986

N2 - Variable-temperature 19F n.m.r. studies of the hexafluorobut-2-yne complex [W(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] reveal three distinct phases of fluxional behaviour between -90 and +80°C, attributed to restricted rotation about (a) the S-C6F5 bond, (b) the W-SC6F5 bond, and (c) the CF3CCCF3-W bond ('propeller rotation'), in increasing order of energy. The oxo complex [W(SC6F5)(O)(CF3C=CCF 3)(?5-C5H5)], obtained by air oxidation of the parent carbonyl in diethyl ether, in contrast shows only restricted rotation about the W-SC6F5 bond over the same temperature range. Reactions of the carbonyls [M(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] (M = Mo or W) with tertiary phosphines and phosphites (L) give carbonyl-substitution products [M(SC6F5)(L)(CF3C=CCF 3)(?5-C5H5)] [M = Mo or W, L = P(OMe)3, PMe2Ph, or PEt3; M = Mo, L = PPh3 or PMePh2] under unusually mild conditions which undergo alkyne propeller rotation according to 19F n.m.r. studies. In the case of alkylphosphines, carbonyl substitution was observed to proceed via thermally unstable intermediates, [M(SC6F5)(CO){?2-C(CF3)C(CF 3)L}(?5-C5H5)], isolated and characterised for the case M = W, L = PEt3. N.m.r. data indicate the presence of two isomeric forms containing an ?2-vinyl ligand C(CF3)C(CF3)L resulting from attack of the phosphine at an alkyne carbon atom.

AB - Variable-temperature 19F n.m.r. studies of the hexafluorobut-2-yne complex [W(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] reveal three distinct phases of fluxional behaviour between -90 and +80°C, attributed to restricted rotation about (a) the S-C6F5 bond, (b) the W-SC6F5 bond, and (c) the CF3CCCF3-W bond ('propeller rotation'), in increasing order of energy. The oxo complex [W(SC6F5)(O)(CF3C=CCF 3)(?5-C5H5)], obtained by air oxidation of the parent carbonyl in diethyl ether, in contrast shows only restricted rotation about the W-SC6F5 bond over the same temperature range. Reactions of the carbonyls [M(SC6F5)(CO)(CF3C=CCF 3)(?5-C5H5)] (M = Mo or W) with tertiary phosphines and phosphites (L) give carbonyl-substitution products [M(SC6F5)(L)(CF3C=CCF 3)(?5-C5H5)] [M = Mo or W, L = P(OMe)3, PMe2Ph, or PEt3; M = Mo, L = PPh3 or PMePh2] under unusually mild conditions which undergo alkyne propeller rotation according to 19F n.m.r. studies. In the case of alkylphosphines, carbonyl substitution was observed to proceed via thermally unstable intermediates, [M(SC6F5)(CO){?2-C(CF3)C(CF 3)L}(?5-C5H5)], isolated and characterised for the case M = W, L = PEt3. N.m.r. data indicate the presence of two isomeric forms containing an ?2-vinyl ligand C(CF3)C(CF3)L resulting from attack of the phosphine at an alkyne carbon atom.

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DO - 10.1039/DT9860002423

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JO - Journal of the Chemical Society, Dalton Transactions

JF - Journal of the Chemical Society, Dalton Transactions

SN - 1472-7773

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