TY - JOUR
T1 - Molybdenum carbonyl assisted reductive tetramerization of CO by activated magnesium(i) compounds
T2 - squarate dianion vs. metallo-ketene formation
AU - Yuvaraj, K.
AU - Mullins, Jeremy C.
AU - Rajeshkumar, Thayalan
AU - Douair, Iskander
AU - Maron, Laurent
AU - Jones, Cameron
N1 - Funding Information:
CJ thanks the Australian Research Council and the US Air Force Asian Office of Aerospace Research and Development (grant FA2386-21-1-4048). LM is a senior member of the Institut Universtaire de France and thanks the Humboldt Foundation.
Publisher Copyright:
© 2023 The Royal Society of Chemistry.
PY - 2023/5/21
Y1 - 2023/5/21
N2 - Reactions of a dimagnesium(i) compound, [{(DipNacnac)Mg}2] (DipNacnac = [HC(MeCNDip)2]−, Dip = 2,6-diisopropylphenyl), pre-activated by coordination with simple Lewis bases (4-dimethylaminopyridine, DMAP; or TMC, :C(MeNCMe)2), with 1 atmosphere of CO in the presence of one equivalent of Mo(CO)6 at room temperature, led to the reductive tetramerisation of the diatomic molecule. When the reactions were carried out at room temperature, there is an apparent competition between the formation of magnesium squarate, [{(DipNacnac)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(DipNacnac)}]2, and magnesium metallo-ketene products, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(D)(DipNacnac)}], which are not inter-convertible. Repeating the reactions at 80 °C led to the selective formation of the magnesium squarate, implying that this is the thermodynamic product. In an analogous reaction, in which THF is the Lewis base, only the metallo-ketene complex, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(THF)(DipNacnac)}] is formed at room temperature, while a complex product mixture is obtained at elevated temperature. In contrast, treatment of a 1 : 1 mixture of the guanidinato magnesium(i) complex, [(Priso)Mg-Mg(Priso)] (Priso = [Pri2NC(NDip)2]−), and Mo(CO)6, with CO gas in a benzene/THF solution, gave a low yield of the squarate complex, [{(Priso)(THF)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(THF)(Priso)}]2, at 80 °C. Computational analyses of the electronic structure of squarate and metallo-ketene product types corroborate the bonding proposed from experimental data, for the C4O4 fragments of these systems.
AB - Reactions of a dimagnesium(i) compound, [{(DipNacnac)Mg}2] (DipNacnac = [HC(MeCNDip)2]−, Dip = 2,6-diisopropylphenyl), pre-activated by coordination with simple Lewis bases (4-dimethylaminopyridine, DMAP; or TMC, :C(MeNCMe)2), with 1 atmosphere of CO in the presence of one equivalent of Mo(CO)6 at room temperature, led to the reductive tetramerisation of the diatomic molecule. When the reactions were carried out at room temperature, there is an apparent competition between the formation of magnesium squarate, [{(DipNacnac)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(DipNacnac)}]2, and magnesium metallo-ketene products, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(D)(DipNacnac)}], which are not inter-convertible. Repeating the reactions at 80 °C led to the selective formation of the magnesium squarate, implying that this is the thermodynamic product. In an analogous reaction, in which THF is the Lewis base, only the metallo-ketene complex, [{(DipNacnac)Mg}[μ-O = CC{Mo(CO)5}C(O)CO2]{Mg(THF)(DipNacnac)}] is formed at room temperature, while a complex product mixture is obtained at elevated temperature. In contrast, treatment of a 1 : 1 mixture of the guanidinato magnesium(i) complex, [(Priso)Mg-Mg(Priso)] (Priso = [Pri2NC(NDip)2]−), and Mo(CO)6, with CO gas in a benzene/THF solution, gave a low yield of the squarate complex, [{(Priso)(THF)Mg}{cyclo-(κ4-C4O4)}{μ-Mg(THF)(Priso)}]2, at 80 °C. Computational analyses of the electronic structure of squarate and metallo-ketene product types corroborate the bonding proposed from experimental data, for the C4O4 fragments of these systems.
UR - http://www.scopus.com/inward/record.url?scp=85158832700&partnerID=8YFLogxK
U2 - 10.1039/d3sc01487h
DO - 10.1039/d3sc01487h
M3 - Article
AN - SCOPUS:85158832700
SN - 2041-6539
VL - 14
SP - 5188
EP - 5195
JO - Chemical Science
JF - Chemical Science
IS - 19
ER -