NCN–pincer palladium complexes with multiple anchoring points for functional groups

Slagt, Martijn Q.; Zwieten, Don A.P. van; Moerkerk, Adrianus J.C.M.; Gebbink, Robertus J. M. Klein; Koten, Gerard van

doi:10.1016/j.ccr.2004.08.014

Cited by 105 publications

(30 citation statements)

References 48 publications

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“…Such stability makes it easier to modify the NCN pincer platform by changing different functional groups within their multiple anchoring points [18,19]. These efforts have culminated in the construction of chiral pincer ligands and complexes that offer promising utility in asymmetric catalytic synthesis.…”

Section: Introductionmentioning

confidence: 98%

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

Liang

Wobser

Protasiewicz

2007

Journal of Organometallic Chemistry

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Section: Introductionmentioning

confidence: 98%

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

Liang

Wobser

Protasiewicz

2007

Journal of Organometallic Chemistry

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“…in the field of supramolecular chemistry, [45][46][47][48][49][50][51][52] or as chemosensors, [53][54][55][56][57][58][59] switches, 60-62 metallomesogens [63][64][65][66][67][68] and also due to their photoluminescent and electronic properties, [69][70][71][72][73][74][75][76][77][78][79][80][81][82][83] no attempts will be made to include these aspects, even when related to ''rollover'' cyclometalated complexes, because the ''rollover'' cyclometalated ligands in these systems mostly act as mere spectators. In this review, the focus will be rather on the ''rollover'' process itself.…”

Section: -42mentioning

confidence: 99%

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

2012

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''Rollover'' cyclometalation constitutes a special case among the well-known class of cyclometalation reactions. An overview is given that covers the very first description of this reaction type, as well as recent developments. In addition, not only condensed-phase experiments are reviewed, but also investigations based on mass spectrometric techniques, together with ''in silico'' studies using DFTbased calculations are considered. While the latter two methods allow for a detailed analysis of the intrinsic factors that affect the reaction mechanisms, consideration of all three regimes permits to develop a coherent mechanistic picture and to address the often noted gap between condensed-and gasphase studies. Moreover, the quite unexpected reactivity of ''rollover'' cyclometalated complexes in gasphase experiments, as well as potential applications, e.g. in synthetic procedures, are discussed in some detail.

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“…The approach is akin to a macromolecular "kinetic isotope effect", in that kinetic contributions to rate-determining processes are revealed by the differences in two isostructural systems. We find that it is the dynamics of molecular crosslinks, much more so than their thermodynamics, which are specifically and quantitatively responsible for the bulk viscoelastic properties of the supramolecular networks.The system under consideration is poly(4-vinylpyridine) (PVP) that is cross-linked by bis(M ii -pincer) compounds 1 (see Figure 2) derived from the work of van Koten [8] (M = Pd or Pt, Figure 1). [9] We recently reported that simple steric effects in the alkylamino ligands of 1 and related compounds change the rate of ligand exchange by approximately two orders of magnitude while leaving the thermodynamics of association effectively constant.…”

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confidence: 99%

Strong Means Slow: Dynamic Contributions to the Bulk Mechanical Properties of Supramolecular Networks

2005

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The desire to control rationally, through small-molecule synthesis, the properties of bulk materials has led to supramolecular approaches to, for example, polymers, [1,2] strong and weak organogels, [3] amphiphilic assemblies, [4] and liquid crystals.[5] In these materials, specific and well-defined interactions between molecules contribute to bulk material properties on two levels: structure and dynamics. Although the dynamic nature of the defining interactions is often the attribute that distinguishes supramolecular materials from their covalent counterparts, [6] direct mechanistic studies of the molecular contributions to the dynamic properties of materials are less abundant than structural studies.[7] Herein, we report that a simple structural variation in the networks of supramolecular sols and organogels provides a direct and quantitative measure of the relationship between molecular dynamics and macroscopic rheological properties. The approach is akin to a macromolecular "kinetic isotope effect", in that kinetic contributions to rate-determining processes are revealed by the differences in two isostructural systems. We find that it is the dynamics of molecular crosslinks, much more so than their thermodynamics, which are specifically and quantitatively responsible for the bulk viscoelastic properties of the supramolecular networks.The system under consideration is poly(4-vinylpyridine) (PVP) that is cross-linked by bis(M ii -pincer) compounds 1 (see Figure 2) derived from the work of van Koten [8] (M = Pd or Pt, Figure 1). [9] We recently reported that simple steric effects in the alkylamino ligands of 1 and related compounds change the rate of ligand exchange by approximately two orders of magnitude while leaving the thermodynamics of association effectively constant. [10] This independent control of dynamics is particularly significant; cross-linkers 1 a and 1 b (Figure 2) are structurally identical components within the network, and so their similar thermodynamics ensure that the extent and nature of cross-linking is essentially the same in the samples prepared from them. By extending the family of cross-linkers to the Pt II -pincer molecules 1 c and 1 d (Figure 2) we are able to probe the effect of a wide range of molecular dynamics.The addition of 2 % (by functional group) 1 b to a 100 mg mL À1 DMSO solution of PVP (Aldrich, M r = 60 000) gives rise to a clear, thick, deep yellow solution whose viscosity is approximately 2000-times greater than that of PVP alone (33 Pa s vs. 0.016 Pa s). Two control experiments confirm that the viscosity increase is due to coordinative cross-linking of the PVP by 1 b. First, the viscosity does not increase upon the addition of the same quantity of monomeric À .

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NCN–pincer palladium complexes with multiple anchoring points for functional groups

Cited by 105 publications

References 48 publications

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

A new platform for NCN dimethylamino pincer complexes: Synthesis and structural studies

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

Strong Means Slow: Dynamic Contributions to the Bulk Mechanical Properties of Supramolecular Networks

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