Polyamine Macrocycles Incorporating a Phenanthroline Unit: Their Synthesis, Basicity, and
Cu(II) Coordination
Carla Bazzicalupi
Andrea Bencini
Vieri Fusi
Claudia Giorgi
Piero Paoletti
Barbara Valtancoli
10.1021/ic9708428.s001
https://acs.figshare.com/articles/dataset/Polyamine_Macrocycles_Incorporating_a_Phenanthroline_Unit_Their_Synthesis_Basicity_and_Cu_II_Coordination/3619854
Synthesis and characterization of the two new polyamine
macrocycles
2,5,8,11,14-pentaaza[15]-16,29-phenanthrolinophane (<b>L1</b>) and
8-methyl-8-aza-1(1,4),11(1,4)-dipiperazina[15]-16,29-phenanthrolinophane
(<b>L2</b>) are reported. Both ligands incorporate a 2,9-phenanthroline unit as
integral part of their cyclic structure. <b>L1</b>
contains
a pentaamine chain linking the 2,9-phenanthroline positions.
<b>L2 </b>contains two piperazine rings within the
macrocyclic framework. The basicity constants and the formation
constants of their complexes with Cu(II) have been
determined by potentiometric measurements in aqueous solution (298.1 K,
<i>I</i> = 0.1 mol dm<sup>-3</sup>). Both
<b>L1</b> and <b>L2</b>
form mono- and binuclear complexes in aqueous solution. In the
[Cu<b>L1</b>]<sup>2+</sup> and
[Cu<b>L2</b>]<sup>2+</sup> complexes, the metal
ion is coordinated by the aromatic nitrogens and one or two nitrogens
adjacent to the phenanthroline moiety.
The remaining polyamine chain is not coordinated. These
results are confirmed by the crystal structure of
[H<sub>2</sub><b>L2</b>Cu(NCS)<sub>2</sub>](ClO<sub>4</sub>)<sub>2</sub>·3H<sub>2</sub>O
(space group <i>P</i><i>1̄</i>, <i>a</i> =
9.770(10) Å, <i>b</i> = 12.027(5) Å, <i>c</i> =
18.006(7) Å, α = 106.87(3)°,
β = 90.22(8)°, γ = 104.48(8)°, <i>V</i> =
1954(2) Å<sup>3</sup>, <i>Z</i> = 2, <i>R</i> =
0.0971, w<i>R</i>2 = 0.2553). The metal ion is
five-coordinated by the phenanthroline nitrogens, by one adjacent amine nitrogen,
and by two isothiocyanate ions. The
noncoordinated polyamine chain can bind a second Cu(II) ion in
aqueous solution, giving binuclear
[Cu<sub>2</sub><b>L</b>]<sup>4+</sup>
complexes (<b>L </b>= <b>L1 </b>or <b>L2</b>). In
the case of <b>L2</b>, the formation of the binuclear complex leads
to piperazine inversion
from the chair to the boat conformation, as shown by the crystal
structure of
[Cu<sub>2</sub><b>L2</b>(μ-OH)(H<sub>2</sub>O)(ClO<sub>4</sub>)](ClO<sub>4</sub>)<sub>2</sub>·2H<sub>2</sub>O (space group
<i>P</i>2<sub>1</sub>/<i>a</i>, <i>a</i> =
19.573(2) Å, <i>b</i> = 9.320(10) Å, <i>c</i> =
21.552(2) Å, β = 108.556(9)°, <i>V</i> =
3727(4) Å<sup>3</sup>, <i>Z</i> = 4, <i>R</i> =
0.0835, w<i>R</i>2 = 0.2759). This structure displays a
piperazine ring unusually bridging
two metal cations.
1998-02-19 00:00:00
noncoordinated polyamine chain
R 2
OH
solution
metal ion
L 2
L 1
Cu L 2
crystal structure
Cu L 1
phenanthroline
piperazine
Polyamine Macrocycles Incorporating
L 2 form
Cu 2 L
complex