A manganese(II) coordination polymer with ditopic bis(pyrazol-1-yl)borate bridges

Article abstract of DOI:10.1002/zaac.200800107

The synthesis and characterization of the ditopic bis(pyrazol-1-yl)borate ligand Li₂[p-C₆H₄(B(C₆F ₅)pz₂)₂] is reported (pz = pyrazol-1-yl). Compared to the corresponding t-butyl derivative Li₂[p-C ₆H₄(B(t-Bu)pz₂)₂], the C ₆F₅-substituted scorpionate is significantly more stable towards hydrolysis. Reaction of Li₂[p-C₆H ₄(B(C₆F₅)pz₂)₂] with two equivalents of MnCl₂ leads to the formation of coordination polymers {(MnCl₂)₂(Li(THF)₃)₂[p-C ₆H₄(B(C₆F₅)pz₂) ₂]}_∞ featuring penta-coordinate Mn^II ions chelated by one bis(pyrazol-1-yl)borate fragment and further bonded to three chloride ions. Two of the three chloride ions are also coordinated to a neighbouring Mn^II ion; the third chloro ligand is shared between the Mn^II centre and a Li(THF)₃ moiety.

Full text of DOI:10.1002/zaac.200800107

DOI: 10.1002/zaac.200800107
A Manganese(II) Coordination Polymer with Ditopic Bis(pyrazol-1-yl)borate
Bridges
Thorsten Morawitz, Michael Bolte, Hans-Wolfram Lerner, and Matthias Wagner*
Frankfurt am Main, Institut für Anorganische Chemie der J. W. Goethe-Universität
Received February 8th, 2008.
Dedicated to Professor Heinrich Nöth on the Occasion of his 80th Birthday
Abstract. The synthesis and characterization of the ditopic
bis(pyrazol-1-yl)borate ligand Li2[p-C6H4(B(C6F5)pz2)2] is reported
(pz ϭ pyrazol-1-yl). Compared to the corresponding t-butyl
derivative Li2[p-C6H4(B(t-Bu)pz2)2], the C6F5-substituted scor-
pionate is significantly more stable towards hydrolysis. Reaction of
Li2[p-C6H4(B(C6F5)pz2)2] with two equivalents of MnCl2 leads to
the formation of coordination polymers {(MnCl2)2(Li(THF)3)2[p-
C6H4(B(C6F5)pz2)2]}ϱ featuring penta-coordinate MnII ions che-
lated by one bis(pyrazol-1-yl)borate fragment and further bonded
to three chloride ions. Two of the three chloride ions are also coor-
dinated to a neighbouring MnII ion; the third chloro ligand is
shared between the MnII centre and a Li(THF)3 moiety.
Keywords: Manganese; Poly(pyrazol-1-yl)borate; Scorpionate li-
gand; Crystal structures; Coordination polymer
1 Introduction
(C) [11Ϫ14], have been synthesized and used for the prep-
aration of oligonuclear transition metal compounds (A; B,
x ϭ 0; C, x ϭ 0, 1) [5, 7, 9, 13Ϫ16], and multiple-decker
sandwich complexes (B, x ϭ 1, 2) [10, 17, 18].
The presence of two or more metal ions in the same mol-
ecule can lead to synergistic effects that profoundly influ-
ence both the chemical and the physical properties of the
molecule. In the context of homogeneous catalysis, the pos-
sibility of more efficient catalytic transformations based on
the cooperative reactivity of active centres in multinuclear
complexes is therefore being intensively investigated [1].
Similarly, in the field of materials science, great attention
is currently paid to the development of metal-containing
polymers in which metal-metal interactions bring about
useful magnetic, optical or electronic behaviour [2]. For
both applications, the design of the bridging ligands is of
crucial importance, because they not only form the back-
bones of the oligometallic aggregates, but can also act as
transmitters of metal-metal communication. Ditopic poly-
(pyrazol-1-yl)borate („scorpionate“) ligands [3, 4] are par-
ticularly well-suited to stabilize oligonuclear complexes due
to the fact that their steric and electronic properties can
easily be modified over a wide range to identify the optimal
derivative for a specific purpose. So far, ditopic scorpionates
containing a B-B bond (A; Figure 1) [5], a 1,1Ј-ferroceny-
lene bridge (B) [6Ϫ10], or meta-/ para-phenylene linkers
* Prof. Dr. M. Wagner
Institut für Anorganische Chemie der J. W. Goethe-Universität
Max-von-Laue-Straße 7
D-60438 Frankfurt (Main)
Fax: ϩ49(0)69-79829260
E-mail: Matthias.Wagner@chemie.uni-frankfurt.de
Figure 1 Three classes of ditopic scorpionate ligands A Ϫ C; the
dinuclear MnII complex D featuring a C-type bridge.
Z. Anorg. Allg. Chem. 2008, 634, 1409Ϫ1414
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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T. Morawitz, M. Bolte, H.-W. Lerner, M. Wagner
Using a t-butyl-substituted p-C-type heteroscorpionate li-
gand, we have recently synthesized complex D featuring two
MnII ions bridged by two chloride ions (Figure 1) [13]. This
molecule provided an important proof-of-principle, because
it showed that the ligand is indeed apt to bring two metal
ions into close proximity so that they can act on a common
substrate. One shortcoming, however, is the sensitivity of
the ligand towards water and strong Lewis acids which in-
duce B-N bond rupture. The fact that tris(pyrazol-1-yl)-
borates are usually less prone to hydrolysis and loss of pyr-
azolyl substituents than bis(pyrazol-1-yl)borates, led us to
the conclusion that most of the problem was caused by the
t-butyl-group that had initially been introduced for solu-
bility reasons. Due to its positive inductive effect and high
steric demand, the t-butyl-substituent has the disadvantage
that it stabilizes three-coordinate boron atoms and thereby
promotes the degradation of the scorpionate moiety. We
therefore decided to replace the t-butyl-group by a smaller
substituent with higher group electronegativity and selected
the C6F5-moiety as promising alternative. The purpose of
this paper is to describe the synthesis of the ditopic C6F5-
substituted scorpionate 4 (Scheme 1) and its reaction with
MnCl2.
2 Results and Discussion
2.1 Synthesis and Spectroscopy
C6F5-substituted poly(pyrazol-1-yl)borates have not been
reported in the literature so far. Our synthesis sequence to
scorpionate 4 is outlined in Scheme 1.
Scheme 1 Synthesis of the ditopic scorpionate ligand 4 and the
MnII coordination polymer 5. (i) toluene, Ϫ78 °C to r.t.; (ii) tolu-
ene / Et2O, Ϫ78 °C to r.t.; (iii) toluene, r.t.; (iv) THF, r.t.
Starting from readily available p-bis(dibromoboryl)ben-
zene (1) [19], we first prepared the aminoborane 2 by treat-
ment of 1 with 2 equivalents of Me3SiNMe2 at low tem-
peratures. This transformation is important in order to re-
duce the Lewis acidity of the boron centres so that no ether
cleavage takes place during the subsequent synthesis step.
To generate 3, the two remaining bromine atoms of 2 were
replaced by C6F5-groups using freshly prepared C6F5MgBr
[20] in Et2O. For the preparation of the lithium heteroscor-
pionate ligand 4, 3 was treated with 2 equivalents of Lipz
and 2 equivalents of Hpz in toluene (pz ϭ pyrazol-1-yl). In
our first synthesis attempt, the toluene suspension was
heated to reflux for 1 h, which led to the formation of a
complex mixture of products, even though a similar proto-
col had successfully been applied for the preparation of the
corresponding t-butyl-substituted heteroscorpionate ligand
[11]. Transamination of 3 to 4 was finally achieved by stir-
ring the reaction mixture for 3 days at room temperature.
To investigate the sensitivity of 4 towards moisture, a solu-
tion of this compound in THF was stirred in an open vessel
at room temperature. The progress of the hydrolytic decay
was monitored by 1H NMR spectroscopy. After 1 h, the
sample was found to be virtually unchanged, also after 12 h
only little decomposition could be observed. After 3 d,
however, the solution contained mainly free pyrazole and
almost no (pyrazol-1-yl)borate was left. Under the same
conditions, the corresponding t-butyl-substituted ligand
Li2[p-C6H4(B(t-Bu)pz2)2] showed about 50 % decompo-
sition already after 1 h and was fully degraded after 12 h
(cf. also refs. [11, 14]).
Coordination polymer 5 was prepared by stirring a mix-
ture of 4 and MnCl2 (molar ratio 1:2) in THF for 12 h.
Single crystals suitable for X-ray diffraction were grown by
gas-phase diffusion of hexane into a THF solution of 5.
The most revealing NMR data of 2 and 3 are their 11B
NMR shift values of 36.5 ppm and 38.3 ppm, respectively,
which point to the presence of three-coordinate boron
atoms [21]. The 1H NMR spectrum of 2 is characterized by
three singlets at δ(1H) ϭ 2.94, 3.15, and 7.49 with an inte-
gral ratio of 6:6:4. Compound 3 gives rise to a qualitatively
similar signal pattern (δ(1H) ϭ 2.33, 2.47, 7.46). In both
cases, the two resonances at higher field correspond to the
dimethylamino moieties, and the third signal has to be as-
1
signed to the phenylene bridge. The 11B and H NMR data
confirm the proposed molecular structures of 2 and 3 with
chemically equivalent [B(R)(NMe2)] fragments (Scheme 1).
The two signals for the dimethylamino groups are caused
by hindered rotation about the B-N axes resulting from a
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© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2008, 1409Ϫ1414

A Manganese(II) Coordination Polymer
a)
Table 1 Crystallographic data of the compounds 2 and 3
Table 2 Crystallographic data of the compounds 4([12]crown-4)2
and 5a)
2
3
4([12]crown-4)2
5
formula
fw
C10H16B2Br2N2
345.69
colourless, block
173(2)
monoclinic
P21/n
7.9507(13)
7.3059(8)
12.495(2)
90
99.162(13)
90
716.52(18)
2
1.602
340
C22H16B2F10N2
519.99
colourless, block
173(2)
formula
fw
C46H48B2F10Li2N8O8 C54H64B2Cl4F10Li2Mn2N8O6
colour, shape
temp /K
cryst syst
space group
1066.42
colourless, block
173(2)
monoclinic
P21/n
8.8011(10)
15.1808(11)
18.877(2)
90
100.256(9)
90
2481.8(4)
2
1.427
1100
0.122
1398.31
colourless, plate
173(2)
triclinic
P1
11.2963(19)
12.936(2)
16.593(3)
110.068(12)
98.677(13)
99.317(13)
2191.0(6)
1
colour, shape
temp /K
cryst syst
space group
triclinic
¯
P1
˚
a /A
9.7713(14)
10.4624(14)
12.8142(18)
104.258(11)
94.947(11)
114.368(10)
1130.1(3)
2
¯
˚
b /A
˚
a /A
˚
c /A
˚
b /A
Ͱ /°
β /°
γ /°
˚
c /A
Ͱ /°
β /°
γ /°
3
˚
V /A
3
Z
˚
V /A
Dcalcd. /g cmϪ3
F(000)
1.528
524
0.147
Z
Dcalcd. /g cmϪ3
F(000)
1.060
716
0.470
μ /mmϪ1
5.632
μ /mmϪ1
crystal size /mm
Θmin,max /°
no. of rflns collected
no. of indep rflns (Rint
Rflns with I > 2σ(I)
0.35 ϫ 0.33 ϫ 0.26 0.22 ϫ 0.14 ϫ 0.11
3.81, 27.31
4443
1597 (0.0670)
1423
1597 / 0 / 76
1.056
0.0445, 0.1150
0.0502, 0.1185
1.453 , Ϫ1.293
3.66, 26.25
14055
4255 (0.0978)
3115
4255 / 0 / 331
1.104
0.1240, 0.3253
0.1510, 0.3451
0.622 , Ϫ0.509
crystal size /mm
Θmin,max /°
no. of rflns collected
no. of indep rflns (Rint
Rflns with I > 2σ(I)
0.21 ϫ 0.16 ϫ 0.14
3.47, 25.70
19962
4673 (0.0828)
3100
0.36 ϫ 0.19 ϫ 0.09
3.48, 25.03
25784
7722 (0.1208)
3681
7722 / 0 / 397
1.273
0.1200, 0.2677
0.2054, 0.3028
0.687, Ϫ0.517
)
)
data/restraints/parameters
GOOF on F2
data/restraints/parameters 4673 / 0 / 344
GOOF on F2
R1, wR2 (I>2σ(I))
R1, wR2 (all data)
largest diff peak and
1.021
R1, wR2 (I>2σ(I))
R1, wR2 (all data)
largest diff peak and hole /e A
0.0600, 0.1350
0.0995, 0.1531
0.300, Ϫ0.268
Ϫ3
˚
Ϫ3
˚
a) Crystallographic data of the structures have been deposited with
the Cambridge Crystallographic Data Centre, CCDC 677199 (2),
677200 (3). Copies of the data can be obtained free of charge on
application to The Director, CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK.
hole /e A
a)
Crystallographic data of the structures have been deposited with
the Cambridge Crystallographic Data Centre, CCDC 677201
(4([12]crown-4)2), 677202 (5). Copies of the data can be obtained
free of charge on application to The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK.
significant degree of B-N double bond character. All 13C
NMR signals of 2 and 3 appear in the expected regions of
the spectra and therefore do not merit further discussion;
no 13C NMR resonances have been observed for the C6F5-
substituents due to extensive 13C-19F coupling (C-o, m, p)
and quadrupolar broadening (C-i). Nevertheless, the suc-
cessful introduction of C6F5 groups is documented by three
signals in the 19F NMR spectrum of 3 (δ(19F) ϭ Ϫ161.7,
Ϫ155.0, Ϫ133.4).
sion located at the centroid of the respective phenylene
spacer; compound 5 has a second inversion centre at the
midpoint of the four-membered Mn2Cl2 ring (Figure 5).
The C6F5-substituted borane 3 crystallizes from toluene
with two crystallographically independent molecules (3A,
3B) in the asymmetric unit. Since the key structural param-
eters of 3A and 3B are the same within experimental error,
only the bond lengths and angles of 3A are considered here.
The molecular structures of the mono(amino)boranes 2
and 3 have been determined in order to find out whether
replacement of a bromine atom by the highly electronega-
tive C6F5-fragment has a visible impact on the B-N bond
length, which in turn could be interpreted as a change in
the degree of N-B π-bonding. As evidenced by the very
The 11B NMR spectrum of 4 features one signal at
0.0 ppm, testifying to the presence of chemically equivalent,
tetra-coordinate boron centres [21]. The pyrazolyl protons
give rise to one multiplet at δ(1H) ϭ 6.06 and two doublets
at δ(1H) ϭ 7.46 and 7.52. A singlet at δ(1H) ϭ 7.19 has
to be assigned to the p-disubstituted phenylene bridge. The
relative integral values of the four observed proton signals
(4:4:4:4) are in accordance with the assumption that 4 con-
tains two bis(pyrazol-1-yl)borate moieties. Similar to 3, no
13C6F5-signals could be detected; all 13C NMR data of 4
are unexceptional. The 19F NMR spectrum of 4 reveals
three signals (δ(19F) ϭ Ϫ167.9, Ϫ163.3, Ϫ135.8) from
which the first two (F-m, p) are considerably more shielded
than in the precursor compound 3.
˚
similar values of B(1)-N(1) ϭ 1.388(5) A in 2 (Figure 2) and
1.395(11) A in 3A (Figure 3), no such effect is apparent. The
B-N bond of 3A is, however, slightly longer than
˚
the corresponding bond in the related aminoborane
˚
(CH2)4N-B(C6F5)2 (1.366(3) A) [22] bearing two electron-
withdrawing C6F5-substituents.
As to be expected, the boron as well as the nitrogen
atoms of 2 and 3A adopt perfectly planar configurations
(sums of the bond angles about these atoms: 360°). We also
observe almost identical conformations of the [(N)(R)B-
C6H4-B(R)(N)] cores in 2 and 3A with dihedral angles
2.2 X-ray Crystallography
Crystallographic data of the compounds 2 Ϫ 5 are compiled
in Tables 1 and 2. All four molecules have a centre of inver-
Z. Anorg. Allg. Chem. 2008, 1409Ϫ1414
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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1411

T. Morawitz, M. Bolte, H.-W. Lerner, M. Wagner
located in the plane bisecting the N-B-N angles, while the
C6F5-rings are oriented almost perpendicular to it (dihedral
angle C6H4//C6F5 ϭ 74.1°). The overall structure of
4([12]crown-4)2 closely resembles that of the Liϩ salt of the
t-butyl derivative (Li(THF)2)2[p-C] [13] (Figure 1).
Figure 2 Structure of 2 in the crystal. Displacement ellipsoids are
drawn at the 50 % probability level.
Figure 4 Structure of 4([12]crown-4)2 in the crystal. H atoms are
omitted for clarity, displacement ellipsoids are drawn at the 50 %
probability level.
˚
Selected bond lengths/A, bond angles/°, and dihedral angles/°: B(1)ϪBr(1) ϭ
1.980(4), B(1)ϪN(1) ϭ 1.388(5), B(1)ϪC(1) ϭ 1.569(5), N(1)ϪC(11) ϭ
˚
Selected bond lengths/A, bond angles/°, and torsion angles/°: B(1)ϪN(11) ϭ
1.473(5), N(1)ϪC(12)
ϭ
1.472(5); C(1)ϪB(1)ϪN(1)
ϭ
ϭ
ϭ
126.1(3),
118.6(3),
126.6(3),
1.564(3), B(1)ϪN(21) ϭ 1.580(4), B(1)ϪC(31) ϭ 1.659(4), B(1)ϪC(41) ϭ
C(1)ϪB(1)ϪBr(1)
B(1)ϪN(1)ϪC(11)
ϭ
ϭ
115.3(2),
122.0(3),
N(1)ϪB(1)ϪBr(1)
B(1)ϪN(1)ϪC(12)
1.633(4), N(12)ϪLi(1)
N(11)ϪB(1)ϪN(21)
C(42)ϪC(41)ϪB(1)ϪC(31)
Ϫ55.7(3), C(42)ϪC(41)ϪB(1)ϪN(21) ϭ 61.6(3).
ϭ
2.123(5),
N(22)ϪLi(1)
ϭ
2.109(5);
ϭ
108.0(2), N(12)ϪLi(1)ϪN(22)
ϭ
ϭ 87.6(2);
C(11)ϪN(1)ϪC(12) ϭ 111.4(3); N(1)B(1)Br(1)//C6H4 ϭ 58.4°.
Ϫ178.5(2), C(42)ϪC(41)ϪB(1)ϪN(11) ϭ
The scorpionate ligand in the solid state structure of the
MnII complex 5 (Figure 5) adopts the same conformation
as in the Liϩ salt 4([12]crown-4)2.
Each MnII ion is chelated by one bis(pyrazol-1-yl)borate
˚
unit (N(12)ϪMn(1)
ϭ
2.174(6) A, N(22)ϪMn(1)
ϭ
˚
2.223(6) A) and further bonded to three chloro ligands. The
resulting coordination polyhedron is intermediate between
a distorted square pyramid and a trigonal bipyramid
(trigonality index τ [23] ϭ 0.48). Two of the three chloride
ions act as bridges to a neighbouring MnII ion so that a
coordination polymer is formed (Cl(1)ϪMn(1)
ϭ
˚
˚
2.501(3) A, Cl(1B)ϪMn(1) ϭ 2.578(2) A) [24]. The apical
chloride ion is also a bridging ligand, because it coordinates
not only to the MnII centre but also to a Li(THF)3 frag-
Figure 3 Structure of 3A in the crystal. Displacement ellipsoids
are drawn at the 50 % probability level.
˚
Selected bond lengths/A, bond angles/°, and dihedral angles/°: B(1)ϪN(1) ϭ
˚
1.395(11), B(1)ϪC(11) ϭ 1.584(11), B(1)ϪC(21) ϭ 1.610(11), N(1)ϪC(2) ϭ
ment (Cl(2)ϪMn(1) ϭ 2.396(3) A). It is revealing to com-
1.475(9), N(1)ϪC(3)
ϭ
1.466(9); N(1)ϪB(1)ϪC(11)
120.4(7), C(11)ϪB(1)ϪC(21) ϭ
ϭ
123.4(7),
116.2(6),
124.4(6),
pare the structure of coordination polymer 5 with that of
the dinuclear complex D (Figure 1). In D [13], the two MnII
ions are also penta-coordinate and we observe a similar
[R2Bpz2Mn(μ-Cl)2Mnpz2BR2] core as in the case of 5 (D:
Cl-Mn ϭ 2.516(2) A; N-Mn ϭ 2.175(5) A). However, the
fifth ligand in D is a THF molecule and the coordination
polyhedron of MnII is an ideal square-pyramid (τ ϭ 0).
N(1)ϪB(1)ϪC(21)
B(1)ϪN(1)ϪC(2)
ϭ
ϭ
122.9(7),
B(1)ϪN(1)ϪC(3)
ϭ
C(2)ϪN(1)ϪC(3) ϭ 112.3(6); N(1)B(1)C(21)//C6H4 ϭ 58.2°.
˚
˚
N(1)B(1)Br(1)//C6H4 ϭ 58.4° (2) and N(1)B(1)C(21)//
C6H4 ϭ 58.2° (3A). With regard to the crystal packing of 3,
intermolecular edge-to-face interactions between phenylene
spacers and C6F5-rings appear to play a prominent role
(CH···COG(C6F5) ϭ 3.039 A, 3.052 A; COG: ring cen-
troid).
˚
˚
3 Conclusion
In the solid state structure of the lithium scorpionate 4,
each Liϩ ion is coordinated to one molecule of [12]crown-
4 (4([12]crown-4)2; Figure 4) and to two pyrazolyl rings
(N(12)ϪLi(1) ϭ 2.123(5) A, N(22)ϪLi(1) ϭ 2.109(5) A;
N(12)ϪLi(1)ϪN(22) ϭ 87.6(2)°). The phenylene spacer is
Replacement of the t-butyl-substituents in the ditopic
bis(pyrazol-1-yl)borate ligand [p-C6H4(B(t-Bu)pz2)2]2Ϫ by
C6F5-rings leads to a significantly enhanced stability of the
resulting scorpionate [p-C6H4(B(C6F5)pz2)2]2Ϫ towards air
and moisture. The seemingly innocent spectator group has
˚
˚
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A Manganese(II) Coordination Polymer
Synthesis of 2. A solution of Me3SiNMe2 (3.05 g, 26.02 mmol) in
toluene (20 mL) was added dropwise with stirring at Ϫ78 °C to 1
(5.43 g, 13.01 mmol) in toluene (40 mL). The clear solution was
slowly allowed to warm to room temperature, stirred for 12 h and
evaporated to dryness in vacuo. Yield: 4.05 g (90 %). Colourless
crystals of 2 were grown by slow evaporation of a toluene solution
at ambient temperature.
11B NMR (128.4 MHz, CDCl3): 36.5 (h1/2 ϭ 280 Hz). 1H NMR (300.0 MHz,
CDCl3): 2.94, 3.15 (2 ϫ s, 2 ϫ 6H, NCH3), 7.49 (s, 4H, C6H4). 13C NMR
(75.5 MHz, CDCl3): 41.1, 42.5 (NCH3), 131.6 (C6H4), n.o. (CB).
Synthesis of 3. A solution of C6F5MgBr in Et2O (2.2 M, 4.25 mL,
9.35 mmol) was added dropwise under vigorous stirring at Ϫ78 °C
to a solution of 2 (1.62 g, 4.68 mmol) in toluene (30 mL). The re-
sulting light brown mixture was allowed to warm to room tempera-
ture and all volatiles were removed in vacuo. The solid product was
extracted into hexane (2 ϫ 50 mL) and the extract evaporated to
dryness in vacuo. Yield: 1.80 g (74 %). Crystals suitable for X-ray
diffraction were grown by recrystallization of the crude material
from toluene.
11B NMR (96.3 MHz, C6D6): 38.3 (h1/2 ϭ 490 Hz). 1H NMR (300.0 MHz,
C6D6): 2.33, 2.47 (2 ϫ s, 2 ϫ 6H, NCH3), 7.46 (s, 4H, C6H4). 13C NMR
(75.4 MHz, CDCl3): 40.9, 41.7 (NCH3), 131.3 (C6H4), n.o. (CB, CF). 19F
NMR (282.3 MHz, C6D6): Ϫ161.7 (m, 4F, F-m), Ϫ155.0 (m, 2F, F-p),
Ϫ133.4 (m, 4F, F-o).
Figure 5 a) Structure of 5 in the crystal. b) Ball-and-stick model
of the polymer chain of 5. H atoms are omitted for clarity, displace-
ment ellipsoids are drawn at the 30 % probability level.
˚
Selected bond lengths/A, bond angles/°, and torsion angles/°: B(1)ϪN(11) ϭ
1.571(10), B(1)ϪN(21) ϭ 1.542(11), B(1)ϪC(31) ϭ 1.664(12), B(1)ϪC(41) ϭ
1.628(10), N(12)ϪMn(1)
Cl(1)ϪMn(1) 2.501(3), Cl(1B)ϪMn(1)
2.396(3), Cl(2)ϪLi(1) 2.34(2); N(12)ϪMn(1)ϪN(22)
ϭ
2.174(6), N(22)ϪMn(1)
ϭ
2.223(6),
ϭ
ϭ
2.578(2), Cl(2)ϪMn(1)
ϭ
84.0(2),
160.8(2),
111.2(1),
97.8(1),
3.8(10),
Synthesis of 4. A mixture of neat Lipz (0.115 g, 1.55 mmol) and
neat Hpz (0.106 g, 1.56 mmol) was added to a solution of 3
(0.410 g, 0.78 mmol) in toluene (50 mL) at room temperature. The
suspension was stirred for 72 h and then evaporated to dryness in
vacuo. Yield: 0.440 g (79 %). X-ray quality crystals of 4([12]crown-
4)2 were grown by gas-phase diffusion of hexane into a saturated
solution of 1 equivalent of 4 and 2 equivalents of [12]crown-4 in
THF at room temperature. Anal. Calcd. for C46H48B2F10Li2N8O8
(1066.42) ϫ 2 H2O (18.02): C, 50.12; H, 4.75; N, 10.16. Found: C,
50.30; H, 4.82; N, 9.89 %.
11B NMR (96.3 MHz, THF-d8): 0.0 (h1/2 ϭ 340 Hz). 1H NMR (400.1 MHz,
THF-d8): 6.06 (m, 4H, pzH-4), 7.19 (s, 4H, C6H4), 7.46, 7.52 (2 ϫ d, 2 ϫ
4H, 3JHH ϭ 2.0 Hz, 1.4 Hz, pzH-3/5). 13C NMR (75.4 MHz, THF-d8): 103.3
(pzC-4), 134.7 (pzC-3/5), 137.1 (C6H4), 140.1 (pzC-3/5), n.o. (CB, CF). 19F
NMR (282.3 MHz, THF-d8): Ϫ167.9 (m, 4F, F-m), Ϫ163.3 (m, 2F, F-p),
Ϫ135.8 (m, 4F, F-o).
ϭ
ϭ
ϭ
ϭ
ϭ
Cl(1)-Mn(1)-N(12)
Cl(1)ϪMn(1)ϪCl(1B)
Cl(1B)ϪMn(1)ϪCl(2)
ϭ
131.8(2), Cl(1B)-Mn(1)-N(22)
82.2(1), Cl(1)ϪMn(1)ϪCl(2)
95.7(1), Mn(1)ϪCl(1)ϪMn(1B)
ϭ
ϭ
Mn(1)-Cl(2)-Li(1) 118.5(5); C(42)ϪC(41)ϪB(1)ϪC(31)
C(42)ϪC(41)ϪB(1)ϪN(11)
ϭ
ϭ
Ϫ116.9(8), C(42)ϪC(41)ϪB(1)ϪN(21) ϭ
124.0(8). Symmetry transformation used to generate equivalent atoms:
B ϭ Ϫxϩ2,Ϫyϩ1,Ϫzϩ1.
also considerable impact on the molecular structures of cor-
responding MnII complexes. From 2 : 1 mixtures of MnCl2
with Li2[p-C6H4(B(t-Bu)pz2)2] or Li2[p-C6H4(B(C6F5)pz2)2]
in THF/hexane we isolated single crystals consisting of dis-
crete dinuclear metallomacrocycles in the case of the t-bu-
tyl-derivative (D; Figure 1) and coordination polymers in
the case of the C6F5 analogue (5, Figure 5). Detailed in-
vestigations into the magnetic properties of both species are
currently underway in our laboratory.
Synthesis of 5. A solution of 4 (0.243 g, 0.34 mmol) in THF
(20 mL) was added to neat MnCl2 (0.086 g, 0.68 mmol). The sus-
pension was stirred at room temperature for 12 h to give a clear
light brown solution. After the solvent had been removed in vacuo
the product was extracted into CH2Cl2 (50 mL). The extract was
evaporated to dryness in vacuo to give a pale brown solid. Yield:
0.400 g. Few crystals suitable for X-ray analysis were grown by gas-
phase diffusion of hexane into a saturated THF solution of the
product at room temperature.
4 Experimental Section
General Considerations
All reactions and manipulations of air-sensitive compounds were
carried out in dry, oxygen-free argon using standard Schlenk ware.
˚
CH2Cl2 and CDCl3 were passed through a 4 A molecular sieves
X-ray Crystal Structure Determinations of 2؊5
column prior to use. All other solvents were freshly distilled under
argon from Na/benzophenone. p-C6H4(BBr2)2 (1) [19] and
C6F5MgBr [20] were prepared following literature procedures.
NMR: Bruker AMX 250, AMX 300, AMX 400, Bruker DPX 250
spectrometers. 1H- and 13C NMR spectra are calibrated against
residual solvent signals. 11B NMR spectra were reported relative to
external BF3 ·Et2O. All NMR spectra were run at room tempera-
ture. Abbreviations: s ϭ singlet, d ϭ doublet, m ϭ multiplet, n.o. ϭ
signal not observed, pz ϭ pyrazol-1-yl. Elemental analyses were
performed by the microanalytical laboratory of the University of
Frankfurt.
Data collection was performed on a Stoe-IPDS-II two-circle-dif-
fractometer with graphite-monochromated MoKα radiation
˚
(0.71073 A). Empirical absorption corrections with the MULABS
option in the program PLATON [25] were performed for 2 and 5.
The structures were solved by direct methods [26] and refined with
full-matrix least-squares on F2 using the program SHELXL97 [27].
Hydrogen atoms were placed on ideal positions and refined with
fixed isotropic displacement parameters using a riding model.
CCDC reference numbers: 677199 (2), 677200 (3), 677201
(4([12]crown-4)2), 677202 (5).
Z. Anorg. Allg. Chem. 2008, 1409Ϫ1414
© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
1413

T. Morawitz, M. Bolte, H.-W. Lerner, M. Wagner
Acknowledgement. The authors are grateful to the Deutsche For-
schungsgemeinschaft (DFG) for financial funding. T. M. wishes to
thank the Fonds der Chemischen Industrie (FCI) for a Ph. D. grant.
[18] A. Haghiri Ilkhechi, J. M. Mercero, I. Silanes, M. Bolte, M.
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[19] M. C. Haberecht, J. B. Heilmann, A. Haghiri, M. Bolte, J. W.
Bats, H.-W. Lerner, M. C. Holthausen, M. Wagner, Z. Anorg.
Allg. Chem. 2004, 630, 904Ϫ913.
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1414
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Z. Anorg. Allg. Chem. 2008, 1409Ϫ1414