Synthesis and characterization of an N-coordinated amidate copper(II) complex of deprotonated N-(2,6-diisopropylphenyl)-2-(bis-(2-pyridylmethyl))aminoethanamide

Article abstract of DOI:10.1016/j.ica.2007.06.003

The title ligand, N-(2,6-diisopropylphenyl)-2-(bis-(2-pyridylmethyl))aminoethanamide (DIPMAE-H), was prepared by a nucleophilic substitution reaction between N-(2,6-diisopropyl)phenyl-2-bromoethanamide and bis-(2-pyridylmethyl)amine. An analogous ligand (TBPMAE-H) in which the 2,6-diisopropylphenyl group was substituted for a tert-butyl group was also prepared in this manner. Then, [(DIPMAE-H)CuBr]⁺Br^- and [(TBPMAE-H)CuBr]⁺Br^- were prepared by heating one equivalent of ligand and CuBr₂ in CH₃CN. In both compounds the geometry about the copper center is square pyramidal with distortions due to the geometrical constraints of the ligand. The amide oxygen occupies the axial position, and the three amine nitrogens and the bromide ligand form the basal plane of the square pyramid. Pairs of complexes in the unit cell are associated via weak donation of a lone pair on the bromide ligand of one complex to the copper center of another (Cu?Br distances in the range of 3.3576-3.4022 ?). The title compound, (DIPMAE)CuBr, was prepared by deprotonation of [(DIPMAE-H)CuBr]⁺Br^- using NaH. The key feature of (DIPMAE)CuBr is the amidate group η¹- and N-coordinated to the copper center. The compound also exhibits distorted trigonal bipyramidal coordination geometry with the bromide and tertiary amine donors occupying the axial sites and the amidate and pyridyl donors occupying the equatorial positions. The copper atom is displaced from the trigonal plane towards the bromide donor apex due to the geometrical demands of the ligand.

Full text of DOI:10.1016/j.ica.2007.06.003

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Inorganica Chimica Acta 361 (2008) 365–372
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Note
Synthesis and characterization of an N-coordinated amidate
copper(II) complex of deprotonated
N-(2,6-diisopropylphenyl)-2-(bis-(2-pyridylmethyl))aminoethanamide
*
Timothy E. Patten , Marilyn M. Olmstead, Christina Troeltzsch
Department of Chemistry, University of California at Davis, One Shields Avenue, Davis, CA 95616-5292, United States
Received 6 April 2007; accepted 2 June 2007
Available online 12 June 2007
Abstract
The title ligand, N-(2,6-diisopropylphenyl)-2-(bis-(2-pyridylmethyl))aminoethanamide (DIPMAE-H), was prepared by a nucleophilic
substitution reaction between N-(2,6-diisopropyl)phenyl-2-bromoethanamide and bis-(2-pyridylmethyl)amine. An analogous ligand
(TBPMAE-H) in which the 2,6-diisopropylphenyl group was substituted for a tert-butyl group was also prepared in this manner. Then,
[(DIPMAE-H)CuBr]+Brꢀ and [(TBPMAE-H)CuBr]+Brꢀ were prepared by heating one equivalent of ligand and CuBr2 in CH3CN. In
both compounds the geometry about the copper center is square pyramidal with distortions due to the geometrical constraints of the
ligand. The amide oxygen occupies the axial position, and the three amine nitrogens and the bromide ligand form the basal plane of
the square pyramid. Pairs of complexes in the unit cell are associated via weak donation of a lone pair on the bromide ligand of one
˚
complex to the copper center of another (Cuꢁ ꢁ ꢁBr distances in the range of 3.3576–3.4022 A).
The title compound, (DIPMAE)CuBr, was prepared by deprotonation of [(DIPMAE-H)CuBr]+Brꢀ using NaH. The key feature of
(DIPMAE)CuBr is the amidate group g1- and N-coordinated to the copper center. The compound also exhibits distorted trigonal bipy-
ramidal coordination geometry with the bromide and tertiary amine donors occupying the axial sites and the amidate and pyridyl donors
occupying the equatorial positions. The copper atom is displaced from the trigonal plane towards the bromide donor apex due to the
geometrical demands of the ligand.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Tetradentate ligand; Distorted square pyramidal Cu(II) complex; Distorted trigonal pyramidal Cu(II) complex; g1- and N-Coordinated
amidate ligand
1. Introduction
dioxygen activation, electron transfer, and transport pro-
cesses [13].
Copper (I) and (II) coordination complexes of polyden-
tate ligands play key roles in the chemistry of atom transfer
radical addition (ATRA) [1–7] and atom transfer radical
polymerization (ATRP) [8–12]. These methods are catalytic
processes that mediate single radical additions to various
alkenes, as in the case of ATRA, and multiple additions
to alkene monomers, as in the case of ATRP. Furthermore,
these types of coordination complexes have been studied as
analogs of active centers in metalloproteins that mediate
Copper-based ATRA and ATRP involve atom transfer
from an organic halide to a copper(I) complex to yield a reac-
tive free-radical and a copper(II) complex, also called the
deactivator. The free radicals can be used for productive
addition reactions with little or no accompanying self-termi-
nation by coupling or disproportionation due to the persis-
tent radical effect [14–17]. Consequently, it is important to
identify factors that make copper(I) complexes efficient at
abstracting halogen atoms and copper(II) complexes profi-
cient at halogen atom donation. Prior studies on copper(I)
and copper(II) complexes with tripodal tetradentate amines
showed that variations in several structural parameters, such
*
Corresponding author. Tel.: +1 530 754 6181; fax: +1 530 752 8995.
E-mail address: patten@chem.ucdavis.edu (T.E. Patten).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.06.003

366
T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
as chelate ring size and the nature of the donor group, were
found to have dramatic effects upon the structure, redox
potential and spectroscopic features of the corresponding
complexes [18–22]. Many copper(I) complexes of multiden-
tate amines and their derivatives are effective catalysts for
ATRP [23,24], and changes in the ligand sphere affect the
polymerization kinetics and molecular weight control in
ways that are often unexpected and just understood qualita-
tively [25–31]. A better understanding of the inorganic chem-
istry side of ATRP can be gained through knowledge about
the structure, solution dynamics, and chemistry of the cop-
per centers involved in the atom transfer step, and current
efforts are directed at developing methods to quantify the
effects of catalyst structure on the chemistry of ATRP [32–34].
Recently, an atom transfer catalyst system based on a
monoanionic, tripodal tetradentate ligand design was
reported, and the copper(I) and (II) complexes of this
ligand exhibited simple solution structures that mirrored
their solid-state structures [35]. The ligand design imparted
stability to the complex structure via maximization of the
chelate effect and incorporation of electrostatic attraction
between the ligand and metal center. This catalyst system
provides the opportunity to develop quantitative correla-
tions between the structures and chemical characteristics
of the atom transfer complexes and their reactivity in
polymerizations or other organic transformations. During
the course of searching for effective ligand systems, the
coordination chemistry of N-(2,6-diisopropylphenyl)-2-
(bis-(2-pyridylmethyl))aminoethanamide (DIPMAE-H), a
bis(picolyl)amine-based ligand containing a C-linked ami-
date donor group, with copper(II) was studied. The synthe-
sis and structural characterization of copper(II) complexes
of neutral and deprotonated DIPMAE-H and the related
tert-butyl derivative N-(tert-butyl)-2-(bis-2-pyridylmethyl)-
aminoethanamide (TBPMAE-H) are reported here. The
copper coordination chemistry of different, yet comparable
ligand systems were also investigated recently [35–40].
2.2. Characterization
1H NMR and 13C NMR spectra were recorded on a
Varian Inova 400 instrument or a Varian Mercury 300
NMR spectrometer. Chemical shifts, d (ppm), were refer-
enced to the proton or carbon signal of the NMR sol-
vent. FTIR spectra were obtained with a Mattson
Galaxy Series FTIR 3000. UV–Vis spectra were recorded
on an HP 8452A Spectrophotometer in THF sol-
vent. Elemental analyses were performed by Midwest
Microlabs.
2.3. X-ray structure determinations
Diffraction data for DIPMAE were collected on a Sie-
mens P4 diffractometer employing Cu Ka radiation and a
nitrogen cold stream provided by a Siemens LT-2 appara-
tus. No absorption correction was applied. Data for com-
plex 2 were collected using a Siemens P3 diffractometer,
Mo Ka radiation, and a locally modified Siemens LT-1
apparatus. An empirical absorption correction (XABS)
was applied. Diffraction data for complexes 1 and 3 were
collected with a Bruker SMART 1000 diffractometer,
graphite-monochromated Mo Ka radiation, and a nitrogen
cold stream provided by a CRYO Industries apparatus.
Corrections for absorption were applied using the program
SADABS-2.03 [41]. The structures were solved by direct meth-
ods (SHELXS-97) [42] and refined by full-matrix least-squares
on F2 (SHELXL-97) [42]. All non-hydrogen atoms at full
occupancy were refined with anisotropic thermal parame-
ters. Certain disordered solvate molecules are present in
the structures of complexes 1, 2, and 3. Crystal data and
refinement details for the complexes are shown in Table
1. Additional experimental information, including atomic
positional parameters, and a description of the disorder
are supplied in CIF format as described in Supplementary
material.
2. Experimental
2.4. N-(2,6-Diisopropyl)phenyl-2-bromoethanamide
2.1. Materials
A solution of 4.00 ml (21.2 mmol) of 2,6-diisopropylan-
iline and 3.00 ml (21.2 mmol) of triethylamine in 50 ml of
dry CH2Cl2 was added dropwise to 1.84 ml (21.2 mmol)
of bromoacetyl bromide in 50 ml of dry CH2Cl2 stirred in
an ice bath. The reaction was stirred overnight. The solu-
tion was then washed with NaHCO3 (50 ml), H2O
(50 ml), diluted HCl (50 ml) and H2O (50 ml). The CH2Cl2
layer was dried over anhydrous Na2SO4, filtered, and con-
centrated. The resulting white powder was recrystallized
from toluene, yielding 5.37 g (85%). m.p. = 166–168 ꢁC;
1H NMR (300 MHz, CD2Cl2): d (ppm) 7.7 (s, 1H), 7.3
(m, 2H), 4.1 (s, 2H), 3.0 (m, J = 6.9 Hz, 2H), 1.2 (d,
J = 6.9 Hz, 12H); 13C NMR (75 MHz, CD2Cl2): d (ppm)
160.1, 159.7, 146.0, 128.8, 123.6, 29.4, 28.9, 23.7; IR
(CH2Cl2): m (cmꢀ1) 3392, 1676, 1500. Anal. Calc. for
C14H19NOBr: C, 56.56; H, 6.45; N, 4.71. Found: C,
56.46; H, 6.76; N, 4.68%.
Tetrahydrofuran was distilled from sodium and benzo-
phenone just prior to use. Chloroform, methylene chloride,
methylene chloride-d2 and acetonitrile were stirred over
P2O5, distilled and degassed. Triethylamine was stirred
over CaH2, distilled and degassed. Bis-(2-methylpyridyl)-
amine was prepared as described previously. Alumina gel
used for column chromatography was Acros aluminum
oxide, which was activated and neutral (50–200 lm). Ana-
lytical TLC was performed on commercial EM Science
plates coated with aluminum oxide 60 F254, neutral
(0.2 mm thick). Unless stated otherwise, all materials were
purchased from commercial sources and used without
further purification. Reagents were handled under nitro-
gen atmosphere using standard drybox and Schlenk
techniques.

T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
367
Table 1
Crystal data for DIPMAE and complexes 1, 2 and 3
Compound
DIPMAE
[CuBr(DIPMAE-
[CuBr(TBMAE-
[CuBr(DIPMAE)] Æ 0.25H2O
H)]Br Æ 0.125acetone Æ 0.125toluene Æ 0.375H2O H)]Br Æ 2.59H2O Æ 0.41CH3OH (2) (3)
(1)
Formula
Formula weight
C26H32N4O C27.25H34.50Br2CuN4O1.5
C18.41H26.80Br2CuN4O4
591.52
C26H31.5 BrCuN4O1.25
563.50
416.56
665.45
ꢀ
ꢀ
Space group
Pca21
P1
P1
P21/n
˚
a (A)
10.8433(10) 15.420(3)
12.8258(10) 15.671(3)
16.2960(14) 25.552(4)
7.8338(17)
11.254(2)
14.309(3)
85.087(18)
76.438(18)
82.257(18)
1213.3(5)
130(2)
9.8522(14)
12.0835(17)
21.988(3)
90
101.837(5)
90
2562.0(6)
91(2)
4
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
90
90
88.490(11)
82.958(9)
89.354(9)
6125.9(18)
91(2)
3
˚
V (A )
2266.4(3)
130(2)
4
1.221
0.592 (Cu
Ka)
T (K)
Z
8
2
Dcalc (Mg mꢀ3
)
1.443
3.349 (Mo Ka)
1.619
4.223 (Mo Ka)
1.465
2.439 (Mo Ka)
l (mmꢀ1
)
Range of
0.842–
0.965
0.569–0.753
0.408–0.567
0.775–0.867
transmission
factors
a
wR2 (all data)
0.0671
0.0274
0.2792
0.1065
0.1763
0.0718
0.1134
0.0437
b
R1 [I > 2r(I) data]
P
P
2
2
1=2
2
a
wR2 ¼ ½ ½wðF o2 ꢀ F 2c Þ ꢂ= ½ðwF o2Þ ꢂꢂ ; w ¼ 1=½r2ðF o2Þ þ ðaPÞ þ bPꢂ, where P ¼ ðF o2 þ 2F 2c Þ=3.
P
P
b
R1 = iFoj ꢀ jFci/ jFoj.
2.5. N-(2,6-Diisopropylphenyl)-2-(bis-2-
pyridylmethyl)aminoethanamide (DIPMAE-H)
2,6-diisopropylaniline. Yield: 3.54 g (64%) of white crys-
1
tals. H NMR (300 MHz, CDCl3): d (ppm) 6.3 (s, 1H),
3.8 (s, 2H), 1.4 (s, 9H); 13C NMR (75 MHz, CDCl3): d
To 20 ml of degassed toluene, 1.53 g (7.69 mmol) of bis-
(2-pyridylmethyl) amide was added. Then, 2.30 g
(7.67 mmol) of N-(2,6-diisopropyl)phenyl-2-bromoethana-
mide was added. The reaction was stirred at 80 ꢁC for 3
days. The solution was then extracted with (3 · 50 ml)
10% HCl. The acidic layers were combined, and the pH
was adjusted to >9 with 10% NaOH. The resulting solution
was then extracted with (4 · 100 ml) CH2Cl2. The organic
layers were combined, dried over anhydrous Na2SO4, fil-
tered and concentrated. The crude product was purified
using alumina column chromatography, eluted with 5%
Et3N in EtOAc. The fractions containing the product were
combined and concentrated, and volatile materials were
removed under vacuum, yielding 1.36 g (42%) of an orange
solid. 1H NMR (300 MHz, CD3CN): d (ppm) 10.0 (s, 1H),
8.5 (d, J = 3.6 Hz, 2H), 7.7 (m, 2H), 7.4 (d, J = 5.7 Hz,
2H), 7.2 (m, 3H), 7.1 (d, J = 3.7 Hz, 2H), 3.9 (s, 4H), 3.4
(s, 2H), 2.9 (m, J = 5.1 Hz, 2H), 1.1 (d, J = 5.4 Hz, 12H);
13C NMR (75 MHz, CD3CN): d (ppm) 171.7, 158.9,
149.4, 146.7, 136.8, 133.4, 128.0, 123.4, 123.3, 122.6, 60.5,
57.9, 28.8, 23.2; IR (CH2Cl2): m (cmꢀ1) 3435, 2962, 1678,
1592, 1494. Anal. Calc. for C26H32N4O: C, 74.97; H,
7.74; N, 13.45. Found: C, 75.11; H, 7.71; N, 13.44%.
(ppm) 165.3, 52.2, 30.3, 28.8; IR (CH2Cl2): m (cmꢀ1
)
3320, 1675, 1550.
2.7. N-(tert-Butyl)-2-(bis-2-
pyridylmethyl)aminoethanamide (TBPMAE-H)
A similar procedure was followed as in the synthesis of
DIPMAE except for the following changes. An equivalent
molar amount of N-tert-butyl-2-bromoethanamide was
substituted for N-(2,6-diisopropyl)phenyl-2-bromoethana-
mide. The acid extraction step was omitted, and instead
the concentrated crude product was purified using alumina
column chromatography, eluted with 5% Et3N in EtOAc.
The fractions containing the product were combined and
concentrated, and volatile materials were removed under
vacuum, yielding 0.213 g (38%) of an orange solid. 1H
NMR (300 MHz, CDCl3): d (ppm) 8.6 (d, J = 4.8 Hz,
2H), 8.3 (s, 1H), 7.6 (m, 2H), 7.3 (d, J = 5.7 Hz, 2H),
7.17 (m, 2H), 3.8 (s, 4H), 3.2 (s, 2H), 1.4 (s, 9H); 13C
NMR (75 MHz, CDCl3): d (ppm) 170.4, 158.3, 149.4,
136.8, 123.4, 122.6, 60.9, 59.1, 51.0, 29.1.
2.8. (DIPMAE-H)CuBr2
2.6. N-(tert-Butyl)-2-bromoethanamide
A solution of 1.07 g (2.57 mmol) of DIPMAE-H in
35 ml of dry CH3CN was transferred via a cannula onto
0.59 g (2.64 mmol) of CuBr2. The solution was heated at
reflux for 10 min and then cooled. Volatile materials were
removed by rotary evaporation, and the resulting blue-
A similar procedure was followed as in the synthesis of
N-(2,6-diisopropyl)phenyl-2-bromoethanamide, substitut-
ing an equivalent molar amount of tert-butyl amine for

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T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
green solid was recrystallized from acetone/toluene to yield
1.08 g (65%) of blue crystals. IR (CH2Cl2): m (cmꢀ1) 3428,
1652, 1608, 1504, 1446; UV–Vis:
kmax = 805 nm,
e = 208 nmꢀ1 cmꢀ1; Anal. Calc. for C26H32N4OCuBr2: C,
48.79; H, 5.05; N, 8.75. Found: C, 49.50; H, 5.22; N, 8.18%.
2.9. (TBPMAE-H)CuBr2
A similar procedure was followed as in the synthesis of
(DIPMAE-H)CuBr2, except that the resulting solid was
recrystallized from CH3OH.
2.10. (DIPMAE)CuBr
A solution of 0.414 g (0.647 mmol) of (DIPMAE-
H)CuBr2 in 30 ml of dry THF was transferred via a can-
nula onto 17.4 mg (0.725 mmol) of NaH. The solution
was heated at reflux for 1 h and then stirred at room tem-
perature for 2 days. The solution was hot filtered, and
green/orange crystals formed when the filtrate cooled.
The crystals were isolated by filtration and any remaining
volatile materials were removed under vacuum to yield
0.290 g (63%) of green crystals.
Fig. 1. The molecular structure of DIPAME-H, probability ellipsoids are
set to 50%.
yielded blue crystals, complex 1. In a similar manner, a
complex between TBPMAE-H and CuBr2 was prepared,
complex 2. The molecular structures are shown in Figs. 2
and 3, and the crystal data are contained in Table 1.
H
R
O
3. Results and discussion
Br
N
N
Cu
N
H
R
CH3CN, Δ
N
N
CuBr2
+
The ligand in this study was N-(2,6-diisopropylphenyl)-
2-(bis-2-pyridylmethyl)aminoethanamide (DIPMAE-H),
and it was prepared in two steps. First, N-(2,6-diisopro-
pyl)phenyl-2-bromoethanamide was prepared by the addi-
tion–elimination reaction of 2,6-diisopropyl aniline with
bromoacetyl bromide. Then, bis-(2-pyridylmethyl)amine
was added to the product via a nucleophilic substitution
process (Scheme 1). An analogous ligand (TBPMAE-H)
in which the 2,6-diisopropylphenyl group was substituted
for a tert-butyl group was also prepared in this manner
starting with tert-butyl amine. Purified DIPMAE-H readily
formed crystals suitable for X-ray analysis from a THF/
CH2Cl2 solvent system, so X-ray structural analysis was
performed. The molecular structure is shown in Fig. 1,
and the crystal data are contained in Table 1.
O
Br
N
N
ð1Þ
N
R = 2,6-diisopropyphenyl or tert-butyl
Br
THF
N
N
H
N
R
N
N
+
NaH
O
Cu
N
-NaBr
Cu
N
Br
N
O
Br
R
R= 2,6-diisopropyphenyl
ð2Þ
ꢀ
Complex 1 crystallized in the space group P1, and the
unit cell contained fractional occupancies of the solvent
system used to grow the crystals. The geometry about the
copper center is square pyramidal with distortions due to
the geometrical constraints of the ligand. Tables 2 and 3
show key bond distance and bond angle data, respectively,
for complex 1 as well as for DIPMAE-H and the other
complexes studied. There are two complex dimers in the
unit cell related to two others by an inversion center, for
a total of four unique molecular structures and eight com-
plexes overall. For each structure, the amide oxygen occu-
pies the axial position, and the three amine nitrogens and
the bromide ligand form the basal plane of the square pyr-
amid. The copper center has only one negatively charged
donor and therefore carries a formal positive charge. A
bromide anion (such as Br5) is present to maintain overall
charge neutrality, and it is involved in an N–Hꢁ ꢁ ꢁBr hydro-
The title complex was formed in two steps. First, one
equivalent of DIPMAE-H was added to CuBr2 in CH3CN,
and the solution was heated at reflux (Eq. (1)). Evaporation
of the solvent and recrystallization from acetone/toluene
O
O
Et3N, CH2Cl2
+
Br
R
Br
H2N R
N
H
Br
R= 2,6-diisopropyphenyl or tert-butyl
H
N
R
N
O
Δ
O
H
N
+
Br
R
N
N
N
N
H
N
Scheme 1. Synthetic route for the preparation of DIPMAE-H.

T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
369
Fig. 2. The molecular structure of complex 1, probability ellipsoids are set to 50%.
Fig. 3. The molecular structure of complex 2, probability ellipsoids are set to 50%.
gen bond to the amide hydrogen of the ligand. (This hydro-
gen bonding pattern was not observed in the structure of
complex 2.) The angles between the central nitrogen of
the ligand (N2) and the other nitrogens (N1 and N3) and
oxygen (O1) of the ligand are all 8–9ꢁ less than the ideal
square pyramidal geometry of 90ꢁ due to the bite angles
of the ligand. Consequently, the copper center is displaced
from the center of the basal plane towards the bromide
ligand Fig. 4.
complex might also be considered to be octahedral with a
severe axial elongation distortion. The pyridyl C–C and
C–N bond lengths are within the range found for the par-
ent ligand, and the Cu–N and Cu–Br bond distances reveal
no other unusual features. The structural features of com-
plex 2 are very similar to those of complex 1 with no nota-
ble differences other than the aforementioned absence of
hydrogen bonding to the bromide counterion.
The next step involved deprotonation of the ligand to
prepare the neutral complex. One equivalent of (DIP-
MAE-H)CuBr2 dissolved in dry THF was transferred
onto a small excess of NaH. The solution was heated
at reflux for 1 h and then stirred at room temperature
for 2 days. The solution was then heated at reflux again
and hot filtered. Upon cooling green-orange crystals
formed, complex 3. Complex 3 crystallized in the space
group P21/n with four symmetry-related molecules, and
the unit cell contained fractional occupancies of the sol-
vent system used to grow the crystals. Tables 2 and 3
When compared to the bond distances of DIPMAE-H,
the shorter amide C–N and longer amide C@O distances
indicate more resonance delocalization consistent with a
greater partial negative charge on the donor oxygen atom
coordinated to the copper center. The two complexes of
the dimer are associated via weak donation of a lone pair
on the bromide ligand of one complex to the copper center
of another (Cuꢁ ꢁ ꢁBr distances in the range of 3.3576–
˚
3.4022 A). The bridging bromide occupies the coordination
site opposite to the axial oxygen, so the geometry of each

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T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
Table 2
Selected bond lengths for DIPMAE and complexes 1, 2, and 3
Compound
DIPMAE
[CuBr(DIPMAE-H)]Br Æ 0.125acetone Æ
0.125toluene Æ 0.375H2O (1)
[CuBr(TBMAE-H)]Br Æ 2.59H2O Æ
0.41CH3OH (2)
[CuBr(DIPMAE)] Æ 0.25H2O (3)
˚
Bond lengths (A)
Amide C–N
Amide C@O
1.347(3)
1.227(3)
1.321(13), 1.315(15), 1.317(14), 1.350(12)
1.258(13), 1.225(12), 1.242(14), 1.243(12)
1.317(11)
1.254(10)
1.333(6)
1.243(6)
N2–Cu1
N1–Cu1
N3–Cu1
2.094(9), 2.092(8), 2.083(9), 2.080(9)
2.008(9), 1.992(9), 2.001(11), 1.991(10)
2.015(10), 2.011(9), 2.011(10), 2.014(9)
2.065(7)
2.012(7)
2.014(8)
2.030(4)
2.118(4)
2.165(4)
Cu1–N4
Cu1–O1
1.987(4)
2.228(8)
2.291(6)
Bond angles (ꢁ)
N–Hꢁ ꢁ ꢁO
3.213(3)
N–Hꢁ ꢁ ꢁBr
3.319(10), 3.309(9), 3.329(10), 3.270(9)
Cu1–Br1
Cu1ꢁ ꢁ ꢁBr2
2.4125(16), 2.3857(17), 2.3875(16), 2.3959(16)
3.4022(14), 3.3576(14), 3.3653(13), 3.3887(14)
2.4100(15)
3.1384(15)
2.3755(7)
Table 3
Selected bond angles for DIPMAE and complexes 1, 2, and 3
Compound
DIPMAE
[CuBr(DIPMAE-H)]Br Æ 0.125acetone Æ [CuBr(TBMAE-H)]Br Æ 2.59H2O Æ [CuBr(DIPMAE)] Æ 0.25H2O (3)
0.125toluene Æ 0.375H2O (1) 0.41CH3OH (2)
Amide N–C–O
123.9(2) 122.7(10), 125.4(9), 124.9(9), 125.2(11) 124.5(8)
128.2(4)
Br1–Cu1–N1
Br1–Cu1–N2
Br1–Cu1–N3
Br1–Cu1–O1
Br1–Cu1–N4
97.9(3), 97.7(3), 97.4(3), 97.1(3)
176.6(2), 179.5(2), 178.3(3), 176.2(2)
97.8(2), 96.8(3), 97.0(3), 96.4(3)
101.5(2), 98.81(19), 99.3(2), 102.37(19)
97.6(2)
179.1(2)
98.2(2)
99.10(10)
175.78(11)
97.40(10)
98.97(15)
100.84(11)
N2–Cu1–N1
N2–Cu1–N3
N2–Cu1–O1
N2–Cu1–N4
82.8(4), 81.9(3), 83.4(4), 83.3(4)
81.8(4), 83.6(3), 82.0(4), 82.5(4)
81.8(3), 81.3(3), 82.1(3), 81.4(3)
81.7(3)
82.5(3)
81.6(2)
80.61(14)
78.64(14)
82.62(15)
N3–Cu1–O1
O1–Cu1–N1
N3–Cu1–N1
90.2(3), 89.8(3), 96.7(3), 100.4(3)
92.0(3), 98.8(3), 89.2(4), 88.3(3)
163.3(4), 161.8(4), 163.3(4), 162.0(4)
84.6(3)
101.8(3)
161.8(3)
N4–Cu1–N1
N1–Cu1–N3
N3–Cu1–N4
126.00(15)
104.05(15)
122.18(15)
Cu1–O1–C14
Cu1–N4–C14
N–Hꢁ ꢁ ꢁBr
109.9(7), 106.6(6), 108.5(7), 107.6(6)
169.6, 170.6, 172.5, 174.3
105.3(5)
114.8(3)
N–Hꢁ ꢁ ꢁO
134(2)
˚
show key bond distance and bond angle data, respec-
tively, for complex 3.
(1.243(6) A) bond lengths were very similar to those
found for a recently reported N-coordinated amidate–
copper(I) complex [38] and are consistent with substantial
localization of the formal negative charge of the amidate
group on the nitrogen atom. The pyridyl C–C and C–N
bond lengths are within the range found for complexes 1
and 2. The Cu–N and Cu–Br bond distances reveal no
other unusual features.
The key feature of complex 3 is the amidate group g1-
and N-coordinated to the copper center. The bromide
counterion as found in complexes 1 and 2 is not
observed in the unit cell, which is consistent with the
DIPMAE ligand having been deprotonated during the
˚
reaction. The amide C–N (1.333(6) A) and C–O

T.E. Patten et al. / Inorganica Chimica Acta 361 (2008) 365–372
371
Appendix A. Supplementary material
CCDC 642628, 642629, 642631 and 642630 contain the
supplementary crystallographic data (excluding structure
factors) for DIPMAE, 1, 2 and 3. These data can be obtained
free of charge via http://www.ccdc.cam.ac.uk/conts/retriev-
ing.html, or from the Cambridge Crystallographic Data
Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Supplementarydata associated with thisarticle canbe found,
in the online version, at doi:10.1016/j.ica.2007.06.003.
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