Synthesis and characterization of oxorhenium(V)-'3 + 1' mixed thiolate [SNS]/[S] and [ONS]/[S] complexes

Article abstract of DOI:10.1016/S0020-1693(00)00209-7

The reaction of [ReOCl₃(PPh₃)₂] with the tridentate ligands 2,6-dithiomethylpyridine (4) or 6-thiomethyl-2-pyridinemethanol (5) and the appropriate monothiols, such as para-substituted benzenethiols (C₆H₄X-4-SH) (where X = F, Cl, Br and OCH₃) and para-substituted benzylmercaptans (C₆H₄X-4-CH₂SH) (where X = F, Cl and OCH₃) in the presence of Et₃N leads to the isolation of a series of integrated '3 + 1' oxorhenium(V) complexes. Similarly, reaction of [ReOCl₃(PPh₃)₂] with 2-mercaptopyridine and 4 afforded a cationic oxorhenium(V) complex, [ReO(η³-SCH₂C₅H₃NCH₂S)(η¹-C₅H₄NH-2-S)][Cl] (22). Crystal data for 10. C₁₃H₁₁BrNOS₃Re: triclinic, P1, a = 7.2909(5), b = 14.1978(9), c = 15.991(1) A?, α = 77.184(1), β = 86.588(1), γ = 75.507(1)°, V = 1562.69(18) A?³, Z = 4. For 16, C₁₃H₁₁ClNO₂S₂Re: orthorhombic, P2₁2₁2₁, a = 6.9728(6), b = 13.477(1), c = 15.761(1) A?, V = 1481.1(2) A?³, Z = 4. For 18, C₁₄H₁₄NO₃S₂Re: monoclinic, P2₁/c, a = 15.6512(14), b = 7.6678(7), c = 13.732(1) A?, β = 112.489(1)°, V = 1522.7(2) A?³, Z = 4. For 21, C₁₅H₁₆NO₃S₂Re: monoclinic, P2₁/c, a = 13.929(1), b = 7.741(1), c = 15.583(2) A?, β = 103.600(2)°, V = 1633.1(3) A?³, Z = 4. For 22, C₁₂H₁₁ClN₂OS₃Re: monoclinic, C2₁/c, a = 27.827(3), b = 8.529(1), c = 14.957(2) A?, β = 119.314(2)°, V = 3095.3(6) A?³, Z = 8. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(00)00209-7

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Inorganica Chimica Acta 307 (2000) 88–96
Synthesis and characterization of oxorhenium(V)–‘3+1’ mixed
thiolate [SNS]/[S] and [ONS]/[S] complexes. Crystal and molecular
structures of [ReO(h3-SCH2C5H3NCH2S)(h1-C6H4Br-4-S)],
[ReO(h3-SCH2C5H3NCH2O)(h1-C6H4X-4-S)] (X=Cl, OMe),
[ReO(h3-SCH2C5H3NCH2O)(h1-C6H4OCH3-4-CH2S)] and
[ReO(h3-SCH2C5H3NCH2S)(h1-C5H4NH-2-S)][Cl]
Xiaoyuan Chen a, Frank J. Femia a, John W. Babich b, Jon Zubieta a,*
a Department of Chemistry, Syracuse Uni6ersity, Syracuse, NY 13244, USA
b Biostream, Inc., 160 Second Street, Cambridge, MA 02142, USA
Received 11 February 2000; accepted 31 May 2000
Abstract
The reaction of [ReOCl3(PPh3)2] with the tridentate ligands 2,6-dithiomethylpyridine (4) or 6-thiomethyl-2-pyridinemethanol (5)
and the appropriate monothiols, such as para-substituted benzenethiols (C6H4X-4-SH) (where X=F, Cl, Br and OCH3) and
para-substituted benzylmercaptans (C6H4X-4-CH2SH) (where X=F, Cl and OCH3) in the presence of Et3N leads to the isolation
of a series of integrated ‘3+1’ oxorhenium(V) complexes. Similarly, reaction of [ReOCl3(PPh3)2] with 2-mercaptopyridine and 4
afforded a cationic oxorhenium(V) complex, [ReO(h3-SCH2C5H3NCH2S)(h1-C5H4NH-2-S)][Cl] (22). Crystal data for 10,
,
C13H11BrNOS3Re: triclinic, P1, a=7.2909(5), b=14.1978(9), c=15.991(1) A, h=77.184(1), i=86.588(1), k=75.507(1)°,
3
,
,
V=1562.69(18) A , Z=4. For 16, C13H11ClNO2S2Re: orthorhombic, P212121, a=6.9728(6), b=13.477(1), c=15.761(1) A,
3
,
,
V=1481.1(2) A , Z=4. For 18, C14H14NO3S2Re: monoclinic, P21/c, a=15.6512(14), b=7.6678(7), c=13.732(1) A, i=
112.489(1)°, V=1522.7(2) A , Z=4. For 21, C15H16NO3S2Re: monoclinic, P21/c, a=13.929(1), b=7.741(1), c=15.583(2) A,
i=103.600(2)°, V=1633.1(3) A , Z=4. For 22, C12H11ClN2OS3Re: monoclinic, C21/c, a=27.827(3), b=8.529(1), c=14.957(2)
A, i=119.314(2)°, V=3095.3(6) A , Z=8. © 2000 Elsevier Science S.A. All rights reserved.
3
,
,
3
,
3
,
,
Keywords: Crystal structures; Oxorhenium complexes; Mixed thiolate complexes
radiotherapeutic applications (186Re: Emax=1.07 MeV,
1/2=90 h; 188Re: Emax=2.12 MeV, t1/2=17 h) [2].
1. Introduction
t
Chemists have been actively involved in technetium and
rhenium coordination chemistry during the past few
decades to design materials as potential radiopharma-
ceuticals. Continuous efforts are still applied to find
efficient chelating systems for the [MO]3+ cores (M=
Tc and Re). A major class of technetium and rhenium
complexes involves a tetradentate N2S2 donor system to
the oxometal(V) core [3]. A considerable variety of such
complexes has been prepared, evaluated, modified, and
optimized in the attempt to achieve appropriate chemi-
cal stability, biomedical properties, and in vivo distribu-
tion behavior for specific imaging and therapy
purposes. More recently the so-called ‘3+1’ design, in
Technetium-99m has become the isotope of choice in
the development of diagnostic radioisotopes by virtue
of its optimal nuclear properties (g-emitter, Emax=140
keV, t1/2=6 h) and the advantage of radionuclide
availability through the molybdenum-99/technetium-
99m generator system [1]. Furthermore, the radionu-
clides of rhenium, the group 7 congener of Tc, are
b-emitters with properties which make them suitable for
* Corresponding author. Tel.: +1-315-443 2925; fax: +1-315-443
4070.
E-mail address: jazubiet@syr.edu (J. Zubieta).
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(00)00209-7

X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
89
which a neutral oxometal complex was prepared by
employing the mixed tridentate and monodentate ligands
with the appropriate MO(V) precursors. The advantage
of such a ‘3+1’ concept over N2S2 systems lies in the fact
that ‘3+1’ complexes lack syn and anti stereoisomers
that are often produced in the tetradentate oxorhenium
and technetium complexes. In addition, substituent mod-
ifications can be introduced at either the tridentate or
monodentate ligand or at both sites with ease, whereas
the attachment of a bifunctional linker onto a planar
tetradentate ligand usually requires tremendous amount
of synthetic effort [4].
Elmer Series 1600 FTIR. Elemental analysis for carbon,
hydrogen and nitrogen were carried out by Oneida
Research Services, Whitesboro, NY. Analytical thin-
layer chromatography (TLC) was performed with Merck
silica gel F-254 glass-backed plates. Visualization was
achieved by UV illumination. Flash chromatography
was performed according to Still [8] using Aldrich silica
gel (70–230 mesh). Ammonium perrhenate (Aldrich),
4-fluorobenzyl mercaptan (Lancaster), 4-chlorobenzyl
mercaptan (Aldrich), 4-methoxybenzyl mercaptan (Lan-
caster), benzenethiol (Aldrich), 4-fluorobenzenethiol
(Aldrich), 4-chlorobenzenethiol (Aldrich), 4-bromoben-
zenethiol (Aldrich), 4-methoxybenzenethiol (Aldrich),
and 2,6-pyridinedimethanol (Aldrich) were used as re-
ceived without further purification. ReOCl3(PPh3)2 was
prepared according to literature [9].
Several examples of ‘3+1’ 99mTc-oxo complexes incor-
porating biologically active fragments, such as tropane
or ketanserin mimetics, have been proposed as receptor-
binding tracers. All of these ‘3+1’ complexes contain a
dianionic tridentate ligand of the type [SXS], where
X=S, O, or N(R) and a monodentate thiol, which
usually bears a pharmacophore [5]. The major problem
accompanied with these ‘3+1’ systems was the relatively
poor in vitro and in vivo stability of these complexes in
whole blood due to metabolism and replacement of the
monothiol group through transchelation by glutathione
[6]. The rate of this metabolism is strongly dependent
upon fine-tuning of structural variation of tridentate/
monodentate ligands, especially of the tridentate ligand.
For example, [SN(CH3)S] donor complexes are signifi-
cantly more stable than SSS complexes. To better under-
stand the synergistic effects of ‘3+1’ type of oxometal
complexes, significant efforts to develop new tridentate
ligands must be undertaken. Up to now, very little has
been done on the [ONS] donor class of tridentate ligands
due to the difficulty of synthesis. We recently reported
a series of [ONS]/[S] ‘3+1’ ReO(V) complexes, exploit-
ing the tridentate Schiff-base [HOC6H4-2-C(H)=
NꢀC6H4-2-SH] ligand which afforded phenol oxygen,
imine nitrogen and benzene thiol as ONS donors. para-
Substituted benzenethiols or benzylmercaptans were
used as the monothiol donors [7]. As part of our
continuing development of the coordination chemistry of
Tc(V) and Re(V) complexes in order to provide new
methodology for radiolabeling of chemotatic peptides,
we now report herein on the synthesis and characteriza-
tion of a series of [XNS]/[S] ‘3+1’ complexes (where
X=O or S). The [SNS] tridentate ligand used in this
study is 2,6-dithiomethylpyridine (4) and the [ONS]
tridentate ligand is 6-thiomethyl-2-pyridinemethanol (5).
2.2. Synthesis
2.2.1. Preparation of 2,6-dibromomethylpyridine (2)
and 2-bromomethyl-6-pyridinemethanol (3)
2,6-Dibromomethylpyridine (2) and 2-bromomethyl-
6-pyridinemethanol (3) were prepared according to liter-
ature with modifications [10,11]. 2,6-Pyridinedimethanol
(5 g, 36 mmol) in 48% aqueous HBr (60 cm3) was heated
under gentle reflux for 10 h. The completeness of the
1
reaction was monitored by H NMR by the disappear-
ance of starting material. The resulting solution was
cooled to 0°C, and neutralized by addition of aqueous
sodium hydroxide (10 M, 60 cm3). The temperature was
kept below 5°C during the neutralization. The neutral-
ized mixture was then diluted to 200 cm3, and extracted
with CH2Cl2 (3×100 cm3). The combined extracts were
collected, washed with a saturated aqueous NaCl and
dried over Na2SO4. The solvent was removed under
reduced pressure to give a pink solid residue which was
purified by column chromatography on silica gel using
CH2Cl2 as eluent to give 3.72 g of 2 (39%, m.p. 88–89°C)
and 3.78 g of 3 (52%, m.p. 76–78°C). 1H NMR (CDCl3,
ppm) for 2: 4.54 (s, 4H, CH2Br), 7.37 (d, J=7.8 Hz, 2H,
1
pyrH meta), 7.71 (t, J=7.8 Hz, 1H, pyrH para). H
NMR (CDCl3, ppm) for 3: 3.70 (t, J=5.6 Hz, 1H, OH),
4.55 (s, 2H, CH2Br), 4.77 (d, J=5.6 Hz, 2H, CH2OH),
7.17 (d, J=8.1 Hz, 1H, pyrH ortho to CH2OH), 7.35 (d,
J=8.1 Hz, 1H, pyrH ortho to CH2Br), 7.70 (t, J=8.1
Hz, 1H, pyrH para). Caution!! Dibromide 2 and mono-
bromide 3 are strong lachrymators and trace amount of
each may be dermatic.
2. Experimental
2.2.2. Preparation of tridentate ligands 2,6-
dithiomethylpyridine (4) and 6-thiomethyl-2-
pyridinemethanol (5)
2.1. General considerations
NMR spectra were recorded on a Bruker DPX 300 (1H
300.10 MHz) spectrometer in CDCl3 (l 7.27 ppm). IR
spectra were recorded as KBr pellets with a Perkin–
2.2.2.1. Preparation of 2,6-dithiomethylpyridine (4). 2,6-
Dithiomethylpyridine (4) was prepared according to the

90
X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
method of Constable et al. [12] with minor modifica-
tions. After decomposition of 2,6-bis[(methylthiocar-
bamoylthio)methyl]pyridine using NaOH, the reaction
mixture was cooled to room temperature and neutral-
ized to pH 5 with concentrated hydrochloric acid and
extracted with chloroform (3×100 cm3). The combined
extracts were washed with H2O, and concentrated NaCl
solution and dried over MgSO4. The solvent was re-
moved under reduced pressure to give 4 as yellow oil.
Further column chromatographic purification was
made on silica gel using CHCl3 as the eluent under a
nitrogen atmosphere. The colorless syrup was stored
under nitrogen and solidified upon standing. Yield:
55%. B.p. 96–102°C/0.2 mmHg. 1H NMR (CDCl3,
ppm): 2.02 (t, J=7.9 Hz, 2H, –SH), 3.82 (d, J=7.9
Hz, 4H, CH2SH), 7.21 (d, J=7.8 Hz, 2H, pyrH meta),
7.62 (t, J=7.8 Hz, 1H, pyrH para). Anal. Calc. for
C7H9NS2: C, 49.1; H, 5.26; N, 8.19. Found: C, 49.3; H,
5.10; N, 8.30%.
or 6-thiomethyl-2-pyridinemethanol (5) in CHCl3 (0.1
M, 1 cm3) and the mixture was refluxed until the
green–yellow color of the precursor turned to grass-
green. After being cooled to room temperature, the
reaction mixture was washed with water. The organic
layer was separated from the mixture and dried over
Na2SO4. The volume was reduced to 3 cm3 and then
purified on silica gel column using gradient eluent (from
100% CHCl3 to 100% acetone).
2.2.3.1.
[ReOCl(p3-SCH2C5H3NCH2S)(PPh3)]
(6).
(Yield: 50 mg, 75%). FTIR (cm−1, KBr pellet): 968
(ReꢁO). Anal. Calc. for C25H22ClNOS2PRe: C, 44.9; H,
3.29; N, 2.09. Found: C, 44.5; H, 3.41; N, 2.02%.
2.2.3.2.
[ReOCl(p3-OCH2C5H3NCH2S)(PPh3)]
(7).
(Yield: 41 mg, 63%). FTIR (cm−1, KBr pellet): 970
(ReꢁO). Anal. Calc. for C25H22ClNO2SPRe: C, 46.0; H,
3.37; N, 2.15. Found: C, 45.8; H, 3.29; N, 2.30%.
2.2.2.2. Preparation of 6-thiomethyl-2-pyridinemethanol
(5). Although compound 5 has been reported in a
patent by one-pot reaction from 2,6-pyrid-
inedimethanol, thiourea and 48% HBr [13], we were
unable to repeat the reaction. Instead we developed the
following procedure: 2-bromomethyl-6-pydinemethanol
(3) (3 g, 14.9 mmol) and thiourea (1.18 g, 15.5 mmol)
were dissolved in EtOH (30 cm3) and the mixture was
heated to reflux for 8 h, after which the solution was
evaporated to dryness under reduced pressure to give a
pale yellow oil. The thiouronium salt 6-[(methylthiocar-
2.2.4. General procedure for the preparation of
[ReO(p3-SCH2C5H3NCH2S)(p1-C6H4X-4-S)] where
X=F(8), Cl(9), Br(10), and OCH3 (11)
To a stirred suspension of trichlorobis(triphenylphos-
phine)rhenium(V) oxide (83 mg, 0.1 mmol) in CHCl3
(30 cm3) was added dropwise with stirring a CHCl3
solution (5 cm3) consisting of one equivalent of 2,6-
dithiomethylpyridine (4) (1 M, 1 cm3) and one equiva-
lent of the benzenethiol [C6H4X-4-S] (X=F, Cl, Br,
and OCH3) (0.1 mmol). A reddish brown solution
formed immediately, which intensified when Et3N (2
drops) was added. The reaction was stirred under reflux
for 20 min, concentrated and purified by flash chro-
matography. The eluent first applied was CHCl3 to
remove PPh3 and trace amounts of unreacted thiols;
then 10% acetone–CHCl3 was used to obtain the
product as a reddish solid. X-ray quality crystals for
compound 10 were grown by slow diffusion of ethyl
ether into a solution of the compound dissolved in
minimum amount of CH2Cl2.
bamoylthio)methyl]-2-pyridinemethanol
was
then
treated with a solution of NaOH (1 g, 25 mmol) in H2O
(20 cm3) to give a clear solution. The solution was then
heated under reflux for 2 h in a stream of nitrogen. The
reaction mixture was then cooled to room temperature
and neutralized to pH 5 with concentrated HCl and
extracted with CHCl3 (3×100 cm3). The combined
extracts were washed with H2O, concentrated NaCl
solution, and the solvent removed in vacuo to give a
pale yellow oil which solidified upon standing in refrig-
erator overnight. Yield: 1.11 g (48%). M.p. 63–66°C
1
(dec.) H NMR (CDCl3, ppm): 3.85 (d, J=3Hz, 2H,
2.2.4.1.
[ReO(p3-SCH2C5H3NCH2S)(p1-C6H4F-4-S)]
CH2SH), 4.74 (s, 2H, CH2OH), 7.12 (d, J=7.8 Hz, 1H,
pyrH ortho to CH2SH), 7.26 (d, J=7.8 Hz, 1H, pyrH
ortho to CH2OH), 7.67 (t, J=7.8 Hz, 1H, pyrH para).
Anal. Calc. for C7H9NOS: C, 54.2; H, 5.81; N, 9.03.
Found: C, 54.4; H, 5.95; N, 9.08%.
(8). (Yield: 31 mg, 62%). FTIR (cm−1, KBr pellet): 963
1
(ReꢁO). H NMR (CDCl3, ppm): 4.97 (d, J=18 Hz,
2H, –SCH2), 5.2 (s br, 1H, –SCH2), 5.5 (s br, 1H,
–SCH2), 7.10 (dd, J=8.7 Hz, 2H, –SArH), 7.6–7.7
(dd, J=7.8 Hz, 2H, pyrH meta), 7.8 (d, J=7.8 Hz,
1H, pyrH para), 8.00 (dd, J=8.7 Hz, 2H, –SArH).
Anal. Calc. for C13H11NOFS3Re: C, 31.3; H, 2.21; N,
2.81. Found: C, 31.6; H, 2.18; N, 2.79%.
2.2.3. General procedure for the preparation of
[ReOCl(p3-XCH2C5H3NCH2S)(PPh3)] where X=S (6),
and X=O (7)
To a stirred suspension of trichlorobis(triphenylphos-
phine)rhenium(V) oxide (83 mg, 0.1 mmol) in chloro-
form (30 cm3) was added 2,6-dithiomethylpyridine (4)
2.2.4.2. [ReO(p3-SCH2C5H3NCH2S)(p1-C6H4Cl-4-S)]
(9). (Yield: 28 mg, 54%). FTIR (cm−1, KBr pellet): 965
1
(ReꢁO). H NMR (CDCl3, ppm): 4.98 (d, J=16 Hz,

X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
91
2H, –SCH2), 5.1–5.6 (m, 2H, –SCH2), 7.35 (d, J=8.4
Hz, 2H, –SArH), 7.61 (d, J=8.7 Hz, 2H, pyrH meta),
7.81 (d, J=8.7 Hz, 1H, pyrH para), 8.00 (dd, J=8.4
Hz, 2H, –SArH). Anal. Calc. for C13H11NOClS3Re: C,
30.3; H, 2.14; N, 2.72. Found: C, 30.6; H, 2.23; N,
2.88%.
J=15 Hz, 2H, –SCH2), 5.48 (d, J=15 Hz, 2H, –
SCH2), 7.32 (dd, J=8.7 Hz, 2H, –SArH), 7.61 (dd,
J=7.8 Hz, 2H, pyrH meta), 7.82 (d, J=7.8 Hz, 1H,
pyrH para), 8.05 (dd, J=7.6 Hz, 2H, –SArH). Anal.
Calc. for C14H13NOClS3Re: C, 31.8; H, 2.46; N, 2.65.
Found: C, 32.0; H, 2.37; N, 2.73%.
2.2.4.3. [ReO(p3-SCH2C5H3NCH2S)(p1-C6H4Br-4-S)]
(10). (Yield: 37 mg, 67%). FTIR (cm−1, KBr pellet):
965 (ReꢁO). H NMR (CDCl3, ppm): 4.97 (d, J=16
Hz, 2H, –SCH2), 5.1–5.6 (m, 2H, –SCH2), 7.45–7.60
(m, 4H, 2-SArH and 2 pyrH meta), 7.83 (d, J=8.7 Hz,
1H, pyrH para), 7.99 (dd, J=7.8 Hz, 2H, –SArH).
Anal. Calc. for C13H11NOBrS3Re: C, 27.9; H, 1.97; N,
2.50. Found: C, 28.0; H, 2.04; N, 2.39%.
2.2.5.3. [ReO(p3-SCH2C5H3NCH2S)(p1-C6H4OCH3-4-
CH2S)] (14). (Yield: 28 mg, 53%). FTIR (cm−1, KBr
pellet): 965 (ReꢁO). H NMR (CDCl3, ppm): 3.79 (s,
3H, –OCH3), 4.9–5.0 (m, 2H, –SCH2), 5.03 (d, J=15
Hz, 2H, –SCH2), 5.50 (d, J=15 Hz, 2H, –SCH2), 6.85
(d, J=7.8 Hz, 2H, –SArH), 7.35 (d, J=8.7 Hz, 2H,
pyrH meta), 7.62 (d, J=8.7 Hz, 1H, pyrH para), 8.00
(dd, J=7.8 Hz, 2H, –SArH). Anal. Calc. for
C15H16NO2S3Re: C, 34.4; H, 3.05; N, 2.67. Found: C,
34.2; H, 2.98; N, 2.81%.
1
1
2.2.4.4. [ReO(p3-SCH2C5H3NCH2S)(p1-C6H4OCH3-4-
S)] (11). (Yield: 33 mg, 65%). FTIR (cm−1, KBr pellet):
968 (ReꢁO). 1H NMR (CDCl3, ppm): 3.85 (s, 3H,
OCH3), 4.98 (d, J=15 Hz, 2H, –SCH2), 5.2 (s br, 1H,
–SCH2), 5.55 (s br, 1H, –SCH2), 6.96 (d, J=8.7 Hz,
2H, –SArH), 7.59 (d, J=8.7 Hz, 2H pyrH meta), 7.8
(m, 1H, pyrH para), 8.00 (dd, J=8.7 Hz, 2H, –SArH).
Anal. Calc. for C14H14NO2S3Re: C, 32.9; H, 2.75; N,
2.75. Found: C, 32.8; H, 2.83; N, 2.71%.
2.2.6. General procedure for the preparation of
[ReO(p3-SCH2C5H3NCH2O)(p1-C6H4X-4-S)] where
X=F(15), Cl(16), Br(17), and OCH3 (18)
To a stirred suspension of trichlorobis(triphenylphos-
phine)rhenium(V) oxide (83 mg, 0.1 mmol) in CHCl3
(30 cm3) was added dropwise with stirring a CHCl3
solution (5 cm3) consisting of one equivalent of 6-
thiomethyl-2-pyridinemethanol (5) in CHCl3 (0.1 M, 1
cm3) and one equivalent of the benzenethiol [C6H4X-4-
S] (X=F, Cl, Br, and OCH3) (0.1 mmol). Et3N (4
drops) was then added and the resulting solution was
refluxed for 20 min until the green–yellow color of the
precursor turned to reddish-brown. The dark red
product was purified as mentioned above for the [SNS]/
[S] analogs. X-ray quality crystals for compounds 16
and 18 were grown by slow diffusion of pentane into a
solution of the compounds dissolved in CH2Cl2.
2.2.5. General procedure for the preparation of
[ReO(p3-SCH2C5H3NCH2S)(p1-C6H4X-4-CH2S)]
where X=F(12), Cl(13), and OCH3 (14)
To
a
refluxing
solution
of
[ReOCl(h3-
SCH2C5H3NCH2S)(PPh3)] (6) (33.5 mg, 0.05 mmol) in
acetonitrile (10 cm3) was added dropwise a solution of
benzenethiol [C6H4X-4-CH2S] (X=F, Cl, and OCH3)
(0.1 mmol) in acetonitrile (3 cm3). The solution turned
from grass-green to wine-red color. Upon addition of
three drops of Et3N, the color of the reaction mixture
turned immediately from red to brown. The solution
was stirred and refluxed for an additional 15 min and
was then evaporated to dryness. The dark red residue
was purified by a short silica gel column similar to that
mentioned above.
2.2.6.1.
[ReO(p3-OCH2C5H3NCH2S)(p1-C6H4F-4-S)]
(15). (Yield: 27 mg, 57%). FTIR (cm−1, KBr pellet):
1
958 (ReꢁO). H NMR (CDCl3, ppm): 4.78 (d, J=16
Hz, 1H, –SCH2), 5.34 (s br, 1H, –OCH2), 6.0–6.2 (m,
2H, –SCH2 and–OCH2), 6.98 (d, J=7.8 Hz, 2H,
–SArH), 7.63 (d, J=8.7 Hz, 2H, pyrH meta), 7.81 (d,
J=8.7 Hz, 1H, pyrH para), 8.01 (dd, J=7.8 Hz, 2H,
–SArH). Anal. Calc. for C13H11NO2FS2Re: C, 32.4; H,
2.28; N, 2.90. Found: C, 32.5; H, 2.19; N, 3.01%.
2.2.5.1.
[ReO(p3-SCH2C5H3NCH2S)(p1-C6H4F-4-
CH2S)] (12). (Yield: 29 mg, 56%). FTIR (cm−1, KBr
1
pellet): 967 (ReꢁO). H NMR (CDCl3, ppm): 4.9–5.0
(m, 2H, –SCH2), 5.02 (d, J=16 Hz, 2H, –SCH2), 5.47
(d, J=16 Hz, 2H, –SCH2), 7.00 (dd, J=8.7 Hz, 2H,
–SArH), 7.69–7.74 (dd, J=5.6 Hz, 2H, pyrH meta),
7.83 (d, J=7.8 Hz, 1H, pyrH para), 8.00 (dd, J=7.6
Hz, 2H, –SArH). Anal. Calc. for C14H13NOFS3Re: C,
32.8; H, 2.54; N, 2.73. Found: C, 33.0; H, 2.48; N,
2.83%.
2.2.6.2. [ReO(p3-OCH2C5H3NCH2S)(p1-C6H4Cl-4-S)]
(16). (Yield: 31 mg, 64%). FTIR (cm−1, KBr pellet):
1
962 (ReꢁO). H NMR (CDCl3, ppm): 4.78 (d, J=16
Hz, 1H, –SCH2), 5.40 (s br, 1H, –OCH2), 6.0–6.2 (m,
2H, –SCH2 and–OCH2), 7.31 (d, J=7.8 Hz, 2H,
–SArH), 7.58 (d, J=8.7 Hz, 2H, pyrH meta), 7.84 (d,
J=8.7 Hz, 1H, pyrH para), 8.02 (dd, J=7.8 Hz, 2H,
2.2.5.2.
[ReO(p3–SCH2C5H3NCH2S)(p1-C6H4Cl-4-
CH2S)] (13). (Yield: 35 mg, 66%). FTIR (cm−1, KBr
1
pellet): 960 (ReꢁO). H NMR (CDCl3, ppm): 5.01 (d,

92
X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
–SArH). Anal. Calc. for C13H11NO2ClS2Re: C, 31.3; H,
2.21; N, 2.81. Found: C, 31.1; H, 2.35; N, 2.77%.
(s br, 1H, –OCH2), 6.0 (s br, 1H, –SCH2), 6.2 (s br,
1H, –OCH2), 7.34 (d, J=8.1 Hz, 2H, –SArH), 7.6–7.7
(dd, J=8.1 Hz, 2H, pyrH meta), 7.82 (d, J=8.1 Hz,
1H, pyrH para), 8.05 (dd, J=7.8 Hz, 2H, –SArH).
Anal. Calc. for C14H13NO2ClS2Re: C, 32.8; H, 2.54; N,
2.73. Found: C, 32.6; H, 2.35; N, 2.91%.
2.2.6.3. [ReO(p3-OCH2C5H3NCH2S)(p1-C6H4Br-4-S)]
(17). (Yield: 37 mg, 69%). FTIR (cm−1, KBr pellet):
1
956 (ReꢁO). H NMR (CDCl3, ppm): 4.81 (d, J=16
Hz, 1H, –SCH2) 5.45 (s br, 1H, –OCH2), 6.0–6.2 (m,
2H, –SCH2 and–OCH2), 7.48 (d, J=7.8 Hz, 2H,
–SArH), 7.60 (d, J=8.7 Hz, 2H, pyrH meta), 7.82 (d,
J=8.7 Hz, 1H, pyrH para), 8.00 (dd, J=7.8 Hz, 2H,
–SArH). Anal. Calc. for C13H11NO2BrS2Re: C, 28.7; H,
2.03; N, 2.58. Found: C, 28.6; H, 1.94; N, 2.51%.
2.2.7.3. [ReO(p3-OCH2C5H3NCH2S)(p1-C6H4OCH3-4-
CH2S)] (21). (Yield: 28 mg, 55%). FTIR (cm−1, KBr
pellet): 957 (ReꢁO). H NMR (CDCl3, ppm): 3.78 (s,
3H, –OCH3), 4.78 (d, J=18 Hz, 1H, –SCH2), 4.9–5.0
(m, 2H, –SCH2), 5.5 (m, 1H, –OCH2), 6.12(d, J=18
Hz, 1H, –SCH2), 6.25 (s br, 1H, –OCH2), 6.84 (d,
J=8.4 Hz, 2H, –SArH), 7.34 (d, J=7.8 Hz, 2H, pyrH
meta), 7.65, 7.81 (dd, J=7.8 Hz, 1H, pyrH para), 8.03
(dd, J=7.8 Hz, 2H, –SArH). Anal. Calc. for
C15H16NO3S2Re: C, 35.4; H, 3.15; N, 2.76. Found: C,
35.7; H, 3.03; N, 2.85%.
1
2.2.6.4. [ReO(p3–OCH2C5H3NCH2S)(p1-C6H4OCH3-4-
S)] (18). (Yield: 33 mg, 66%). FTIR (cm−1, KBr pellet):
962 (ReꢁO). 1H NMR (CDCl3, ppm): 3.84 (s, 3H,
–OCH3), 4.76 (d, J=18 Hz, 1H, –SCH2), 5.35 (s br,
1H, –OCH2), 6.10–6.25 (m, 2H, –SCH2 and–OCH2),
6.93 (d, J=8.7 Hz, 2H, –SArH), 7.60 (d, J=8.4 Hz,
2H, pyrH meta), 7.80 (dd, J=8.4 Hz, 1H, pyrH para),
8.02 (dd, J=8.7 Hz, 2H, –SArH). Anal. Calc. for
C14H14NO3S2Re: C, 34.0; H, 2.83; N, 2.83. Found: C,
33.9; H, 2.93; N, 2.80%.
2.2.8. Preparation of
[ReO(p3-SCH2C5H3NCH2S)(p1-C5H4NH-2-S)][Cl] (22)
To a solution of [ReOCl(h3-SCH2C5H3NCH2S)-
(PPh3)] (6) (20 mg, 0.03 mmol) in methanol (20 cm3)
was added 2-mercaptopyridine (11 mg, 0.1 mmol) and
the resulting mixture was refluxed for 30 min, and
subsequently evaporated to dryness. The pink residue
was dissolved in methanol and layered with ethyl ether
to form crystals of 22 suitable for X-ray crystallogra-
2.2.7. General procedure for the preparation of
[ReO(p3-OCH2C5H3NCH2S)(p1- C6H4X-4-CH2S)]
where X=F(19), Cl(20), and OCH3 (21)
To a refluxing solution of [ReOCl(h3-OCH2C5H3-
NCH2S)] (7) (33 mg, 0.05 mmol) in acetonitrile (10 cm3)
was added dropwise a solution of benzylmercaptan
[C6H4X-4-CH2S] (X=F, Cl, and OCH3) (0.1 mmol) in
acetonitrile (3 cm3). The solution turned from grass
green to reddish. Upon addition of 6 drops of Et3N, the
color of the reaction mixture turned immediately from
red to brown. The solution was stirred and refluxed for
an additional 45 min and then evaporated to dryness.
Column purification was similar to the procedure men-
tioned above. X-ray quality crystals for compound 21
were grown by slow diffusion of pentane in a solution
of the compounds dissolved in CH2Cl2.
phy. (Yield:
7
mg, 41%). Anal. Calc. for
C12H12ClN2OS3Re: C, 27.8; H, 2.32; N, 5.41. Found: C,
28.0; H, 2.18; N, 5.35%.
2.3. X-ray crystallography
The selected crystals of 10, 16, 18, 21 and 22 were
measured with a Siemens P4 diffractometer equipped
with the SMART CCD system [14] and using graphite-
,
monochromated Mo Ka radiation (u=0.71073 A). All
the data collections were carried out 89(5) K. The data
were corrected for Lorentz and polarization effects, and
absorption corrections were made using SADABS [15].
Neutral atom scattering factors were taken from
Cromer and Waber [16]. And anomalous dispersion
corrections were taken from those of Creagh and
McAuley [17]. All calculations were performed using
SHELXL [18]. The structures were solved by direct meth-
ods [19] and all of the non-hydrogen atoms were lo-
cated from the initial solution. After locating all the
initial nonhydrogen atoms in each structure, the models
were refined against F2, initially using isotropic and
later anisotropic thermal displacement parameters until
the final value of D/|max was less than 0.001. At this
point the hydrogen atoms were located from the elec-
tron density difference map and a final cycle of refine-
ments was performed, until the final value of D/|max
2.2.7.1.
[ReO(p3-OCH2C5H3NCH2S)(p1-C6H4F-4-
CH2S)] (19). (Yield: 31 mg, 57%). FTIR (cm−1, KBr
1
pellet): 960 (ReꢁO). H NMR (CDCl3, ppm): 4.79 (d,
J=18 Hz, 1H, –SCH2), 5.0 (m, 2H, –SCH2), 5.45 (s
br, 1H, –OCH2), 6.05–6.25 (m, 2H, –SCH2 and
–OCH2), 7.09 (dd, J=8.7 Hz, 2H, –SArH), 7.6–7.7
(dd, J=8.7 Hz, 2H, pyrH meta), 7.82 (dd, J=8.7 Hz,
1H, pyrH para), 8.06 (dd, J=7.8 Hz, 2H, –SArH).
Anal. Calc. for C14H13NO2ClS2Re: C, 33.9; H, 2.62; N,
2.82. Found: C, 34,0; H, 2.57; N, 2.95%.
2.2.7.2.
[ReO(p3-OCH2C5H3NCH2S)(p1-C6H4Cl-4-
CH2S)] (20). (Yield: 33 mg, 64%). FTIR (cm−1, KBr
1
pellet): 962 (ReꢁO). H NMR (CDCl3, ppm): 4.78 (d,
J=18 Hz, 1H, –SCH2), 4.9–5.0 (m, 2H, –SCH2), 5.5

X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
93
Table 1
Summary of crystal, intensity, collection, and refinement data for complexes [ReO(h3-SCH2C5H3NCH2S)(h1-C6H4Br-4-S)] (10), [ReO(h3-
SCH2C5H3NCH2O)(h1-C6H4-Cl-4-S)] (16), [ReO(h3-SCH2C5H3NCH2O)(h1-C6H4-OCH3-4-S)] (18), [ReO(h3-SCH2C5H3NCH2O)(h1-C6H4OCH3-
4-CH2S)] (21) and [ReO(h3-SCH2C5H3NCH2S)(h1-C5H4NH-2-S)][Cl] (22)
10
16
18
21
22
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
Unit cell dimensions
C13H11BrNOS3Re C13H11ClNO2S2Re C14H14NO3S2Re
C15H16NO3S2Re
508.61
0.5×0.1×0.04
monoclinic
P21/c
C12H11ClN2OS3Re
517.06
0.15×0.1×0.1
monoclinic
C21/c
559.52
499.00
494.58
0.1×0.1×0.05
triclinic
0.5×0.5×0.3
orthorhombic
P212121
0.2×0.1×0.04
monoclinic
P21/c
(
P1
,
a (A)
7.2909(5)
14.1978(9)
15.991(1)
77.184(1)
86.588(1)
75.507(1)
1562.7(2)
4
6.9728(6)
13.477(1)
15.761(1)
90
90
90
1481.1(2)
4
2.238
15.651(1)
7.6678(7)
13.732(1)
90
112.489(1)
90
1522.7(2)
4
2.157
13.930(1)
7.741(1)
15.583(2)
90
103.600(2)
90
1633.1(3)
4
2.069
27.827(3)
8.5287(10)
14.9574(18)
90
119.314(2)
90
3095.3(6)
8
2.219
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Dcalc (Mg m−1
F(000)
)
2.378
1048
944
944
976
1960
,
u (A)
0.71073
10.726
0.71073
8.665
0.71073
8.262
0.71073
7.706
0.71073
8.423
v (mm−1
)
q Range (°)
h, k, l
1.31–28.33
−9/9; −18/14;
−21/20
10612
7212
3.70
1.99–28.3
−9/8; −17/17;
−20/17
9872
3554
3.85
2.82–28.29
−20/15; −10/0;
−18/18
9618
3624
4.30
1.50–28.3
−18/18; −9/10;
−15/20
10178
3804
11.29
1.68–28.27
−32/36; −8/11;
−19/19
9964
3700
3.64
No. of reflections
No. of unique data
Rint (%)
Parameters refined
Final indices (2| data), R1
(wR2)
361
182
190
200
181
a
0.0414 (0.0927)
0.0312 (0.0761)
0.0473 (0.1168)
0.0658 (0.1746)
0.0256 (0.0579)
a
All data, R1 (wR2)
0.0597 (0.0996)
0.985
0.0319 (0.0764)
1.069
0.0522 (0.1200)
1.066
0.0685 (0.1780)
1.043
0.0340 (0.0603)
1.032
Goodness-of-fit, S (F2)
a R1=S(ꢀFoꢀ−ꢀFcꢀ)/SꢀFoꢀ, wR2=[S[w(Fo2−Fc2)2]/S[w(Fo2)2]]1/2
was again less than 0.001. No anomalies were encoun-
tered in the refinement of any of the structures. The
relevant parameters for crystal data, data collection,
structure solution and refinement are summarized in
Table 1, and important bond lengths and angles in
Table 2 and Table 3. A complete description of the
details of the crystallographic methods is given in Sec-
tion 5.
tuted benzyl mercaptan, two-step synthesis gives higher
yields of monophasic material than one-pot reaction. In
the first step of a two-step strategy, the labile precursor
[ReOCl3(PPh3)2] was reacted with equivalent amount of
Table 2
,
Selected bond distances (A) and angles (°) for complexes 10 and 22
10
22
ReꢀS(1)
ReꢀS(2)
ReꢀS(3)
ReꢀN(1)
ReꢀO(1)
2.290(2)
2.294(2)
2.306(2)
2.107(6)
1.690(5)
2.291(1)
2.292(1)
2.317(1)
2.105(3)
1.688(3)
3. Results and discussion
3.1. Synthesis and general properties
S(1)ꢀReꢀS(2)
S(1)ꢀReꢀS(3)
S(2)ꢀReꢀS(3)
S(1)ꢀReꢀN(1)
S(2)ꢀReꢀN(1)
S(3)ꢀReꢀN(1)
S(1)ꢀReꢀO(1)
S(2)ꢀReꢀO(1)
S(3)ꢀReꢀO(1)
N(1)ꢀReꢀO(1)
136.79(7)
89.84(7)
83.16(7)
81.35(17)
81.00(17)
145.63(18)
111.84(19)
110.96(19)
107.26(17)
106.9(2)
136.38(4)
90.29(4)
83.88(4)
81.18(9)
81.33(9)
147.81(9)
111.82(10)
111.31(10)
106.25(10)
105.74(13)
As shown in Fig. 1, the tridentate [SNS] (4) and
[ONS] (5) ligands can be synthesized from the dibro-
mide (2) and monobromide (3) precursors through the
thiouronium salts and subsequent decomposition under
basic condition. The ‘3+1’ complexes 8–22 can be
prepared using either one-pot or a two-step synthesis.
When the monothiolate ligand is a para-substituted
benzenethiol, one-pot synthesis is more effective. How-
ever, when the monothiolate ligand is a para-substi-

94
X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
Table 3
silica gel yielded the neutral 5-coordinated 16-electron
complexes [20].
,
Selected bond distances (A) and angles (°) for complexes 16, 18 and
21
Elemental analyses, as given in Section 2, were in
good agreement with the proposed formulations. The
IR spectra exhibit the characteristic ReꢁO stretching
vibration around 960 cm−1 [21]. Due to the symmetry
of the complexes 8–11 (vide infra), the corresponding
protons of the two methylene thiolate arms resonated
at the same frequency at room temperature. However,
germinal protons at the same methylene carbon of the
tridentate [SNS] backbone were distinguished as endo
(protons pointing toward the oxygen) and exo (protons
pointing away from the oxygen) [22,23]. Proton reso-
nances of the methylene backbone and pyridine ring
were all shifted downfield. The observed differences
between meta and para protons of the pyridine ring
decreased from 0.4 ppm in the uncomplexed form to
0.2 ppm in the oxorhenium complexes. The para-sub-
stituent on the aromatic ring of monothiolate ligands
had little effect on the chemical shifts of protons of the
chelated tridentate ligand backbone, since variation of
the para-substituent from F (8) to Br (10) to OCH3 (11)
produced no significant changes in the chemical shifts
of the ligand backbone atoms. This fact indicated that
electronic properties of the ring were not transmitted to
the chelated part of the ligand through the metal core
of this type of complex. Changing the monothiol ligand
from para-substituted benzenethiols to para-substituted
benzyl mercaptans resulted, again, in little influence on
the chemical shifts of the [SNS] ligand backbone. Be-
cause of the fast rotation of the benzyl methylene
group, no distinction between the two protons on this
carbon was observed at room temperature. A broad-
ened singlet was thus seen overlapping with the endo
protons of the methylene thiolate at around 5 ppm.
Two doublets were observed for the endo and exo
protons on the methylene thiolate backbone of the
[ONS]/[S] ‘3+1’ complexes. Despite the differences of
the monothiolate ligands, chemical shifts for the pro-
tons assigned to endo position of the methylene thiolate
of the [ONS] tridentate ligand was around 4.7 ppm, and
the exo position at 6.1 ppm. Due to the more rapid
rotational scrambling of the protons on the hydroxy-
methyl pyridine methylene carbon than the protons on
the methylene thiolate backbone, no sharp AB doublet
pattern was observable, but rather two broad coalesced
singlets were seen at approximately 5.4 ppm for the
endo proton and 6.3 ppm for the exo proton,
respectively.
16
18
21
ReꢀS(1)
ReꢀS(2)
ReꢀO(2)
ReꢀN(1)
ReꢀO(1)
2.268(2)
2.295(1)
1.987(4)
2.073(5)
1.675(5)
2.287(2)
2.285(2)
2.015(6)
2.063(7)
1.679(6)
2.289(2)
2.284(2)
2.042(5)
2.096(5)
1.693(5)
S(1)ꢀReꢀS(2)
S(1)ꢀReꢀO(2)
S(2)ꢀReꢀO(2)
S(1)ꢀReꢀN(1)
S(2)ꢀReꢀN(1)
O(2)ꢀReꢀN(1)
S(1)ꢀReꢀO(1)
S(2)ꢀReꢀO(1)
O(2)ꢀReꢀO(1)
N(1)ꢀReꢀO(1)
92.70(6)
136.49(13)
82.39(14)
80.69(16)
141.10(14)
76.93(19)
109.96(17)
107.90(16)
112.7(2)
87.31(8)
138.10(16)
87.83(15)
79.9(2)
141.00(17)
78.2(2)
109.6(2)
107.7(2)
111.5(3)
111.3(3)
87.84(7)
136.16(14)
88.56(13)
78.91(16)
142.88(7)
78.1(2)
109.60(19)
106.31(18)
113.3(2)
110.4(2)
110.8(2)
Fig. 1. Reaction scheme for the preparation of tridentate ligands 4
and 5. (a) 48% HBr; (b) (1) thiourea, EtOH; (2) NaOH.
Fig. 2. ORTEP drawing of [ReO(h3-SCH2C5H3NCH2S)(h1-C6H4Br-4-
S)] (10). Ellipsoids corresponds to 50% probability.
the tridentate ligand to give [ReOCl(h3-SCH2C5H3-
NCH2S)(PPh3)] (6) or [ReOCl(h3-OCH2C5H3NCH2S)-
(PPh3)] (7). The intermediate was then reacted with
excess amount of para-substituted benzylmercaptans in
refluxing chloroform with the existence of Et3N until
the original red color turned to dark brown. Purifica-
tion of the raw material via column chromatography on
3.2. Description of the structures
ORTEP diagrams of complexes 10, 16 and 22 are given
in Figs. 2–4, respectively. Selected bond distances and
angles for complexes 10 and 22 are given in Table 2.
Selected bond distances and angles for complexes 16, 18
and 21 are given in Table 3. The structure of 10, as

X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
95
the form (i−h)/60 to give a unitless value ranging
from 0 to 1 with ~=0 for perfect square pyramid, and
~=1 for ideal trigonal bipyramid. The ~ indices for the
rhenium mixed thiolate compounds of this study are
listed in Table 4. The ~ value for 10 is 0.147, which is
much lower than common [SSS]/[S] and [SOS]/[S] com-
plexes [25], but similar to those reported previously in
this laboratory in the investigation of [ONS] Schiff base
tridentate/monothiolate ‘3+1’ complexes [7]. The rhe-
shown in Fig. 2, is prototypical of ‘3+1’ complexes
with the [MO]3+ core. The rhenium site exhibits dis-
torted square pyramidal geometry with the basal plane
defined by the two sulfur donors and the pyridine
nitrogen donor of the NS2 tridentate ligand and thiolate
donor of the monodentate moiety and the apical posi-
tion occupied by the oxygen group. The distorted five-
coordinate geometry may be quantitatively evaluated
by using the trigonality index, ~, described by Addison
et al. [24]. The measurement uses the two largest angles
contained in the mean basal plane, which expressed in
,
nium atom is situated 0.742 A above the basal plane
defined by the four coordinated atoms.
As shown in Fig. 4, the structure of [ReO(h3-
SCH2C5H3NCH2S)(h1-C5H4NH-2-S)][Cl] (22) consists
of discrete complex cations and charge balancing Cl−
anions. The nature of the ligand, specifically the steric
requirement of the [SNS] tridentate ligand (4), the
inability of the tridentate ligand to occupy the idealized
equatorial positions while sterically blocking the sixth
potential coordination position, possibly from the
pyridyl nitrogen of potentially bidentate ligand, 2-mer-
captopyridine, as well as the trans influence of the axial
oxo-group, prohibits the formation of ‘3+2’ complexa-
tion geometry [26]. In common with 10, this cationic
complex also has a slightly distorted square pyramidal
coordination sphere for rhenium with a ~ value close to
Fig. 3. ORTEP drawing of [ReO(h3-OCH2C5H3NCH2S)(h1-C6H4Cl-4-
S)] (16). Ellipsoids corresponds to 50% probability.
,
0.2 and out-of-plane distance of 0.726 A defined by the
mean plane of four [SNS]/[S] coordination atoms.
Complexes 16, 18 and 21 are structurally identical
except for the difference of monothiolate ligand. They
all possess square pyramidal geometry with less distor-
tion (~B0.12) compared to those of [SNS]/[S] analogs
mentioned above. The out-of-plane distances for rhe-
nium from the basal plane of oxygen, nitrogen and two
,
sulfur atoms are 0.742, 0.737, and 0.740 A for 16, 18
and 21, respectively. The average bond lengths of
ReꢁO, ReꢀO, ReꢀN and ReꢀS are 1.682, 2.015, 2.078
Fig. 4. ORTEP drawing of [ReO(h3-OCH2C5H3NCH2S)(h1-C5H4NH-
2-S)][Cl] (22). Ellipsoids corresponds to 50% probability.
,
and 2.285 A, respectively. All the ReꢀS bonds are
identical within statistical limits. These values are agree-
ment with those of analogous oxorhenium complexes
observed [7].
Table 4
The ~ index for the five-coordinated rhenium complexes of this study,
as a measurement of geometric distortion from idealized geometries
a
b
c
Complex
h
i
~
4. Conclusions
[ReO(SꢀNꢀS)(C6H4Brꢀ4ꢀS)] (10)
[ReO(OꢀNꢀS)(C6H4Cl-4-S)] (16)
[ReO(OꢀNꢀS)(C6H4OCH3-4-S)] (18)
[ReO(OꢀNꢀS)(C6H4OCH3-4-CH2S)]
(21)
136.79 145.63 0.147
136.49 141.10 0.077
138.10 141.00 0.048
136.16 142.88 0.112
We have described the synthesis of a number of novel
‘3+1’ oxorhenium(V) complexes (8–22) using designed
tridentate ligands [SNS] 2,6–dithiomethylpyridine (4)
or [ONS] 6-thiomethyl-2-pyridinemethanol (5) in com-
bination with para-substituted benzenethiol or para-
substituted benzyl mercaptans. The 5-coordinated
16-electron complexes possess nearly ideal square pyra-
midal geometry. The series of complexes described here
may be considered as mimics for tetrahydrochrysene
(THC) and estradiol [27].
[ReO(SꢀNꢀS)(C5H4NH-2-S)][Cl] (22)
136.38 147.81 0.191
a hꢀthe second largest basal plane, S1ꢀReꢀS2 for 10 and 22,
S1ꢀReꢀO2 for 16, 18 and 21.
b iꢀthe largest basal plane, S3ꢀReꢀN1 for 10 and 22, S2ꢀReꢀN1
for 16, 18 and 21.
c ~ꢀ(i−h)/60. SꢀNꢀS=h3-SCH2C5H3NCH2S and OꢀNꢀS=h3-
OCH2C5H3NCH2S.

96
X. Chen et al. / Inorganica Chimica Acta 307 (2000) 88–96
Maresca, T.M. Shoup, J.W. Babich, J. Zubieta, Inorg. Chim.
5. Supplementary material
Acta, in press. (c) K.P. Maresca, G.H. Bonavia, J.W. Babich, J.
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All atomic and thermal parameters and all inter-
atomic angles are available from the author upon re-
quest. Crystallographic data (excluding structure
factor) for the structure reported in this paper have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 139786 to 139790. Copies of
this information may be obtained free of charge from:
The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (fax: +44-1223-336033; e-mail: deposit
@ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
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