Abstract
In this work are described the synthesis of several new dppp-like ligands (dppp = 1,3-bis(diphenylphosphino)propane) bearing different substituents on the carbon backbone and of their palladium(II) complexes with acetate or trifluoroacetate coligands (L). The complexes exhibit the general formula Pd(P-P)(L)2 and have been experimental conditions that are comparable to those reported in the relevant monoxide in MeOH under experimental conditions that are comparable to those reported in the relevant literature and patents for dppp-based Pd(II) copolymerization catalysts. It has been found that the introduction of alkyl substituents in the 2-position of the carbon backbone of dppp does not significantly improve the performance of the corresponding catalyst precursors (highest productivity value 6.2 kg of copolymer (g of Pd h)-1 vs 5.4 kg of copolymer (g of Pd h)-1 for Pd(dppp)(L)2). In contrast, the productivity increases remarkably when methyl groups are introduced in both 1-positions of the diphosphine ligand, particularly with R,S (S,R) stereochemistry as in meso-CH2(CH3CHPPh2)2 (productivity of 8.0 kg of copolymer (g of Pd h)-1). On the basis of NMR and cyclic voltammetric studies of the catalyst precursors, it is suggested that the increased productivity provided by the C1-substituted ligands is both electronic and steric in nature. In situ high-pressure NMR experiments in sapphire tubes equipped with Ti alloy valves showed that the only phosphorus-containing species visible on the NMR time scale in effective copolymerization conditions are Pd(II) complexes with the formula Pd(diphosphine)X2 (X = p-toluene-sulfonate, trifluoroacetate, or MeOH). It has been proposed that these Pd(II) complexes act as a reservoir of [Pd(diphosphine)]2+ moieties which may either be delivered into the catalysis cycle by action of various reagents (MeOH, H+, H2O, H2) or be withdrawn after the termination step and watched over deactivation paths.
| Original language | English |
|---|---|
| Pages (from-to) | 4183-4193 |
| Number of pages | 11 |
| Journal | Macromolecules |
| Volume | 32 |
| Issue number | 13 |
| DOIs | |
| Publication status | Published - 1999 Jun 29 |
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All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry
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Copolymerization of carbon monoxide with ethene catalyzed by palladium(II) complexes of 1,3-bis(diphenylphosphino)propane ligands bearing different substituents on the carbon backbone. / Bianchini, Claudio; Lee, Hon Man; Meli, Andrea; Moneti, Simonetta; Vizza, Francesco; Fontani, Marco; Zanello, Piero.
In: Macromolecules, Vol. 32, No. 13, 29.06.1999, p. 4183-4193.Research output: Contribution to journal › Article
TY - JOUR
T1 - Copolymerization of carbon monoxide with ethene catalyzed by palladium(II) complexes of 1,3-bis(diphenylphosphino)propane ligands bearing different substituents on the carbon backbone
AU - Bianchini, Claudio
AU - Lee, Hon Man
AU - Meli, Andrea
AU - Moneti, Simonetta
AU - Vizza, Francesco
AU - Fontani, Marco
AU - Zanello, Piero
PY - 1999/6/29
Y1 - 1999/6/29
N2 - In this work are described the synthesis of several new dppp-like ligands (dppp = 1,3-bis(diphenylphosphino)propane) bearing different substituents on the carbon backbone and of their palladium(II) complexes with acetate or trifluoroacetate coligands (L). The complexes exhibit the general formula Pd(P-P)(L)2 and have been experimental conditions that are comparable to those reported in the relevant monoxide in MeOH under experimental conditions that are comparable to those reported in the relevant literature and patents for dppp-based Pd(II) copolymerization catalysts. It has been found that the introduction of alkyl substituents in the 2-position of the carbon backbone of dppp does not significantly improve the performance of the corresponding catalyst precursors (highest productivity value 6.2 kg of copolymer (g of Pd h)-1 vs 5.4 kg of copolymer (g of Pd h)-1 for Pd(dppp)(L)2). In contrast, the productivity increases remarkably when methyl groups are introduced in both 1-positions of the diphosphine ligand, particularly with R,S (S,R) stereochemistry as in meso-CH2(CH3CHPPh2)2 (productivity of 8.0 kg of copolymer (g of Pd h)-1). On the basis of NMR and cyclic voltammetric studies of the catalyst precursors, it is suggested that the increased productivity provided by the C1-substituted ligands is both electronic and steric in nature. In situ high-pressure NMR experiments in sapphire tubes equipped with Ti alloy valves showed that the only phosphorus-containing species visible on the NMR time scale in effective copolymerization conditions are Pd(II) complexes with the formula Pd(diphosphine)X2 (X = p-toluene-sulfonate, trifluoroacetate, or MeOH). It has been proposed that these Pd(II) complexes act as a reservoir of [Pd(diphosphine)]2+ moieties which may either be delivered into the catalysis cycle by action of various reagents (MeOH, H+, H2O, H2) or be withdrawn after the termination step and watched over deactivation paths.
AB - In this work are described the synthesis of several new dppp-like ligands (dppp = 1,3-bis(diphenylphosphino)propane) bearing different substituents on the carbon backbone and of their palladium(II) complexes with acetate or trifluoroacetate coligands (L). The complexes exhibit the general formula Pd(P-P)(L)2 and have been experimental conditions that are comparable to those reported in the relevant monoxide in MeOH under experimental conditions that are comparable to those reported in the relevant literature and patents for dppp-based Pd(II) copolymerization catalysts. It has been found that the introduction of alkyl substituents in the 2-position of the carbon backbone of dppp does not significantly improve the performance of the corresponding catalyst precursors (highest productivity value 6.2 kg of copolymer (g of Pd h)-1 vs 5.4 kg of copolymer (g of Pd h)-1 for Pd(dppp)(L)2). In contrast, the productivity increases remarkably when methyl groups are introduced in both 1-positions of the diphosphine ligand, particularly with R,S (S,R) stereochemistry as in meso-CH2(CH3CHPPh2)2 (productivity of 8.0 kg of copolymer (g of Pd h)-1). On the basis of NMR and cyclic voltammetric studies of the catalyst precursors, it is suggested that the increased productivity provided by the C1-substituted ligands is both electronic and steric in nature. In situ high-pressure NMR experiments in sapphire tubes equipped with Ti alloy valves showed that the only phosphorus-containing species visible on the NMR time scale in effective copolymerization conditions are Pd(II) complexes with the formula Pd(diphosphine)X2 (X = p-toluene-sulfonate, trifluoroacetate, or MeOH). It has been proposed that these Pd(II) complexes act as a reservoir of [Pd(diphosphine)]2+ moieties which may either be delivered into the catalysis cycle by action of various reagents (MeOH, H+, H2O, H2) or be withdrawn after the termination step and watched over deactivation paths.
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U2 - 10.1021/ma990045o
DO - 10.1021/ma990045o
M3 - Article
VL - 32
SP - 4183
EP - 4193
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 13
ER -