An unusually flexible expanded hexaamine cage and its Cu(II) complexes: Variable coordination modes and incomplete encapsulation

Qin, Chang-Jin, James, Lloyd, Chartres, Jy D., Alcock, Leighton J., Davis, Kimberley J., Willis, Anthony C., Sargeson, Alan M., Bernhardt, Paul V. and Ralph, Stephen F. (2011) An unusually flexible expanded hexaamine cage and its Cu(II) complexes: Variable coordination modes and incomplete encapsulation. Inorganic Chemistry, 50 18: 9131-9140.


Author Qin, Chang-Jin
James, Lloyd
Chartres, Jy D.
Alcock, Leighton J.
Davis, Kimberley J.
Willis, Anthony C.
Sargeson, Alan M.
Bernhardt, Paul V.
Ralph, Stephen F.
Title An unusually flexible expanded hexaamine cage and its Cu(II) complexes: Variable coordination modes and incomplete encapsulation
Formatted title An unusually flexible expanded hexaamine cage and its CuII complexes: Variable coordination modes and incomplete encapsulation
Journal name Inorganic Chemistry  (ERA 2012 Listed)    (ERA 2010 Rank A*)   Check publisher's open access policy
Publication date 2011-09-19
Sub-type Article
DOI 10.1021/ic201326d
Volume number 50
Issue number 18
ISSN 0020-1669; 1520-510X
Start page 9131
End page 9140
Total pages 10
Place of publication Washington, DC, U.S.A.
Publisher American Chemical Society
Collection year 2012
Language eng
Formatted abstract The bicyclic hexaamine “cage” ligand Me8tricosaneN6 (1,5,5,9,13,13,20,20-octamethyl-3,7,11,15,18,22-hexaazabicyclo[7.7.7]tricosane) is capable of encapsulating octahedral metal ions, yet its expanded cavity allows the complexed metal to adopt a variety of geometries comprising either hexadentate or pentadentate coordination of the ligand. When complexed to CuII the lability of the metal results in a dynamic equilibrium in solution between hexadentate- and pentadentate-coordinated complexes of Me8tricosaneN6. Both [Cu(Me8tricosaneN6)](ClO4)2 (6-coordinate) and [Cu(Me8tricosaneN6)](S2O6) (5-coordinate) have been characterized structurally. In weak acid (pH 1) a singly protonated complex [Cu(HMe8tricosaneN6)]3+ has been isolated that finds the ligand binding as a pentadentate with the uncoordinated amine being protonated. vis–NIR and electron paramagnetic resonance (EPR) spectroscopy show that the predominant solution structure of [Cu(Me8tricosaneN6)]2+ at neutral pH comprises a five-coordinate, square pyramidal complex. Cyclic voltammetry of the square pyramidal [Cu(Me8tricosaneN6)]2+ complex reveals a reversible CuII/I couple. All of these structural, spectroscopic, and electrochemical features contrast with the smaller cavity and well studied “sarcophagine” (sar, 3,6,10,13,16,19-hexaazabicyclo[6.6.6]eicosane) CuII complexes which are invariably hexadentate coordinated in neutral solution and cannot stabilize a CuI form.
Keyword Copper(II) complexes
Macrobicyclic hexaamines
Anion-binding
Ion
Chemistry
Polyamines
Nitrogen
Ligands
Dimensionality
Transition
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article
Collections: Official 2012 Collection
School of Chemistry and Molecular Biosciences
 
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