ic971164s_si_001.pdf (794.93 kB)
Structures of the Copper(I) and Copper(II) Complexes of 2,9-Diphenyl-1,10-phenanthroline: Implications for Excited-State Structural Distortion
journal contribution
posted on 1998-04-14, 00:00 authored by Mark T. Miller, Peter K. Gantzel, Timothy B. KarpishinThe syntheses, crystal structures, and electronic absorption
spectra of the copper(I) and copper(II) complexes
of
2,9-diphenyl-1,10-phenanthroline (dpp) are reported. The
complex [Cu(dpp)2](PF6)
(1) crystallizes in space group
P21/c with a =
11.081(4) Å, b = 25.491(8) Å, c =
14.263(5) Å, β = 92.84(3)°, Z = 4, and
V = 4024(2) Å3. For
4813 unique data with F > 4.0σ(F),
R = 5.41% and Rw = 6.43%.
The coordination geometry about the copper(I) center in [Cu(dpp)2]+ is best
described as distorted tetrahedral with approximate
C2 symmetry. The structure
of [Cu(dpp)2]+ is largely determined
by interligand π-stacking interactions that occur between the phenyl
groups
of one ligand and the phenanthroline moiety of the other ligand.
Solution-state absorption and 1H NMR
spectra
indicate that the [Cu(dpp)2]+ complex
is fluxional in solution, rocking between two enantiomeric structures
of C2
molecular symmetry through an intermediate of
Cs symmetry. The complex
[Cu(dpp)2](ClO4)2
(2) crystallizes in
space group P1̄ with a = 7.809(3) Å,
b = 13.027(6) Å, c = 20.344(10)
Å, α = 87.68(4)°, β = 89.16(4)°, γ
=
79.26(4)°, Z = 2, and V = 2032(1)
Å3. For 4943 unique data with F >
4.0σ(F), R = 5.22% and
Rw = 5.37%.
The coordination geometry about the copper(II) center in
[Cu(dpp)2]2+ is best described as
flattened tetrahedral
with approximate D2 symmetry. There are no
interligand π-stacking interactions in the structure of
[Cu(dpp)2]2+.
The four-coordinate geometry in
[Cu(dpp)2]2+ persists in solution on
the basis of solution-state and solid-state
absorption spectroscopy. Structural distortion in the
metal-to-ligand charge-transfer excited state of
[Cu(dpp)2]+
is discussed on the basis of the structures of 1 and
2.
