Jump to main content
Jump to site search
PLANNED MAINTENANCE Close the message box

Scheduled maintenance work on Wednesday 22nd May 2019 from 11:00 AM to 1:00 PM (GMT).

During this time our website performance may be temporarily affected. We apologise for any inconvenience this might cause and thank you for your patience.


Issue 34, 2010
Previous Article Next Article

The synthesis of, and characterization of the dynamic processes occurring in Pd(II) chelate complexes of 2-pyridyldiphenylphosphine

Author affiliations

Abstract

Pd(II) complexes in which 2-pyridyldiphenylphosphine (Ph2Ppy) chelates the Pd(II) centre have been prepared and characterized by multinuclear NMR spectroscopy and by X-ray crystallographic analysis. trans-[Pd(κ1-Ph2Ppy)2Cl2] is transformed into [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)Cl]Cl by the addition of a few drops of methanol to dichloromethane solutions, and into [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)Cl]X by addition of AgX or TlX, (X = BF4, CF3SO3 or MeSO3). [Pd(κ1-Ph2Ppy)2(p-benzoquinone)] can be transformed into [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)(MeSO3)][MeSO3] by the addition of two equivalents of MeSO3H. Addition of further MeSO3H affords [Pd(κ2-Ph2Ppy)(κ1-Ph2PpyH)(MeSO3)][MeSO3]2. Addition of two equivalents of CF3SO3H, MeSO3H or CF3CO2H and two equivalents of Ph2Ppy to [Pd(OAc)2] in CH2Cl2 or CH2Cl2MeOH affords [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)X]X, (X = CF3SO3, MeSO3 or CF3CO2), however addition of two equivalents of HBF4·Et2O affords a different complex, tentatively formulated as [Pd(κ2-Ph2Ppy)2]X2. Addition of excess acid results in the clean formation of [Pd(κ2-Ph2Ppy)(κ1-Ph2PpyH)(X)]X2. In methanol, addition of MeSO3H and three equivalents of Ph2Ppy to [Pd(OAc)2] affords [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)2][MeSO3]2 as the principal Pd-phosphine complex. The fluxional processes occuring in these complexes and in [Pd 1-Ph2Ppy)3Cl]X, (X = Cl, OTf) and the potential for hemilability of the Ph2Ppy ligand has been investigated by variable-temperature NMR. The activation entropy and enthalpy for the regiospecific fluxional processes occuring in [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)2][MeSO3]2 have been determined and are in the range −10 to −30 J mol−1 K−1 and ca. 30 kJ mol−1 respectively, consistent with associative pathways being followed. The observed regioselectivities of the exchanges are attributed to the constraints imposed by microscopic reversibility and the small bite angle of the Ph2Ppy ligand. X-Ray crystal structure determinations of trans-[Pd(κ1-Ph2Ppy)2Cl2], [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)Cl][BF4], [Pd(κ1-Ph2Ppy)2(p-benzoquinone)], trans-[Pd(κ1-Ph2PpyH)2Cl2][MeSO3]2, and [Pd(κ1-Ph2Ppy)3Cl](Cl) are reported. In [Pd(κ2-Ph2Ppy)(κ1-Ph2Ppy)Cl][BF4] a donor–acceptor interaction is seen between the pyridyl-N of the monodentate Ph2Ppy ligand and the phosphorus of the chelating Ph2Ppy resulting in a trigonal bipyramidal geometry at this phosphorus.

Graphical abstract: The synthesis of, and characterization of the dynamic processes occurring in Pd(ii) chelate complexes of 2-pyridyldiphenylphosphine

Back to tab navigation

Supplementary files

Publication details

The article was received on 03 Sep 2009, accepted on 04 Jun 2010 and first published on 26 Jul 2010


Article type: Paper
DOI: 10.1039/B918162H
Dalton Trans., 2010,39, 7921-7935

  •   Request permissions

    The synthesis of, and characterization of the dynamic processes occurring in Pd(II) chelate complexes of 2-pyridyldiphenylphosphine

    J. Liu, C. Jacob, K. J. Sheridan, F. Al-Mosule, B. T. Heaton, J. A. Iggo, M. Matthews, J. Pelletier, R. Whyman, J. F. Bickley and A. Steiner, Dalton Trans., 2010, 39, 7921
    DOI: 10.1039/B918162H

Search articles by author

Spotlight

Advertisements