Theory-guided experiments on the mechanistic elucidation of the reduction of dinuclear zinc, manganese, and cadmium complexes

Article abstract of DOI:10.1002/anie.201102296

Two Mni-Mn-bonded dimanganese complexes, as well as the tetracadmium complex shown in the picture, were obtained by reduction of [M ₂{η-²-Me₂Si(NDipp)₂} ₂] (M=Mn, Cd; Dipp=2,6-iPr₂C₆H₃). Their structures are consistent with those of calculated intermediates in the reduction of [Zn₂{η-²-Me₂Si(NDipp) ₂}₂]. Copyright

Full text of DOI:10.1002/anie.201102296

DOI: 10.1002/anie.201102296
Metal–Metal Bonds
Theory-Guided Experiments on the Mechanistic Elucidation of the
Reduction of Dinuclear Zinc, Manganese, and Cadmium Complexes**
Duan-Yen Lu, Jen-Shiang K. Yu, Ting-Shen Kuo, Gene-Hsiang Lee, Yu Wang, and Yi-
Chou Tsai*
I
I
À
Since the recognition of the first Zn Zn bond in the
5
À
dinuclear sandwich decamethyldizincocene [(h -C5Me5)Zn
Zn(h5-C5Me5)],[1] the chemistry of Zn Zn-bonded species has
À
À
grown so rapidly that many complexes of the type LZn ZnL
have been characterized and studied.[2] Regardless of the
denticity of the supporting ligands L, they all coordinate to Zn
in a terminally chelating mode.[2] However, formation of these
dinuclear compounds has not been mechanistically examined.
I
À
We recently described the characterization of dinuclear Zn
ZnI-bonded species [{k -Me2Si(NDipp)2}Zn Zn{k -Me2Si-
(NDipp)2}]2À (2) (Dipp = 2,6-iPr2C6H3) from KC8 reduction
of dinuclear zinc complex [Zn2(m-k2-Me2Si(NDipp)2)2] (1),
whereby the coordination mode of the diamido ligands
dramatically changes from bridging to chelating.[2j] We thus
became interested in the structural preference and the
2
2
À
I
I
À
formation mechanism of Zn Zn -bonded complexes. Elabo-
rate calculations were performed to understand the reduction
Scheme 1. Calculated mechanism of transformation of 1 into 2.
of 1, and
a plausible mechanism was then proposed
(Scheme 1). On two-electron reduction of 1, two intermedi-
ates, Ia and Ib, are generated, and the energy difference
Although the application of quantum chemical methods
(ab initio molecular orbital and density functional theory) to
elucidate reaction mechanisms has been very successful,[3]
most of the time it is difficult to prove the theoretically
developed reaction mechanisms by experiments. This is
indeed the case for the transformation from 1 to 2. Attempts
to probe both intermediates Ia and Ib failed. To this end, we
turned our attention from zinc to manganese and cadmium,
because they not only show structural similarity in the
II
I
between them is only 0.3 kcalmolÀ1 [2j]
The Zn Zn -bonded
.
À
mixed-valent intermediate Ia is produced by one-electron
reduction of 1, and subsequently undergoes a dramatic
structural rearrangement to give Ib, in which one three-
coordinate and one one-coordinate Zn atoms are proposed.
The exact valence of the Zn atoms in Ib is still not clear.
I
I
reported
M
M -bonded dinuclear complexes [(k2-Nac-
À
[*] D.-Y. Lu, Prof. Dr. Y.-C. Tsai
Department of Chemistry, National Tsing Hua University
Hsinchu 30013 (Taiwan)
2
(M = Zn,[2o]
Mn;[4]
Nacnac =
À
nac)M M(k -Nacnac)]
[2n]
Cd;[5]
À
HC[C(Me)NDipp]2) and [Ar’M MAr’] (M = Zn,
Ar’ = 2,6-(2,6-iPr2C6H3)2C6H3), but also feature an identical
Fax: (+886)3-571-1082
E-mail: yictsai@mx.nthu.edu.tw
À
M M s-bonding scheme. Herein we report structural trans-
Prof. Dr. J.-S. K. Yu
formations on reduction of dinuclear manganese and cad-
mium complexes [Mn2{k2-Me2Si(NDipp)2}2] (3) and [Cd2{m-
k2-Me2Si(NDipp)2}2] (4). Characterization of the products
supports the computed mechanism shown in Scheme 1.
As shown in Scheme 2, reactions of the dilithiated
diamido ligand and 1 equiv of anhydrous MnCl2 and CdCl2
in diethyl ether and THF, respectively, yielded the corre-
sponding dimeric compounds 3 and 4 in good yields. The
dinuclear nature of 3 and 4 was deciphered by single-crystal
X-ray crystallography,[6] and their molecular structures are
provided in Figures S1 and S2 of the Supporting Information.
Complex 3 is essentially composed of two MnN2Si four-
Institute of Bioinformatics and Systems Biology and Department of
Biological Science and Technology, National Chiao Tung University
Hsinchu, 30010 (Taiwan)
T.-S. Kuo
Department of Chemistry, National Taiwan Normal University
Taipei 11677 (Taiwan)
Dr. G.-H. Lee, Prof. Dr. Y. Wang
Department of Chemistry, National Taiwan University
Taipei 10617 (Taiwan)
[**] J.-S.K.Y. and Y.-C.T are indebted to the National Science Council,
Taiwan for support under Grant NSC 99-2627-B-009-008 and NSC
99-2113-M-007-012-MY3, respectively. The computational facility is
supported by NCTU under the grant from MoE ATU Plan. We thank
Prof. Yen-Hsiang Liu (Fu Jen Catholic University, Taiwan) for his help
with the crystallography of compound 6.
À
membered rings, which are brought together by two Mn N
bonds, and consequently exhibit a boat conformation with
two manganese atoms at the stern and two Si atoms at the
bow. Each Mn atom is embraced by three nitrogen atoms and
adopts a distorted T-shaped geometry. The central Mn2N2
Supporting information for this article (experimental details for the
synthesis and characterization of complexes 3–7) is available on the
WWW under http://dx.doi.org/10.1002/anie.201102296.
Angew. Chem. Int. Ed. 2011, 50, 7611 –7615
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
7611

Communications
manganese centers. The meff value of 4.88 mB at
300 K is significantly lower than the spin-only
value (S = 5/2 for dinuclear manganese species).
Complex 4, on the other hand, is essentially
isostructural with complex 1,[2j] whereby two
metal atoms are spanned by two bidentate
diamido ligands, and the Cd···Cd distance of
3.042(1) ꢀ indicates no bonding interaction
between the two cadmium atoms.
Both 3 and 4 show interesting reduction
chemistry. Whereas 2 is the only isolable product
from the reduction of 1, the reduction of complex
3 is slightly more complicated. As shown in
Scheme 3, treatment of 3 with 1 equiv of KC8 in
the presence of 18-crown-6 in THF afforded
II
I
À
orange mixed-valent Mn Mn complex [(thf)2-
Kꢀ18-crown-6][Mn2{m-k2-Me2Si(NDipp)2]2]
([(thf)2Kꢀ18-crown-6][5]). Subsequent reduction
I
I
À
of [(thf)2Kꢀ18-crown-6][5] gave purple Mn Mn
species
[(thf)2Kꢀ18-crown-6]2[Mn{k2-Me2Si-
Scheme 2.
(NDipp)2}2] ([(thf)2Kꢀ18-crown-6]2[6]). Alterna-
tively, dianionic complex 6 can be prepared
directly from 3 by two-electron reduction. For
crystallographic experiments, two more com-
plexes containing dianionic fragment 6 were
prepared by KC8 reduction of 3 in neat toluene
and in THF in the presence of 222-cryptand to
give [K2ꢀ6] and [Kꢀ222-cryptand]2[6], respec-
tively.
The solid-state molecular structure of anionic
5 was determined by single crystal X-ray crystal-
lography (Figure 1).[6] The structure of 5 is close
to that of calculated intermediate Ia; both feature
II
À
two bidentate diamido ligands spanning an M
MI (M = Mn, Zn) bond. In contrast to the planar
Mo2N4 core in quadruply bonded dimolybdenum
complex [Mo2{m-k2-Me2Si(NDipp)2}2],[9] in which
À
two bidentate diamido ligands also span the Mo
Mo bond, the core structure of 5 displays a
puckered conformation with an N1-Mn1-Mn2-N2
dihedral angle of 24.38. Each Mn atom is ligated
by two nitrogen donors of the ligands and one
adjacent Mn atom, and thus adopts a T-shaped
Scheme 3.
geometry. Although
5
is
a
mixed-valent
(MnIIMnI) species, the two Mn atoms are essen-
tially indistinguishable, because the structure has
four-membered ring adopts a nonplanar conformation, with a
local Ci symmetry. Characterization of 5 therefore supports
the accuracy of the calculated intermediate Ia for the
reduction of 1.
Surprisingly, the X-ray structure of dianionic complex 6 in
both [Kꢀ222-cryptand]2[6] and [K2ꢀ6] (Figure 2) is dramat-
ically different from that of 5, but similar to that of 2. In both
compounds, each Mn atom is terminally chelated by two
bidentate diamido ligands, and the two resultant MnN2Si four-
dihedral angle of 11.08. Presumably, this arrangement is a
consequence of strain between the sterically encumbered
Dipp substituents. A similar bonding mode was also observed
in complexes [M2{k2-N(Dipp)(CH2)3(Dipp)N}2] (M = Mn, Fe,
and Zn).[7]
The Mn···Mn distance of 2.7746(11) ꢀ in 3 is significantly
longer than that of 2.69 ꢀ in [M2{k2-N(Dipp)(CH2)3-
(Dipp)N}2][7] but shorter than those of [Mn2{N(SiMe3)2}4]
(2.811(1) ꢀ at 140 K[8a] and 2.841(1) at room temperature[8b]).
Solid-state magnetic data of 3 are shown in Figure S3 of the
Supporting Information. Variation of cm and meff with temper-
ature indicates antiferromagnetic coupling between two
À
membered rings are brought together by the Mn Mn bond. In
6, each Mn atom is three-coordinate with respect to the
diamido ligand and the neighboring Mn atom, and adopts a
trigonal-planar geometry with a sum of the bond angles at
each Mn center of 3608. Noteworthily, the two MnN2Si four-
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ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Angew. Chem. Int. Ed. 2011, 50, 7611 –7615

Figure 1. Molecular structure of 5 with thermal ellipsoids at 35%
À
probability. Selected bond lengths [ꢀ] and angles [8]: Mn1 Mn2
À
À
À
2.6848(8), Mn1 N1 1.934(3), Mn1 N4 1.940(3), Mn2 N2 1.941(3),
À
Mn2 N3 1.937(3); N1-Mn1-N4 173.99(13), N2-Mn2-N3 177.09(13),
N1-Mn1-Mn2 88.56(9), N4-Mn1-Mn2 91.26(9), N3-Mn2-Mn1 89.52(9),
N2-Mn2-Mn1 91.14(9).
membered rings are coplanar in both complexes regardless of
the encapsulated potassium ions. This array is in sharp
2
2
À
contrast with that of [(k -Nacnac)Mn Mn(k -Nacnac)], in
which two C3N2Mn six-membered rings are orthogonal to
each other.[4]
Not only do monoanionic 5 and dianionic 6 exhibit
different structures, but they have very different metrics
À
according to XRD analysis. The average Mn N bond lengths
are 1.939 (5), 2.054 ([K2ꢀ6]), and 2.089 ꢀ ([Kꢀ222-crypt-
À
and]2[6]). The significantly short Mn N bond lengths in 5
suggest significant p-bonding interactions between manga-
nese atoms and four nitrogen donors. For a dinuclear
complex, the metal–metal distance is usually the most
À
interesting metric parameter. The Mn Mn bond length of
Figure 2. Molecular structures of 6 in [Kꢀ222-cryptand]2[6] (top) and
[K2ꢀ6] (bottom) with thermal ellipsoids at 35% probability. Selected
2.6851(9) ꢀ in 5 is much shorter than those in [Kꢀ222-
cryptand]2[6] (2.7871(8) ꢀ) and [K2ꢀ6] (2.7464(13) ꢀ). Inter-
À
bond lengths [ꢀ] and angles [8]: [Kꢀ222-cryptand]2[6]: Mn1 Mn1A
À
À
À
2.7871(8), Mn1 N1 2.078(3), Mn1 N2 2.100(2); N1-Mn1-N2
estingly, the Mn Mn bond length is strongly dependent on the
À
76.44(10), N1-Mn1-Mn1A-N2A 11.69(10). [K2ꢀ6]: Mn1 Mn1A
À
ancillary ligands. For example, the Mn Mn bond lengths in
À
À
2.7464(13), Mn1 N1 2.065(4), Mn1 N2 2.044(4), Mn1···K1
univalent dimanganese species are 2.721(1) ꢀ in [(k2-Nac-
3.8731(14); N1-Mn1-N2 76.74(15), N1-Mn1-Mn1A-N2 4.02(12).
2
[4]
À
nac)Mn Mn(k -Nacnac)]
and 2.6745(5) ꢀ in [Mn2(m-
S2)(CO)6(m-CO)].[10] In addition, the Mn Mn bond length in
zero-valent dimanganese carbonyl complex [Mn2(CO)10] is
2.9042(8) ꢀ.[11] Nevertheless, all of these values are shorter
than those of diatomic Mn2 (3.4 ꢀ, estimated in rare-gas
À
Me2Si(NDipp)2}]2 (2)[2j] are not coplanar and display a
2À
À
dihedral angle of 50.68. The Zn Zn s-bonding character was
further corroborated by characterization of K2ꢀ2, in which
each potassium atom is sandwiched by two adjacent phenyl
rings of Dipp groups, and consequently the dihedral angle of
the two N2SiZn four-membered rings is reduced to 10.88. The
+
matrix) and Mn2 (3.06 ꢀ, estimated in MgO matrix).[12]
I
I
2
À
Roesky et al. have shown that the Mn Mn bond in [(k -
Nacnac)Mn Mn(k -Nacnac)][4] is formed by overlap of a pair
2
À
À
of 4s orbitals. Accordingly, a similar bonding scheme is also
proposed for the Mn Mn bonds in 5 and 6, but the formal
Mn Mn bond order is 0.5 in 5 and 1 in 6. The shorter Mn Mn
bond length in 5 is presumably due to the bridging ligands,
while 6 bears two chelating ligands.
steady Zn Zn distances of 2.3695(17) and 2.3634(11) ꢀ in
À
À
these two complexes, independent of rotation about the Zn
À
À
Zn axis, indeed signify s bonding between the two Zn atoms.
À
On the other hand, in light of the Mn Mn s-bonding scheme
2
2
[4]
À
in [(k -Nacnac)Mn Mn(k -Nacnac)],
both [K2ꢀ6] and
À
It is noteworthy that the two ZnN2Si four-membered rings
in the reported dinuclear Zn Zn -bonded complex [Zn{k -
[Kꢀ222-cryptand]2[6] should also have a Mn Mn s bond on
I
I
2
À
À
the basis of equivalent Mn Mn distances. However, the
Angew. Chem. Int. Ed. 2011, 50, 7611 –7615
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
7613

Communications
parallel arrangement of two MnN2Si four-membered rings in
both [Kꢀ222-cryptand]2[6] and [K2ꢀ6] suggests strong anti-
ferromagnetic coupling between two Mn centers. This is
indeed the case. The temperature dependence of the magnetic
susceptibility of mixed-valent dimanganese MnIIMnI species
I
I
À
[(thf)2Kꢀ18-crown-6][5] and univalent Mn Mn complex
[K2ꢀ6] in the temperature range of 2–300 K is shown in
Figures S4 and S5 of the Supporting Information, respectively.
The room-temperature effective magnetic moments meff of
[(thf)2Kꢀ18-crown-6][5] and [K2ꢀ6] are 6.10 and 4.84 mB,
respectively. These values are smaller than that expected for
two noninteracting univalent manganese centers (meff = 9.8 mB
for 7S and meff = 6.9 mB for 5D states).
To isolate the 5-analogous dicadmium complex, reduction
of 4 by 1 equiv of potassium hydride in the presence of 18-
crown-6 was also carried out in THF. To our surprise, a
diamagnetic tetranuclear mixed-valent complex formulated
as [(thf)2Kꢀ18-crown-6]2[({k2-Me2Si(NDipp)2}Cd{m-Me2Si-
(NDipp)2}Cd)2] ([(thf)2Kꢀ18-crown-6]2[7]) was obtained
from the reaction (Scheme 4). Two signals at d = 436.0 and
Figure 3. Molecular structure of 7 with thermal ellipsoids at 35%
À
probability. Selected bond lengths [ꢀ] and angles [8]: Cd1 Cd1A
À
À
À
2.6103(9), Cd1 N1 2.103(5), Cd2 N2 2.111(5), Cd2 N3 2.183(6),
À
Cd2 N4 2.169(5); N1-Cd1-Cd1A 158.24(15), N2-Cd2-N3 139.54(19),
N2-Cd2-N4 147.7(2), N3-Cd2-N4 72.3(2).
and Zn atoms, the 7-analogous dimanganese and dizinc
complexes have not yet been observed.
In summary, we have demonstrated the synthesis and
À
characterization of two remarkable Mn Mn-bonded
dimanganese complexes, 5 and 6, and one tetracadmium
I
I
À
complex 7 featuring a Cd Cd bond. Collectively, character-
ization of these complexes is consistent with the proposed
intermediates in the computed mechanism for the trans-
formation of dizinc complex 1 on reduction, and this
mechanism is applicable to the reduction of dimanganese
complex 3 and dicadmium complex 4. Although the recently
[2]
reported dinuclear complexes LM ML (M = Zn, Mn,[4]
À
Cd[5]) can be stabilized by various ligands with different
denticity, the mechanism described herein sheds light on their
formation. Reactivity studies on 5–7 are currently underway.
Scheme 4.
Received: April 2, 2011
Published online: June 29, 2011
420.3 ppm were observed in the 113Cd NMR spectrum. In
contrast to the high stability of the only structurally charac-
Keywords: cadmium · manganese · metal–metal interactions ·
reaction mechanisms · zinc
.
I
I
À
À
terized Cd Cd -bonded dimeric species [Ar’Cd CdAr’]
(Ar’ = 2,6-(2,6-iPr2C6H3)2C6H3), [(thf)2Kꢀ18-crown-6]2[7] is
thermally unstable in organic solvents. On dissolution in THF
at room temperature, it quickly decomposes to cadmium
metal, free ligands, and unidentified cadmium complexes over
12 h. X-ray diffraction analysis of 7 (Figure 3) indicates that it
is a dimeric complex in which two monomers {(k2-Me2Si-
(NDipp)2)Cd(m-Me2Si(NDipp)2)Cd}, containing one one-
coordinate and one three-coordinate Cd atoms, are linked
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I
I
À
through a Cd Cd bond. The structure of this monomer is
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Scheme 1. It is therefore clear that the one-coordinate zinc
atom in Ib is univalent, and the three-coordinate zinc atom is
À
divalent. The Cd1 Cd1A bond length of 2.6103(9) ꢀ is
[5]
À
shorter than that in Ar’Cd CdAr’ (2.6257(5) ꢀ), in which
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7614
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Angew. Chem. Int. Ed. 2011, 50, 7611 –7615

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group P21/n, a = 12.4901(2), b = 18.6490(5), c = 12.7453(3) ꢀ,
1calcd
1.301mgmÀ3, m = 0.880 mmÀ1, reflections collected: 13188, inde-
pendent reflections: 4801 (Rint = 0.0499), final R indices [I >
2s(I)]: R1 = 0.0458, wR2 = 0.1155, R indices (all data): R1 =
b = 116.3250(10)8,
V= 2660.86(10) ꢀ3,
Z = 2,
=
0.0635,
wR2 = 0.1396;
[(thf)2Kꢀ18-crown-6][5]·2THF:
C80H136K1Mn2N4O10Si2: Mr = 1519.09, T= 200(2) K, monoclinic,
space group P21/c, a = 17.1441(2), b = 12.5878(2), c =
41.3059(5) ꢀ, b = 96.5760(10)8, V= 8855.4(2) ꢀ3, Z = 4, 1calcd
=
1.139 mgmÀ3, m = 0.412 mmÀ1, reflections collected: 38589, inde-
pendent reflections: 15930 (Rint = 0.0751), final R indices [I >
2s(I)]: R1 = 0.0754, wR2 = 0.2013, R indices (all data): R1 =
0.1191,
wR2 = 0.2376;
[Kꢀ222-cryptand]2[6]·2THF:
C100H176K2Mn2N8O15Si2: Mr = 1974.75, T= 200(2) K, triclinic,
ꢀ
space group P1, a = 13.9385(9), b = 15.0562(9), c =
17.2750(11) ꢀ, a = 112.6360(10), b = 111.3730(10), g =
92.5690(10)8, V= 3042.9(3) ꢀ3, Z = 1, 1calcd = 1.078 mgmÀ3, m =
0.350 mmÀ1, reflections collected: 20983, independent reflec-
tions: 10374 (Rint = 0.0256), final R indices [I > 2s(I)]: R1 =
0.0671, wR2 = 0.2088, R indices (all data): R1 = 0.0864, wR2 =
0.22379; [K2ꢀ6]: C52H80K2Mn2N4Si2: Mr = 1005.46, T=
200(2) K, monoclinic, space group P21/n, a = 10.0750(5), b =
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S. A. Rice, I. Prigogine), Wiley, New York, 1996, p. 333;
h) Transition Metal Hydrides (Ed.: A. Dedieu), VCH Publishers,
Weinheim, 1992; i) Theoretical Aspects of Homogeneous Catal-
ysis, Applications of Ab Initio Molecular Orbital Theory (Eds.:
P. W. N. M. van Leeuwen, J. H. van Lenthe, K. Morokuma),
Elsevier, Dordrecht, 1994; j) S. Yoshida, S. Sakaki, H. Kobaya-
shi, Electronic Processes in Catalyst, VCH, New York, 1992.
[4] J. Chai, H. Zhu, A. C. Stꢅckl, H. W. Roesky, J. Magull, A.
Bencini, A. Caneschi, D. Gatteschi, J. Am. Chem. Soc. 2005, 127,
9201.
21.3090(12),
2860.3(3) ꢀ3, Z = 2, 1calcd = 1.167 mgmÀ3, m = 0.663 mmÀ1, reflec-
tions collected: 12868, independent reflections: 5538 (Rint
0.0623), final R indices [I > 2s(I)]: R1 = 0.0577, wR2 = 0.1642, R
indices (all data): R1 = 0.1171, wR2 = 0.2271; 7:
c = 13.5660(8) ꢀ,
b = 100.857(5)8,
V=
=
C165H264Cd4K2N8O16Si4: Mr = 3256.00, T= 150(2) K, monoclinic,
space group P21/c, a = 16.7796(4), b = 25.7323(6), c =
20.6035(5) ꢀ, b = 90.3056(11)8, V= 8896.0(4) ꢀ3, Z = 2, 1calcd
=
1.216 mgmÀ3, m = 0.602 mmÀ1, reflections collected: 40979, inde-
pendent reflections: 15648 (Rint = 0.0706), final R indices [I >
2s(I)]: R1 = 0.0711, wR2 = 0.1924, R indices (all data): R1 =
0.1325, wR2 = 0.2176. CCDC 818305 (3), 818306 (4), 818307
([(thf)2Kꢀ18-crown-6][5]·2THF),
818308
([Kꢀ222-crypt-
and]2[6]·2THF) 818309 ([K2ꢀ6]), and 818310 (7) contain the
supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[7] J. Chai, H. Zhu, Q. Ma, H. W. Roesky, H.-G. Schmidt, M.
Noltemeyer, Eur. J. Inorg. Chem. 2004, 4807.
[8] a) D. C. Bradley, M. B. Hursthouse, K. M. A. Malik, R. Mꢂseler,
Transition Met. Chem. 1978, 3, 253; b) B. D. Murray, P. P. Power,
Inorg. Chem. 1984, 23, 4584.
[9] Y.-C. Tsai, Y.-M. Lin, J.-S. K. Yu, J.-K. Hwang, J. Am. Chem. Soc.
2006, 128, 13980.
[10] a) R. D. Adams, O.-S. Kwon, M. D. Smith, Inorg. Chem. 2001, 40,
5322; b) R. D. Adams, O.-S. Kwon, M. D. Smith, Inorg. Chem.
2002, 41, 5525.
[5] Z. Zhu, R. C. Fischer, J. C. Fettinger, E. Rivard, M. Brynda, P. P.
Power, J. Am. Chem. Soc. 2006, 128, 15068.
[6] Crystallographic data for 3·THF: C56H90Mn2N4O1Si2, Mr =
1001.38, T= 200(2) K, orthorhombic, space group Pccn, a =
13.4453(2),
b = 17.8769(3),
c = 24.0109(5) ꢀ,
V=
5771.27(18) ꢀ3, Z = 4, 1calcd = 1.152 mgmÀ3
,
m = 0.518 mmÀ1
,
reflections collected: 21690, independent reflections: 5273
(Rint = 0.0602), final R indices [I > 2s(I)]: R1 = 0.0730, wR2 =
[11] R. Bianchi, G. Gervasio, D. Marabello, Inorg. Chem. 2000, 39,
2360.
0.1966,
R
indices (all data): R1 = 0.1024, wR2 = 0.2261; 4:
[12] S. K. Nayak, B. K. Rao, P. Jena, J. Phys. Condens. Matter 1998,
10, 10863.
C52H80Cd2N4Si2, Mr = 1042.18, T= 200(2) K, monoclinic, space
Angew. Chem. Int. Ed. 2011, 50, 7611 –7615
ꢀ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.angewandte.org
7615