Fac-tricarbonyl(pentylcarbonato)(α-diimine)rhenium complexes: One-pot synthesis, characterization, fluorescence studies, and cytotoxic activity against human MDA-MB-231 breast, CCl-227 colon and BxPC-3 pancreatic carcinoma cell lines

Article abstract of DOI:10.1016/j.inoche.2012.04.004

A series of pentylcarbonato complexes of the general formula fac-(CO) ₃(α-diimine)ReOC(O)O(CH₂)₄CH₃ (1-7) was synthesized from the reactions of Re₂(CO)₁₀ with the corresponding α-diimines in refluxed 1-pentanol while CO₂ was bubbled through the solutions. The α-diimines in 1-7 are 2,2′-bipyridyl, 1,10-phenanthroline, 5-methyl-1,10-phenanthroline, neocuproin, 5,6-dimethyl-1,10-phenanthroline, bathophenanthroline, and bathocuproin, respectively. Complexes 1-7 have been characterized spectroscopically and by elemental analyses. Additionally, 1 and 6 have been characterized in the solid state by X-ray crystallography. The electronic absorption spectra of 1-7 exhibit metal-to-ligand charge-transfer (MLCT) absorption maxima in the range 343-371 nm in acetonitrile. The emission maxima range from 513 to 532 nm. The average life-time and quantum yield are 1.074 ns and 0.011 respectively. Cytotoxicity studies using a few of these pentylcarbonato complexes reveal that the complexes are cytotoxic against BxPC-3 pancreatic, CCL-227 colon, and MDA-MB-231 breast cancer cell lines.

Full text of DOI:10.1016/j.inoche.2012.04.004

Inorganic Chemistry Communications 21 (2012) 35–38
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications
journal homepage: www.elsevier.com/locate/inoche
Fac-tricarbonyl(pentylcarbonato)(α-diimine)rhenium complexes:
One-pot synthesis, characterization, fluorescence studies, and cytotoxic activity
against human MDA-MB-231 breast, CCl-227 colon and BxPC-3 pancreatic carcinoma
cell lines
Michael K. Mbagu a, Divine N. Kebulu a, Angela Winstead a, Saroj K. Pramanik b, Hirendra N. Banerjee c,
Maurice O. Iwunze a, James M. Wachira b, George E. Greco d, Gregory K. Haynes a, Amanda Sehmer e,
Fazlul H. Sarkar f, Douglas M. Ho g, Robert D. Pike h, Santosh K. Mandal a,
⁎
a
Department of Chemistry, Morgan State University, Baltimore, MD 21251, USA
Department of Biology, Morgan State University, Baltimore, MD 21251, USA
Department of Biology, Elizabeth City State University, Elizabeth City, NC 27909, USA
Department of Chemistry, Goucher College, Baltimore, MD 21204, USA
Karmanos Cancer Institute, Detroit, MI 48201, USA
Department of Pathology, Wayne State University School of Medicine, Detroit, MI 48201, USA
Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
b
c
d
e
f
g
h
Department of Chemistry, College of William and Mary, Williamsburg, VA 23167, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of pentylcarbonato complexes of the general formula fac-(CO)3(α-diimine)ReOC(O)O(CH2)4CH3 (1–7)
was synthesized from the reactions of Re2(CO)10 with the corresponding α-diimines in refluxed 1-pentanol
while CO2 was bubbled through the solutions. The α-diimines in 1–7 are 2,2′-bipyridyl, 1,10-phenanthroline,
5-methyl-1,10-phenanthroline, neocuproin, 5,6-dimethyl-1,10-phenanthroline, bathophenanthroline, and
bathocuproin, respectively. Complexes 1–7 have been characterized spectroscopically and by elemental analy-
ses. Additionally, 1 and 6 have been characterized in the solid state by X-ray crystallography. The electronic ab-
sorption spectra of 1–7 exhibit metal-to-ligand charge-transfer (MLCT) absorption maxima in the range
343–371 nm in acetonitrile. The emission maxima range from 513 to 532 nm. The average life-time and quan-
tum yield are 1.074 ns and 0.011 respectively. Cytotoxicity studies using a few of these pentylcarbonato com-
plexes reveal that the complexes are cytotoxic against BxPC-3 pancreatic, CCL-227 colon, and MDA-MB-231
breast cancer cell lines.
Received 17 January 2012
Accepted 15 April 2012
Available online 23 April 2012
Keywords:
Fac-tricarbonyl(pentylcarbonato)(α-diimine)
rhenium complexes
X-ray
Fluorescence
BxPC-3 pancreatic cancer cell lines
CCL-227 colon cancer cell lines
MDA-MB-231 breast cancer cell lines
© 2012 Elsevier B.V. All rights reserved.
Transition metal alkylcarbonato complexes have found applications
in the conversion of methanol to dimethylcarbonate [1], synthesis of
dialkylcarbonates [2], and as the starting materials for the synthesis of
important organometallic complexes including perrhenato and amino
acid complexes [3]. A general method of synthesis of alkylcarbonato
complexes is to insert CO2 into the metal-alkoxide bond (M-OR) of an
alkoxo complex which is synthesized from the metathesis reaction of
a halo, triflato, or tosylato complex with an alkali metal alkoxide [4].
Although the chemistry of metal alkoxo complexes has been explored
in great detail, the chemistry including the photophysical properties and
biological applications of metal alkylcarbonato complexes is almost un-
known. Here, we report the one-pot synthesis of seven pentylcarbonato
complexes, fac-(CO)3(α-diimine)ReOC(O)OC5H11 (1–7), the X-ray struc-
tures of 1 and 6, and the fluorescence and cytotoxic properties of 1–7. The
α-diimines in 1–7 are 2,2′-bipyridyl, 1,10-phenanthroline, 5-methyl-
1,10-phenanthroline, neocuproin, 5,6-dimethyl-1,10-phenanthroline,
bathophenanthroline, and bathocuproin, respectively.
The reactions of Re2(CO)10 and α-diimines in 1-pentanol in the
presence of CO2 afforded the corresponding pentylcarbonato com-
plexes (1–7) in moderate to high yields according to Eq. (1) [5]:
⁎
Corresponding author. Tel.: +1 443 885 1665; fax: +1 443 885 8286.
E-mail addresses: mmbagu@gmail.com (MK.. Mbagu), kndode@yahoo.com
(DN.. Kebulu), angela.winstead@morgan.edu (A. Winstead), sarojpramanik@yahoo.ca
(SK.. Pramanik), bhirendranath@mail.ecsu.edu (HN.. Banerjee),
maurice.iwunze@morgan.edu (MO.. Iwunze), james.wachira@morgan.edu
(JM.. Wachira), ggreco@goucher.edu (GE.. Greco), gregory.haynes@morgan.edu
(GK.. Haynes), sehmera@karmanos.org (A. Sehmer), fsarkar@med.wayne.edu
(FH.. Sarkar), doug32009@gmail.com (DM.. Ho), rdpike@wm.edu (RD.. Pike),
santosh.mandal@gmail.com (SK.. Mandal).
Re2ðCOÞ10 þ 2 ðα−diimineÞ þ 2C5H11OH þ 2CO2→
ð1Þ
2 ðCOÞ3ðα−diimineÞReOCðOÞOC5H11ð1–7Þ þ 4CO þ H2
1387-7003/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2012.04.004

36
MK.. Mbagu et al. / Inorganic Chemistry Communications 21 (2012) 35–38
Table 1
Photophysical parameters of 1–7 in acetonitrile.
a
c
d
f
Complex
λmax
Çb ×10−3
λEx
λEm
Èe
ço
1
2
3
4
5
6
7
364
364
367.
357
371
343
363
1.549
1.489
1.254
1.529
1.199
3.682
4.834
327
372
376
386
384
371
448
532
530
529
527
530
529
513
0.023
0.009
0.011
0.011
0.004
0.019
0.002
2.359
1.151
1.60
1.031
0.560
0.802
0.015
a
Maximum wavelength, nm.
Molar absorptivity, M−1 cm−1
Excitation wavelength, nm.
Emission wavelength, nm.
Quantum yield.
b
c
d
e
f
.
Life-time, ns.
The reaction mechanism for the formation of 1–7 was not explored,
but one plausible scheme is that a [Re(CO)3(α-diimine)]2 dimer is ini-
tially formed which reacts with 1-pentanol to yield the corresponding
(CO)3(α-diimine)ReOC5H11 pentyloxo complex which then undergoes
CO2 insertion into the Re–O bond to ultimately produce fac-(CO)3(α-
diimine)ReOC(O)OC5H11. Due to the fac geometry, the IR spectrum of
each exhibits three strong ν(C`O)'s. Additionally, one medium intensi-
ty ν(C_O) is observed due to the \OC(_O)OC5H11 ligand. The 1H
NMR spectrum of each shows the characteristic resonances due to the
aliphatic protons of the C5H11 group. The 13C NMR spectrum of each ex-
hibits the two characteristic low-field resonances with an intensity ratio
of 2:1 due to three terminal C`O's, a low-field resonance due to the
C_O of the pentylcarbonato ligand and characteristic resonances due
to the aromatic and aliphatic carbons. The molecular structures of 1
and 6 were established by X-ray crystallography [6] and are shown in
Figs. 1 and 2, respectively. The Re atoms possess distorted octahedral
coordination geometries consisting of three carbonyls arranged in a fa-
cial fashion, a chelated α-diimine, and a monodentate pentylcarbonato
ligand. The axial Re\CO bond is slightly shorter than the equatorial
Re\CO bonds consistent with the pentylcarbonato ligand having a
slightly weaker trans-influence than the α-diimine ligand. The slight
lengthening in the C1\O1 bonds are also consistent with the slight
shortening in the axial Re\CO bonds. While small amounts of trans
CO/Cl disorder have been previously observed in related complexes
[7], there is no evidence of any comparable trans CO/OC(O)OC5H11 dis-
order in 1 or 6.
Fig. 1. The X-ray structure of 1. Selected bond lengths and angles (Å, °): Re1–C1
1.898(4), Re1–C2 1.921(5), Re1–C3 1.924(4), Re1–N1 2.178(3), Re1–N2 2.164(3),
Re1–O4 2.142(3), C1–O1 1.155(4), C2–O2 1.146(5), C3–O3 1.149(5), C4–O4 1.259(4),
C4–O5 1.358(4), C4–O6 1.223(4), C1–Re1–O4 173.9(3), C2–Re1–O4 90.7(4), C3–Re1–O4
98.0(3), N1–Re1–O4 84.9(4), N2–Re1–O4 80.2(3), N1–Re1–N2 74.87(12).
Although the UV–vis spectrum of any alkylcarbonato complex has
not been reported to-date, the UV–vis spectra of 1–7 are very similar to
those of analogous fac-tricarbonyl (α-diimine)rhenium(I) complexes
[8]. The higher energy absorptions are due to the expected diimine
ligand-centered π–π* transitions and the lowest energy absorptions are
due to metal-to-ligand charge-transfer (MLCT) transitions. Complexes
1–7 are luminescent in both solid-states and solutions. The emissions
Fig. 2. The X-ray structure of 6. Selected bond lengths and angles (Å, °): Re1–C1
1.911(7), Re1–C2 1.927(6), Re1–C3 1.934(6), Re1–N1 2.187(4), Re1–N2 2.195(4),
Re1–O4 2.157(3), C1–O1 1.157(8), C2–O2 1.141(8), C3–O3 1.141(7), C4–O4 1.274(7),
C4–O5 1.349(8), C4–O6 1.225(8), C1–Re1–O4 175.0(2), C2–Re1–O4 90.9(2), C3–Re1–O4
98.5(2), N1–Re1–O4 84.54(16), N2–Re1–O4 79.77(15), N1–Re1–N2 75.40(14).
Fig. 3. Pancreatic cancer cell lines, BxPC-3 exposed to various concentrations of 4 in
DMSO. Control represents cells exposed to DMSO only.

MK.. Mbagu et al. / Inorganic Chemistry Communications 21 (2012) 35–38
37
Program administered by the Oak Ridge Institute for Science and Educa-
tion. This project was also partially supported by Grant number
G11HD038439 from the Eunice Kennedy Shriver National Institute of
Child Health & Human Development of the National Institutes of Health.
Appendix A. Supplementary material
CCDC 749606 and CCDC 749607 contain the supplementary crys-
tallographic data for 1 and 6. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
Supplementary data to this article can be found online at doi:10.
1016/j.inoche.2012.04.004.
Fig. 4. Pancreatic cancer cell lines, BxPC-3 exposed to various concentrations of 6 in
DMSO for 72 h. Control represents cells exposed to DMSO only.
References
[1] C.A. Stewart, D.A. Dickie, R.A. Kemp, SANDIA REPORT: SAND2009-7228, 2009,
pp. 1–64, and the references cited therein.
[2] M. Kato, T. Ito, Inorg. Chem. 24 (1985) 504–508.
[3] (a) D.A. Brown, D.M. Kimari, A.M. Duzs-Moore, T.A. Budzichowski, D.M. Ho, S.K.
Mandal, J. Organomet. Chem. 658 (2002) 88–93;
(b) D.K. Orsa, M.O. Iwunze, S.K. Pramanik, G.E. Greco, S.K. Mandal, 238th ACS Na-
tional Meeting, Washington, D.C. August 16–20, 2009, INOR 311.
[4] S.K. Mandal, D.M. Ho, M. Orchin, Organometallics 12 (1993) 1714–1719.
are assigned predominantly to the excited states of 3MLCT (dπ(Re)→π*
(diimine)). The quantum yields and fluorescence life-times were deter-
mined according to published procedures [8]. The photophysical pa-
rameters of 1–7 in acetonitrile solutions are summarized in Table 1
(the higher energy ligand peaks are not included).
Cytotoxicity studies in DMSO [9] reveal that 4 and 6 are active
against BxPC-3 pancreatic cancer cell lines with IC50 being approxi-
mately 4 μM (see Figs. 3 and 4). Additional studies with 4 μM 1–7 indi-
cate that 1–4, 6 and 7 are active against CCL-227 colon and MDA-MB-
231 breast cancer cell lines. Interestingly, 6 and 7 are highly effective
against CCL-227 colon cancer cell lines and 1 is very effective against es-
trogen receptor-negative MDA-MB-231 breast cancer cell lines (Fig.5).
The mechanism of action involved is currently unknown, but presumably
does not involve DNA-binding based on a gel electrophoresis experiment
involving the incubation of 4 with DNA [10] and UV–vis spectra of a so-
lution of 4 and DNA in DMSO and phosphate buffer [10,11]. Detailed cy-
totoxicity studies employing a broader range of concentrations for 1–7
are in progress, as well as further studies to ascertain the mechanism
of action of these fac-tricarbonyl(α-diimine)rhenium(I) complexes.
The pentylcarbonato complexes (1–7) are stable in ordinary organic
solvents in the presence of CO2. However, they undergo deinsertion of
CO2 (b 5%) to produce the corresponding pentyloxo complexes, fac-
(CO)3(α-diimine)ReOC5H11 in the absence of CO2. When any of those
complexes (1–7) is dissolved in the cell culture medium and left
undisturbed for 72 h, the IR spectrum of the CH2Cl2-extract confirms the
presence of the pentylcarbonato complex (1–7) and the corresponding
[5] Synthesis of 1–7: In
a typical experiment a mixture of about 1.5 mmol of
Re2(CO)10 and 3.0 mmol of an α-diimine was refluxed in 50 mL of 1-pentanol
for 24–36 h while CO2 was bubbled through the solution. The mixture was cooled
to −5 °C. Microcrystals of 1–7 were collected through filtration. Data for 1: Yield,
83%. MP 198–201 °C. Anal. Calcd. for C19H19N2O6Re . 0.25 CH2Cl2: C, 39.95%; H,
3.39%; N, 4.84%. Found: C, 40.18%; H, 3.20%; N, 4.97%. IR (CH2Cl2, cm−1):
ν(C`O) 2024s, 1920s, 1896s; ν(C_O) 1661 m, br. 1H NMR (CDCl3, δ): 9.11 (s,
br, 2H, Bipy), 8.16 (s, br, 2H, Bipy), 8.00 (s, br, 2H, Bipy), 7.50 (s, br, 2H, Bipy),
3.78 (s, br, 2H, OCH2), 1.73–1.21 (m, 6H, CH2CH2CH2), 0.81 (s, br, 3H, CH3). 13C
NMR (CDCl3, δ): 197.5 (2C`O), 193.3 (C`O), 159.1 (C`O), 155.8 (Bipy), 153.8
(Bipy), 139.1 (Bipy), 126.9 (Bipy), 122.9 (Bipy), 66.4 (\OCH2), 28.8 (\OCH2CH2),
28.0 (CH2CH2CH3), 22.4 (CH2CH3), 14.0 (CH3). Data for 2: Yield, 66%. MP
218–20 °C. Anal. Calcd. for C21H19N2O6Re . 0.15 CH2Cl2: C, 42.74%; H, 3.27%; N,
4.71%. Found: C, 42.87%; H, 2.94%; N, 4.81%. IR (CH2Cl2, cm−1): ν(C`O) 2024s,
1920s, 1896s; ν(C_O) 1660 m, br. 1H NMR (CDCl3, δ): 9.50 (s, br, 2H, Phen), 8.53
(s, br, 2H, Phen), 7.99 (s, br, 2H, Phen), 7.84 (s, br, 2H, Phen), 3.73 (s, br, 2H,
−OCH2), 1.62–1.16(m, 6H, CH2CH2CH2), 0.79 (s, br, 3H, CH3). 13C NMR (CDCl3,
δ): 197.5 (2C`O), 193.5 (C`O), 159.2 (C_O), 153.9 (Phen), 147.2 (Phen), 138.2
(Phen), 130.6 (Phen), 127.5 (Phen), 125.7 (Phen), 66.4 (\OCH2), 28.8
(−OCH2CH2), 28.0 (CH2CH2CH3), 22.4 (CH2CH3), 14.0 (CH3). Data for 3: Yield,
81%. MP 180–84 °C. Anal. Calcd. for C22H21N2O6Re: C, 44.36%; H, 3.55%; N, 4.70%.
Found: C, 44.45; H, 3.32%; N, 4.71%. IR (CH2Cl2, cm−1): ν(C`O) 2023s, 1919s,
1895s; ν(C_O) 1661 m, br. 1H NMR (CDCl3, δ): 9.37 (dd, 1H, J=5.1, 1.3 Hz), 9.37
(dd, 1H, J=5.1, 1.3 Hz), 8.66 (dd, 1H, J=8.5, 1.3 Hz), 8.44 (dd, 1H, J=8.2 Hz,
1.3 Hz), 7.87 (dd, 1H, J=8.4, 5.1 Hz), 7.80 (s, 1H), 7.79 (dd, 1H, J=8.2, 5.1 Hz), 3.72
(t, 2H, J=7.1 Hz, \OCH2), 2.84 (d, 3H, J=0.7 Hz, H3C-Phen), 1.42 (quint, 2H,
J=7.2 Hz, -OCH2CH2), 1.22–1.11 (m, 4H, \CH2CH2CH3), 0.80 (t, 3 H, J=5.5 Hz, CH3).
13C NMR (CDCl3, δ): 197.6 (2C`O), 193.4 (C`O), 159.2 (C_O), 153.4 (Phen), 152.9
(Phen), 147.4 (Phen), 146.5 (Phen), 137.5 (Phen), 135.3 (Phen), 135.2 (Phen), 130.9
(Phen), 130.3 (Phen), 126.4 (Phen), 125.7 (Phen), 125.5 (Phen), 66.4 (\OCH2), 28.8
(\OCH2CH2), 28.0 (CH2CH2CH3), 22.4 (CH2CH3), 18.8 (H3C-Phen), 14.0 (CH3). Data
for 4: Yield, 76%. MP 175–78 °C. Anal. Calcd. for C23H23N2O6Re: C, 45.31%; H, 3.80%;
N, 4.59%. Found: C, 45.07%; H, 3.56%; N, 4.62%. IR (CH2Cl2, cm−1): ν(C`O) 2023s,
1916s, 1894s; ν(C_O) 1661 m, br. 1H NMR (CDCl3, δ): 8.29 (d, 2H, J=8.3 Hz), 7.80
(s, 1H), 7.68 (d, 2H, J=8.3 Hz), 3.59 (t, 2H, J=6.9 Hz, \OCH2), 3.34 (s, 3H, H3C-
Phen), 1.29 (quint, 2H, J=7.2 Hz, \OCH2CH2), 1.14 (m, 2 H, \CH2CH2CH3), 1.03 (m,
2 H, \CH2CH3), 0.77 (t, 3H, J=7.2 Hz, CH3). 13C NMR (CDCl3, δ): 197.2 (2C`O),
193.3 (C`O), 164.1 (C_O), 158.8 (Phen), 148.0 (Phen), 138.5 (Phen), 128.7 (Phen),
126.3 (Phen), 126.0 (Phen), 66.1 (\OCH2), 30.9 (H3C-Phen), 28.7 (\OCH2CH2), 27.9
(CH2CH2CH3), 22.3 (CH2CH3), 14.0 (CH3). Data for 5: Yield, 66%. MP 210–13 °C. Anal.
Calcd. for C23H23N2O6Re . 0.20 CH2Cl2: C, 44.47%; H, 3.76%; N, 4.47%. Found: C,
44.77%; H, 3.44%; N, 4.57%. IR (CH2Cl2, cm−1): ν(C`O) 2022s, 1918s, 1894s;
ν(C_O) 1661 m, br. 1H NMR (CDCl3, δ): 9.39 (dd, 2H, J=5.0, 1.3 Hz), 8.70 (dd, 2H,
J=8.6, 1.3 Hz), 7.83 (dd, 2H, J=8.6, 5.0 Hz), 3.71 (t, 2H, J=7.1 Hz, \OCH2), 2.80
(s, 3H, H3C-Phen), 1.41 (quint, 2H, J=7.2 Hz, \OCH2CH2), 1.22–1.11 (m, 4H,
\CH2CH2CH3), 0.78 (t, 3H, J=7.2 Hz, CH3). 13C NMR (CDCl3, δ): 197.8
(2C`O), 193.5 (C`O), 159.1 (C_O), 152.5 (Phen), 146.4 (Phen), 135.0
(Phen), 131.5 (Phen), 131.1 (Phen), 125.4 (Phen), 66.3 (\OCH2), 28.8 (\OCH2CH2),
28.0 (CH2CH2CH3), 22.4 (CH2CH3), 15.4 (H3C-Phen), 14.0 (CH3). Data for 6: Yield,
72%. MP 150–52 °C. Anal. Calcd. for C33H27N2O6Re: C, 54.02%; H, 3.71%; N,
3.82%. Found: C, 53.95%; H, 3.50%; N, 3.84%. IR (CH2Cl2, cm−1): ν(C`O) 2022s,
1919s, 1894s; ν(C_O) 1660 m, br. 1H NMR (CDCl3, δ): 9.49 (d, 2H, J=5.3 Hz, Phen),
8.05(s), 7.78 (d, 2H, J=5.3 Hz, Phen), 7.63–7.60 (m, 6H, C6H5), 7.56–7.54 (m, 4H,
C6H5), 3.80 (t, 2H, J=7.1 Hz, \OCH2), 1.49 (quint, 2H, J=7.3 Hz, \OCH2CH2),
1.22–1.11 (m, 4H, −CH2CH2CH3), 0.80 (t, 3H, J=6.9 Hz, CH3). 13C NMR (CDCl3, δ):
197.7 (2C`O), 193.6 (C`O), 159.1 (C_O), 153.1 (Phen), 151.2 (Phen), 147.7
(Phen), 135.4 (C6H5), 129.8 (C6H5), 129.4 (C6H5), 129.1 (C6H5), 128.7 (Phen), 125.7
pentyloxo complex, fac-(CO)3(α-diimine)ReOC5H11
.
Acknowledgment
This research was supported in part by an appointment to the US
Nuclear Regulatory Commission's HBCU Faculty Research Participation
Fig. 5. Colon cancer cell lines CCL-227 (blue) and breast cancer cell lines MDA-MB-231
(red) were exposed to 4 μM DMSO solutions of 1–7 for 72 h.

38
MK.. Mbagu et al. / Inorganic Chemistry Communications 21 (2012) 35–38
(Phen), 125.4 (Phen), 66.3 (\OCH2), 28.7 (\OCH2CH2), 27.9 (CH2CH2CH3), 22.3
(CH2CH3), 13.9 (CH3). Data for 7: Yield, 83%. MP 166–69 °C. Anal. Calcd. for
35H31N2O6Re . 0.60 CH2Cl2: C, 52.60%; H, 3.99%; N, 3.45%. Found: C, 52.67%; H,
variables=885, number of restraints=368, R=0.0240, Rw =0.0548, and
goodness-of-fit=1.056. There are two independent molecules in the asymmetric
unit of 6. Both of those molecules contain disordered pentylcarbonato ligands
which were treated with two-site disorder models. The refined site occupancy
factors were 0.52 (2) and 0.48 (2) for the major and minor components of the
disorder in one of the two molecules and 0.63 (2) and 0.37 (2) in the other.
[7] (a) S.F. Haddad, J.A. Marshall, G.A. Crosby, B. Twamley, Acta Crystallogr. E58
(2002) m559–m561;
C
3.66%; N, 3.51%. IR (CH2Cl2, cm−1): ν(C`O) 2022s, 1914s, 1893s; ν(C_O) 1661 m,
br. 1H NMR (CDCl3, δ): 7.85 (s, 2H, Phen), 7.67(s, 2H, Phen), 7.58–7.56 (m, 6H,
C6H5), 7.51–7.48 (m, 4H, C6H5), 3.65 (t, 2 H, J=7.1 Hz, \OCH2), 3.41 (s, H3C-
Phen), 1.36 (quint, 2H, J=7.1 Hz, \OCH2CH2), 1.18–1.07 (m, 4H, \CH2CH2CH3),
0.77 (t, 3H, J=7.1 Hz, CH3). 13C NMR (CDCl3, δ): 197.4 (2C`O), 193.6 (C`O),
163.3 (C_O), 158.9 (Phen), 151.0 (phen), 148.9 (Phen), 136.0 (C6H5), 129.6
(C6H5), 129.4 (C6H5), 129.0 (C6H5), 127.1 (Phen), 126.2 (Phen), 124.2 (Phen), 66.2
(\OCH2), 31.2 (H3C-Phen), 28.8 (\OCH2CH2), 28.0 (CH2CH2CH3), 22.4 (CH2CH3),
14.0
(b) D.K. Orsa, G.K. Haynes, S.K. Pramanik, M.O. Iwunze, G.E. Greco, D.M. Ho, J.A.
Krause, D.A. Hill, R.J. Williams, S.K. Mandal, Inorg. Chem. Commun. 11
(2008) 1054–1056.
[8] See reference 7(b) above and the references 6, 12–14 cited in reference 7(b).
[9] (a) For Trypan Blue assay, see:D.K. Orsa, G.K. Haynes, S.K. Pramanik, M.O.
Iwunze, G.E. Greco, J.A. Krause, D.M. Ho, A.L. Williams, D.A. Hill, S.K.
Mandal, Inorg. Chem. Commun. 10 (2007) 821–824;
[6] Crystal data for 1:
C19H19N2O6Re, M=557.56, orange needle, 0.07×0.08
×0.12 mm3, monoclinic, space group P21/n (No. 14), a=6.3714 (3) Å,
b=17.6930 (7) Å, c=16.9114 (7) Å, β=91.712 (2)°, V=1905.56 (14) Å3,
Z=4, T=200 (2) K, 23826 reflections total, 5559 unique, 4296 observed, number
(b) For MTT assay, see:A.S. Azmi, S. Ali, S. Banerjee, B. Bao, M. Maitah, S. Padhye,
P.A. Philip, R.M. Mohammad, F.H. Sarkar, Am. J. Transl. Res. 3 (2011) 374–382
and the references 7 and 8 cited therein.
of variables=337, number of restraints=293, R=0.0303,
Rw =0.0767, and
goodness-of-fit=1.038. The pentylcarbonato ligand was treated with a two-site
disorder model with refined site occupancy factors of 0.51 (2) and 0.49 (2), re-
[10] A.N. Glazer, K. Peck, R.A. Mathies, Proc. Natl. Acad. Sci. U. S. A. 87 (1990)
3851–3855.
[11] J.L. Kgokong, J.M. Wachira, Eur. J. Pharm. Sci. 12 (2001) 369–376.
spectively. Crystal data for 6:
C33H27N2O6Re, M=733.77, yellow blade,
0.05×0.18×0.56 mm3, monoclinic, space group Pn (No. 7), a=12.1682 (7) Å,
b=13.7618 (8) Å, c=18.6496 (12) Å, β=90.997 (3)°, V=3122.5 (3) Å3, Z=4,
T=296 (2) K, 30766 reflections total, 8648 unique, 8282 observed, number of