Rhenium tricarbonyl complexes of tris(pyrazolyl)methane ligands: First structural characterization of an isomer pair of tris(pyrazolyl)methane derivatives and the supramolecular structure of the homobimetallic complex

Article abstract of DOI:10.1016/S0022-328X(02)01620-0

The reaction of either HC(pz)₃, HC(3,5-Me₂pz)₃, HC(3-Phpz)₃, or a 4:1 HC(3-i-Prpz)₃-HC(3-i-Prpz)₂ (5-i-Prpz) mixture (pz = pyrazolyl ring) and Re(CO)₅Br results in the formation of {[HC(pz) ₃] Re(CO)₃}Br (1), {[HC(3,5-Me₂pz) ₃]Re(CO)₃}Br (3), {[HC(3-Phpz)₃]Re(CO)₃}Br (4), {[HC(3-i-Prpz)₃]Re(CO)₃}Br (5), and {[HC(3-i-Prpz)₂(5-i-Prpz)]Re(CO)₃}Br (6). The reaction of PhC(pz)₂(py) (py = pyridyl ring) and Re(CO)₅Br yields {[PhC(pz)₂(py)]Re (CO)₃}Br (9) while a reaction of Re(CO)₅Br and 1,4-C₆H₄ [CH₂OCH₂C (pz)₃]₂ in a 2:1 mol ratio gives {1,4-C₆H₄[CH₂OCH₂C(pz) ₃]₂ [Re(CO)₃]₂} (Br)₂(10). The reaction of Re(CO)₅Br and AgBF₄ followed by addition of either HC(pz)₃ or the 4:1 HC(3-i-Prpz)₃-HC (3-i-Prpz)₂(5-i-Prpz) mixture results in the preparation of {[HC(pz)₃]Re(CO)₃}BF₄ (2), {[HC(3-i-Prpz)₃]Re(CO)₃}BF₄ (7), and {[HC(3-i-Prpz)₂(5-i-Prpz)]Re(CO)₃}BF₄ (8), respectively. The carbonyl stretching frequencies in all of these complexes are similar, with the exception of 9, which has much lower values. The methine hydrogen atoms of compounds 1, 5, and 6 show deshielded chemical shift values as a result of hydrogen-bonding interactions with the bromide counterion. The solid state structures of the isomeric pair 5 and 6 have very similar bond angles and distances about the metal and show weak hydrogen-bonding interactions between the Br^- anion and the methine hydrogen. The structure of the bimetallic complex, 10, in which two [Re(CO)₃]⁺ units are linked by the bitopic ligand, is organized by π-π and (C)H?π interactions into a two-dimensional supramolecular network of two interpenetrating 'zigzag' chains.

Full text of DOI:10.1016/S0022-328X(02)01620-0

Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
www.elsevier.com/locate/jorganchem
Rhenium tricarbonyl complexes of tris(pyrazolyl)methane ligands:
first structural characterization of an isomer pair of
tris(pyrazolyl)methane derivatives and the supramolecular
structure of the homobimetallic complex {1,4-
C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}(Br)2
Daniel L. Reger *, Kenneth J. Brown, Mark D. Smith
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
Received 15 April 2002; received in revised form 17 May 2002; accepted 17 May 2002
Abstract
The reaction of either HC(pz)3, HC(3,5-Me2pz)3, HC(3-Phpz)3, or a 4:1 HC(3-i-Prpz)3ꢀ
pyrazolyl ring) and Re(CO)5Br results in the formation of {[HC(pz)3]Re(CO)3}Br (1), {[HC(3,5-Me2pz)3]Re(CO)3}Br (3), {[HC(3-
/
HC(3-i-Prpz)2(5-i-Prpz) mixture (pzꢁ
/
Phpz)3]Re(CO)3}Br (4), {[HC(3-i-Prpz)3]Re(CO)3}Br (5), and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br (6). The reaction of
PhC(pz)2(py) (pyꢁ
C6H4[CH2OCH2C(pz)3]2 in a 2:1 mol ratio gives {1,4-C6H4[CH2OCH2C(pz)3]2 [Re(CO)3]2}(Br)2 (10). The reaction of Re(CO)5Br
and AgBF4 followed by addition of either HC(pz)3 or the 4:1 HC(3-i-Prpz)3ꢀHC(3-i-Prpz)2(5-i-Prpz) mixture results in the
/pyridyl ring) and Re(CO)5Br yields {[PhC(pz)2(py)]Re(CO)3}Br (9) while a reaction of Re(CO)5Br and 1,4-
/
preparation of {[HC(pz)3]Re(CO)3}BF4 (2), {[HC(3-i-Prpz)3]Re(CO)3}BF4 (7), and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}BF4 (8),
respectively. The carbonyl stretching frequencies in all of these complexes are similar, with the exception of 9, which has much lower
values. The methine hydrogen atoms of compounds 1, 5, and 6 show deshielded chemical shift values as a result of hydrogen-
bonding interactions with the bromide counterion. The solid state structures of the isomeric pair 5 and 6 have very similar bond
angles and distances about the metal and show weak hydrogen-bonding interactions between the Brꢂ anion and the methine
hydrogen. The structure of the bimetallic complex, 10, in which two [Re(CO)3]ꢃ units are linked by the bitopic ligand, is organized
by pꢀ
/
p and (C)Hꢀ ꢀ ꢀp interactions into a two-dimensional supramolecular network of two interpenetrating ‘zigzag’ chains. # 2002
Published by Elsevier Science B.V.
Keywords: Tris(pyrazolyl)methane ligands; Rhenium carbonyl complexes; Supramolecular structure
1. Introduction
reason the tris(pyrazolyl)methane ligands have not been
studied as extensively as the tris(pyrazolyl)borate li-
gands is that their preparations have been more difficult,
and ‘second generation’ tris(pyrazolyl)methane ligands
with bulky substituents at the third-position of the
pyrazolyl ring have only recently been synthesized [3].
We have recently reported substantial improvements in
the preparations of these ligands and have developed
chemistry where the central methine carbon atom can be
functionalized with groups other than a hydrogen atom
[3c].
We have been exploring the chemistry of metal
complexes of tris(pyrazolyl)methane ligands [1], a tripo-
dal neutral ligand set isoelectronic with the more heavily
studied tris(pyrazolyl)borate ligands [2]. The primary
* Corresponding author. Tel.: ꢃ
9521
E-mail address: reger@mail.chem.sc.edu (D.L. Reger).
/
1-803-777-2587; fax: ꢃ1-803-777-
/
0022-328X/02/$ - see front matter # 2002 Published by Elsevier Science B.V.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 6 2 0 - 0

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An additional driving force for this research is our
recent development of ether-linked bitopic
tris(pyrazolyl)methane ligands, such as 1,4-C6H4[CH2-
OCH2C(pz)3]2 [6], that allow for the syntheses of
bimetallic species and coordination polymers that
should have very interesting physical properties. To
this end, we report here the synthesis and supramole-
cular structure of {1,4-C6H4[CH2OCH2C(pz)3]2-
[Re(CO)3]2}(Br)2.
We are interested in using these ligands to develop
new organometallic compounds of rhenium due to
potentially interesting electrochemical, photophysical,
and photochemical properties that make them promis-
ing candidates for ‘next-generation’ optical switches and
chemical sensors [4]. In addition, the favorable nuclear
2. Results and discussion
The reaction between Re(CO)5Br and either HC(pz)3,
HC(3,5-Me2pz)3, HC(3-Phpz)3, or a 4:1 HC(3-i-Prpz)3ꢀ
HC(3-i-Prpz)2(5-i-Prpz) mixture in toluene results in the
formation of {[HC(pz)3]Re(CO)3}Br (1), {[HC(3,5-
Me2pz)3]Re(CO)3}Br (3), {[HC(3-Phpz)3]Re(CO)3}Br
(4), {[HC(3-i-Prpz)3]Re(CO)3}Br (5), and {[HC(3-i-
Prpz)2(5-i-Prpz)]Re(CO)3}Br (6) (Eq. (1)).
/
properties of the b-emitting nuclides 188Re (t1/2
h) and 186Re (t1/2
3.78 days) have spawned interest in
their potential use as therapeutic agents in nuclear
medicine [4cꢀe]. Previously, we have reported the
ꢁ
/
16.94
ꢁ
/
/
syntheses of a series of manganese tricarbonyl com-
plexes containing the tris(pyrazolyl)methane ligands
[3c]. The complexes were synthesized in high yield and
were found to be very stable. The only analogous report
in rhenium chemistry is the very recent communication
of the solid state structures of {[HC(pz)3]Re(CO)3}Br
and {[MeC(pz)3]Re(CO)3}I [5].
Reported here are the syntheses of the series of
ð1Þ
complexes [LRe(CO)3]ꢃ (Lꢁ
/
HC(pz)3, HC(3,5-Me2-
pz)3, HC(3-Phpz)3, HC(3-i-Prpz)3, HC(3-i-Prpz)2-
(5-i-Prpz), PhC(pz)2(py)) (pzꢁpyrazolyl ring, pyꢁpy-
A
similar reaction between PhC(pz)2(py) and
Re(CO)5Br yields {[PhC(pz)2(py)]Re(CO)3}Br (9), while
the reaction between Re(CO)5Br and 1,4-
C6H4[CH2OCH2C(pz)3]2 in a 2:1 mol ratio gives the
corresponding homobimetallic derivative, {1,4-
C6H4[CH2OCH2C(pz)3]2 [Re(CO)3]2}Br2 (10) (Eq. (2)).
/
/
ridyl ring). We report the structural characterizations of
the first complexes that contain an isomeric pair of
tris(pyrazolyl)methane ligands, {[HC(3-i-Prpz)3]Re-
(CO)3}Br and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br.
ð2Þ

52
D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
The reaction between Re(CO)5Br and AgBF4 followed
by reaction with either HC(pz)3 or the 4:1 HC(3-i-
9, which has much lower values. This result can be
attributed to the more basic nature of the pyridyl ring,
which also breaks the local C3v symmetry of the
Re(CO)3 unit resulting in a splitting of the E mode. In
our previous work [3c], the {[tris(pyrazolyl)metha-
ne]Mn(CO)3}(CF3SO3) complexes and {[PhC(pz)2-
(py)]Mn(CO)3}(CF3SO3) all showed only small varia-
tions in the carbonyl stretching vibrations. The surpris-
ing result is not that the more basic pyridyl ring
influences the carbonyl stretching frequencies of
{[PhC(pz)2(py)]Re(CO)3}(Br), but that it does not
influence those of {[PhC(pz)2(py)]Mn(CO)3}(CF3SO3)
to a greater extent.
Prpz)3ꢀHC(3-i-Prpz)2(5-i-Prpz) mixture results in the
/
formation of {[HC(pz)3]Re(CO)3}BF4 (2), {[HC(3-i-
Prpz)3]Re(CO)3}BF4 (7), and {[HC(3-i-Prpz)2(5-i-
Prpz)]Re(CO)3}BF4 (8), respectively. All of the com-
plexes are air and thermally stable up to 200 8C and are
soluble in acetone, acetonitrile, and methylene chloride,
but insoluble in aliphatic solvents.
The reaction between the HC(3-i-Prpz)3ꢀHC(3-i-
/
Prpz)2(5-i-Prpz) mixture, a mixture that has not been
separated, and Re(CO)5Br was carried out with a slight
excess of the ligands, while the reaction to form the BF4ꢂ
derivative was done in a 1:1 mol ratio. In either case, the
symmetrical, 5 and 7, and asymmetrical complexes, 6
and 8, formed during the reactions. These results
contrast our previous report in the analogous manga-
nese system [3c] where only the symmetrical ligand
complex was formed in reactions that used an excess of
the mixture of ligands. In the Re(CO)5Br reaction, the
1
A very interesting result was found in the H-NMR
shifts of the methine hydrogen atoms of the complexes,
Table 1. The methine hydrogen of compounds 1, 5, and
6, which all have bromide as the counterion, show very
unusual chemical shifts of 13.04, 12.69, and 12.09 ppm,
respectively. These shifts are deshielded from that
observed with the uncomplexed ligand by 4.31, 4.30,
and 3.69 ppm, respectively. The analogous compounds
2, 7, and 8 containing the same cations, respectively, but
BF4ꢂ as the counter ion, show much less dramatic
chemical shifts of 9.88, 9.47, and 9.53 ppm, which are
only deshielded from the uncomplexed ligand by 1.15,
1.08, and 1.13 ppm, respectively. A similar trend was
also seen by Seymore and Brown [7] in the study of
product was a 5.7ꢀ
/
1 mixture of 5ꢀ6, a mixture that
/
could not be separated by recrystallization. Crystals
suitable for X-ray analysis formed when the mixture was
dissolved in acetone and allowed to slowly evaporate.
Individual crystals of 5 and 6 were physically separated
from this mixture for the X-ray studies. In the case of
the BF4ꢂ complexes, recrystallization of the crude 4/1
mixture of 7ꢀ
mixture yields pure 7 in low yield.
The IR stretching frequencies for the carbonyl ligands
for complexes 1ꢀ10 are provided in Table 1. The
carbonyl stretching vibrations of complexes 1ꢀ8 and
10 are comparable and occur within a few wave numbers
of one another. The complexes with alkyl-substituted
ligands have slightly lower values as would be expected
because of the electron donating substituents, but the
differences are only a few wavenumbers. The only
exception is the {[PhC(pz)2(py)]Re(CO)3}(Br) complex,
/
8 from a methylene chlorideꢀ
/
hexane
{[HC(pz)3]ReOCl2}X complexes (XꢁCl and BF4).
/
Their Clꢂ complex has a methine proton shift of
12.54 ppm, while the BF4ꢂ complex has a shift of 9.19
ppm. Our data suggests that the Brꢂ counterion
interacts in solution with the methine hydrogen atom
forming a weak hydrogen-bonding interaction. The
BF4ꢂ counter ion does not interact as strongly, and,
therefore, does not deshield the methine hydrogen atom
as strongly.
/
/
The 13C-NMR chemical shifts are also influenced by
this interaction. In this case, the methine carbon for the
Table 1
IR, 1H-, and 13C-NMR data for complexes 1ꢀ
10
/
a
b
Complex
IR n(CO) cmꢂ1
1H (HC) ppm (D
)
13C (HC) ppm (D
)
{[HC(pz)3]Re(CO)3}Br (1)
{[HC(pz)3]Re(CO)3}BF4 (2)
2042, 1938
2043, 1938
2036, 1930
2040, 1934
2037, 1930
2037, 1930
2037, 1932
2037, 1932
2026, 1922, 1899
2042, 1938
13.04(4.31)
9.88(1.15)
8.31(0.11)
10.68(1.82)
12.69(4.30)
12.09(3.69)
9.47(1.08)
9.53(1.13)
N/A
73.9(9.2)
77.1(6.0)
{[HC(3,5-Me2pz)3]Re(CO)3}Br (3)
{[HC(3-Phpz)3]Re(CO)3}Br (4)
{[HC(3-i-Prpz)3]Re(CO)3}Br (5)
{[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br (6)
{[HC(3-i-Prpz)3]Re(CO)3}BF4 (7)
{[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}BF4 (8)
{[PhC(pz)2(py)]Re(CO)3}Br (9)
73.6(9.5)
77.2(5.9)
N/A
N/A
{1,4-C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}(Br)2 (10)
N/A
a
The number in parenthesis is the difference in the 1H shift between the metal complex and the corresponding proton in the free, uncoordinated
ligand [3c].
b
The number in parenthesis is the difference in the 13C shift between the metal complex and the corresponding carbon in the free, uncoordinated
ligand [3c].

D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ
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53
ligand, although the solid state structure of the free
ligand also shows non-equivalent pyrazolyl rings [6].
Given the inert nature of rheniumÃ
/
carbon and
rheniumÃnitrogen bonds in 10, the fluxional process
/
responsible for the equilibration of the pyrazolyl rings is
rotation about the central carbon atom of the tris(pyr-
azolyl)methane unit (C1 in Fig. 4) and the CH2(C2)
bonded to it. Coordination of the rings to the rhenium
aligns the hydrogen atoms in the 5-position of the
pyrazolyl rings toward the Ã
/
CH2OCH2R linker, causing
a barrier to rotation about the central C(C1)Ã
/CH2(C2)
bond. In the free ligand, the pz rings are rotated to
minimize this interaction [6]. The energy barrier, DG%, of
15.59
0.5 kcal molꢂ1, associated with this process for 10
/
was calculated by using the expression described by
Kessler but with the rate constant modified for an
unsymmetrical two-site exchange [8].
2.1. Solid State Structures
Figs. 2 and 3 show ORTEP diagrams of 5 and 6 and
selected bond distances and angles are collected in Table
2. Fig. 2 shows cation A, one of the three nonequivalent
forms present in the crystal of 5. For each cation, three
nitrogen atoms from the ligand and three carbon atoms
from the carbonyl ligands surround the rhenium in a
nearly octahedral arrangement. The average ReÃ
/
N
˚
distance is 2.19 A for 5 and 2.18 A for 6. Despite nearly
˚
identical averages, the 5-i-Prpz ring in 6 has a ReÃ
/
N
˚
˚
bond distance of 2.15 A, ca. 0.04 A shorter than the
average for 5. Presumably, this bond is slightly shorter
due to the reduction of steric interactions caused by the
absence of the bulky isopropyl group located at the
third-position of the pyrazolyl ring. This steric differ-
ence is not reflected in the bond angles where the
Fig. 1. Variable temperature 1H-NMR spectra of the pyrazolyl
hydrogen atoms for {1,4-C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}(Br)2.
three bromide complexes are substantially more
shielded, when compared with that in the free ligand
and that observed in the BF4ꢂ complexes. The results of
the NMR experiments are supported by the solid-state
structures, vide infra. Also, the most shielded, least
shifted from free ligand, methine hydrogen resonance is
in {[HC(3,5-Me2pz)3]Re(CO)3}Br (3), where the 5-
methyl substituents sterically prevent any type of
hydrogen-bonding interaction with the methine hydro-
gen atom.
A variable temperature 1H-NMR spectroscopic study
of 10 (Fig. 1) in DMF revealed that at low temperatures
each type of hydrogen atom on the pyrazolyl rings
appears as two resonances in a 2/1 ratio. This result is
consistent with the solid state structure of 10 (vide infra,
see Fig. 4) where the oxygen atom of the ether linkage
straddles two of the pyrazolyl rings and is anti with
respect to the third. Upon warming, the resonances
broaden and coalesce, such that at 85 8C only one
resonance for each type of pyrazolyl hydrogen is
observed. The high temperature spectrum showing
equivalent pyrazolyl rings on the NMR time scale is
similar to the room temperature spectrum of the free
average NÃ
/
ReÃ
/
N angles are 828 for both 5 and 6, and
the average CÃ
/
ReÃ
/
C angle for the carbonyl groups are
888 for 5 and 898 for 6. These angles and distances are
consistent with the recent report of the structures of 1
and [MeC(pz)3]Re(CO)3}I [5].
Weak hydrogen-bonding interactions between the
Brꢂ anion and the methine hydrogen are observed in
the structures of 5 and 6. In the case of 5, the C(1)Ã
/
H(1)ꢀ ꢀ ꢀBr distances (corresponding angles) are 2.60
˚
(1478), 2.49 (1608), and 2.39 A (1758) for each of the
three cations in the unit cell, while for 6 this distance is
˚
2.52 A (1588). These distances are all substantially less
˚
than the sum of the van der Waals radii, 2.99 A [9].
Complexes 5 and 6 represent the first example of a
matched isomer pair of poly(pyrazolyl)methane ligands
which have been structurally characterized. In contrast,
metal complexes that contain an asymmetrical arrange-
ment of the ligand substituents are well-known in
poly(pyrazolyl)borate chemistry [10]. Of all the
poly(pyrazolyl)borate examples known, there appears
to be only one case in which both isomers are

54
D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
Fig. 2. ORTEP diagram of {[HC(3-i-Prpz)3]Re(CO)3}ꢃ, cation A. Displacement ellipsoids drawn at the 50% probability level.
Table 2
˚
Selected bond lengths (A) and angles (8) for {[HC(3-i-
Prpz)3]Re(CO)3}Br×(CH3)2CO
Prpz)]Re(CO)3}Br×(CH3)2CO (6)
(5),
and
{[HC(3-i-Prpz)2(5-i-
5
6
A
B
C
Bond lengths
ReÃN(11)
ReÃN(21)
ReÃN(31)
ReÃC(41)
ReÃC(42)
ReÃC(43)
2.187(3)
2.195(3)
2.182(3)
1.896(5)
1.925(5)
1.917(5)
2.182(3)
2.178(3)
2.184(3)
1.910(5)
1.903(4)
1.919(4)
2.180(3)
2.192(3)
2.183(3)
1.909(4)
1.900(5)
1.916(5)
2.153(3)
2.194(3)
2.194(3)
1.916(4)
1.914(4)
1.918(4)
Bond angles
N(11)ÃReÃN(21)
N(11)ÃReÃN(31)
N(21)ÃReÃN(31)
C(41)ÃReÃC(42)
C(41)ÃReÃC(43)
C(42)ÃReÃC(43)
N(11)ÃReÃC(42)
N(11)ÃReÃC(43)
N(21)ÃReÃC(41)
N(21)ÃReÃC(43)
N(31)ÃReÃC(41)
N(31)ÃReÃC(42)
82.42(12)
82.15(12)
80.66(12)
87.1(2)
82.12(12)
83.73(12)
80.45(11)
88.56(18)
90.16(17)
90.89(17)
94.52(15)
91.36(15)
94.68(15)
94.08(14)
94.48(15)
94.35(15)
81.77(12)
81.99(12)
83.48(12)
90.48(17)
89.88(18)
88.78(18)
94.35(15)
94.73(15)
93.14(15)
94.66(15)
93.27(15)
92.89(16)
82.89(9)
81.24(10)
81.06(10)
89.03(14)
89.82(14)
87.95(15)
92.01(13)
92.26(13)
96.00(12)
94.22(12)
96.62(12)
96.23(13)
87.5(2)
88.80(18)
95.43(16)
93.16(17)
94.97(17)
94.90(15)
97.02(18)
95.49(15)
Fig. 3. ORTEP diagram of {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}ꢃ
Displacement ellipsoids drawn at the 50% probability level.
.
structurally characterized, [HB(3-Cum-5-Mepz)3]ZnSH
and
N(11)ÃReÃC(41) 177.35(16) 176.54(15) 173.38(15) 177.71(12)
N(21)ÃReÃC(42) 175.80(15) 174.05(15) 175.00(16) 174.52(12)
N(31)ÃReÃC(43) 173.90(17) 173.08(15) 176.42(16) 172.36(12)
[HB(3-Cum-5-Mepz)2(3-Me-5-Cumpz)]ZnSH
p-isopropylphenyl) [10a]. These two tetrahedral
(Cumꢁ
/
complexes, despite the steric difference around their
metal centers, have nearly identical structures.
Three nonequivalent cations (A, B, and C) are present in the crystal
of 5.
Fig. 4 shows an ORTEP diagram of 10, and selected
bond distances and angles are collected in Table 3. The
unit cell for 10 contains three crystallographically
rhenium atoms in a nearly octahedral arrangement. The
˚
average ReÃ
/
N distance for 10 is 2.15 A, the average NÃ
/
inequivalent
but
structurally
similar
{1,4-
C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}2ꢃ cationic units.
In this complex, which contains a bitopic ligand, the
three nitrogen atoms from the pyrazolyl rings and three
carbon atoms from the carbonyl ligands surround both
ReÃ
/
N angle is 818, and the average OCÃ
/
ReÃ
/
CO angle
is 898. The overall arrangement of each bimetallic unit is
a stepped structure formed by a trans arrangement of
the two ether side arms about the linking arene group.

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Table 3
˚
Selected bond lengths (A) and angles (8) for the three nonequivalent
cations (A, B, and C) of {1,4-C6H4 [CH2OCH2C(pz)3]2[Re(CO)3]2}2ꢃ
(10)
10
A
B
C
Bond lengths
ReÃN(11)
ReÃN(21)
ReÃN(31)
ReÃC(41)
ReÃC(42)
ReÃC(43)
2.135(11)
2.150(11)
2.184(12)
1.900(17)
1.859(15)
1.80(2)
2.135(13)
2.158(12)
2.151(11)
1.918(16)
1.81(2)
2.137(17)
2.140(13)
2.159(12)
1.89(2)
1.896(17)
1.93(2)
1.894(18)
Bond angles
N(11)ÃReÃN(21)
N(11)ÃReÃN(31)
N(21)ÃReÃN(31)
C(41)ÃReÃC(42)
C(41)ÃReÃC(43)
C(42)ÃReÃC(43)
N(11)ÃReÃC(42)
N(11)ÃReÃC(43)
N(21)ÃReÃC(41)
N(21)ÃReÃC(43)
N(31)ÃReÃC(41)
N(31)ÃReÃC(42)
N(11)ÃReÃC(41)
N(21)ÃReÃC(42)
N(31)ÃReÃC(43)
80.4(4)
80.6(4)
80.0(4)
89.8(6)
87.7(6)
89.8(7)
94.1(5)
94.1(5)
95.5(5)
95.3(6)
97.3(5)
94.5(6)
175.7(5)
172.8(6)
173.4(6)
81.5(4)
81.1(4)
81.8(4)
91.8(7)
89.1(7)
88.2(9)
95.3(6)
93.8(6)
91.2(6)
97.8(7)
96.1(5)
91.9(7)
172.5(6)
173.4(6)
174.8(6)
79.7(6)
81.8(6)
81.1(5)
89.7(8)
88.6(9)
88.3(8)
96.5(7)
90.8(8)
94.3(7)
98.2(7)
98.8(7)
91.9(6)
173.8(8)
172.4(6)
172.6(7)
Fig. 4. ORTEP diagram of {1,4-C6H4[CH2OCH2C(pz)3]2[Re-
(CO)3]2}2ꢃ, cation A. displacement ellipsoids drawn at the 30%
probability level.
sponding CÃ
chain, there are two 4-C(pz)Ã
C and C to B. The (C)H(B)ꢀ ꢀ ꢀcentroid(C) distance is
/
Hꢀ ꢀ ꢀ centroid angle of 1538. For the Bꢀ
/
C
Three cationic units, A, B, and C, are present in a
2:1:1 ratio and are organized into two similar ‘zigzag’
shaped chains by non-covalent interactions. The first
type of chain is comprised of only the A-type cationic
/
4-H(pz) interactions, B to
˚
˚
2.78 A (CÃ
sponding CÃ
(C)H(C)ꢀ ꢀ ꢀcentroid(B) distance is 2.87 A (CÃ
/
centroid distance of 3.62 A) with a corre-
/
H(B)ꢀ ꢀ ꢀcentroid(C) angle of 1508, while the
˚
units (Aꢀ
alternating B- and C-type units (Bꢀ
formed by a series of pꢀp interactions between a
/A), while the second chain is made up of
/
centroid
˚
/C). Each chain is
distance of 3.68 A) with
H(C)ꢀ ꢀ ꢀcentroid(B) angle of 1488.
Fig. 6a and b show the orientation of the chains with
respect to one another. Fig. 6a shows that the AꢀA and
BꢀC chains are oriented in an interpenetrating ‘zigzag’
a
corresponding CÃ
/
/
pyrazolyl ring of one bimetallic building block and a
pyrazolyl ring of an adjacent bimetallic building block.
C chain from two angles that
/
Fig. 5a and b show the Bꢀ
/
/
are oriented 908 with respect to each other. The Aꢀ
/A
structure, with the two chains ca. one half of a bimetallic
unit out of phase. Both chains run down the a-axis, Fig.
6b, with the ‘planes’ of each ‘zigzag’ chain oriented at a
698 angle with respect to one another. These two chains
chains are similar. Fig. 5a shows the interactions that
hold the bimetallic units together in chains, while Fig. 5b
displays the ‘zigzag’ shape of the chains due to the
stepped structure of each individual unit. The pyrazolyl
are held together by two types of pyrazolylꢀ
/
areneꢀ
/
rings involved in the pꢀ
/
p interactions are parallel
displaced with a centroid-to-centroid distance of 3.61
pyrazolyl pꢀp interactions, where the pyrazolyl rings
/
sandwich the central arene ring. The pyrazolyl rings are
parallel displaced (in opposite directions) above and
below the plane of the arene (ar) ring. One interaction is
˚
˚
A for the Aꢀ
/
A chain and 3.70 A for the BꢀC chain, with
/
average centroid-to-ring plane perpendicular distances
˚
of 3.41 and 3.53 A, respectively. These distances are well
between C(pz)ꢀ
A(pz)ꢀB(ar)ꢀA(pz), Fig. 7. For the Aꢀ
the centroid-to-centroid distance is 3.77 A with several
/
A(ar)ꢀ/C(pz), while the other is between
˚
inside the 3.8 A limit for pꢀ
/
p interactions [11].
/
/
/
BꢀA interaction,
/
˚
The chains are also supported by (C)Hꢀ ꢀ ꢀp interac-
˚
tions [12]. The pyrazolyl rings involved in the aforemen-
C(pz)Ã
an A(pz) planeꢀ
centroid-to-centroid distance is 3.77 A with several
/
C(ar) distances in the range of 3.40ꢀ/3.80 A, and
tioned pꢀ
/
p stacking have their 4-C(pz)Ã
/
4-H(pz) bond
/
B(ar) plane angle of 198. The Cꢀ
/
Aꢀ/C
˚
directed toward another pyrazolyl ring of an adjacent
˚
3.80 A,
unit. For the Aꢀ
/
A chain, the (C)Hꢀ ꢀ ꢀcentroid distance is
C(pz)Ã
/
C(ar) distances in the range of 3.48ꢀ
/
˚
˚
centroid distance of 3.70 A) with a corre-
2.85 A (CÃ
/
and a C(pz) planeꢀ
/
A(ar) plane angle of 218. These pꢀp
/

56
D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
Fig. 5. (a) View of the Bꢀ
showing the stepped structure of each unit, and the resulting ‘zigzag’ shape.
/
C chain showing the pꢀ
/
p (dashed line) and (C)Hꢀ ꢀ ꢀp (dotted line) interactions. (b) View of Bꢀ
/C, orthogonal to (a),
and (C)Hꢀ ꢀ ꢀp interactions organize the bimetallic {1,4-
C6H4 [CH2OCH2C(pz)3]2[Re(CO)3]2}2ꢃ building blocks
into a two-dimensional network. The Brꢂ counter-ions
presumably further organize the organometallic build-
ing blocks into a 3D array, but since the anions were
found to be disordered, detailed information on indivi-
dual interactions is not available.
prepared according to our recently reported procedures
[3c,6].
3.1. Synthesis of {[HC(pz)3]Re(CO)3}Br (1)
In a 100 ml Schlenk flask, Re(CO)5Br (0.30 g, 0.74
mmol) and HC(pz)3 (0.16 g, 0.74 mmol) were dissolved
in toluene (15 ml). The resulting solution was stirred and
heated at reflux for 20 h. During this time, a white solid
precipitated. The slurry was allowed to cool to r.t. and
filtered. The remaining solid was washed with toluene
3. Experimental
(3ꢄ5 ml) and dried in vacuo to yield a white solid (0.38
/
g, 91%). Melting point (m.p.) 310 8C (dec.). The
preparation of this compound in ethanol has been
briefly mentioned, although no spectral characterization
was presented [5]. 1H-NMR(acetone-d6): d 13.04 (s, 1H,
All operations were carried out under a nitrogen
atmosphere using either standard Schlenk techniques or
a Vacuum Atmospheres HE-493 dry box. All solvents
1
were dried and distilled prior to use. H (400 MHz) and
13C (101.62 MHz) NMR chemical shifts are reported in
ppm versus TMS and referenced to the residual solvent
peaks for (CD3)2CO, d 2.06 (1H) and d 29.8 (13C). The
HC), 9.04, 8.53 (d, d, 3H, 3H, Jꢁ
/
2.4, 2.4 Hz, 3,5-H pz),
2.4 Hz, 4-H pz). 13C-NMR (acetone-
6.75 (dd, 3H, Jꢁ
/
d6): d 148.1 (3-C pz), 134.7 (5-C pz), 109.1 (4-C pz), 73.9
(HC). IR(CH2Cl2, n(CO), cmꢂ1): 2042 (s), 1938 (m).
Accurate FABꢃMS Calc. for [Mꢃ], [C13H10-
N6O3187Re]ꢃ, 485.0372. Found: 485.0392.
13C-NMR spectrum of 2 was acquired at ꢂ
75 8C,
/
whereas those of the remainder of the complexes were
taken at room temperature (r.t.). Variable temperature
1H- (500 MHz) NMR spectra of 10 were obtained in
DCON(CD3)2 (DMF-d7) with 10 ml TMS added as an
internal standard. Re(CO)5Br was prepared by the
literature procedure [13]. HC(pz)3, HC(3,5-Me2pz)3,
3.2. Synthesis of {[HC(pz)3]Re(CO)3}BF4 (2)
In a 100 ml Schlenk flask wrapped in aluminum foil,
Re(CO)5Br (0.20 g, 0.49 mmol) and AgBF4 (0.095 g,
0.49 mmol) were dissolved in DME (40 ml). The
HC(3-Phpz)3, HC(3-i-Prpz)3ꢀ/HC(3-i-Prpz)2(5-i-Prpz),
PhC(pz)2(py), and 1,4-C6H4[CH2OCH2C(pz)3]2 were

D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ
/61
57
Fig. 6. Views of Aꢀ
p (dashed line) interactions shown. The Bꢀ
chains, orthogonal to (a). In the picture, the Aꢀ
/
A and Bꢀ
/
C chains with respect to each other. (a) The Aꢀ
C chain is in a similar orientation to Fig. 5b. (b) View down the chains (a-axis) of the Aꢀ
A chain is horizontal, and the BꢀC chain is nearly vertical.
/
A chain is in the same orientation as Fig. 5a, with the corresponding pꢀ
/
/
/
A and BꢀC
/
/
/
solution was stirred and heated at reflux for 40 h. AgBr
was removed by cannula filtration, and the clear,
colorless filtrate was added to a flask that contained
HC(pz)3 (0.10 g, 0.49 mmol). The resulting solution was
stirred and heated at reflux for 4 h during which time a
precipitate appeared. The solvent was removed in vacuo
yielding an off-white solid. The solid was dissolved in
CH2Cl2 (30 ml), and hexane (60 ml) was added to
precipitate the desired product. The solid was collected
and dried under vacuum yielding a white solid (0.19 g,
66%). M.p. 250 8C (dec.). 1H-NMR (acetone-d6): d 9.88
NMR (acetone-d6): d 197.3 (CO), 148.7 (3-C pz), 135.6
(5-C pz), 109.4 (4-C pz), 77.1 (HC). IR(CH2Cl2, n(CO),
cmꢂ1): 2043 (s), 1938 (m). Accurate ESꢃMS Calc. for
[Mꢃ],
[C13H10N6O3185Re]ꢃ,
483.0344.
Found:
483.0352.
3.3. Synthesis of {[HC(3,5-Me2pz)3]Re(CO)3}Br (3)
This compound was prepared (0.36 g, 74%) as
described above for 1 using Re(CO)5Br (0.30 g, 0.74
mmol) and HC(3,5-Me2pz)3 (0.22 g, 0.74 mmol). M.p.
250 8C (dec.). 1H-NMR(acetone-d6): d 8.31 (s, 1H,
HC), 6.47 (s, 3H, 4-H pz), 2.86, 2.56 (s, s, 9H, 9H, 3,5-
(s, 1H, HC), 8.64, 8.61 (d, d, 3H, 3H, Jꢁ
/
2.4 Hz, Jꢁ2.4
/
Hz, 3,5-H pz), 6.78 (dd, 3H, Jꢁ
/
2.4 Hz, 4-H pz). 13C-

58
D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
Fig. 7. View showing the C(pz)ꢀ
/
A(ar)ꢀ
/
C(pz) pꢀ
/
p (dotted line) interaction and the A(pz)ꢀ
/
B(ar)ꢀ
/
A(pz) pꢀp (dashed line).
/
Me). IR(CH2Cl2, n(CO), cmꢂ1): 2036 (s), 1930 (m).
Accurate FABꢃMS Calc. for [Mꢃ], [C19H22-
N6O3185Re]ꢃ, 567.1283. Found: 567.1298.
suitable for X-ray analysis were grown by slow evapora-
tion of an acetone solution, and the crystals used for the
structural determinations of 5 and 6 were mechanically
separated from the same vial. 1H-NMR (acetone-d6) for
5: d 12.69 (s, 1H, HC), 8.93 (d, 3H, Jꢁ
6.72 (d, 3H, Jꢁ2.8 Hz, 4-H pz), 3.50 (septet, 3H, Jꢁ
6.8 Hz,
/
2.8 Hz, 5-H pz),
3.4. Synthesis of {[HC(3-Phpz)3]Re(CO)3}Br (4)
/
/
6.8 Hz, CH(CH3)2), 1.35 (d, 18H, Jꢁ
/
This compound was prepared (0.43 g, 73%) as
described above for 1 using Re(CO)5Br (0.30 g, 0.74
mmol) and HC(3-Phpz)3 (0.33 g, 0.74 mmol). M.p.
CH(CH3)2). 13C-NMR (acetone-d6) for 5: d 166.9 (3-C
pz), 135.0 (5-C pz), 105.1 (4-C pz), 73.6 (HC), 30.1
(CH(CH3)2), 22.5 (CH(CH3)2). 1H-NMR(acetone-d6)
1
240 8C (dec.). H-NMR (acetone-d6): d 10.68 (s, 1H,
for 6: d 12.09 (s, 1H, HC), 9.48 (d, 2H, Jꢁ
H 3-i-Prpz), 8.40 (d, 1H, Jꢁ2.4 Hz, 3-H 5-i-Prpz), 6.70
(d, 2H, Jꢁ3.2 Hz, 4-H 3-i-Prpz), 6.57 (d, 1H, Jꢁ2.4
Hz, 4-H 5-i-Prpz), 4.39 (septet, 1H, Jꢁ6.8 Hz,
CH(CH3)2 5-i-Prpz), 3.40 (septet, 2H, Jꢁ
CH(CH3)2 3-i-Prpz), 1.36 (d, 12H, Jꢁ
/3.2 Hz, 5-
HC), 9.49 (d, 3H, Jꢁ
/
2.4 Hz, 5-H (pz)), 7.47ꢀ/7.57 (m,
/
15H, C6H5), 6.75 (d, 3, Jꢁ
/
2.4 Hz, 4-H (pz)).
/
/
IR(CH2Cl2, n(CO), cmꢂ1): 2040 (s), 1934 (m). Accurate
FABꢃMS Calc. for [Mꢃ], [C31H22N6O3187Re]ꢃ,
713.1312. Found: 713.1302.
/
/
6.8 Hz,
/
6.8 Hz,
CH(CH3)2 3-i-Prpz), 1.33 (d, 6H, Jꢁ6.8 Hz,
/
CH(CH3)2 5-i-Prpz). IR(CH2Cl2, n(CO), cmꢂ1): 2037
(s), 1930 (m). Accurate FABꢃMS Calc. for [Mꢃ],
[C22H28N6O3187Re]ꢃ, 611.1781. Found: 611.1786.
3.5. Synthesis of {[HC(3-i-Prpz)3]Re(CO)3}Br (5)
and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br (6)
In a 100 ml Schlenk flask, Re(CO)5Br (0.30 g, 0.74
mmol) and a 4:1 mixture of HC(3-i-Prpz)3ꢀHC(3-i-
/
Prpz)2(5-i-Prpz) (0.31 g, 0.90 mmol) were dissolved in
toluene (40 ml). The orange solution was stirred and
heated at reflux for 20 h, was cooled to r.t., and solvent
was removed in vacuo. The remaining brown solid was
3.6. Synthesis of {[HC(3-i-Prpz)3]Re(CO)3}BF4 (7)
and {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}BF4 (8)
In a 100 ml Schlenk flask wrapped in aluminum foil,
Re(CO)5Br (0.41 g, 1.0 mmol) and AgBF4 (0.20 g, 1.0
mmol) were dissolved in DME (40 ml). The solution was
stirred and heated at reflux for 36 h. AgBr was removed
by cannula filtration, and the colorless filtrate was
washed with diethyl ether (3ꢄ10 ml) to remove
/
unreacted starting materials, and the resulting white
solid (0.32 g, 63%) was dried in vacuo. NMR analysis
showed the solid to be 85% 5 and 15% 6. Crystals

D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ
/61
59
added to a flask that contained a 4:1 HC(3-i-Prpz)3ꢀ
HC(3-i-Prpz)2(5-i-Prpz) mixture (0.34 g, 1.0 mmol). The
yellowꢀorange solution was stirred and heated at reflux
/
1938 cmꢂ1 (m). Accurate FABꢃMS Calc. for [M],
[C36H30BrN12O8185Re2]ꢃ,
1207.0552. Found:
1207.0557.
/
for 8 h, cooled to r.t., and solvent was removed in vacuo
yielding a light brown oil. NMR analysis of the crude
mixture showed the solid to be 80% 7 and 20% 8. The
solid was dissolved in CH2Cl2 (10 ml), and hexane (50
ml) was added. After filtration, the remaining off-white
solid (0.23 g, 32%) was dried under vacuum and was
4. Crystallographic studies
Single crystals of 5, 6, and 10 were grown by slow
evaporation of a saturated acetone solution of each
complex. Crystal, data collection, and refinement para-
meters are given in Table 4. An irregular colorless
crystal of 5 and a colorless plate crystal of 6 were
mounted on the ends of thin glass fibers using inert oil,
and quickly transferred to the diffractometer cold
stream for data collection at 173(2) K. For 10, a
colorless bar was epoxied to the end of a glass fiber
for data collection at 293 K. Raw X-ray intensity data
frames were measured on a Bruker SMART APEX
1
shown by NMR to be pure 7. M.p. 200 8C (dec.). H-
NMR (acetone-d6) for 7: d 9.47 (s, 1H, HC), 8.48 (d,
3H, Jꢁ
pz), 3.52 (septet, 3H, Jꢁ
18H, Jꢁ
6.8, CH(CH3)2). 13C-NMR (acetone-d6) for 7:
/
2.8 Hz, 5-H pz), 6.75 (d, 3H, Jꢁ/2.8 Hz, 4-H
/6.8 Hz, CH(CH3)2), 1.36 (d,
/
d 167.5 (3-C pz), 135.9 (5-C pz), 105.7 (4-C pz), 77.2
(HC), 30.2 (CH(CH3)2), 22.5 (CH(CH3)2). 1H-NMR
(acetone-d6) for 8: d 9.46 (s, 1H, HC), 8.58 (d, 2H, Jꢁ
3.2 Hz, 5-H 3-i-Prpz), 8.48 (d, 1H, Jꢁ2.4 Hz, 3-H 5-i-
Prpz), 6.77 (d, 2H, Jꢁ3.2 Hz, 4-H 3-i-Prpz), 6.64 (d,
1H, Jꢁ2.4 Hz, 4-H 5-i-Prpz), 3.76 (septet, 1H, Jꢁ6.8
Hz, CH(CH3)2 5-i-Prpz), 3.12 (septet, 2H, Jꢁ6.8 Hz,
CH(CH3)2 3-i-Prpz), 1.36 (d, 12H, Jꢁ6.8 Hz,
6.8 Hz,
/
/
/
CCD-based diffractometer system (Moꢀ
/
Ka radiation,
0.71073 A). The raw data frames were integrated
using SAINTꢃ [14], which also applied corrections for
˚
/
/
lꢁ
/
/
/
/
Lorentz and polarization effects. Analysis of the data
sets showed negligible crystal decay during data collec-
tion in any case. An empirical absorption correction
based on the multiple measurement of equivalent
reflections was applied to each data set with the
program SADABS [15]. All structures were solved by a
combination of direct methods and difference Fourier
syntheses, and refined by full-matrix least-squares
against F2, using the SHELXTL software package [15].
CH(CH3)2 3-i-Prpz), 1.34 (d, 6H, Jꢁ
/
CH(CH3)2 5-i-Prpz). IR (CH2Cl2, n(CO), cmꢂ1): 2037
(s), 1932 (m). Accurate ESꢃMS Calc. for [Mꢃ],
[C22H28N6O3185Re]ꢃ, 609.1753. Found: 609.1750.
3.7. Synthesis of {[PhC(pz)2(py)]Re(CO)3}Br (9)
This compound was prepared (0.20 g, 61%) as
described above for the 5ꢀ
/
6 mixture using Re(CO)5Br
{[HC(3-i-Prpz)3]Re(CO)3}Br×
¯
lizes in the triclinic system; the space group P1 was
assumed and confirmed by successful solution and
refinement of the structure. {[HC(3-i-Prpz)2(5-i-
/
(CH3)2CO (5), crystal-
(0.20 g, 0.50 mmol) and PhC(pz)2(py) (0.15 g, 0.50
mmol. M.p. 230 8C (dec.). 1H-NMR (acetone-d6, in-
dividual resonances could not be assigned due to the
complexity of the spectrum): complex resonances cen-
tered at d 9.37, 8.58, 8.24, 8.21, 7.94, 7.75, 7.65, 7.49,
6.65, 6.20. IR(CH2Cl2, n(CO), cmꢂ1): 2026 (s), 1922
(m), 1899 (m). Accurate FABꢃMS Calc. for [Mꢃ],
[C21H15N5O3187Re]ꢃ, 572.0733. Found: 572.0731.
/
Prpz)]Re(CO)3}Br×/(CH3)2CO (6), crystallizes in the
space group P21/c as determined by the systematic
absences in the intensity data, with one {[HC(3-i-
Prpz)2(5-i-Prpz)]Re(CO)3}Br moiety and one acetone
molecule of crystallization in the asymmetric unit. The
asymmetric unit of 5 contains three crystallographically
independent {[HC(3-i-Prpz)3]Re(CO)3}Br moieties and
three acetone molecules of crystallization. Six restraints
were employed via a SHELX SAME instruction to main-
tain a chemically reasonable geometry for one of the
acetones. Eventually, all non-hydrogen atoms were
refined with anisotropic displacement parameters; hy-
drogen atoms were placed in idealized positions and
refined using a riding model.
3.8. Synthesis of {1,4-C6H4
[CH2OCH2C(pz)3]2[Re(CO)3]2}Br2 (10)
This compound was prepared (0.30 g, 77%) as
described above for the 5ꢀ6 mixture using Re(CO)5Br
/
(0.24 g, 0.60 mmol) and 1,4-C6H4[CH2OCH2C(pz)3]2
(0.18 g, 0.30 mmol). M.p. 225 8C (dec.). 1H-NMR
(acetone-d6, ambient): d 9.10, 8.89 (2H, 4H, 5-H pz),
8.52 (6H, 3-H pz), 7.64 (s, 4H, C6H4), 6.70, 6.66 (2H,
4H, 4-H pz), 6.36 (s, 4H, OCH2Ph), 5.47 (s, 4H,
OCH2C(pz)3 1H-NMR (DMF-d7, -5 8C): d 9.10, 9.07
{1,4-C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}(Br)2 (10),
crystallizes in the monoclinic space group I2/a based
on systematic absences. The space group I2/a is a non-
standard setting of C2/c and was chosen to give a more
orthogonal cell. Three crystallographically inequivalent
(d, d, 2H, 4H, Jꢁ
2H, 4H, Jꢁ2.5, 2.0 Hz, 3-H pz), 7.65 (s, 4H, C6H4),
6.94, 6.90 (dd, dd, 2H, 4H, Jꢁ2.5, 3.0 Hz; Jꢁ2.5, 3.0
/3.0, 3.0 Hz, 5-H pz), 8.90, 8.88 (d, d,
/
/
/
but
chemically
similar
{1,4-C6H4-[CH2OCH2-
Hz, 4-H pz), 6.16 (s, 4H, OCH2Ph), 5.31 (s, 4H,
OCH2C(pz)3). IR (CH2Cl2, n(CO)): 2042 cmꢂ1 (s),
C(pz)3]2[Re(CO)3]2}2ꢃ cations were located. All three
are situated about centers of symmetry, and, therefore,

60
D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ61
/
Table 4
Crystal data and structure refinement for {[HC(3-i-Prpz)3]Re(CO)3}Br×(CH3)2CO (5), {[HC(3-i-Prpz)2(5-i-Prpz)]Re(CO)3}Br×(CH3)2CO (6), and
{1,4-C6H4 [CH2OCH2C(pz)3]2[Re(CO)3]2}Br2 (10)
5
6
10
Empirical formula
Formula weight
Temperature (K)
C
25H34BrN6O4Re
C25H34BrN6O4Re
748.69
173(2)
C36H30Br2N12O8Re2
1290.94
293(2)
748.69
173(2)
˚
Wavelength (A)
0.71073
triclinic
0.71073
monoclinic
P21/c
0.71073
monoclinic
I2/a
Crystal system
Space group
Unit cell dimensions
¯
P
/ /
1
˚
a(A)
12.8953(8)
19.2725(12)
19.4746(12)
76.0720(10)
72.0680(10)
85.8090(10)
4469.4(5)
6
15.9401(11)
12.3926(9)
16.0470(11)
90
23.0216(17)
21.2920(16)
30.813(3)
90
˚
b(A)
˚
c(A)
a(8)
b(8)
113.8110(10)
90
93.1930(10)
90
g(8)
3
V (A )
˚
2900.1(4)
4
1.715
15080(2)
12
1.706
Z
Density (calculated) (g cmꢂ3
Absorption coefficient (mmꢂ1
Crystal size (mm3)
)
1.669
5.458
)
5.608
0.20ꢄ0.13ꢄ0.05
6.456
0.22ꢄ0.08ꢄ0.05
0.40ꢄ0.22ꢄ0.12
u range for data collection (8)
Index ranges
1.38ꢀ
/
26.39
2.15ꢀ
/
26.40
1.82ꢀ25.11
/
ꢂ165h 516, ꢂ245k 524,
ꢂ245l 524
41 399
ꢂ175h 519, ꢂ155k 513,
ꢂ205l 517
19 019
ꢂ225h 527, ꢂ255k 523,
ꢂ365l 536
44 981
Reflections collected
Independent reflections
Completeness to uꢁ26.48
Absorption correction
Max/min transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I ꢀ2s(I)]
R indices (all data)
18 233 [Rintꢁ0.0334]
99.6%
5932 [Rintꢁ0.0332]
99.8%
13 382 [Rintꢁ0.0731]
99.4%
Semi-empirical from equivalents
0.6220 and 0.4029
18 233/6/1024
Semi-empirical from equivalents
0.8250 and 0.5424
5932/0/341
Semi-empirical from equivalents
0.7384 and 0.3309
13 382/0/847
1.011
R1ꢁ0.0302, wR2ꢁ0.0509
R1ꢁ0.0396, wR2ꢁ0.0519
1.003
1.007
R1ꢁ0.0249, wR2ꢁ0.0484
R1ꢁ0.0314, wR2ꢁ0.0495
0.977 and ꢂ0.569
R1ꢁ0.0560, wR2ꢁ0.1176
R1ꢁ0.1186, wR2ꢁ0.1232
0.940 and ꢂ1.274
Largest difference peak and hole 1.401 and ꢂ1.105
ꢂ3
˚
(e A
)
only half of each is present in the asymmetric unit. The
inversion centers reside at the centroid of the phenyl ring
in each ligand. The packing of the {1,4-
C6H4[CH2OCH2C(pz)3]2[Re(CO)3]2}2ꢃ cations gener-
ates sizable channels running along the crystallographic
a axis, which contain the bromine counterions and the
solvent molecules. Significant positional disorder was
observed for two of the three bromine counterions per
asymmetric unit (Br2ꢂ and Br3ꢂ). Both were found to
be disordered over three partially occupied sites. Their
site occupation factors were adjusted to give reasonable
thermal parameters, with the constraint of summing to
unity. Further severe disorder afflicts the acetone
solvent molecules, for which no reasonable solution
could be obtained despite several attempted models.
These were accounted for using the SQUEEZE [16]
program in PLATON [17] for modeling diffusely scatter-
cell. The contribution of these diffuse solvent molecules
was then subtracted from the structure factor calcula-
tions. Eventually, all non-hydrogen atoms were refined
with anisotropic displacement parameters; all hydrogen
atoms were placed in idealized positions and refined
using a riding model. Note that the tabulated crystal-
lographic data reflect only the known cell contents.
5. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge crystallographic
Centre, CCDC 181222 for compound 5, CCDC
181223 for compound 6, and CCDC 181224 for
compound 10. Copies of this information may be
obtained free of charge from the director, CCDC, 12
ing solvent molecules. The program calculated a solvent-
3
accessible volume in the unit cell of 3138.8 A (20.8% of
˚
Union Road, Cambridge, CB2 1EZ UK (Fax: ꢃ44-
/
the total cell volume), corresponding to 962 electrons,
which in turn corresponds to 30 acetone molecules per
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk.

D.L. Reger et al. / Journal of Organometallic Chemistry 658 (2002) 50ꢀ
/61
61
(d) D.L. Reger, J.E. Collins, S.M. Myers, A.L. Rheingold, L.M.
Liable-Sands, Inorg. Chem. 35 (1996) 4904.
Acknowledgements
[4] (a) V.W.W. Yam, Y. Yang, H.P. Yang, K.K. Cheung, Organo-
metallics 18 (1999) 5252;
We thank the National Science Foundation (CHE-
0110493) for support. The Bruker CCD Single Crystal
Diffractometer was purchased using funds provided by
the NSF Instrumentation for Materials Research Pro-
gram through Grant DMR:9975623. The NSF (Grants
CHE-8904942 and CHE-9601723) and NIH (Grant RR-
02425) have supplied funds to support NMR equipment
and the NIH (Grant RR-02849) has supplied funds to
support mass spectrometry equipment at the University
of South Carolina.
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