Copper(I) complexes of heterocyclic thiourea ligands

Article abstract of DOI:10.1016/j.poly.2009.08.023

The coordination of heterocyclic thiourea ligands (L = N-(2-pyridyl)-N′-phenylthiourea (1), N-(2-pyridyl)-N′-methylthiourea (2), N-(3-pyridyl)-N′-phenylthiourea (3), N-(3-pyridyl)-N′-methylthiourea (4), N-(4-pyridyl)-N′-phenylthiourea (5), N-(2-pyrimidyl)

Full text of DOI:10.1016/j.poly.2009.08.023

Polyhedron 28 (2009) 4017–4031
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Copper(I) complexes of heterocyclic thiourea ligands
*
Aakarsh Saxena, Emily C. Dugan, Jeffrey Liaw, Matthew D. Dembo, Robert D. Pike
Department of Chemistry, College of William and Mary, Williamsburg, VA 23187, United States
a r t i c l e i n f o
a b s t r a c t
The coordination of heterocyclic thiourea ligands (L = N-(2-pyridyl)-N0-phenylthiourea (1), N-(2-pyridyl)-
N0-methylthiourea (2), N-(3-pyridyl)-N0-phenylthiourea (3), N-(3-pyridyl)-N0-methylthiourea (4),
N-(4-pyridyl)-N0-phenylthiourea (5), N-(2-pyrimidyl)-N0-phenylthiourea (6), N-(2-pyrimidyl)-N0-meth-
ylthiourea (7), N-(2-thiazolyl)-N0-methylthiourea (8), N-(2-benzothiazolyl)-N0-methylthiourea (9),
N,N0-bis(2-pyridyl)thiourea (10) and N,N0-bis(3-pyridyl)thiourea (11)) with CuX (X = Cl, Br, I, NO3) has
been investigated. CuX:L product stoichiometries of 1:1–1:5 were found, with 1:1 being most common.
X-ray structures of four 3-coordinate mononuclear CuXL2 complexes (CuCl(6)2, CuCl(7)2, CuBr(6)2, and
CuBr(9)2) are reported. In contrast, CuBr(1)2 is a 1D sulfur-bridged polymer. CuIL structures (L = 7, 8)
Article history:
Received 16 June 2009
Accepted 31 August 2009
Available online 4 September 2009
Keywords:
Copper complexes
Crystal structures
Thiourea ligands
Heterocycles
Metal–organic networks
Oxidative cyclization
are 1D chains with corner-sharing Cu2(l-I)2 and Cu2(l-S)2 units, and CuCl(10) is a 2D network having
l-Cl and N-/S-bridging L. Two [CuL2]NO3 structures are reported: a mononuclear 4-coordinate copper
complex with chelating ligands (L = 10) and a 1D link-chain with N-/S-bridging L (L = 3). Two ligand
oxidative cyclizations were encountered during crystallization. CuI crystallized with 6 to produce zigzag
ladder polymer [(CuI)2(12)]ꢀ1/2CH3CN (12 = N-(pyrimidin-2-yl)benzo[d]thiazol-2-amine) and CuNO3
crystallized with 10 to form [Cu2(NO3)(13)2(MeCN)]NO3 (13 = dipyridyltetraazathiapentalene).
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
known. One important group of organic SABs is comprised of thio-
carbonyl compounds. A remarkable collection of copper(I) net-
The self-assembly of transition metals with bridging ligands to
produce metal–organic networks (MONs) is currently a very active
area of study [1]. Copper(I) centers are especially flexible with
respect to coordination environment [2], ranging from 2- to
4-coordinate (see examples in Chart 1 below). However, also
important in MON formation are the bonding capabilities of the
ligands chosen. A recent review has divided MONs according to
dimensionality produced through organic versus inorganic ligand
bridging [3]. According to the authors’ scheme, the 2D network
CuBr(Pyz) (Pyz = pyrazine) [4] would be classified as I1O1, since
the inorganic ligand bromide links the copper atoms into 1D chains
(I1) and the organic Pyz ligand links them in a perpendicular direc-
tion (O1). The sum of the exponents gives the overall dimensional-
ity of the MON, a 2D sheet in this case.
Halide bridging behavior in MONs such as CuBr(Pyz) may be de-
scribed as single-atom-bridging (SAB). Unlike conventional organic
bridging ligands, such as Pyz or 4,40-bipyridine, which have two or
more widely separated and geometrically constrained lone pair-
bearing atoms, SAB ligands have two or more lone pairs residing
on a single atom and consequently form short bridges between
two or more metal centers. While group 16 or 17 anions are obvi-
ous candidates for SAB behavior, organic SAB examples are also
works with thiourea ligands is known, many showing sulfur SAB
behavior [5]. The Cu(I) centers bridged by thiocarbonyl sulfur (S)
and halide SABs (X) can form rhomboid Cu2X2 or Cu2S2 dimers,
Cu4X4 or Cu4S4 cubane tetramers, (Cu2X2)n or (Cu2S2)n stair-step
polymers, and (CuX)n or (CuS)n chains [2]. Examples of SAB com-
plexes are shown in Chart 1. As is suggested by the variety of the
products shown in Chart 1, it can be very difficult to predict afore-
hand when sulfur or halide atoms will act in SAB fashion and when
they will remain monodentate. In addition, halide ions can also act
as outer sphere anions.
In the following study we have examined the network-forming
behavior of thiourea ligands bearing nitrogen heterocycle groups
with copper(I) halides and nitrate. The heterocyclic thiourea mole-
cules (HetTu) 1–11 shown in Chart 2 are themselves network-
formers through hydrogen-bonding [6]. It was expected that they
would show a variety of bridging behaviors involving the sulfur
(monodentate or SAB) and nitrogen centers, leading to network
formation. Additional network-forming behavior was anticipated
from the halide (SAB) and possibly the nitrate ions. To date, a single
HetTu complex of copper(I) has been reported [7]. This compound
is [Cu(10)2]ClO4. It is monomeric, with a single 4-coordinate cop-
per coordinated to sulfur and one pyridyl nitrogen from each li-
gand. The remaining pyridyl nitrogen on each ligand engages in
intramolecular hydrogen-bonding with a thiourea N–H. The Zn(II)
complex is similar. However, more complicated and highly
* Corresponding author. Tel.: +1 757 221 2555.
E-mail address: rdpike@wm.edu (R.D. Pike).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.08.023

4018
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
X
S
2 X
S
S
X
S
S
S
S
Cu
Cu
Cu
Cu
S
S
S
S
S
S
S
S
S
S
X
X
S
X
X
S
Cu
Cu
Cu
Cu
Cu
S
S
S
S
X
X
X
X
Cu
X
Cu
S
S
Cu
Cu
S
S
S
S
X
X
Cu
Cu
Cu
Cu
X
X
X
X
S
S
S
S
Cu
Cu
S
S
Cu
Cu
X
S
S
S
X = Cl, Br, I
S =
HN
NH HN
N
H2N
NH2
Chart 1. Coordination arrangements in Cu(I) thiourea structures.
networked structures are to be expected when the pyridyl groups
and thiocarbonyl sulfur are geometrically prevented from chelat-
ing a single metal center.
2.2.2. Synthesis of [CuBr(1)]ꢀMeCN
The procedure for CuCl(1)2 was followed using CuBr. A grey-
green solid was isolated (77.6%). Anal. Calc. for C14H14N4BrCuS: C,
40.64; H, 3.41; N, 13.54. Found: C, 42.44; H, 3.42; N, 13.53%.
2. Experimental
2.2.3. Synthesis of CuI(1)
2.1. General methods
The procedure for CuCl(1)2 was followed using CuI. An off-white
solid was isolated (94.5%). Anal. Calc. for C12H11N3CuIS: C, 34.34; H,
2.64; N, 10.01. Found: C, 34.24; H, 2.63; N, 10.05%.
All syntheses were carried out under nitrogen atmosphere.
Microanalyses for C, H, and N were carried out by Atlantic Microlab
Inc., Norcross, GA. HetTu ligands, N-(2-pyridyl)-N0-phenylthiourea
(1), N-(2-pyridyl)-N0-methylthiourea (2), N-(3-pyridyl)-N0-phenyl-
thiourea (3), N-(3-pyridyl)-N0-methylthiourea (4), N-(4-pyridyl)-
N0-phenylthiourea (5), N-(2-pyrimidyl)-N0-phenylthiourea (6),
N-(2-pyrimidyl)-N0-methylthiourea (7), N-(2-thiazolyl)-N0-methyl-
thiourea (8), N-(2-benzothiazolyl)-N0-methylthiourea (9), N,N0-
bis(2-pyridyl)thiourea (10) and N,N0-bis(3-pyridyl)thiourea (11),
were synthesized as previously described [6]. Copper(I) chloride
and bromide were freshly recrystallized from aqueous HCl or
HBr. Copper(I) iodide was used as received from Aldrich. Copper(I)
nitrate was prepared in situ by conproportionation of Cu(NO3)2ꢀ
2.5H2O in MeCN as described below.
2.2.4. Synthesis of CuNO3(1)
Cu(NO3)2ꢀ2.5H2O (116 mg, 0.500 mmol) and excess copper wool
were stirred under N2 in 25 mL MeCN for 30 min. until the blue
solution color was discharged. The copper wool was removed
and 1 (229 mg, 1.00 mmol) was added as a solid. The resulting
suspension was stirred under nitrogen for 1 h at room temp. This
resulted in a precipitate. The solid was collected via filtration,
and was washed with diethyl ether. The light brown solid was
dried under vacuum (226 mg, 63.8% yield). Anal. Calc. for C12H11N4-
CuO3S: C, 40.62; H, 3.12; N, 15.79. Found: C, 42.23; H, 3.06; N,
15.85%.
2.2. Syntheses
2.2.5. Synthesis of (CuCl)2(2)3
The procedure for CuCl(1)2 was followed using CuCl and 2. A
white solid was isolated (75.1%). Anal. Calc. for C21H27N9Cl2Cu2S3:
C, 36.05; H, 3.89; N, 18.02. Found: C, 35.88; H, 3.81; N, 17.81%.
2.2.1. Synthesis of CuCl(1)2
Copper(I) chloride (99 mg, 1.00 mmol) was dissolved in 25 mL
MeCN under N2. 1 (229 mg, 1.00 mmol) was added as a solid. The
resulting suspension was stirred under nitrogen for 1 h at room
temp. The white solid was collected via filtration, and washed with
diethyl ether. It was dried under vacuum (184 mg, 68.5% yield).
Anal. Calc. for C24H22N6ClCuS2: C, 51.70; H, 3.98; N, 15.70. Found:
C, 52.08; H, 3.97; N, 15.13%.
2.2.6. Synthesis of [CuBr(2)]ꢀMeCN
The procedure for CuCl(1)2 was followed using CuBr and 2. A
white solid was isolated (59.1%). Anal. Calc. for C9H12N4CuBrS: C,
30.73; H, 3.44; N, 15.93. Found: C, 31.41; H, 3.43; N, 15.62%.

A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
4019
3
3
Chart 2. HetTu ligands.
2.2.7. Synthesis of [CuI(2)]ꢀMeCN
2.2.11. Synthesis of CuI(3)
Theprocedure for compoundCuCl(1)2 was followedusingCuI and
2. A cream solid was isolated (88.2%). Anal. Calc. for C9H12N4CuIS:
C, 27.11; H, 3.03; N, 14.05. Found: C, 27.88; H, 3.01; N, 13.86%.
The procedure for CuCl(1)2 was followed using CuI and 3. A pale
yellow solid was isolated (86.2%). Anal. Calc. for C12H11N3CuIS: C,
34.34; H, 2.64; N, 10.01. Found: C, 33.62; H, 2.66; N, 10.22%.
2.2.8. Synthesis of [CuNO3(2)]ꢀMeCN
2.2.12. Synthesis of [CuNO3(3)]ꢀMeCN
The procedure for CuNO3(1) was followed using 2. A pale yellow
solid was isolated (89.2%). Anal. Calc. for C9H12N5CuO3S: C, 32.38;
H, 3.62; N, 20.98. Found: C, 31.97; H, 3.51; N, 20.65%.
The procedure for CuNO3(1) was followed using 3. A yellow so-
lid was isolated (90.4%). Anal. Calc. for C14H14N5CuO3S: C, 42.47; H,
3.56; N, 17.69. Found: C, 42.48; H, 3.64; N, 17.43%.
2.2.9. Synthesis of CuCl(3)4
2.2.13. Synthesis of CuCl(4)
The procedure for CuCl(1)2 was followed using CuCl and 3. A
yellow solid was isolated (83.8%). Anal. Calc. for C48H44N12ClCuS4:
C, 56.73; H, 4.36; N, 16.54. Found: C, 56.08; H, 4.40; N, 16.33%.
The procedure for CuCl(1)2 was followed using CuCl and 4. A
yellow solid was isolated (69.5%). Anal. Calc. for C7H9N3ClCuS: C,
31.58; H, 3.41; N, 15.78. Found: C, 32.20; H, 3.46; N, 15.95%.
2.2.10. Synthesis of CuBr(3)2
The procedure for CuCl(1)2 was followed using CuBr and 3. A
straw-colored solid was isolated (87.7%). Anal. Calc. for C24H22N6-
BrCuS2: C, 47.88; H, 3.68; N, 13.96. Found: C, 48.79; H, 3.78; N,
14.09%.
2.2.14. Synthesis of CuBr(4)
The procedure for CuCl(1)2 was followed using CuBr and 4. A
cream solid was isolated (62.9%). Anal. Calc. for C7H9N3BrCuS: C,
27.06; H, 2.92; N, 13.53. Found: C, 26.46; H, 2.83; N, 13.12%.

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A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
2.2.15. Synthesis of CuI(4)
2.2.28. Synthesis of CuNO3(7)2
The procedure for CuCl(1)2 was followed using CuI and 4. A
white solid was isolated (94.1%). Anal. Calc. for C7H9N3CuIS: C,
23.51; H, 2.54; N, 11.75. Found: C, 23.57; H, 2.57; N, 11.56%.
The procedure for CuNO3(1) was followed using 7. A yellow so-
lid was isolated (71.4%). Anal. Calc. for C18H24N14Cu2O6S3: C, 28.61;
H, 3.20; N, 25.95. Found: C, 29.07; H, 3.19; N, 25.46%.
2.2.29. Synthesis of (CuCl)2(8)3
2.2.16. Synthesis of (CuNO3)2(4)3
The procedure for CuCl(1)2 was followed using CuCl and 8. A
white solid was isolated (57.3%). Anal. Calc. for C15H21N9Cl2Cu2S6:
C, 25.10; H, 2.95; N, 17.56. Found: C, 25.24; H, 2.93; N, 17.50%.
The procedure for CuNO3(1) was followed using 4. A cream solid
was isolated (86.5%). Anal. Calc. for C21H27N11Cu2O6S3: C, 33.51; H,
3.62; N, 20.47. Found: C, 32.78; H, 3.80; N, 20.30%.
2.2.30. Synthesis of (CuBr)2(8)3
2.2.17. Synthesis of CuCl(5)
The procedure for CuCl(1)2 was followed using CuBr and 8. A
cream solid was isolated (80.5%). Anal. Calc. for C15H21N9Br2Cu2S6:
C, 22.33; H, 2.62; N, 15.63. Found: C, 22.53; H, 2.63; N, 15.66%.
The procedure for CuCl(1)2 was followed using CuCl and 5. A
yellow solid was isolated (74.0%). Anal. Calc. for C12H11N3ClCuS:
C, 43.90; H, 3.38; N, 12.80. Found: C, 43.69; H, 3.32; N, 12.88%.
2.2.31. Synthesis of CuI(8)
2.2.18. Synthesis of CuBr(5)
The procedure for CuCl(1)2 was followed using CuI and 8. A yel-
low solid was isolated (68.6%). Anal. Calc. for C5H7N3CuIS2: C,
16.51; H, 1.94; N, 11.55. Found: C, 16.90; H, 1.93; N, 11.58%.
The procedure for CuCl(1)2 was followed using CuBr and 5. A
yellow solid was isolated (48.4%). Anal. Calc. for C12H11N3BrCuS:
C, 38.67; H, 2.97; N, 11.27. Found: C, 39.07; H, 3.04; N, 11.62%.
2.2.32. Synthesis of CuNO3(8)2
2.2.19. Synthesis of CuI(5)
The procedure for CuNO3(1) was followed using 8. A light brown
solid was isolated (12.7%). Anal. Calc. for C10H14N7CuO3S4: C, 25.44;
H, 2.99; N, 20.77. Found: C, 25.41; H, 2.80; N, 20.16%.
The procedure for CuCl(1)2 was followed using CuI and 5. A yel-
low solid was isolated (82.3%). Anal. Calc. for C12H11N3CuIS: C,
34.34; H, 2.64; N, 10.01. Found: C, 34.89; H, 2.66; N, 9.91%.
2.2.33. Synthesis of [CuCl(9)]ꢀ½MeCN
2.2.20. Synthesis of (CuNO3)2(5)3
The procedure for CuCl(1)2 was followed using CuCl and 9. A
The procedure for CuNO3(1) was followed using 5. A yellow so-
lid was isolated (57.8%). Anal. Calc. for C36H33N11Cu2O6S3: C, 46.05;
H, 3.54; N, 16.41. Found: C, 45.02; H, 3.48; N, 15.64%.
pale yellow solid was isolated (87.6%). Anal. Calc. for C10H10.5N3.5
ClCuS2: C, 35.03; H, 3.09; N, 14.30. Found: C, 35.20; H, 3.03; N,
13.85%.
-
2.2.21. Synthesis of CuCl(6)2
2.2.34. Synthesis of CuBr(9)
The procedure for CuCl(1)2 was followed using CuCl and 6. A
white solid was isolated (85.1%). Anal. Calc. for C22H20N8ClCuS2:
C, 47.22; H, 3.60; N, 20.02. Found: C, 47.19; H, 3.66; N, 19.76%.
The procedure for CuCl(1)2 was followed using CuBr and 9. An
off-white solid was isolated (72.0%). Anal. Calc. for C9H9N3BrCuS2:
C, 29.47; H, 2.47; N, 11.46. Found: C, 29.17; H, 2.57; N, 11.31%.
2.2.35. Synthesis of (CuI)2(9)3
2.2.22. Synthesis of CuBr(6)2
The procedure for CuCl(1)2 was followed using CuI and 9. A
cream solid was isolated (88.8%). Anal. Calc. for C27H27N9Cu2I2S6:
C, 30.86; H, 2.59; N, 12.00. Found: C, 30.04; H, 2.58; N, 11.88%.
The procedure for CuCl(1)2 was followed using CuBr and 6. A
white solid was isolated (70.2%). Anal. Calc. for C22H20N8BrCuS2:
C, 43.75; H, 3.34; N, 18.55. Found: C, 43.47; H, 3.21; N, 18.27%.
2.2.36. Synthesis of [CuNO3(9)]ꢀMeCN
2.2.23. Synthesis of CuI(6)
The procedure for CuNO3(1) was followed using 9. A light yellow
solid was isolated (63.4%). Anal. Calc. for C11H12N5CuO3S2: C, 33.88;
H, 3.10; N, 17.96. Found: C, 34.32; H, 3.07; N, 17.38%.
The procedure for CuCl(1)2 was followed using CuI and 6. A yel-
low solid was isolated (54.2%). Anal. Calc. for C11H10N4CuIS: C,
31.40; H, 2.40; N, 13.32. Found: C, 30.67; H, 2.35; N, 13.07%.
2.2.37. Synthesis of (CuCl)2(10)3
2.2.24. Synthesis of CuNO3(6)2
The procedure for CuCl(1)2 was followed using CuCl and 10. A
yellow solid was isolated (68.7%). Anal. Calc. for C33H30N12Cl2-
Cu2S3: C, 44.59; H, 3.40; N, 18.91. Found: C, 43.54; H, 3.36; N,
18.63%.
The procedure for CuNO3(1) was followed using 6. A yellow so-
lid was isolated (79.8%). Anal. Calc. for C22H20N9CuO3S2: C, 45.08;
H, 3.44; N, 21.51. Found: C, 45.14; H, 3.44; N, 21.51%.
2.2.25. Synthesis of CuCl(7)4
2.2.38. Synthesis of CuBr(10)
The procedure for CuCl(1)2 was followed using CuCl and 7. A
white solid was isolated (85.0%). Anal. Calc. for C24H32N16ClCuS4:
C, 37.35; H, 4.18; N, 29.03. Found: C, 37.84; H, 4.27; N, 29.22%.
The procedure for CuCl(1)2 was followed using CuBr and 10. A
yellow solid was isolated (79.7%). Anal. Calc. for C11H10N4BrCuS:
C, 35.35; H, 2.70; N, 14.99. Found: C, 35.11; H, 2.74; N, 15.08%.
2.2.26. Synthesis of CuBr(7)
2.2.39. Synthesis of CuI(10)
The procedure for CuCl(1)2 was followed using CuBr and 7. A
pale yellow solid was isolated (78.5%). Anal. Calc. for C6H8N4BrCuS:
C, 23.12; H, 2.59; N, 17.98. Found: C, 23.47; H, 2.59; N, 17.99%.
The procedure for CuCl(1)2 was followed using CuI and 10. A
cream solid was isolated (79.0%). Anal. Calc. for C11H10N4CuIS: C,
31.40; H, 2.40; N, 13.32. Found: C, 31.50; H, 2.46; N, 13.47%.
2.2.27. Synthesis of CuI(7)
2.2.40. Synthesis of [(CuNO3)2(10)3]ꢀMeCN
The procedure for CuCl(1)2 was followed using CuI and 7. A pale
yellow solid was isolated (97.5%). Anal. Calc. for C6H8N4CuIS: C,
20.09; H, 2.25; N, 15.62. Found: C, 20.33; H, 2.29; N, 15.66.
The procedure for CuNO3(1) was followed using 10. A yellow so-
lid was isolated (24.8%). Anal. Calc. for C35H33N15Cu2O6S3: C, 42.76;
H, 3.38; N, 21.37. Found: C, 43.11; H, 3.44; N, 20.91%.

A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
4021
2.2.41. Synthesis of CuNO3(10)2
Copper(I) nitrate was prepared in MeCN through conproportiona-
tion of Cu(NO3)2ꢀ2.5H2O and Cu and was used without isolation.
The HetTu ligands were added to MeCN solutions of CuX, either
as solutions or suspensions in MeCN. In all cases solid products
were obtained after stirring for an hour at room temperature.
The various stoichiometric trends are summarized in Table 1. As
is evident in Table 1, a remarkable variety of CuX:HetTu product
ratios was found. The stoichiometries noted in the bulk synthesis
products spanned a wide range from the Cu-rich 1:1 to the very
HetTu-rich 1:5. Some general comments about metal-to-ligand ra-
tio in these complexes are in order. It should be expected that me-
tal-rich product ratios are indicative of ligand bridging behavior,
since when there are fewer ligands each must occupy more metal
coordination sites. Copper(I) shows a roughly equal preference for
3- and 4-coordination. So CuX:HetTu ratios of less than 1:2 are
highly suggestive of network formation.
The 1:1 CuX:HetTu ratio was the most common among the bulk
synthesis products, occurring (with or without MeCN present in
the product) in 25 of 45 cases. As rationalized above, a copper-rich
ratio of 1:1 suggests some sort of ligand bridging behavior. As is
evident from Chart 1 and the X-ray crystal structures discussed be-
low, there are a variety of ways in which bridging can occur with
the ligands used in this study. The halides and HetTu sulfur atom
can engage in SAB behavior and the HetTu and nitrate can bridge
through pairs of heteroatoms. Of course in the eight 1:1 complexes
that also have MeCN present, the solvent may act as a ligand, obvi-
ating network formation. The solvent-free 1:1 cases in which li-
gand bridging need not occur would be the complexes of HetTu
having ortho-type heteroatoms (1, 2, 6–10), since these ligands
can potentially chelate through a combination of S- and heterocy-
cle N-coordination [7]. The prevalence of 1:1 stoichiometry found
in this study favors CuI and CuBr products over those of CuCl and
CuNO3. This fact is not surprising given the greater tendency of lar-
ger halides to engage in SAB behavior. Like 1:1 stoichiometry, the
2:3 ratio seen in nine additional bulk products is probably also
indicative of ligand bridging.
The procedure for CuNO3(1) was followed using 10 and stirring
for 4 h. An orange solid was isolated (45.0%). Anal. Calc. for
C22H20N9CuO3S2: C, 45.08; H, 3.44; N, 21.51. Found: C, 45.05; H,
3.41; N, 21.50%.
2.2.42. Synthesis of CuCl(11)4
The procedure for CuCl(1)2 was followed using CuCl and 11. A
pale green solid was isolated (81.9%). Anal. Calc. for C44H40N16
ClCuS4: C, 51.80; H, 3.95; N, 21.97. Found: C, 52.09; H, 3.97; N,
21.79%.
-
2.2.43. Synthesis of CuBr(11)5
The procedure for CuCl(1)2 was followed using CuBr and 11. An
off-white solid was isolated (90.7%). Anal. Calc. for
C55H50N20BrCuS5: C, 51.02; H, 3.89; N, 21.63. Found: C, 51.71; H,
3.98; N, 21.62%.
2.2.44. Synthesis of CuI(11)4
The procedure for CuCl(1)2 was followed using CuI and 11. A
cream solid was isolated (82.9%). Anal. Calc. for C44H40N16CuIS4:
C, 47.54; H, 3.63; N, 20.16. Found: C, 48.44; H, 3.78; N, 20.48%.
2.2.45. Synthesis of [CuNO3(11)]ꢀMeCN
The procedure for CuNO3(1) was followed using 11. A yellow so-
lid was isolated (80.4%). Anal. Calc. for C13H13N6CuO3S: C, 39.34; H,
3.30; N, 21.17. Found: C, 39.77; H, 3.36; N, 20.94%.
2.3. X-ray data collection, structure solutions and refinements
Crystals were grown in 5 mm tubes by two techniques. Solution
concentrations were 20 mM. Typically, CuX was dissolved in MeCN
and layered with a HetTu dissolved in MeCN. When the HetTu was
insoluble in MeCN, the HetTu was dissolved in acetone. In success-
ful cases, X-ray quality crystals formed in about a week. All mea-
surements were made using graphite-monochromated Cu K
a
The moderately ligand-rich 1:2 stoichiometry was found in six
instances. This ratio is most likely reflective of monomeric species
CuX(HetTu)2 (although dimer or polymer formation is also possi-
ble, see the structure of CuBr(1)2 below). No 1:3 species, CuX(Het-
Tu)3, were encountered. Four 1:4 CuX:HetTu complexes were
found, presumably representing [Cu(HetTu)4]X. The single 1:5
species uncovered herein, CuBr(11)5 is quite remarkable. Since
copper(I) has virtually no tendency to form 5-coordinate com-
plexes, one can only speculate that the extra ligand(s) are trapped
radiation on a Bruker-AXS three-circle diffractometer, equipped
with a SMART Apex II CCD detector. Initial space group determina-
tion was based on a matrix consisting of 120 frames. The data were
corrected for Lorentz and polarization [8] effects and absorption
using SADABS [9]. The structures were solved by use of direct methods
or Patterson map. Least squares refinement on F2 was used for all
reflections. Structure solution, refinement and the calculation of de-
rived results were performed using the SHELXTL [10] package of soft-
ware. The non-hydrogen atoms were refined anisotropically. For
CuCl(10), CuCl(6)2, and CuNO3(10)2 all hydrogens were refined.
For CuBr(6)2 and CuCl(7)2 some hydrogens were refined. In all other
cases, all hydrogen atoms were located then placed in theoretical
positions. Acetone molecules (1.5/copper) were present in the
structure of [Cu(3)2]NO3. These very badly disordered solvent mol-
ecules were eliminated from the structure using Platon SQUEEZE
[11]. The half-independent MeCN molecule in [(CuI)2(12)]ꢀ½CH3CN
was badly disordered and was only partially modeled. For CuI(9),
fairly large (>2 e/Å3) residual peaks remained near the iodine atom
after refinement. This was clearly the result of imperfect absorption
correction, despite the use of a face-indexed model. Crystallo-
graphic parameters for all complexes are provided in Table 2. Se-
lected bond lengths and angles are provided in Table 3.
Table 1
Stoichiometry summary for bulk CuX:HetTu reactions.a
Ligand CuCl
CuBr
CuI
1:1
CuNO3
1:1
1
1:2
1:1ꢀMeCN
(1:2)
2
3
2:3
1:4
1:1ꢀMeCN
1:1ꢀMeCN 1:1ꢀMeCN
1:2
1:1
1:1ꢀMeCN (1:2ꢀ1½
acetone)
2:3
4
5
6
7
8
9
1:1
1:1
1:1
1:1
1:2 (1:2)
1:1
2:3
1:1
1:1
2:3
1:2 (1:2)
1:4 (1:2)
2:3
1:1ꢀ½
MeCN
2:3 (1:1)
1:4
1:1
1:1
1:1 (1:1)
1:1
2:3
1:2
1:1 (1:2)
2:3 (1:1)
1:1ꢀMeCN
3. Results and discussion
10
11
1:1
1:5
1:1
1:4
2:3ꢀMeCNb, 1:2c (1:2)
1:1ꢀMeCN
3.1. Synthesis and stoichiometry of bulk products
a
b
c
Results for crystal structures in parentheses.
One hour reaction result.
Four hours reaction result.
The reactions of copper(I) salts, CuX (X = Cl, Br, I, NO3), with var-
ious HetTu were carried out using a 1:1 metal salt:HetTu ratio.

4022
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
in the lattice of CuBr(11)n (n = 3 or 4), possibly through hydrogen-
bonding interactions.
Reaction time was varied for a number of combinations studied
herein. However, in only one case were two separate bulk products
encountered. Combination of CuNO3 with 10 resulted in the imme-
diate formation of a yellow precipitate which, when isolated, re-
vealed
a
yellow product, [(CuNO3)2(10)3]ꢀMeCN, based on
analytical data. When the reaction time scale was lengthened to
4 h, the initial yellow precipitate gave way to an orange solid. Ele-
mental analysis results confirmed that the latter complex was
CuNO3(10)2.
3.2. Description of X-ray structures
A total of twelve crystal structures were solved during the
course of this study. Surprisingly, two of these revealed cyclization
of the thioureas to form thiazoles (see below). In both cases ligand
oxidation resulted in the loss of H2. Although no analytical evi-
dence of such a transformation was noted in the bulk synthesis
products described above, the analytical difference due to H2 loss
would be fairly small. Also remarkable was the fact that of the
remaining ten structures, only four showed stoichiometry in agree-
ment with that of the corresponding bulk synthesis product (see
Table 1).
3.2.1. Monomeric complexes (I0O0)
Two types of monomeric compounds were encountered in the
current study. The first type that we will consider are halide com-
plexes having 1:2 CuX:HetTu ratio and 3-coordinate copper. Four
such complexes were identified: CuCl(6)2, CuCl(7)2, CuBr(6)2, and
CuBr(9)2. The two complexes of 6 showed the identical 1:2 stoichi-
ometry in the bulk, while the other complexes did not. In all four
cases, two crystallographically-independent HetTu ligands and a
terminal halide ligand were bound to a single copper center. Struc-
tural diagrams for CuCl(6)2 and CuBr(9)2 are provided in Fig. 1A
and B. The four 3-coordinate monomeric structures are overlaid
in Fig. 1C, roughly aligning an S–Cu–X sequence of atoms. As is evi-
dent, the structures are highly analogous, showing trigonal planar
copper angles very close to 120°. In each of these compounds, and
in fact all but one of the structures presented herein, the thioureas
adopt E, Z conformations [6]. This arrangement results from an in-
tra-ligand hydrogen-bond between a thiourea N–H and a heterocy-
cle nitrogen (e.g. N2–Hꢀ ꢀ ꢀN6 and N4–Hꢀ ꢀ ꢀN7 in Fig. 1A, see
Supplementary Table S1 for a complete list of H-bonds). In all four
structures, weak hydrogen-bonding type interactions exist be-
tween the halogen and two thiourea nitrogen atoms (e.g. N1–
Hꢀ ꢀ ꢀCl1 and N3–Hꢀ ꢀ ꢀCl1 in Fig. 1A). No intermolecular hydrogen-
bonding is evident in these structures. In all four compounds, three
nearly coplanar central atom planes may be identified: two NC(S)N
and SCu(X)S (see Supplementary Table S2), although in CuBr(1) the
copper atom shows a significant –0.4106(3) Å displacement from
the best SCu(X)S plane. The heterocycle rings that are oriented to-
ward the halogen atom in each compound are nearly coplanar with
these central planes. When a second HetTu ring is present, it is ori-
ented away from the halogen and is not coplanar with the central
plane (see Fig. 1A and C and Supplementary Table S2).
The second category of monomer includes nitrate complexes
with potentially chelating HetTu ligands. The sole representative
of this class in the current study was [Cu(10)2]NO3. However,
[Cu(10)2]NO3 is directly analogous to the previously reported
[Cu(10)2]ClO4 [7]. The nitrate complex consists of a 4-coordinate
copper(I) tetrahedrally chelated to S and NPy from two ligands,
see Fig. 2. The nitrate ion is non-coordinating. Although this cation
is analogous to that previously seen for the perchlorate ion [7], in
the current case the S–Cu–S bond angle is much more open
(129.35(2)° versus 119.85(7)°, respectively). This larger angle

Table 3
Selected Bond Distances (Å) and Angles (°).
d
CuCl(6)2
CuCl(7)2
CuBr(6)2
CuBr(9)2
[Cu(10)2]NO3
CuBr(1)2
[Cu(3)2]NO3
CuI(9)
CuI(7)
CuCl(10)
[(CuI)2(12)]ꢀ½MeCN
[Cu2(NO3)(13)2(MeCN)]NO3
Cu–S
2.2141(5),
2.2162(5)
2.2188(5),
2.2247(5)
2.2142(6),
2.2261(6)
2.2354(7),
2.2374(7)
2.2178(5),
2.2846(5)
2.2611(6),
2.3147(6),
2.5169(6)
2.4395(3)
2.2792(4),
2.3100(4)
2.3185(15),
2.4258(15)
2.3413(11), 2.4205(11),
2.3244(11), 2.4866(11)
2.2475(4)
–
–
Cu–Xa
2.2497(5)
2.2557(6)
2.3548(4)
2.4216(4)
–
–
2.6142(7),
2.6553(7)
2.6063(6), 2.6590(6),
2.6071(6), 2.6339(6)
2.4070(4),
2.4251(4)
2.6367(5), 2.7070(7),
2.7203(5), 2.6042(7),
2.6753(7), 2.7041(5)
2.036(4), 2.053(4)
2.341(4),b 2.589(5)b
Cu–N
–
–
–
–
2.0069(15),
2.0954(15)
–
–
–
2.0629(13),
2.0751(14)
–
–
–
2.0642(13)
3.0049(5)
–
1.912(4), 1.916(4), 1.960(8),
1.973(8), 2.104(8)c
2.672(7)
Cuꢀ ꢀ ꢀCu
S–Cu–S
–
–
–
–
2.7194(17),
3.0171(17)
101.06(5)
2.7935(8), 2.9346(8)
102.85(4), 101.35(4)
2.7223(13), 2.6936(13)
–
117.671(18)
119.64(2)
113.51(2)
114.72(3)
129.354(19)
–
105.79(2),
99.96(2),
107.44(2)
–
115.614(16)
–
–
–
X–Cu–X
S–Cu–X
S–Cu–N
–
–
–
–
117.87(3)
113.64(2), 112.78(2)
103.099(14)
115.91(3), 118.66(3),
109.97(2), 96.08(2),
121.97(4), 110.088(8),
97.070(8), 122.51(4)
–
120.021(18),
122.308(18)
119.75(2),
120.60(2)
121.31(2),
125.12(2)
122.41(2),
122.65(2)
–
123.079(18),
114.951(18),
103.579(16)
–
119.39(4),
105.77(4),
103.49(4),
107.56(4)
–
118.46(3), 109.46(3),
102.91(3), 108.65(3),
117.36(3), 110.13(3),
103.51(3), 111.01(3)
–
108.578(16),
115.840(16)
–
–
–
–
–
101.16(4),
108.53(4),
115.55(4),
91.67(4)
–
–
118.90(4),
111.48(4),
101.16(4),
106.99(4)
–
118.24(4)
–
–
N–Cu–X
N–Cu–N
–
–
–
–
–
–
–
–
–
–
–
–
–
–
109.02(4),
100.85(4)
114.76(10), 100.06(10),
111.26(11), 107.02(11),
113.10(11)
97.29(16),b 98.40(17)b
109.15(6)
101.02(5)
–
112.0(2)
163.96(19), 152.3(3),
101.1(3)c, 106.0(3)c
Cu–S–Cu
Cu–X–Cu
–
–
–
–
–
–
–
–
–
–
107.44(2)
–
–
–
78.94(5)
62.13(3)
74.80(3), 76.38(3)
64.075(18), 64.414(18)
–
–
–
–
76.900(14)
83.759(17), 61.06(2),
111.899(16), 61.34(2),
109.304(19),
83.089(17)
a
b
c
X = Cl, Br, I.
X = ONO2.
NMeCN
.
d
Full formula = [Cu(3)2]NO3ꢀ1.5acetone; solvent molecules removed with Platon SQUEEZE [11].

4024
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
Fig. 1. (A) Thermal ellipsoid (50%) drawing of CuCl(6)2. (B) Thermal ellipsoid (50%) drawing of CuBr(9)2. (C) Overlay of CuCl(6)2 (red), CuCl(7)2 (blue), CuBr(6)2 (green), and
CuBr(9)2 (purple). Central plane atom colors: S = yellow, Cu = orange, Cl = lime green, Br = brown. (For interpretation of the references to color in this figure legend, the reader
is referred to the web version of this article.)
comes at the expense of a more constricted S–Cu–N (115.55(4)°
versus 120.6(1)°) and N–Cu–N (109.15(6)° versus 115.6(2)°). The
non-coordinated NPy (N4, N8) on each ligand engages in intramo-
lecular hydrogen-bonding with a thiourea N–H (N1, N5). The
remaining thiourea N–H on each ligand (N3, N7) hydrogen-bonds
to the nitrate ion, producing a 1D chain (Supplementary Fig. S1).
The 1:2 stoichiometry seen for [Cu(10)2]NO3 was in agreement
with that of the bulk product.
3.2.2. Polymeric complexes (I0O1)
Closely related to the four halide 1:2 monomers described
above is CuBr(1)2, which is depicted in Fig. 3. The difference is

A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
4025
the planes of the heterocycles are oriented toward the Br. Very
weak
p
-stacking (centroidꢀ ꢀ ꢀcentroid = 4.036 Å) occurs between
symmetry-related, non-coordinating pyridyl rings on adjacent li-
gands. The bulk product of CuBr with 1 does not show 1:2 stoichi-
ometry (see Table 1).
The nitrate complex [Cu(3)2]NO3 is a HetTu-bridged 1D poly-
mer (Fig. 4). It is instructive to compare [Cu(3)2]NO3 to
[Cu(10)2]NO3 (see above), which have identical stoichiometry
and analogous connectivity. In contrast to the 2-pyridyl HetTu li-
gands of 10, 3-pyridyl ligands cannot chelate; instead they bridge
metal centers. Both thiourea ligands in [Cu(3)2]+ bridge pairs of
Fig. 2. Thermal ellipsoid (50%) drawing of [Cu(10)2]NO3. The nitrate counterion is
omitted.
4-coordinate copper centers in a jS:N fashion (Fig. 4A). The result-
ing dimers share copper centers, resulting in an I0O1 chain-link
polymer propagating in the crystallographic b-direction (Fig. 4B).
p-Stacking is evident between symmetry-related pyridyl rings that
bridge pairs of Cu atoms (centroidꢀ ꢀ ꢀcentroid = 3.618 Å). Since both
pyridyl nitrogen atoms coordinate to copper, no intramolecular
thiourea hydrogen-bonding is possible. Instead, the nitrate oxy-
gens act as hydrogen-bond donors for three thiourea N–H units.
The nitrate ions sit in grooves along the metal–organic chain, link-
ing adjacent thiourea ligands (N1–Hꢀ ꢀ ꢀO3, N4–Hꢀ ꢀ ꢀO1, N5–Hꢀ ꢀ ꢀO2)
within the chain (see Supplementary Fig. S2). Hydrogen-bonding
to nitrate causes N4/N5 in this 3 ligand to adopt a Z, Z conforma-
tion [6], a unique occurence in the current study and the direct
result of the lack of the internal hydrogen-bonds. Disordered
acetone molecules (1.5 per Cu) were found lying between the me-
tal–organic ribbons. These solvent molecules were removed using
Platon SQUEEZE [11] to improve the structure quality (removed
the addition of SAB behavior by HetTu sulfur atom, S2. This bridg-
ing increases the copper center to 4-coordinate and produces a 1D
I0O1-type [3] zigzag polymer chain having a ꢀ ꢀ ꢀCu–S–Cu–Sꢀ ꢀ ꢀ back-
bone. The chain propagates in parallel direction to the crystallo-
graphic a-axis. Although one of the two Cu1–S2 bonds is about
0.2 Å longer than the other two Cu–S bonds, the bond angles
around Cu reflect approximately tetrahedral geometry, confirming
4-coordination. As with the monomeric structures described
above, the heterocycle ring nitrogen (N3, N6) on each ligand does
not interact with copper, but instead forms an intramolecular
hydrogen-bond with a HetTu N–H (N2, N5). Also in like fashion
to the CuX(HetTu)2 monomers, approximate coplanarity is found
between the thiourea planes (less Cu, which is displaced), and
Fig. 3. Thermal ellipsoid (50%) drawings of CuBr(1)2. (A) Repeat unit with atomic numbering. (B) The long-range chain arrangement.

4026
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
Fig. 4. Thermal ellipsoid (50%) drawing of [Cu(3)2]NO3. Acetone molecules removed using Platon Squeeze [11]. (A) Repeat unit with atomic numbering. (B) The long-range
chain-link arrangement. Nitrate ion and hydrogen atoms are omitted.
Fig. 5. Thermal ellipsoid (50%) drawings of CuI(9). (A) Repeat unit with atomic numbering. (B) The long-range chain-link arrangement. Hydrogen atoms are omitted.
volume per unit cell = 328.4 Å3). The bulk product of CuNO3-3 is of
different stoichiometry than that of the crystal structure.
is in agreement with that of the bulk product. Both structures are
composed of 4-coordinate Cu centers alternately bridged by pairs
of iodide ions and pairs of thiocarbonyl sulfur atoms, acting as
SABs. The resulting 1D ribbons consist of corner-sharing Cu2I2
and Cu2S2 rings propagating parallel to the crystallographic b-
direction. Since a single polymeric strand is produced through
3.2.3. Polymeric complexes (I0.5O0.5
)
Two closely related 1:1 CuI:HetTu structures were solved:
CuI(7) and CuI(9). The 1:1 ratio of the former, but not of the latter,

A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
4027
the bridging of both inorganic and organic SABs, it seems appropri-
ate to label this sort of networking I0.5O0.5. Although structures
with copper-sharing (Cu2X2)1 [12] or (Cu2S2)1 chains [5] are fairly
common, the alternating arrangement (Cu2X2Cu2S2)1 seen in the
following two structures is very unusual, having been reported
only once previously [13].
In CuI(9) (Fig. 5), there are single crystallographically-unique
Cu, I, and HetTu units. Therefore, the corner-sharing Cu2I2 and
Cu2S2 rings are rigorously planar. These planes are nearly mutally
perpendicular (interplanar angle = 84.4°). An intramolecular N1–
Hꢀ ꢀ ꢀN3 hydrogen-bond is present in the 9 ligand and the benzothi-
azole group is nearly coplanar with the thiourea core. The Cuꢀ ꢀ ꢀCu
distance in the Cu2I2 unit is just under the van der Waals sum of
2.8 Å (2.719(2) Å), and for Cu2S2, the Cuꢀ ꢀ ꢀCu is slightly larger
(3.017(2) Å). There is no interaction between the heterocyclic rings
in CuI(9).
In like fashion to CuI(9), CuI(7) shows corner-sharing Cu2I2 and
Cu2S2 rings propagating parallel to the crystallographic b-direction
(Fig. 6). In contrast however, the pyrimidyl rings in CuI(7) are
noticeably inclined toward one another to allow
p-stacking (cen-
troidꢀ ꢀ ꢀcentroid = 3.552 Å). This results in significant puckering of
the rings and a slightly wavy chain. There are two crystallograph-
ically-independent Cu, I, and HetTu in this structure. The Cu2I2 and
Cu2S2 rings are both puckered, with maximum atom RMS
Fig. 6. Thermal ellipsoid (50%) drawings of CuI(7). (A) Repeat unit with atomic numbering. (B) The long-range chain-link arrangement. Hydrogen atoms are omitted.
Fig. 7. Thermal ellipsoid (50%) drawings of CuCl(10). Hydrogen atoms are omitted. (A) Repeat unit with atomic numbering. (B) The long-range sheet arrangement.

4028
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
deviations from best-fit planarity of 0.1871 and 0.0699 Å, respec-
tively. The best planes for Cu2I2 and Cu2S2 show an interplanar an-
gle of 85.64(2)°. The two 7 ligands are nearly coplanar (interplanar
angle = 4.1(1)°). Near-van der Waals Cuꢀ ꢀ ꢀCu interactions across
the Cu2I2 and Cu2S2 rhombs of 2.7927(9) and 2.9349(9) Å are seen.
An intramolecular N1–Hꢀ ꢀ ꢀN4 hydrogen-bond is noted between
the coplanar Pym ring and the HetTu core.
structure of CuCl(10) features the Cu2Cl2 rhomboid dimers, akin
to the Cu2I2 units in CuI(9) and CuI(7). One crystallographically-
independent Cu, Cl and HetTu are present. Each 4-coordinate cop-
per center is also coordinated by a sulfur atom and an NPy from
separate HetTu ligands (Fig. 7A). As a result, the 10 ligands bridge
the Cu2Cl2 units, creating (Cu2Cl2)4(10)4 rings, which are tiled to-
gether into a 2D I1O1 sheet running in the a, b plane (Fig. 7B).
The Cuꢀ ꢀ ꢀCu distance in the Cu2Cl2 unit is greater than the van
der Waals sum of 2.8 Å (3.0049(5) Å), suggesting a lack of signifi-
cant metal–metal bonding. The expected N2–Hꢀ ꢀ ꢀN3 and N1–
Hꢀ ꢀ ꢀCl1 H-bonds are found. As a result of the latter interaction,
the N3-bearing ring is roughly coplanar with the NC(S)N plane.
The bulk CuCl-10 product shows 2:3 stoichiometry.
3.2.4. Sheet complex (I1O1)
The structure of CuCl(10) features the HetTu bridging in a jS:N
fashion, as was described above for [Cu(3)2]NO3 (Fig. 7). Ligand 10,
which was seen to chelate in both [Cu(10)2]ClO4 [7] and
[Cu(10)2]NO3 (see above), acts as a network-former here. The
3.2.5. Cyclized ligand complexes
The final two structures show ligand reconstruction. Crystalli-
zation of a CuI-6 mixture resulted in a CuI complex of N-(pyrimi-
din-2-yl)benzo[d]thiazol-2-amine (12, Scheme 1). The copper
iodide network arrangement within the structure of
[(CuI)2(12)]ꢀ½CH3CN is interesting in its own right (Fig. 8). Two
half-independent and one fully-independent 4-coordinate copper
atoms are present. They are bridged by two fully-independent
l3-iodine atoms to form a modified stair-step pattern. As shown
in Chart 3, a conventional stair-step pattern (whether truncated
[14] or infinite [4,15]) is produced when Cu2X2 rings share opposite
edges. Conventional stair-step chains propagate in a single crystal-
lographic direction. The metal centers may be decorated with
monodentate ligands, chelated by bidentate ligands (I1O0) [14],
or multiple chains may be crosslinked with bridging ligands
(I1O1) [4,15]. In the case of infinite stair-step structures, all copper
atoms feature CuX3L coordination. Uniquely in the current struc-
Scheme 1. Oxidative cyclization of HetTu ligands.
Fig. 8. Thermal ellipsoid (50%) drawings of [(CuI)2(12)]ꢀ½CH3CN. (A) Repeat unit with atomic numbering. (B) The long-range stair-step arrangement. The disordered CH3CN is
omitted.

A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
4029
Chart 3. Stair-step arrangements: conventional and [(CuI)2(12)].
ture, the infinite stair-step ribbons show a zigzag structure, see
Fig. 8B. Bond distances for Cu–I are fairly consistent, suggesting a
true stair-step configuration, rather than a sequence of weakly
interacting dimers. As illustrated in Chart 3, sequences of five
opposite edge-sharing Cu2I2 rings are linked by adjacent edge-
sharing. Forming each ‘‘corner” Cu2I2 unit are two half-indepen-
dent copper atoms having CuI2L2 and CuI4 coordination (Cu1 and
Cu3, respectively). The linear section of the chain is formed by
opposite edge-sharing Cu1/I1/Cu3/I2 and Cu2/I2/Cu2/I2 units.
Close Cuꢀ ꢀ ꢀCu interactions across the Cu2X2 rings measuring
2.694(1) and 2.722(1) Å are noted for Cu2ꢀ ꢀ ꢀCu2 and Cu1ꢀ ꢀ ꢀCu3.
Since both iodide and 12 ligands participate in formation of a 1D
structure, we will classify the networking in [(CuI)2(12)] as I0.5O0.5
.
The ligand has undergone an oxidative cyclization 6 ? 12
(Scheme 1), converting the phenylthioamide portion into a benzo-
thiazole, with the pyrimdyl ring remaining unaffected. The two
Fig. 9. Thermal ellipsoid (50%) drawings of [Cu2(NO3)(13)2(MeCN)]NO3, two views.

4030
A. Saxena et al. / Polyhedron 28 (2009) 4017–4031
rings in the single independent 12 ligand are nearly coplanar
(interplanar angle = 2.2(2)°). They coordinate to the metal atoms
in bridging fashion through one nitrogen atom on each of the rings,
with a pair of ligands lying alongside each linear section of the zig-
zag stair-step. As is the case for the CuI(9) structure, the sulfur
atoms in the heterocyclic ring do not coordinate. A disordered half
molecule CH3CN of crystallization is also present.
When a solution of 10 in acetone was layered with a CuNO3/
CH3CN solution, two different crystalline products formed in
approximately equal proportions. While the orange blocks proved
to be the expected monomeric [Cu(10)2]NO3 described above,
coordination environment of Cu2 can be described as approxi-
mately trigonal planar, with coordination to two nitrogens from
13 and one from MeCN. However, the nominally trigonal N2–
Cu2–N6 angle is quite large (152.3(3)°). The remaining nitrate in
the crystal structure is neither coordinated nor hydrogen-bonded
to the cation. There is a rather close Cuꢀ ꢀ ꢀCu interaction of
2.672(7) Å which is certainly the result of the dinuclear bridging
arrangement forced by 13.
4. Conclusions
the yellow blades yielded
a surprising dinuclear structure:
The preparation of CuCl, CuBr, CuI, and CuNO3 complexes of var-
ious HetTu thiourea ligands has produced a variety of product stoi-
chiometries and structural types, including both monomeric and
polymeric species. Product CuX:HetTu stoichiometries ranged
from 1:1 to 1:5, with 1:1, 2:3, and 1:2 being most common. These
relatively copper-rich products are polymeric or networked in
some cases. The marked tendency for stoichiometrically distinct
products to result from bulk synthesis versus slow crystal growth
experiments emphasizes a propensity toward variable product for-
mulations. The full extent of this trend was not explored herein.
This study was undertaken with the intent of using the poten-
tially polydentate HetTu ligands to produce highly networked
MONs containing Cu(I). Therefore, it was surprising that simple,
3-coordinate CuX(HetTu)2 monomers were found in so many of
the structures. The versatility of the HetTu species as polydentate
ligands appears to be offset by several factors: (1) the relatively
weak donor ability of aromatic nitrogen atoms, (2) the relatively
large size of the HetTu ligands, (3) their proclivity to tie up lone
pairs through internal hydrogen-bond formation, and (4) a ten-
dency toward ligand oxidative cyclization. Finally, the copper(I)
ion’s willingness to remain 3-coordinate works against network
formation.
[Cu2(NO3)(13)2(MeCN)]NO3 (13 = dipyridyltetraazathiapentalene
[16]), Fig. 9. The structure of the unusual 13 molecule is known
[17]. It has previously been prepared via the reaction of 2-amino-
pyridine with carbon disulfide under air. Thus, in the present case,
the oxidation of some free 10 to 13 most likely took place during
the week-long crystallization experiment (Scheme 1).
The dinuclear structure shown in Fig. 9 represents the first re-
ported metal complex of 13. The bond lengths within the ligand
are only slightly altered from those of the free ligand, see Table
4. The major structural difference noted in 13 upon coordination
is that the two S–N bonds become much more alike, suggesting
greater
p-bond delocalization. It acts as a bidentate, bridging li-
gand through a pair of nitrogen atoms lying on the same side of
the ring system. As has been noted with the other thiazole ligands
in this study, the ring sulfur atoms do not coordinate. Both 13 li-
gands are relatively planar, the S1-bearing ring being slightly more
so. The maximum RMS deviation from planarity in the S1 ring is
0.0430(5) Å for C6, while that in the S2 ring is 0.119(5) Å for C16.
The two ligands are almost mutually coplanar (interplanar
angle = 6.46(6)°).
Given the neutral charge of 13 and the presence of two nitrate
ions in the structure, both copper atoms are clearly Cu(I). This con-
clusion is also supported by the Cu coordination geometries. Atom
Cu1 shows approximately linear coordination with two 13 nitro-
gen atoms (N1–Cu1–N5 = 164.0(2)°). However, it is also weakly
bonded to a nitrate atom in chelating fashion (Cu1ꢀ ꢀ ꢀO1 = 2.341(4),
Cu1ꢀ ꢀ ꢀO2 = 2.588(5) Å). Atom Cu2 shows slight positional disorder.
Its major position is elevated slightly from the ligand planes. How-
ever, there is a second weaker center of electron density about
0.23 Å beneath primary Cu2 site, lying roughly in the plane. The
Nevertheless, HetTu ligands were sometimes found to act as
network-formers. In such cases HetTu bridging was accomplished
via coordination of the thiourea sulfur atom and a ring nitrogen
atom. In addition, the well-known SAB behavior of thiourea sulfur
and/or halide (particularly iodide) was seen, resulting in polymer
or network formation. An overall bonding preference: thiocarbonyl
S ꢃ halide > heterocycle N > nitrate ꢄ heterocycle S, thiourea N
was noted for Cu(I).
Acknowledgements
Table 4
Comparison of selected patp bond distances (Å) and angles (°) between 13 [17] and
[Cu2(NO3)(13)2(MeCN)]NO3.
This research was supported in part by donors of the American
Chemical Society Petroleum Research Fund (44891-B3). We are in-
debted to NSF (CHE-0443345) and the College of William and Mary
for the purchase of the X-ray equipment.
N
c
N
d
C
a
C
c
C
b
Appendix A. Supplementary data
S
N
N
b
a
CCDC 734325, 734326, 734327, 734328, 734329, 734330,
734331, 734332, 734333, 734334 and 734335 contain the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.
13
[Cu2(NO3)(13)2(MeCN)]NO3
Ca–S
S–Na
S–Nb
1.782(3)
1.962(2)
1.889(2)
1.346(4)
1.353(3)
1.330(4)
1.331(3)
1.349(3)
1.352(3)
165.50(10)
82.26(12)
83.27(12)
1.770(5), 1.756(5)
1.942(5), 1.935(4)
1.938(5), 1.938(4)
1.355(7), 1.347(7)
1.370(7), 1.367(7)
1.323(7), 1.342(7)
1.343(7), 1.336(7)
1.367(7), 1.381(6)
1.347(7), 1.330(6)
165.14(19), 165.07(19)
82.6(2), 82.8(2)
Na–Cb
Cb–Nc
Nc–Ca
Ca–Nd
Nd–Cc
Cc–Nb
Na–S–Nb
Na–S–Ca
Ca–S–Nb
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.poly.2009.08.023.
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