Abstract
Reaction of [Pd(TFA)2] (1; TFA = trifluoroacetate) with 2 equiv of benzyldiisopropylphosphine resulted in formation of the metalated complex [Pd {C6H4(CH2PiPr2)}{(C 6H5CH2)PiPr2 }(TFA)] (2). The dinuclear trifluoroacetate complex [Pd(C6H4(CH 2PiPr2)}[TFA)]2 (3) was formed when the reaction was performed with an equimolar amount of the phosphine. Both complexes were structurally characterized. Reduction of the cyclometalated palladium complex 2 with sodium metal in THF gave a mixture of cis and trans isomers of the dimetalated bis(o-benzyldiisopropylphosphine)palladium(II) (6a,b) and bis(benzyldiisopropylphosphine)palladium(0) (7). A mechanism for the reduction process is presented. Treatment of the reaction mixture of 6a,b and 7 with an equimolar amount of hydrochloric acid led to a mixture of 7, [Pd(C 6H4(CH2PiPr2)Ji(C 6H5CH2)PiPr2}(Cl)] (9), [Pd{(C6H5CH2)PiPr2J 2(H)(Cl)] (8), [Pd((C6H5CH2)-P iPr2}2(Cl)2] (4), and both isomeric forms of [Pd(C6H4(CH2PiPr 2)}2] (6a,b). All complexes were independently prepared and fully characterized. The addition of another 1 equiv of hydrochloric acid to this reaction mixture resulted in the exclusive formation of 4. Reduction of 4 with sodium metal in THF cleanly yielded the Pd0 complex 7 in high yields, offering a new, facile, and high-yield route toward the synthesis of dicoordinated bis(phosphine) Pd0 complexes. Reaction of 7 with an equimolar amount of HCl led to the clean formation of [PdJ(C6H 5CH2)PiPr2}2(H)(Cl)] (8). The addition of another 1 equiv of HCl led to the quantitative formation of 2 and H2. Reactions of 9 and an equimolar amount of NaBHEt3 cleanly yielded complex 7, which was also exclusively formed by treatment of 4 with 2 equiv of NaBHEt3. Mixtures of the cis and trans isomers 6a,b were formed by the addition of 2 equiv of (lithiobenzyl)diisopropylphosphine to benzene solutions of bis(diethyl sulfide)palladium dichloride (5) at room temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 894-899 |
| Number of pages | 6 |
| Journal | Organometallics |
| Volume | 27 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - Mar 10 2008 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
Cite this
Processes involved in the reduction of a cyclometalated palladium(II) complex. / Frech, Christian M.; Leitus, Gregory; Milstein, David.
In: Organometallics, Vol. 27, No. 5, 10.03.2008, p. 894-899.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Processes involved in the reduction of a cyclometalated palladium(II) complex
AU - Frech, Christian M.
AU - Leitus, Gregory
AU - Milstein, David
PY - 2008/3/10
Y1 - 2008/3/10
N2 - Reaction of [Pd(TFA)2] (1; TFA = trifluoroacetate) with 2 equiv of benzyldiisopropylphosphine resulted in formation of the metalated complex [Pd {C6H4(CH2PiPr2)}{(C 6H5CH2)PiPr2 }(TFA)] (2). The dinuclear trifluoroacetate complex [Pd(C6H4(CH 2PiPr2)}[TFA)]2 (3) was formed when the reaction was performed with an equimolar amount of the phosphine. Both complexes were structurally characterized. Reduction of the cyclometalated palladium complex 2 with sodium metal in THF gave a mixture of cis and trans isomers of the dimetalated bis(o-benzyldiisopropylphosphine)palladium(II) (6a,b) and bis(benzyldiisopropylphosphine)palladium(0) (7). A mechanism for the reduction process is presented. Treatment of the reaction mixture of 6a,b and 7 with an equimolar amount of hydrochloric acid led to a mixture of 7, [Pd(C 6H4(CH2PiPr2)Ji(C 6H5CH2)PiPr2}(Cl)] (9), [Pd{(C6H5CH2)PiPr2J 2(H)(Cl)] (8), [Pd((C6H5CH2)-P iPr2}2(Cl)2] (4), and both isomeric forms of [Pd(C6H4(CH2PiPr 2)}2] (6a,b). All complexes were independently prepared and fully characterized. The addition of another 1 equiv of hydrochloric acid to this reaction mixture resulted in the exclusive formation of 4. Reduction of 4 with sodium metal in THF cleanly yielded the Pd0 complex 7 in high yields, offering a new, facile, and high-yield route toward the synthesis of dicoordinated bis(phosphine) Pd0 complexes. Reaction of 7 with an equimolar amount of HCl led to the clean formation of [PdJ(C6H 5CH2)PiPr2}2(H)(Cl)] (8). The addition of another 1 equiv of HCl led to the quantitative formation of 2 and H2. Reactions of 9 and an equimolar amount of NaBHEt3 cleanly yielded complex 7, which was also exclusively formed by treatment of 4 with 2 equiv of NaBHEt3. Mixtures of the cis and trans isomers 6a,b were formed by the addition of 2 equiv of (lithiobenzyl)diisopropylphosphine to benzene solutions of bis(diethyl sulfide)palladium dichloride (5) at room temperature.
AB - Reaction of [Pd(TFA)2] (1; TFA = trifluoroacetate) with 2 equiv of benzyldiisopropylphosphine resulted in formation of the metalated complex [Pd {C6H4(CH2PiPr2)}{(C 6H5CH2)PiPr2 }(TFA)] (2). The dinuclear trifluoroacetate complex [Pd(C6H4(CH 2PiPr2)}[TFA)]2 (3) was formed when the reaction was performed with an equimolar amount of the phosphine. Both complexes were structurally characterized. Reduction of the cyclometalated palladium complex 2 with sodium metal in THF gave a mixture of cis and trans isomers of the dimetalated bis(o-benzyldiisopropylphosphine)palladium(II) (6a,b) and bis(benzyldiisopropylphosphine)palladium(0) (7). A mechanism for the reduction process is presented. Treatment of the reaction mixture of 6a,b and 7 with an equimolar amount of hydrochloric acid led to a mixture of 7, [Pd(C 6H4(CH2PiPr2)Ji(C 6H5CH2)PiPr2}(Cl)] (9), [Pd{(C6H5CH2)PiPr2J 2(H)(Cl)] (8), [Pd((C6H5CH2)-P iPr2}2(Cl)2] (4), and both isomeric forms of [Pd(C6H4(CH2PiPr 2)}2] (6a,b). All complexes were independently prepared and fully characterized. The addition of another 1 equiv of hydrochloric acid to this reaction mixture resulted in the exclusive formation of 4. Reduction of 4 with sodium metal in THF cleanly yielded the Pd0 complex 7 in high yields, offering a new, facile, and high-yield route toward the synthesis of dicoordinated bis(phosphine) Pd0 complexes. Reaction of 7 with an equimolar amount of HCl led to the clean formation of [PdJ(C6H 5CH2)PiPr2}2(H)(Cl)] (8). The addition of another 1 equiv of HCl led to the quantitative formation of 2 and H2. Reactions of 9 and an equimolar amount of NaBHEt3 cleanly yielded complex 7, which was also exclusively formed by treatment of 4 with 2 equiv of NaBHEt3. Mixtures of the cis and trans isomers 6a,b were formed by the addition of 2 equiv of (lithiobenzyl)diisopropylphosphine to benzene solutions of bis(diethyl sulfide)palladium dichloride (5) at room temperature.
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U2 - 10.1021/om7008815
DO - 10.1021/om7008815
M3 - Article
VL - 27
SP - 894
EP - 899
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 5
ER -