A high molecular weight reversible coordination polymer of PdCl2 and 1,12-bis(diphenylphosphino)dodecaneElectronic supplementary information (ESI) available: experimental details, SEC results and NMR spectra. See http://www.rsc.org/suppdata/cc/b3/b301874a/

Paulusse, Jos Marie Johannes; Sijbesma, Rint P.

doi:10.1039/b301874a

Cited by 44 publications

(25 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although mechanical forces act on even the smallest molecules, the effect of extensional forces is most pronounced in macromolecular species. If these forces act on a coordination polymer [2] of sufficient length, the noncovalent bonds may be broken.[3] Reversibility [4,5] of the coordinative interactions could then result in the continuous reformation of polymer chains until a steady-state degree of polymerization is reached. Irreversible disruption of covalent bonds is known to occur in polymers subject to strong shear forces; [6] it is the basis of some processing technologies, such as the mastication of natural rubber, [7] and even causes undesired degradation of macromolecules in chromatography.…”

mentioning

confidence: 99%

Reversible Mechanochemistry of a Pd^II Coordination Polymer

2004

Self Cite

View full text Add to dashboard Cite

CommunicationsUltrasound-induced chain scission in dissolved Pd II coordination polymers is highly selective for the dissociation of phosphane ligands from palladium and therefore reversible. The original molecular weight of the polymer is restored after sonication. See the Communication by J. M. J. Paulusse and R. P. Sijbesma on the following pages for more details. The design and synthesis of appropriate ligands is a wellestablished, but sometimes cumbersome method for controlling the coordination chemistry of transition-metal complexes. Manipulation of the coordination sphere by mechanical means is an exciting, yet barely explored alternative, [1] which may open up novel avenues in coordination chemistry and catalysis. Although mechanical forces act on even the smallest molecules, the effect of extensional forces is most pronounced in macromolecular species. If these forces act on a coordination polymer [2] of sufficient length, the noncovalent bonds may be broken.[3] Reversibility [4,5] of the coordinative interactions could then result in the continuous reformation of polymer chains until a steady-state degree of polymerization is reached. Irreversible disruption of covalent bonds is known to occur in polymers subject to strong shear forces; [6] it is the basis of some processing technologies, such as the mastication of natural rubber, [7] and even causes undesired degradation of macromolecules in chromatography.[8] Ultrasonication is one of the most efficient methods to induce breakage in polymer chains in homogeneous solution.[9] The shear forces required for chain scission are provided by the collapse of cavitation bubbles created by ultrasound.Herein, we report on the reversible sonochemistry of high-molecular-weight coordination polymers in dilute solution. The polymeric diphosphane 1 was prepared by the cationic polymerization of tetrahydrofuran initiated by triflic anhydride [10] with subsequent termination by the diphenylphosphane anion (M n = 7300 g mol À1 ; M w /M n = 1.11). Linear coordination polymers 2 were obtained by stirring a solution in toluene of ligand 1 with a small excess of palladium dichloride for 2 days (Scheme 1).Size-exclusion chromatographic (SEC) analysis of the equilibrated samples of 2 at different concentrations (Figure 1 a) shows the presence of high-molecular-weight material [11] (M top = 2.50 10 5 g mol À1 , M w = 1.70 10 5 g mol À1 , based on polystyrene standards), as well as peaks at 10 500 and 23 000 g mol À1 , which decrease in intensity relative to the peak for the high-molecular-weight material with increasing concentration. The low-molecular-weight peaks correspond well with the molecular weights of cyclic monomers and dimers (7500 and 15 000 g mol À1 ). The molecular-weight distributions in Figure 1 a show that even at the lowest concentration high-molecular-weight material is present, and the data are in line with an equilibrium between cyclic and linear complexes with a critical polymerization concentration [12] of approximately 0.15 mm.[13]In linear coordinatio...

show abstract

mentioning

confidence: 99%

Reversible Mechanochemistry of a Pd^II Coordination Polymer

2004

Self Cite

View full text Add to dashboard Cite

show abstract

“…This purification process was repeated several times. A yellow solid was obtained in a 50% yield (16 mg 6 ) 1448.2, calix ¼ 5,11-bis(methyl(diphenylphosphino))-25,26,27,28-tetra-n-propoxycalix [4]arene (12). The presence of oxide fragments was unavoidable because the measurements were run in air.…”

Section: Experimental Partmentioning

confidence: 99%

“…This equation requires the knowledge of the interatomic distances between the 31 P probe nucleus and the surrounding 1 H nuclei. The standard molecule is the ligand itself (12). The greatest magnetic interactions between the P and H atoms are the P ÁÁÁ H 2 C and P ÁÁÁ H(ortho-Ph), which exhibit the shortest distances based on average values extracted from computer modeling (Scheme 4).…”

Section: T1 Measurementsmentioning

confidence: 99%

“…We now report the synthesis and characterization of bis [5,11-bis(methyl-(diphenylphosphino))-25,26,27,28-tetran-propoxycalix [4] The title compound (10) was prepared from the calix [4]arene precursor (11) to form the ligand 5,11-bis(methyl(diphenylphosphino))-25,26,27,28-tetra-n-propoxy calix [4]arene (12), which was reacted with [Rh(COD)Cl] 2 (COD ¼ 1,5-cyclooctadienyl) and TlPF 6 as chloride scavenger, in 31% overall chemical yield. The dimer structure in solution was demonstrated by the measurements of the 31 P NMR spin-lattice relaxation time (T 1 ) in comparison with the ligand itself.…”

Section: Introductionmentioning

confidence: 99%

“…[9] In addition, organometallic and coordination polymers are known to be in equilibrium in solution between dimers, oligomers, and polymers, with often one species being dominant. [10][11][12] This group has anchored Rhcontaining fragments at diphosphinated calix [4]arene macrocycles at the upper-rim, but these amorphous materials that appear as polymers in the solid state, are essentially dimers in solution that exhibit obvious ring stress and steric hindrance (see compounds 1-8 in Scheme 1). [13] The equilibrium between the polymer (solid state) and the 'stressed' dimer (solution) is not unprecedented ({Pd 2 (dmb) 2 Cl 2 } n (solid) versus Pd 2 (dmb) 2 Cl 2 (solution); dmb ¼ 1,8-diisocyano-p-menthane).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

An Original Calix[4]arene‐Containing Oligomer/Polymer Catalyst for Homogeneous Hydroformylation

Mongrain

Harvey

2008

Macromol. Rapid Commun.

View full text Add to dashboard Cite

The title compound (10) was prepared from the calix[4]arene precursor (11) to form the ligand 5,11‐bis(methyl(diphenylphosphino))‐25,26,27,28‐tetra‐n‐propoxy calix[4]arene (12), which was reacted with [Rh(COD)Cl]2 (COD = 1,5‐cyclooctadienyl) and TlPF6 as chloride scavenger, in 31% overall chemical yield. The dimer structure in solution was demonstrated by the measurements of the 31P NMR spin‐lattice relaxation time (T1) in comparison with the ligand itself. Computer modeling shows that the dimer macrocycle exhibits many possible conformers, including some with obvious steric hindrance about the Rh atom, but no apparent ring stress. 10 was tested for the catalytic homogeneous hydroformylation of hex‐1‐ene and compared with other closely related analogue systems recently reported in the literature.magnified image

show abstract