121918-86-3Relevant academic research and scientific papers
Investigations into the steric influences on the reaction mechanism of CO2 insertion into metal-oxygen bonds. COS activation as a model for CO2
Darensbourg, Donald J.,Mueller, Brian L.,Bischoff, Christopher J.,Chojnacki, Stephen S.,Reibenspies, Joseph H.
, p. 2418 - 2424 (2008/10/08)
Steric influences on the insertion of CO2 into metal-oxygen bonds have been investigated. The compounds [Et4N][W(CO)5O-2,6-Ph2-C6H 3] (1) and [Et4N][W(CO)4(PPh2Me)OPh] (2) have been synthesized and their reactivities toward CO2 studied. Complex 1 showed no reactivity toward CO2 even at elevated pressures (900 psi). The anion of 2 demonstrated a retarded rate of reaction with CO2 as compared to the parent complex, [Et4N][W(CO)5OPh], a result ascribed to the steric bulk of the cis phosphine ligand. In general, it was found that the reactivity of metal-oxygen bonds toward CO2 was adversely affected by the increased steric demands of substituents on either the metal center or the aryl group of the ligated aryloxide. Complexes 1 and 2 were characterized in the solid state by X-ray crystallography. Complex 1 crystallized in the space group P21/c with cell dimensions a = 12.658 (3) ?, b = 15.136 (3) ?, c = 33.471 (6) ?, β = 95.388 (15)°, V = 0.6385 (2) ?3, Z = 8, and RF = 6.4%. Complex 2 crystallized in the space group P21/n with cell dimensions a = 11.309 (7) ?, b = 16.9389 (8) ?, c = 16.888 (13) ?, β = 102.39 (5)°, V = 3160 (3) ?3, Z = 4, and RF = 4.3%. These compounds were also reacted with COS as a model for CO2. [Et4N][W(CO)5O-2,6-Ph2-C6H 3] reacted cleanly under 1 atm of COS and at ambient temperature to afford the product of COS insertion into a metal-oxygen bond, [Et4N][W(CO)5SC(O)O-2,6-Ph2-C6H 3] (3). The enhanced reactivity of 1 toward COS as compared to CO2 is proposed to be in part due to W?S bond formation in the transition state. Complex 3 was subjected to X-ray crystallographic investigation. Complex 3 crystallized in the space group Pcmn (No. 62) with cell dimensions a = 11.803 (6) ?, b = 14.844 (8) ?, c = 18.752 (11) ?, V = 3285(3) ?3, Z = 8, and RF = 6.3%.
Synthesis, Structure, and Reactivity of Zerovalent Group 6 Metal Pentacarbonyl Aryl Oxide Complexes. Reactions with Carbon Dioxide
Darensbourg, Donald J.,Sanchez, Kathryn M.,Reibenspies, Joseph H.,Rheingold, Arnold L.
, p. 7094 - 7103 (2007/10/02)
The synthesis of (M=Cr, Mo, W; R=Ph, C6H4CH3-m) from the reaction of M(CO)5THF and in tetrahydrofuran is reported.In the absence of a carbon monoxide atmosphere these mononuclear species readily aggregate via a CO dissociation pathway to the tetranuclear species 44.It was possible to isolate pure crystalline samples of the derivatives by precipitation from solutions under a carbon monoxide atmophere.The complex was characterized in the solid-state by X-ray crystallography. crystallizes in the space group with cell dimensions a=9.416(3) Angstroem, b=12.665(2) Angstroem, c=18.371(3) Angstroem, α=92.38(1) deg, β=94.50(2) deg, γ=95.85(2) deg, V=2168.3 Angstroem3, Z=4, and RF=7.71percent.An additional salt of the tungsten phenoxide complex has been crystallized that contains 0.5 equiv of water, i.e., .This species has as well been characterized by X-ray crystallography. crystallizes in the space group P21/c with cell dimensions a=17.545(5), b=25.322(8), c=10.337(3), β=102.52(3) deg, V=4483(2) Angstroem3, Z=8, and RF=5.60percent.The water molecule is shown to be hydrogen bonded between ligated -OPh ligands of adjacent W(CO)5OPh(1-) anions.This intermolecular hydrogen-bonding interaction is observed in tetrahydrofuran solution as well between alcohols and W(CO)5OPh(1-).The M(CO)5OR(1-) (M=Cr, W) derivatives were demonstrated to undergo facile insertion reactions with CO2, COS, and CS2 to afford the corresponding metal pentacarbonyl phenyl carbonate, phenyl thiocarbonate, and phenyl dithiocarbonate complexes.This carbon dioxide insertion reaction isreversible, and the rate of insertion is unaffected by carbon monoxide pressures up to 10 atm.The relative rates of insertion of CO2, COS, and CS2 into the M(CO)5OPh(1-) anions are Cr > W and CS2 > COS > CO2.On the other hand, in the presence of ligands at the metal center that are sterically more demanding than CO, i.e., cis-M(CO)4(L)OPh(1-) derivatives, the relative rates of carbon dioxide insertion are W > Cr and L=P(OMe)3 > PMe3 > PPh3.The W(CO)5XC(X)OPh(1-) (X=O or S) derivatives underwent hydrolysis in the presence of small quantities of water to provide the corresponding W(CO)4(CX2O)(2-) products.One of these products, namely, 2, was subjected to an X-ray crystallographic investigation.The salt crystallizes in the space group with cell dimensions a=10.513(5) Angstroem, b=15.881(10) Angstroem, c=8.130(6) Angstroem, α=101.69(6) deg, β=92.12(5) deg, γ=83.25(5) deg, V=1319.8 Angstroem3, Z=2, and RF=3.01percent.The W-O bond distances (2.204 Angstroem) are quite similar to those observed (2.203 Angstroem) in the W-OPh(1-) complexes.The carbonate ligand is bidentate with a very acute O-W-O angles of 59.4 deg.
