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Three-Coordinate, Cyclic Bent Allene Iron Complexes
No full textNovel
three-coordinate Fe complexes featuring 1,2-diphenyl-3,5-bis(2,6-dimethylphenoxy)pyrazolin-4-ylidine
or “cyclic bent allene” (CBA) have been synthesized.
Reaction with FeCl2(PPh3)2 results
in the loss of both phosphines to yield monomeric Fe(CBA)Cl2. Treatment with 2 equiv of benzyl Grignard affords the three-coordinate
alkylated product Fe(CBA)(Bn)2. Exposure of the alkylated
species to an atmosphere of CO results in reductive elimination of
1,3-diphenylpropanone and formation of trigonal-bipyramidal Fe(CBA)(CO)4
Three-Coordinate, Cyclic Bent Allene Iron Complexes
No full textNovel
three-coordinate Fe complexes featuring 1,2-diphenyl-3,5-bis(2,6-dimethylphenoxy)pyrazolin-4-ylidine
or “cyclic bent allene” (CBA) have been synthesized.
Reaction with FeCl2(PPh3)2 results
in the loss of both phosphines to yield monomeric Fe(CBA)Cl2. Treatment with 2 equiv of benzyl Grignard affords the three-coordinate
alkylated product Fe(CBA)(Bn)2. Exposure of the alkylated
species to an atmosphere of CO results in reductive elimination of
1,3-diphenylpropanone and formation of trigonal-bipyramidal Fe(CBA)(CO)4
Cationic and Neutral Phosphido-Bridged Pentamethylcyclopentadienyl−Chromium Dimers
No full textThe species [(Cp*Cr)2(μ-Cl)3]X (X = [AlCl4] (3), [GaCl4] (4), [B(C6F5)4] (5)) were generated
from (Cp*CrCl(μ-Cl))2 (1) via reaction with a chloride abstraction reagent. Using a similar
synthetic route, the reaction of 1, generated in situ, with MeLi and the borane B(C6F5)3
gave crystals of the salt [(Cp*Cr)2(μ-Cl)3][MeB(C6F5)3] (6), while the complex [(Cp*Cr)2(μ-Cl)3][Me2B(C6F5)2] (7) was obtained, albeit in low yield, from the reaction of [Cp*CrMe(μ-Cl)]2 with HB(C6F5)2. Monoalkylation of 5 with MeLi gave [(Cp*Cr(μ-Cl))2(μ-Me)][B(C6F5)4]
(8), while the related mono(phosphide)-bridged cationic species [(Cp*Cr)2(μ-PPh2)(μ-Cl)2][B(C6F5)4] (9) was derived from 5 via reaction with Ph2PLi. The bis(phosphide)-bridged species
[(Cp*Cr(μ-PPh2))2(μ-Cl)][AlMe3Cl] (10) was derived from reaction mixtures of 1, Ph2PLi, and
AlMe3, while monoalkylation of 1 with MeLi followed by treatment with Ph2PLi and AlMe3
yielded [(Cp*Cr(μ-PPh2))2(μ-Me)][(Me3Al)2(μ-Cl)] (11). The neutral phosphide-bridged species
(Cp*Cr(μ-PPh2))2(μ-CH2) (12) and (Cp*Cr)2(μ-PPh2)(μ-Cl)(μ-CH2) (13) were obtained from
reactions of 1, MeLi, and Ph2PLi. X-ray structural data are reported from compounds 5−13.
The synthetic routes and the structural data are discussed
Salts of the Cation [(Cp*Cr)<sub>4</sub>(μ-Cl)<sub>3</sub>(μ-CH<sub>2</sub>)<sub>3</sub>AlMe]<sup>+</sup> with the Oxo- and Methine-Based Aluminum Anions [(Me<sub>2</sub>Al)<sub>2</sub>(μ-CH)(AlCl<sub>2</sub>Me)<sub>2</sub>]<sup>-</sup> and [(Me<sub>2</sub>Al)(μ<sub>3</sub>-O)(AlCl<sub>2</sub>Me)(AlMe<sub>2</sub>Cl)]<sup>-</sup>
No full textReactions of (Cp*CrCl2)2 (1) and Cp*Cr(HNP-i-Pr3)Cl2 (3) with excess AlMe3 gave [(Cp*Cr)4(μ-Cl)3(μ-CH2)3AlMe][(Me2Al)(μ3-O)(AlCl2Me)(AlMe2Cl)] (2)
and [(Cp*Cr)4(μ-Cl)3(μ-CH2)3AlMe][(Me2Al)2(μ-CH)(AlCl2Me)2] (4), respectively. Although the cations are the same,
the former salt has a Al3O-based anion, whereas the
latter contains an Al4−methine anion
Room Temperature Reduction of CO<sub>2</sub> to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Borane
No full textRoom Temperature Reduction of CO2 to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Boran
Ruthenium and Rhodium Complexes of Thioether-Alkynylborates
No full textThe species ((C6F5)2BCH2SPh)2 reacts with PhCCLi to give
the thioether-alkynylborate
(C6F5)2BCH2SPh(CCPh)Li(THF)2 (1). Subsequent reaction with (Ph3P)3RuHCl, (Ph3P)3RhCl, and [(COD)Rh(μ-Cl)]2 gives (C6F5)2BCH2SPh(CCPh)RuH(PPh3)2 (2), (C6F5)2BCH2SPh(CCPh)Rh(PPh3)2 (4), and (C6F5)2BCH2SPh(CCPh)Rh(COD) (5), respectively, demonstrating a bidentate binding mode via the alkynyl
and thioether donors of the borate. Subsequent reactions of 2 and 4 with H2 gave (C6F5)2BCH2SPh(CH2CH2Ph)RuH(PPh3)2 (3) and ((C6F5)2BCH2SPh(CHCHPh))Rh(PPh3)2 (6). In the former case, the borate
remains bound to the metal via a π-interaction with the thioether-arene
ring, while in the latter case, S and alkene binding is observed
Synthesis and Reactivity of Neutral, Zwitterionic and Cationic Pentamethylcyclopentadienyl−Tantalum−Phosphinimide Complexes
No full textThis paper focuses on the synthesis and reactivity of Cp*Ta(V)−phosphinimide complexes.
Reaction of stoichiometric mixtures of Cp*TaCl4 and phosphinimine R3PNSiMe3 affords the
complexes Cp*Ta(NPR3)Cl3, R = t-Bu 1, i-Pr 2. These species are readily derivatized to the
alkylated complexes Cp*Ta(NPR3)Me3, R = t-Bu3, i-Pr 4; Cp*Ta(NPt-Bu3)(CH2Ph)Cl2, 5;
and Cp*Ta(NPt-Bu3)(CH2Ph)Me2, 6. Reaction with 3 equiv of BnMgCl afforded the robust
alkylidene species Cp*Ta(NPR3)(CHPh)(CH2Ph), R = t-Bu 7, i-Pr 8. Reaction of 7 with MeI
gives the metallacycle Cp*Ta(NPt-Bu3)(η2-CHPhCH2)(CH2Ph), 9. Alkylation of 1 and 2 with
2 equiv of EtMgCl results in formation of the complexes Cp*Ta(NPR3)(η2-C2H4)Cl, R = t-Bu
10, i-Pr 11, while further reaction of 10 with EtMgCl affords Cp*Ta(NPt-Bu3)(η2-C2H4)(CH2CH3), 12. Reaction of 1 with 1 equiv of B(C6F5)3 results in generation of the salt [Cp*Ta(NPt-Bu3)Cl2][ClB(C6F5)3], 13, while the analogous reaction with Ph3C[B(C6F5)4] affords the
related salt [Cp*Ta(NPt-Bu3)Cl2][B(C6F5)4], 14. The zwitterionic species Cp*Ta(NPR3)Me2(MeB(C6F5)3) (R = t-Bu 15, i-Pr 16) are derived via reaction of 3 or 4 with B(C6F5)3. The
analogous reaction of 3 and 4 with [Ph3C][B(C6F5)4] affords the related salts [Cp*Ta(NPR3)Me2][B(C6F5)4] (R = t-Bu 17, i-Pr 18). Treatment of 10 with Ph3CB(C6F5)4, Ph3CBF4, or
B(C6F5)3 gives the complexes [Cp*Ta(NPt-Bu3)(Cl)CH2CH2CPh3][B(C6F5)4], 20, [Cp*Ta(NPt-Bu3)(Cl)(CH2CH2CPh3)][BF4], 21 and the zwitterionic species [Cp*Ta(NPt-Bu3)(Cl)(CH2CH2B(C6F5)3)], 22, respectively. The relevance of this chemistry to the related group IV metal
olefin polymerization catalysts is discussed and considered. X-ray structural studies of 1, 3,
5, 7, 9, 10, and 22 are reported
Room Temperature Reduction of CO<sub>2</sub> to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Borane
No full textRoom Temperature Reduction of CO2 to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Boran
Room Temperature Reduction of CO<sub>2</sub> to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Borane
No full textRoom Temperature Reduction of CO2 to Methanol by Al-Based Frustrated Lewis Pairs and Ammonia Boran
Stoichiometric Metal-Free Reduction of CO in Syn-Gas
No full textReaction
of a 2:1 mixture of B(C6F5)3 and tBu3P with syn-gas results
in the stoichiometric reduction of CO to give a formyl derivative
which reacts further via an epoxy-borate intermediate to capture CO,
affording a heterocylic alkoxyborate. Heating the reaction prompts
reaction with H2 to give a borane-oxy-borate derivative,
the product of C–O bond cleavage
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