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Diphosphinoamines are quite flexible ligands and capable of
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a 4-membered ring with the PNP bond angle close to 105° that in-
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formation in the bridging mode was confirmed by the fact that the
tetramer and the trimer retain the bridging mode in solution.
Although bridging dppipa is also labile, Cu–P bonds are shorter
in bridges than in the chelate structures showing that the bonding
of copper(I) with dppipa is clearly stronger in its bridging mode.
The variety of structures found in these complexes was orches-
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ligands, the ligand was forced to form a bis chelate. Structural
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three different complexes: dimer, trimer and tetramer are ob-
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of how the trimer is formed. Even though the trimer is thermody-
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trimer permits isolation of the dimer (in the case of chloride and
bromide) when crystallization is accelerated.
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The present work brings out the ability of diphosphinoamines
to adopt various binding modes. By just tuning the ligand to metal
ratio, a variety of Cu(I) complexes with different nuclearity can be
synthesized. The structures formed by the ligand with copper(I)
are similar to formed by the ligand where H and Ph are replaced
i
by Pr on the nitrogen. In solution, the electronic differences are
clearly manifested as the dppipa complexes were labile due to its
poorer p-accepting character.
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Acknowledgements
We wish to thank CSIR and DST, New Delhi for the financial sup-
port and DST for funding the CCD facility.
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Appendix A. Supplementary material
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CCDC 191475, 191472, 191474, 191473 and 254021 contain the
supplementary crystallographic data for 1, 2, 3, 4 and 6. These data
can be obtained free of charge from The Cambridge Crystallo-
Supplementary data associated with this article can be found, in
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