Structural diversity in cobalt camphorate coordination polymers with flexible dipyridylamide ligands including looped layers and self-penetrated topologies

Article abstract of DOI:10.1016/j.ica.2019.119087

Hydrothermal reaction of cobalt nitrate, D-camphoric acid, and flexible dipyridylamide ligands afforded a series of coordination polymers with diverse structural topologies, as characterized by single crystal X-ray diffraction.{[Co₂(DL-cam)₂(edn)]·2H₂O}_n (1, edn = N,N′-(ethane-1,2-diyl)dinicotinamide) shows a 3D 4¹²6³ pcu net built from straight-pillaring of {Co₂(OCO)₄} paddlewheel dimer-based [Co₂(DL-cam)₂]_n layer motifs. In contrast, [Co(D-cam)(edin)]_n (2, edin = N,N′-(ethane-1,2-diyl)diisonicotinamide) manifests a two-fold parallel interpenetrated looped layer topology. {[Co₂(DL-cam)₂(bdin)]·2H₂O}_n (3, bdin = N,N′-(butane-1,4-diyl)diisonicotinamide) displays a very rare 3D 4⁴6¹⁰8 roa self-penetrated net built from cross-pillaring of {Co₂(OCO)₄} paddlewheel dimer-based [Co₂(DL-cam)₂]_n layer motifs, as does {[Co₂(DL-cam)₂(pedin)]·2H₂O}_n (4, pedin = N,N′-(pentane-1,5-diyl)diisonicotinamide). [Co(D-cam)(hdin)]_n (5, hdin = N,N′-(hexane-1,6-diyl)diisonicotinamide) shows a simple stacked system of sawtooth (4,4) grid motifs. Thermal properties are discussed herein.

Full text of DOI:10.1016/j.ica.2019.119087

InorganicaChimicaActa498(2019)119087
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Research paper
Structural diversity in cobalt camphorate coordination polymers with
flexible dipyridylamide ligands including looped layers and self-penetrated
topologies
Jack J. Przybyla, Frederick C. Ezenyilimba, Robert L. LaDuca⁎
Lyman Briggs College and Department of Chemistry, Michigan State University, East Lansing, MI 48825, USA
A R T I C L E I N F O
A B S T R A C T
Keywords:
Hydrothermal reaction of cobalt nitrate, D-camphoric acid, and flexible dipyridylamide ligands afforded a series
of coordination polymers with diverse structural topologies, as characterized by single crystal X-ray diffraction.
{[Co2(DL-cam)2(edn)]·2H2O}n (1, edn = N,N′-(ethane-1,2-diyl)dinicotinamide) shows a 3D 41263 pcu net built
from straight-pillaring of {Co2(OCO)4} paddlewheel dimer-based [Co2(DL-cam)2]n layer motifs. In contrast, [Co
Crystal structure
Coordination polymer
Cobalt
Self-penetration
Interpenetration
(D-cam)(edin)]n (2, edin = N,N′-(ethane-1,2-diyl)diisonicotinamide) manifests
a two-fold parallel inter-
penetrated looped layer topology. {[Co2(DL-cam)2(bdin)]·2H2O}n (3, bdin = N,N′-(butane-1,4-diyl)diisonicoti-
namide) displays a very rare 3D 446108 roa self-penetrated net built from cross-pillaring of {Co2(OCO)4} pad-
dlewheel dimer-based [Co2(DL-cam)2]n layer motifs, as does {[Co2(DL-cam)2(pedin)]·2H2O}n (4, pedin = N,N′-
(pentane-1,5-diyl)diisonicotinamide). [Co(D-cam)(hdin)]n (5, hdin = N,N′-(hexane-1,6-diyl)diisonicotinamide)
shows a simple stacked system of sawtooth (4,4) grid motifs. Thermal properties are discussed herein.
1. Introduction
a neutral dipyridyl coligand. Bu’s group reported the synthesis and
characterization of three distinct 3-D cadmium D-camphorate phases by
Investigations towards the preparation, structural characterization,
and property measurements of crystalline divalent metal coordination
polymer networks remain intense in many research groups around the
world. This intriguing class of materials possesses exciting applications
in hydrogen storage [1], molecular absorption [2], ion exchange [3],
heterogeneous catalysis for organic transformations [4], second har-
monic generation [5], explosives trace detection [6], and even delivery
of active pharmaceuticals [7]. Chiral coordination polymers can be
employed in enantioselective separations or stereospecific organic
transformations [8]. Lin’s group reported using a chiral dipyridyl
linking ligand to prepare a two-fold interpenetrated cadmium co-
ordination polymer that can catalyze the stereospecific formation of
chiral secondary alcohols from aromatic aldehydes in the presence of
diethyl zinc, after post-synthetic reaction with titanium isopropoxide
[8a]. Rosseinsky’s group employed the conjugate base of the amino acid
L-aspartatic acid (L-aspH) as the carboxylate ligand to form the 3D chiral
phase [Ni2(L-asp)2(bpy)]n (bpy = 4,4′-bipyridine), which can perform
gas phase enantiospecific separation of aliphatic diols [8b].
varying temperature conditions [10]. Control of dimensionality can be
achieved by varying the divalent metal ion with the more con-
formationally flexible coligand 1,3-di-4-pyridylpropane (dpp). [Ni(D-
cam)(dpp)]n showed an unusual chiral bilayer structure with 42638
topology, while its cobalt congener {[Co(D-cam)(dpp)]·H2O}n manifests
a chiral three-fold interpenetrated diamondoid net [9a]. {[Cd(D-cam)
(dpp)]·2H2O}n has a similar diamondoid topology to {[Co(D-cam)
(dpp)]·H2O}n, and also undergoes a thermally induced single crystal-to-
single crystal structural reorganization [9b].
Employing the “V-shaped” and hydrogen-bonding capable coligand
4,4′-dipyridylamine (dpa), our group prepared a series of chiral D-
camphorate coordination polymers with structural topologies depen-
dent on the nature of the divalent metal ion [11]. {[Cd(dpa)(D-
cmphH)2(H2O)]•0.875H2O}n possessed 1D helical chains with a very
long pitch of over 67 Å. [Zn2(D-cmph)2(dpa)(H2O)]n showed a 2D 3,4-
connected binodal net with a rare (53)2(5482) topology. {[Ni(D-cmph)
(dpa)]·3H2O}n showed an uncommon 2-fold interpenetrated 4-con-
nected 3D 4284 lvt topology, while its cobalt analog [Co2(D-
cmph)2(dpa)]·H2O}n possessed a 41263 pcu topology based on 6-con-
nected {Co2(OCO)4} paddlewheel dimers. Other hydrogen-bonding
capable and conformationally flexible dipyridyl ligands allowed access
The D-camphorate ligand (D-cam, Scheme 1) has shown to be an
excellent ligand for promoting the formation of chiral divalent metal
coordination networks, either in the presence [9] or the absence [10] of
⁎ Corresponding author.
E-mail address: laduca@msu.edu (R.L. LaDuca).
https://doi.org/10.1016/j.ica.2019.119087
Received 5 August 2019; Received in revised form 20 August 2019; Accepted 21 August 2019
Availableonline29August2019
0020-1693/©2019ElsevierB.V.Allrightsreserved.

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
Table 1
Crystal and Structure Refinement Data for 1–5.
Data
1
2
Empirical Formula
C34H46Co2N4O12
820.61
monoclinic
P21/c
10.1393(17)
13.651(2)
13.221(2)
90
97.637(2)
90
1813.7(5)
2
1.503
0.982
0.9148
C24H28CoN4O6
527.43
monoclinic
P21
10.655(7)
10.152(7)
11.788(8)
90
112.724(10)
90
1176.2(14)
2
Formula Weight
Crystal system
Space group
a (Å)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
V (Å3)
Scheme 1.
Z
D (g cm−3
)
1.489
0.778
0.7279
μ (mm−1
Min./max.
transmission
hkl ranges
)
to a diverse of structural topologies in cobalt camphorate coordination
polymers, sometimes with scrambling of the original D-camphorate
chirality [12]. {[Co2(DL-cam)2(bdn)]·2H2O}n (1, bdn = N,N′-(butane-
1,4-diyl)dinicotinamide) possesses {Co2(OCO)4}paddlewheel dimer-
based chirality-scrambled [Co2(DL-cam)2] grid layers pillared by bdn
ligands into a 6-connected 41263 pcu network, similar in topology to
the dpa derivative [Co2(D-cmph)2(dpa)]·H2O}n. The shorter dipyr-
idylamide N,N′-(propane-1,3-diyl)dinicotinamide (pdn) afforded
{[Co2(D-cam)2(pdn)]·2H2O}n. In contrast to the pcu straight-pillared
topology of the bdn-containing analog, this pdn-containing phase
manifests a cross-pillared self-penetrated 446810 mab network along
–12 ≤ h ≤ 12,
–16 ≤ k ≤ 16,
–15 ≤ l ≤ 15
14,046
3326
0.0566
–12 ≤ h ≤ 12,
–12 ≤ k ≤ 12,
–14 ≤ l ≤ 15
8762
4227
0.2215
Total reflections
Unique reflections
R(int)
Parameters
245
0.0671
0.0607
0.1633
0.1597
1.403/–0.471
259
0.2480
0.1166
0.3138
0.2378
1.048/–1.359
R1 (all data)
R1 (I > 2σ(I))
wR2 (all data)
wR2 (I > 2σ(I))
Max/min residual (e–/
Å3)
with
retention
of
chirality.
{[Co2(DL-cam)2(pedn)]·2H2O}n
(pedn = N,N′-(pentane-1,5-diyl)dinicotinamide) shows a highly crys-
tallographically disordered hybrid structure of discrete slabs of 3D pcu
network with interleaved 2D hxl (3,6) layers at random intervals, in-
stead of the self-penetrated mab network seen in the pdn-containing
derivative. Thus the length of the dipyridylamide aliphatic unit can
play an extremely significant role in structure direction among cobalt
camphorate coordination polymers.
We have intended in this study to expand the scope of our previous
work and prepare additional chiral cobalt D-camphorate coordination
networks with hydrogen-bonding capable and conformationally flexible
dipyridylnicotinamide and dipyridylisonicotinamide ligands. In this
contribution we present the synthesis, single-crystal structures, topo-
G.O.F.
1.104
0.946
Data
3
4
5
Empirical
Formula
Formula Weight
Crystal system
Space group
a (Å)
C36H50Co2N4O12
C37H52Co2N4O12
C28H34CoN4O6
848.66
monoclinic
P21/c
22.681(7)
12.340(4)
13.694(4)
90
90.146(4)
90
3833(2)
4
862.68
monoclinic
P21/c
12.5972(10)
23.6951(19)
13.4045(11)
90
90.2670(10)
90
4001.1(6)
4
1.432
0.894
0.8696
581.54
orthorhombic
P21212
20.518(4)
9.241(2)
15.071(3)
90
b (Å)
c (Å)
α (°)
β (°)
90
90
logical
analysis,
and
thermal
properties
of
{[Co2(DL-
γ (°)
cam)2(edn)]·2H2O}n (1, edn = N,N′-(ethane-1,2-diyl)dinicotinamide,
Scheme 1), [Co(D-cam)(edin)]n (2, edin = N,N′-(ethane-1,2-diyl)diiso-
V (Å3)
2857.7(11)
4
1.352
0.648
0.9109
Z
D (g cm−3
)
1.471
0.932
0.9029
nicotinamide,
Scheme
1),
{[Co2(DL-cam)2(bdin)]·2H2O}n
(3,
μ (mm−1
Min./max.
transmission
hkl ranges
)
bdin = N,N′-(butane-1,4-diyl)diisonicotinamide, Scheme 1), {[Co2(DL-
cam)2(pedin)]·2H2O}n (4, pedin = N,N′-(pentane-1,5-diyl)diisonicoti-
namide, Scheme 1), and [Co(D-cam)(hdin)]n (5, hdin = N,N′-(hexane-
1,6-diyl)diisonicotinamide, Scheme 1).
–27 ≤ h ≤ 27,
–14 ≤ k ≤ 14,
–16 ≤ l ≤ 16
30,253
–15 ≤ h ≤ 15,
–28 ≤ k ≤ 28,
–16 ≤ l ≤ 16
32,117
–24 ≤ h ≤ 24,
–11 ≤ k ≤ 11,
–18 ≤ l ≤ 18
23,350
Total reflections
Unique
2. Experimental section
7014
7348
5310
reflections
R(int)
0.0556
501
0.0633
462
0.0724
290
2.1. General considerations
Parameters
R1 (all data)
R1 (I > 2σ(I))
wR2 (all data)
wR2 (I > 2σ(I))
Max/min residual
(e–/Å3)
0.1089
0.0812
0.1752
0.1649
0.815/–0.397
0.1365
0.0926
0.2924
0.2587
1.745/–0.979
0.1380
0.1025
0.2800
0.2582
0.730/–0.908
Cobalt nitrate and D-camphoric acid were commercially obtained
from Sigma Aldrich. N,N′-(ethane-1,2-diyl)dinicotinamide (edn) was
prepared by condensation of 1,2-ethanediamine and two molar
equivalents of nicotinoyl chloride hydrochloride in dry pyridine. The
reaction mixture was quenched with water, and then the product was
isolated via CH2Cl2 extraction and removal of solvent in vacuo [13].
Other dipyridylamides were prepared similarly by using the requisite
diamines and isonicotinoyl chloride hydrochloride in dry pyridine.
Water was deionized above 3 MΩ–cm in-house. IR spectra were re-
corded on powdered samples using a Perkin Elmer Spectrum One DRIFT
instrument. Thermogravimetric analysis was performed on a TA In-
struments Q-50 Thermogravimetric Analyzer with a heating rate of
10 °C/min up to 600 °C. Elemental Analysis was carried out using a
Perkin Elmer 2400 Series II CHNS/O Analyzer.
G.O.F.
1.199
1.049
1.053
2.2. Preparation of {[Co2(DL-cam)2(edn)]·2H2O}n (1)
Co(NO3)2·6H2O (107 mg, 0.37 mmol), D-camphoric acid (73 mg,
0.37 mmol), and edn (99 mg, 0.37 mmol), and 0.75 mL of a 1.0 M NaOH
solution were mixed with 10 mL of distilled H2O in a 23 mL Teflon-lined
acid digestion bomb. The bomb was sealed and heated in an oven at
120 °C for 48 h, and then was cooled slowly to 25 °C. Magenta crystals
2

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
Fig. 1. a) {CoNO4} square pyramidal coordination environment, {Co2(CO2)4} paddlewheel dimeric unit and complete ligand set in 1. Only one disordered cam ligand
component is shown. Thermal ellipsoids are drawn at 50% probability. b) [Co2(DL-cam)2]n (4,4) grid layer motif in 1.
Table 2
air. Anal. Calc. for C24H28CoN4O6 2: C, 54.65; H, 5.35; N, 10.62%
Found: C, 54.84; H, 5.29; N, 10.56%. IR (cm−1): 2962(w), 1660(m),
1577(w), 1525(s), 1461(m), 1403(s), 1363(w), 1321(w), 1293(w),
1086(m), 997(w), 861(w), 836(w), 802(s), 697(s), 666(w).
Selected Bond Distance (Å) and Angle (°) Data for 1.
Co1–O1#1
2.055(3)
2.008(3)
2.146(3)
2.047(3)
2.082(4)
83.69(13)
94.30(13)
164.39(13)
O2–Co1–O3#2
O2–Co1–O4#3
O2–Co1–N1
85.99(13)
97.18(14)
96.93(14)
89.37(13)
162.66(14)
108.90(14)
87.52(14)
Co1–O2
Co1–O3#2
Co1–O4#3
O4#3–Co1–O1#1
O4#3–Co1–O3#2
O4#3–Co1–N1
N1–Co1–O3#2
2.4. Preparation of {[Co2(DL-cam)2(bdin)]·2H2O}n (3)
Co1–N1
O1#1–Co1–O3#2
O1#1–Co1–N1
O2–Co1–O1#1
Co(NO3)2·6H2O (107 mg, 0.37 mmol), D-camphoric acid (73 mg,
0.37 mmol), and bdin (111 mg, 0.37 mmol), and 0.75 mL of a 1.0 M
NaOH solution were mixed with 10 mL of distilled H2O in a 23 mL
Teflon-lined acid digestion bomb. The bomb was sealed and heated in
an oven at 120 °C for 48 h, and then was cooled slowly to 25 °C. A few
magenta crystals of 3 were found embedded in a large amount of
flocculent light pink powder and colorless crystals (presumably un-
reacted ligands). Multiple attempts at a monophasic preparation of 3
were unfortunately unsuccessful.
Symmetry transformations: #1 × – 1, y – 1, z – 1; #2 × , –y + 1/2, z – 1/2; #3
–x + 1, y + 1/2, –z + 3/2
of 1 (25 mg, 16% yield based on Co) were isolated after washing with
distilled water, ethanol, and acetone and drying in air. Anal. Calc. for
C
34H46Co2N4O12 1: C, 49.76; H, 5.65; N, 6.83% Found: C, 50.14; H,
5.48; N, 6.84%. IR (cm−1): 3299 (w), 2960 (w), 1649 (m), 1581 (s),
1550 (s), 1403 (s), 1368 (m), 1325 (m), 1301 (m), 1195 (w), 1167 (w),
1109 (w), 1056 (w), 1038 (w), 887(w), 835 (w), 802 (w), 783 (w), 758
(w), 694 (m)
2.5. Preparation of {[Co2(DL-cam)2(pedin)]·2H2O}n (4)
Co(OAc)2·4H2O (92 mg, 0.37 mmol), D-camphoric acid (73 mg,
0.37 mmol), and pedin (114 mg, 0.37 mmol), and 0.75 mL of a 1.0 M
NaOH solution were mixed with 10 mL of distilled H2O in a 23 mL
Teflon-lined acid digestion bomb. The bomb was sealed and heated in
an oven at 120 °C for 48 h, and then was cooled slowly to 25 °C.
Magenta crystals of 4 (35 mg, 22% yield based on Co) were isolated
after washing with distilled water, ethanol, and acetone and drying in
air. Anal. Calc. for C37H52Co2N4O12 4: C, 51.51; H, 6.08; N, 6.49%
Found: C, 50.78; H, 6.01; N, 6.13%. IR (cm−1): 3300(w, br), 1674(s),
1540(s), 1415(m), 1301(w), 1053(w), 852(m), 797(w), 764(w),
2.3. Preparation of [Co(D-cam)(edin)]n (2)
Co(NO3)2·6H2O (107 mg, 0.37 mmol), D-camphoric acid (73 mg,
0.37 mmol), and edin (99 mg, 0.37 mmol), and 0.75 mL of a 1.0 M
NaOH solution were mixed with 10 mL of distilled H2O in a 23 mL
Teflon-lined acid digestion bomb. The bomb was sealed and heated in
an oven at 120 °C for 48 h, and then was cooled slowly to 25 °C.
Magenta crystals of 2 (26 mg, 13% yield based on Co) were isolated
after washing with distilled water, ethanol, and acetone and drying in
Fig. 2. [Co2(DL-cam)2(edn)]n 3D coordination
polymer network in 1. [Co2(DL-cam)2]n layer motifs
are shown in red. b) Schematic perspective of the
straight-pillared 41263 pcu net in 1. Gold spheres
represent the centroids of the {Co2(OCO)4} paddle-
wheel dimers. The DL-cam and edn ligands connec-
tions are shown as red and blue rods, respectively.
(For interpretation of the references to colour in this
figure legend, the reader is referred to the web
version of this article.)
3

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
Fig. 3. {CoN2O3} distorted trigonal bipyramidal coordination environment and complete ligand set in 2. Thermal ellipsoids are drawn at 50% probability.
radiation (λ = 0.71073 Å) at 173 K. The data were processed via SAINT
Table 3
Selected Bond Distance (Å) and Angle (°) Data for 2.
[14], and corrected for both Lorentz and polarization effects and ab-
sorption effects using SADABS [15]. The structures were solved using
direct methods with SHELXTL [16] within the OLEX2 crystallographic
software suite [17]. All non-hydrogen atoms were refined aniso-
tropically. Hydrogen atoms were placed in calculated positions and
refined isotropically with a riding model. Crystallographic disorder
within the DL-camphorate ligands and the aliphatic groups in some of
the dipyridylamide ligands were successfully modeled with partial oc-
cupancies and separate parts. The Flack parameters [18] for the crystal
structures of 2 and 5 were 0.00(7) and 0.11(2), respectively, indicating
excellent to good racemic purity within the crystals. The Rint value for
the crystal of 2 along with refinement parameters were elevated due to
small crystal size with concomitant weak diffraction. Nevertheless the
connectivity and topology of compound 2 were unambiguous. Attempts
to solve and refine the structures of 2 and 5 in centrosymmetric space
groups were unsuccessful; the crystal of 5 showed a small amount of
racemic twinning as per the Flack parameter above. Crystallographic
details for 1–5 are given in Table 1.
Co1–O1#1
Co1–O3
Co1–O4
2.106(15)
2.131(13)
2.014(14)
2.24(2)
1.973(17)
89.4(6)
O4–Co1–O1#1
O4–Co1–O3
137.6(5)
63.0(6)
97.8(7)
102.1(7)
166.8(7)
103.8(6)
90.9(7)
O4–Co1–N1
Co1–N1
N4#2–Co1–O1#1
N4#2–Co1–O3
N4#2–Co1–O4
N4#2–Co1–N1
Co1–N4#2
O1#1–Co1–O3
O1#1–Co1–N1
O3–Co1–N1
114.7(6)
90.0(6)
Symmetry transformations: #1 –x, y – 1/2, –z + 1; #2 –x + 2, y – 1/2, –z + 1.
684(w).
2.6. Preparation of [Co(D-cam)(hdin)]n (5)
Co(NO3)2·6H2O (107 mg, 0.37 mmol), D-camphoric acid (73 mg,
0.37 mmol), and hdin (119 mg, 0.37 mmol), and 0.75 mL of a 1.0 M
NaOH solution were mixed with 10 mL of distilled H2O in a 23 mL
Teflon-lined acid digestion bomb. The bomb was sealed and heated in
an oven at 120 °C for 48 h, and then was cooled slowly to 25 °C.
Magenta crystals of 5 (41 mg, 19% yield based on Co) were isolated
after washing with distilled water, ethanol, and acetone and drying in
air. Anal. Calc. for C28H34CoN4O6 5: C, 57.83; H, 5.89; N, 9.63% Found:
C, 58.15; H, 6.00; N, 10.37%. IR (cm−1): 2961(w), 1640 (m), 1577(s),
1401(s), 1364(m), 1325(w), 1098(m), 1013(w), 802(m), 698(m).
4. Results and discussion
4.1. Synthesis and spectra
Crystalline samples of 1–5 were produced by the hydrothermal re-
action of a divalent cobalt salt, D-camphoric acid, and the requisite
dipyridylamide ligand in the presence of aqueous base. Unfortunately
compound 3 could not be obtained in phase pure fashion after multiple
attempts at altering synthetic conditions, which precluded bulk ana-
lysis. The infrared spectra of 1–2 and 4–5 were consistent with their
structural components as determined by single-crystal X-ray diffraction.
3. X-ray crystallography
Diffraction data for 1–5 were collected on a Bruker-AXS SMART-
CCD X-ray diffractometer using graphite-monochromated Mo-Kα
Fig. 4. a) [Co(DL-cam)(edin)]n (4,4) grid
layer motif in 2. b) Side view of the 2-fold
parallel interpenetration of [Co(DL-cam)
(edin)]n layer motifs in 2. c) Schematic
perspective of the looped (8)2(84122) to-
pology net invoked for 2. The purple and
green rods represent the DL-cam and ebin
loops, respectively. d) Two-fold parallel in-
terpenetration of looped nets in 2, with DL-
cam and edin ligands acting as loops instead
of straight linkers in order to avoid edge
crossing. (For interpretation of the refer-
ences to colour in this figure legend, the
reader is referred to the web version of this
article.)
4

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
Fig. 5. {CoNO4} square pyramidal coordination environment and complete ligand set in 3. Thermal ellipsoids are drawn at 50% probability.
Table 4
Selected Bond Distance (Å) and Angle (°) Data for 3.
Co1–O5
2.022(4)
2.021(4)
2.277(4)
2.256(5)
2.073(5)
2.093(5)
2.275(4)
2.263(5)
2.065(5)
2.021(4)
2.018(4)
2.093(5)
85.92(16)
83.21(17)
98.41(19)
96.0(2)
O7#2–Co1–O7
O8#2–Co1–O7#2
O8#2–Co1–O7
O8#2–Co1–N4
N4–Co1–O7
101.02(14)
60.30(17)
160.88(17)
111.0(2)
87.68(19)
171.27(19)
100.90(15)
60.33(17)
160.75(17)
111.1(2)
83.21(17)
85.51(17)
98.48(19)
96.1(2)
81.98(17)
85.39(17)
91.60(18)
160.8(2)
Co1–O6#1
Co1–O7#2
Co1–O7#3
Co1–O8#2
Co1–N4
N4–Co1–O7
Co2–O1
O1#4–Co2–O1
O2–Co2–O1
Co2–O1#4
Co2–O2
O2–Co2–O1#4
O2–Co2–N1
Co2–O3#5
Co2–O4#6
O3#5–Co2–O1#4
O3#5–Co2–O1
O3#5–Co2–O2
O3#5–Co2–N1
O4#6–Co2–O1#4
O4#6–Co2–O1
O4#6–Co2–O2
O4#6–Co2–O3#5
O4#6–Co2–N1
N1–Co2–O1
Co2–N1
O5–Co1–O7#2
O5–Co1–O7#2
O5–Co1–O8#2
O5–Co1–N4
O6#1–Co1–O5
O6#1–Co1–O7#2
O6#1–Co1–O7#3
O6#1–Co1–O8#2
O6#1–Co1–N4
Fig. 7. Schematic perspective of the rare cross-pillared self-penetrated 44610
8
161.15(19)
85.26(17)
82.18(17)
91.61(18)
95.3(2)
roa net in 3 and 4. Gold and silver spheres represent the centroids of the
{Co2(OCO)4} paddlewheel dimers. The DL-cam and dipyridylamide ligand
connections are shown as red and blue rods, respectively. (For interpretation of
the references to colour in this figure legend, the reader is referred to the web
version of this article.)
95.4(2)
171.43(19)
87.66(19)
N1–Co2–O1#4
Symmetry transformations: #1 –x + 1, –y + 3, –z + 1; #2 × , –y + 7/2, z – 1/2;
#3 –x + 1, y – 1/2, –z + 3/2; #4 –x + 2, –y, –z + 1; #5 × , –y – 1/2, z + 1/2;
#6 –x + 2, y + 1/2, –z + 1/2
4.2. Structural description of {[Co2(DL-cam)2(edn)]·2H2O}n (1)
The asymmetric unit of compound 1 consists of a divalent cobalt
atom, a camphorate ligand with a methyl group disordered equally over
two sets of positions, revealing the presence of both D-cam and L-cam
ligands in a racemic 50:50 ratio, half of an edn ligand whose central
CeC σ bond rests over a crystallographic inversion center, and a water
molecule of crystallization. A {CoO4N} square pyramidal coordination
environment (Fig. 1a) with a τ value of 0.028 [20] is evident at cobalt,
with single carboxylate oxygen atom donors from four DL-cam ligands in
the basal plane. The apical position is taken up by a pyridyl nitrogen
donor atom from an edn ligand. Bond lengths and angles within the
coordination environment are listed in Table 2.
The DL-cam ligands adopt a bis-bridging exotetradentate binding
mode. Thus {Co2(OCO)4} paddlewheel dimeric units are constructed
with a Co···Co internuclear distance of 2.736(1) Å spanned by syn-syn
bridging carboxylates from four DL-cam ligands. The full span of the DL-
cam ligands forms [Co2(DL-cam)2]n coordination polymer layer motifs
that are oriented along the bc crystal planes (Fig. 1b). The shortest
Intense, broad asymmetric and symmetric CeO stretching bands within
the camphorate ligands were observed at 1550 and 1403 cm−1 for 1,
1525 and 1403 cm−1 for 2, at 1540 and 1415 cm−1 for 4, and at 1577
and 1401 cm−1 for 5. Moderate intensity bands in the range
of ∼1600 cm−1 to ∼1300 cm−1 are attributed to the stretching modes
of the pyridyl rings of the dipyridylamide ligands [19]. Features cor-
responding to CeH bending and ring puckering within the pyridyl
moieties exist in the region between ∼900 and ∼650 cm−1. Broad,
weak spectral bands in the vicinity of ∼3000–3400 cm−1 indicate the
presence of unbound water molecules in the spectra of 1 and 4. The
carbonyl stretching bands for the dipyridylamide ligands appeared at
1649 cm−1 for 1, 1660 cm−1 for 2, 1674 cm−1 for 4, and 1640 cm−1
for 5.
Fig. 6. a) b) [Co2(DL-cam)2]n (4,4) grid layer motif in
3. b) [Co2(DL-cam)2(bdin)]n 3D coordination
polymer network in 3. [Co2(DL-cam)2]n layer motifs
are shown in red with cross-pillaring bdin ligands
situated between the layers. (For interpretation of
the references to colour in this figure legend, the
reader is referred to the web version of this article.)
5

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
Table 6
Selected Bond Distance (Å) and Angle (°) Data for 5.
Table 5
Selected Bond Distance (Å) and Angle (°) Data for 4.
Co1–O3#1
2.286(5)
2.278(5)
2.070(5)
2.012(5)
2.007(5)
2.081(6)
2.020(5)
2.019(5)
2.288(5)
2.264(5)
2.071(6)
2.088(6)
102.23(15)
60.2(2)
162.2(2)
109.7(2)
85.84(19)
82.3(2)
92.9(2)
96.7(2)
O8–Co1–O3#1
O8–Co1–O4#2
O8–Co1–O7#3
O8–Co1–N1
83.6(2)
96.9(2)
161.4(2)
94.9(2)
88.0(2)
169.8(2)
82.4(2)
86.08(19)
92.8(2)
Co1–O3
2.015(9)
2.015(9)
2.295(9)
2.295(9)
2.151(10)
2.151(10)
2.121(11)
2.121(11)
2.202(10)
2.202(10)
2.117(10)
2.116(10)
142.9(6)
94.9(4)
O4–Co1–O4#1
N1#1–Co1–O4
N1–Co1–O4#1
N1–Co1–O4
98.7(5)
156.1(4)
156.1(4)
88.0(3)
88.0(3)
95.1(5)
107.2(6)
60.9(3)
96.1(4)
60.9(3)
96.1(4)
142.7(6)
90.0(4)
148.1(4)
90.0(4)
148.1(4)
91.3(4)
91.3(4)
115.7(4)
115.7(4)
88.7(5)
Co1–O3#2
Co1–O3#1
Co1–O4#2
Co1–O4#1
Co1–O4
Co1–O7#3
Co1–O8
N1–Co1–O3#1
N1–Co1–O3#2
O1#4–Co2–O5#4
O1#4–Co2–O5
O1#4–Co2–O6
O1#4–Co2–N4#5
O2–Co2–O1#4
O2–Co2–O5
Co1–N1
N1#1–Co1–O4#1
N1–Co1–N1
Co1–N1
Co1–N1#1
Co2–O1#4
Co2–O5#2
O5#2–Co2–O5
O5–Co2–O6
Co2–O2
Co2–O5
Co2–O5
Co2–O6
O5#2–Co2–O6
O5#2–Co2–O6#2
O5–Co2–O6#2
O6#2–Co2–O6
N2#2–Co2–O5#2
N2–Co2–O5#2
N2–Co2–O5
Co2–O5#4
96.3(2)
Co2–O6#2
Co2–O6
161.3(2)
84.79(18)
83.7(2)
96.7(2)
95.6(2)
102.36(15)
60.0(2)
162.1(2)
109.9(2)
87.8(2)
Co2–N2
Co2–N4#5
Co2–N2#2
O3#2–Co1–O3#1
O4#2–Co1–O3
O4#2–Co1–O3#1
O4#2–Co1–N1
O7#3–Co1–O3#2
O7#3–Co1–O3#1
O7#3–Co1–O4#2
O7#3–Co1–N1
O8–Co1–O3#2
O2–Co2–O5#4
O2–Co2–O6
O3–Co1–O3#1
O3–Co1–O4#1
O3#1–Co1–O4#1
O3#1–Co1–O4
O3–Co1–O4
O3–Co1–N1
O3#1–Co1–N1
O3–Co1–N1#1
O3#1–Co1–N1#1
O2–Co2–N4#5
O5#4–Co2–O5
O6–Co2–O5
60.0(4)
94.9(4)
60.0(4)
108.2(4)
96.8(4)
N2#2–Co2–O5
N2–Co2–O6#2
N2#2–Co2–O6
N2#2–Co2–O6#2
N2–Co2–O6
O6–Co2–O5#4
O6–Co2–N4#5
N4#5–Co2–O5#4
N4#5–Co2–O5
96.8(4)
108.2(4)
85.36(19)
169.8(2)
N2#2–Co2–N2
Symmetry transformations: #1 –x + 2, –y + 1, –z + 1; #2 × ,y, z – 1; #3 –x + 2,
–y + 1, –z; #4 –x + 3, –y + 1, –z + 1; #5 × + 2, –y + 1/2, z + 1/2.
Symmetry transformations: #1 –x + 2, –y, z; #2 –x + 1, –y + 1, z.
oxygen atom donor from a second D-cam ligand. Thus the two pyridyl
donor atoms are oriented in a cis fashion with respect to each other.
Bond lengths and angles within the distorted coordination sphere are
listed in Table 3.
Co···Co distances through the DL-cam ligands measure 9.249(7) and
9.703(7) Å. Adjacent [Co2(DL-cam)2]n layer motifs in 1 are pillared in
the a crystal direction by dipodal edn ligands to construct a non-in-
terpenetrated 3D {[Co2(DL-cam)2(edn)]n network (Fig. 2a). The edn li-
gands adopt an anti conformation with their pyridyl rings pointing in
opposite directions, and span a Co···Co distance of 14.00(1) Å. Treating
the {Co2(OCO)4} paddlewheels as 6-connected nodes reveals a straight-
pillared 41263 pcu network (Fig. 2b) according to TOPOS [21]. The
water molecules of crystallization are held to the 3D network, and si-
tuated between the [Co2(DL-cam)2]n layer submotifs, by hydrogen
bonding donation to ebn carbonyl oxygen atoms (Table S1).
The D-cam ligands in 2 adopt a chelating/monodentate binding
mode and construct zig-zag [Co(D-cam)]n coordination polymer chains
that are oriented along the b crystal direction, with a Co···Co through-
ligand distance of 8.916(7) Å. These are pillared by cis-disposed dipodal
edin ligands with a Co···Co distance of 14.87(1) Å to construct [Co(D-
cam)(edin)]n grid-like coordination polymer layers (Fig. 4a). The grid
apertures in 2 are large enough to accommodate interpenetration of a
second [Co(D-cam)(edin)]n layer motif along the ab crystal planes as
shown in Fig. 4b. While the grid-like layers in 2 appear to have a
common 4-connected (4,4) grid topology, such a topology would en-
force edge-crossing within an interpenetrated pair of layers. Therefore,
according to the nomenclature of Batten et al. [22], each D-cam and
edin ligand in 2 is considered to be a 2-connected node in a looped net
with the cobalt atoms representing 4-connected nodes. According to
TOPOS, the 2,2,4-connected layer of 2 has a (8)2(84122) topology
(Fig. 4c). A side view of the two-fold interpenetrated system of looped
layers in 2 is shown in Fig. 4d. Sets of interpenetrated layers aggregate
along the c crystal direction by means of non-classical CeH···O inter-
actions between edin central ethylene units and edin C]O moieties
(Fig. S1).
4.3. Structural description of [Co(D-cam)(edin)]n (2)
The asymmetric unit of compound 2 contains a divalent cobalt
atom, a D-cam ligand, and an edin ligand. A distorted five-coordinate
{CoN2O3} coordination sphere is observed at cobalt, with a τ trigonality
factor of 0.48 indicative of a hybrid of square pyramidal and trigonal
bipyramidal coordination geometries (Fig. 3). If a trigonal bipyramidal
coordination sphere is invoked, a carboxylate group from a D-cam li-
gand spans an axial and an equatorial position, with a pyridyl nitrogen
donor atom from an edin ligand also in an axial position. The other two
remaining coordination sites in the equatorial plane contain a pyridyl
nitrogen donor atom from a second edin ligand and a carboxylate
Fig. 8. a) {CoO4N2} octahedral coordination environment and complete ligand set in 5. Thermal ellipsoids are drawn at 50% probability. Only one disordered
conformation of each ligand is shown. b) Sawtooth [Co(D-cam)(hdin)]n (4,4) grid layer motif in 5. Both disordered conformations of each ligand set are shown.
6

J.J. Przybyla, et al.
InorganicaChimicaActa498(2019)119087
4.4. Structural description of {[Co2(DL-cam)2(bdin)]·2H2O}n (3)
are pillared by the hdin ligands into sawtooth [Co(D-cam)(hdin)]n co-
ordination polymer layers (Fig. 8b). The hdin ligands span a Co···Co
distance of 22.365(5) Å; the cis-disposition of the pyridyl nitrogen
donor atoms of the hdin ligands enforce the sharp sawtooth mor-
phology of the layer motifs. Adjacent [Co(D-cam)(hdin)]n coordination
polymer sawtooth layers stack in an ABAB pattern along the c crystal
direction (Fig. S3) by means of hydrogen bonding donation from hdin
NeH groups to bound D-cam carboxylate oxygen atoms.
The asymmetric unit of compound 3 contains two divalent cobalt
atoms (Co1, Co2), two racemized DL-cam ligands, a complete bdin li-
gand, and two water molecules of crystallization. Each cobalt atom
shows a distorted {CoNO5} coordination octahedron (Fig. 5) with a
chelating carboxylate group from one DL-cam ligand and monodentate
oxygen atom donors from three other DL-cam ligands, along with a
pyridyl nitrogen donor atom from a bdin ligand. Bond lengths and
angles within the coordination environments are listed in Table 4.
Both of the crystallographically distinct DL-cam ligands adopt an
exotetradentate μ4-κ4-O,O′:O′:O′′:O′′′ binding mode in which one car-
boxylate group chelates to a cobalt atom while binding in a mono-
dentate fashion to another, with the other carboxylate terminus brid-
ging two cobalt atoms in a syn-syn fashion. As a result {Co2(OCO)4}
paddlewheel dimeric units are formed in 3, with Co1···Co1 distances of
2.883(2) Å and Co2···Co2 distances of 2.890(2) Å.
4.7. Thermal properties
Compound 1 underwent loss of its co-crystallized water molecules
between ∼ 30 and ∼125 °C, with a mass loss of 4.5% matching well
with the predicted value for elimination of two molar equivalents of
water. Ligand combustion occurred above ∼260 °C. Compound 2 un-
derwent combustion above 340 °C. Compound 4 lost its water mole-
cules of crystallization upon long term storage, and the framework itself
combusted above 300 °C. Compound 5 underwent combustion above
270 °C. The TGA traces for 1–2 and 4–5 are shown in Figs. S4–S7, re-
spectively.
The {Co2(OCO)4} paddlewheel dimers are connected by the full
span of the DL-cam ligands to generate undulating [Co2(DL-cam)2]n co-
ordination polymer grid-like layers that are oriented parallel to the bc
crystal planes (Fig. 6a).
The Co1-based [Co2(DL-cam)2]n layers and the Co2-based [Co2(DL-
cam)2]n layers are pillared by dipodal bdin ligands into a [Co2(DL-
cam)2(bdin)]}n 3D coordination polymer network (Fig. 6b). The bdin
ligands have a splayed-open anti conformation of their central aliphatic
5. Conclusions
A wide variety of coligand dependent structural topologies, in-
cluding two rare examples of a cross-pillared roa self-penetrated to-
pology and an intriguing looped layer network, has been obtained in a
series of cobalt camphorate coordination polymers. No clear structural
trends can be identified upon lengthening the central aliphatic tether of
the neutral dipyridylamide coligands. All of the 3D coordination
polymer phases exhibit scrambling of the original D-camphorate chir-
ality. The self-penetrated roa topology shows the highest thermal ro-
bustness of the coordination polymers in this series.
tethers (torsion angle = 162.8°) and span
a Co···Co distance of
19.926(6) Å. As this distance is substantially longer than that spanned
by the edn ligands in 1, a straight-pillared 41263 pcu network is not
formed in 3. Instead, by treating the {Co2(OCO)4} paddlewheel dimers
as 6-connected nodes, a very rare 446108 roa cross-pillared self-pene-
trated network can be invoked (Fig. 7). Water molecules of crystal-
lization are anchored to the coordination polymer network of 3 by
accepting hydrogen bonding from bdin NeH groups and by donating
hydrogen bonds to the bdin C]O groups (Table S1).
Acknowledgements
Support for this work was provided by the Honors College of
Michigan State University. J.J.P.’s research fellowship was provided by
the Michigan State University Chemistry Department’s National Science
Foundation REU Program under award number CHE-1358842.
4.5. Structural description of [Co2(DL-cam)2(pedin)]·2H2O}n (4)
The asymmetric unit of compound 4 contains two divalent cobalt
atoms (Co1, Co2), two racemized DL-cam ligands, a complete pedin li-
gand, and two water molecules of crystallization. As in 3, a distorted
{CoNO5} coordination octahedral geometry is in evidence at each co-
balt atom in 4 (Fig. S2). Bond lengths and angles within the co-
ordination spheres are listed in Table 5. The salient structural features
of 4, namely [Co2(DL-cam)2]n layers constructed from {Co2(OCO)4}
paddlewheel dimers, further pillared by dipodal pedin ligands into a
[Co2(DL-cam)2(pedin)]}n 3D coordination polymer net, are similar to
that of 3. The pedin ligands in 4 adopt an anti-anti conformation of their
central pentamethylene tethers and span a Co···Co distance of 20.435(1)
Å. The resulting 6-connected net in 4 has a 446108 roa cross-pillared
self-penetrated network as seen in 3 (Fig. 7).
Appendix A. Supplementary data
Supplementary data (Hydrogen bonding information, additional
molecular graphics, and thermogravimetric analysis plots.
Crystallographic data (excluding structure factors) for 1–5 have been
deposited with the Cambridge Crystallographic Data Centre with Nos.
1824082–1824086, respectively. Copies of the data can be obtained
free of charge via the Internet at < https://summary.ccdc.cam.ac.uk/
structure-summary-form >) to this article can be found online at
https://doi.org/10.1016/j.ica.2019.119087.
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8