Cyanometalate cages with exchangeable terminal ligands

Article abstract of DOI:10.1002/ejic.200700001

The coordination chemistry of the unusual metallo-ligand Cs?[CpCo(CN)₃]₄[Cp*Ru]₃ (Cs?Co₄Ru₃) is described with attention to the behavior of the ligand itself, its binding to Lewis-acidic metal cations, and its ability to stabilize catalytically relevant Ru-PPh₃ fragments. A series of tests demonstrate that the rim [CpCo(CN)₃] ^- groups in Cs?Co₄Ru₃ are exchangeable. Upon treatment with [(MeC₅H₄)Co(CN)₃] ^- (Co′) Cs?Co₄Ru₃ undergoes vertex exchange to give Cs?Co_4-xCo′_xRu₃. Similarly the cage is degraded by CO. Most convincing, Cs?Co ₄Ru₃ reacts with PhNH₃OTf to precipitate the polymer PhNH₃CpCo(CN)₃ and form the molecular box [Cs?Co₄Ru₄]⁺. Treatment of Cs?Co ₄Ru₃ with [M(NCMe)_x]PF₆ (M = Cu, Ag) gave the Lewis acidic cages {Cs?[CpCo(CN)₃] ₄[Cp*Ru]₃M(NCMe)}PF₆, which reacted with tertiary phosphane ligands to give adducts [Cs?Co₄Ru ₃M(PPh₃)]PF₆. Lewis acidic octahedral vertices were installed using Fe, Ni, and Ru reagents. The boxes [Cs?Co ₄Ru₃M(NCMe)₃]²⁺ (M = Ni, Fe) formed readily from the reaction Cs?Co₄Ru₃ with [Ni(NCMe)₆](BF₄)₂ and [Fe(NCMe) ₆]-(PF₆)₂. Displacement of the MeCN ligands gives [Cs?Co₄Ru₃Ni(9-ane-S3)](BF₄) ₂. A series of boxes were prepared by the reaction of Cs?Co ₄Ru₃ and RuCl₂(PPh₃)₃, RuHCl(PPh₃)₃, and [(C₆H₆)Ru(NCMe) ₃](PF₆)₂. The derivative of the hydride, [Cs?Co₄Ru₃Ru(NCMe)(PPh₃) ₂](PF₆)₂, was characterized crystallographically. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

Full text of DOI:10.1002/ejic.200700001

FULL PAPER
DOI: 10.1002/ejic.200700001
Cyanometalate Cages with Exchangeable Terminal Ligands
Julie L. Boyer,[a] Haijun Yao,[a] Matthew L. Kuhlman,[a] Thomas B. Rauchfuss,*[a] and
Scott Wilson[a]
Keywords: Cyanide / Ruthenium / Hydrogen bonds / Cage compounds / Heterometallic complexes
The coordination chemistry of the unusual metallo-ligand
Csʚ[CpCo(CN)3]4[Cp*Ru]3 (CsʚCo4Ru3) is described with
attention to the behavior of the ligand itself, its binding to
Lewis-acidic metal cations, and its ability to stabilize catalyti-
with tertiary phosphane ligands to give adducts [CsʚCo4-
Ru3M(PPh3)]PF6. Lewis acidic octahedral vertices were in-
stalled using Fe, Ni, and Ru reagents. The boxes [CsʚCo4-
Ru3M(NCMe)3]2+ (M = Ni, Fe) formed readily from the reac-
cally relevant Ru–PPh3 fragments. A series of tests demon- tion CsʚCo4Ru3 with [Ni(NCMe)6](BF4)2 and [Fe(NCMe)6]-
strate that the “rim” [CpCo(CN)3]– groups in CsʚCo4Ru3 are
exchangeable. Upon treatment with [(MeC5H4)Co(CN)3]–
(CoЈ) CsʚCo4Ru3 undergoes vertex exchange to give
CsʚCo4–xCoЈxRu3. Similarly the cage is degraded by CO.
Most convincing, CsʚCo4Ru3 reacts with PhNH3OTf to pre-
cipitate the polymer PhNH3CpCo(CN)3 and form the molecu-
lar box [CsʚCo4Ru4]+. Treatment of CsʚCo4Ru3 with
[M(NCMe)x]PF6 (M = Cu, Ag) gave the Lewis acidic cages
{Csʚ[CpCo(CN)3]4[Cp*Ru]3M(NCMe)}PF6, which reacted
(PF6)2. Displacement of the MeCN ligands gives [CsʚCo4-
Ru3Ni(9-ane-S3)](BF4)2. A series of boxes were prepared by
the reaction of CsʚCo4Ru3 and RuCl2(PPh3)3, RuHCl(PPh3)3,
and [(C6H6)Ru(NCMe)3](PF6)2. The derivative of the hydride,
[CsʚCo4Ru3Ru(NCMe)(PPh3)2](PF6)2, was characterized
crystallographically.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
[Cp*Ru(NCMe)3]+, and CsOTf at the ratio of 4:4:1 pro-
duces the molecular box {Csʚ[CpCo(CN)3]4[Cp*Ru]4}+
(CsʚCo4Ru4+).[10] By changing the ratio of the reactants to
4:3:1, one obtains instead the violet-colored “defect” box
Csʚ[CpCo(CN)3]4[Cp*Ru]3 (CsʚCo4Ru3).[10] Aside from
its novel structure, an exciting aspect of CsʚCo4Ru3 is its
potential as a well-defined building block for the assembly
Introduction
The centuries old field of metal cyanide chemistry[1] has
experienced a renaissance due the zeolitic,[2,3] magnetic,[4]
and electronic properties[5] of cyanometalate materials. Par-
allel to these application-driven studies, we have focused on
synthetic methodologies leading to discrete molecular
architectures that can be characterized in solution. In recent
years we have developed families of molecular cyanomet-
alate ensembles that are synthesized analogously to Prus-
sian Blue (PB), except that our molecular building blocks
are tricyanometalates.[6] Half of the coordination sphere of
these tricyanometalates is occupied by a strongly coordinat-
z
of novel molecular cages via CsʚCo4Ru3 + MLn Ǟ
z
CsʚCo4Ru3MLn , a box-completion process. Proof-of-con-
cept was provided by the finding that CsʚCo4Ru3 reacts
with one equiv. of [Cp*M(NCMe)3](PF6)n to give the com-
pleted box CsʚCo4Ru3Mz (M = Cp*Ru, Cp*Rh, z = 1, 2)
in high yield.[10]
All previously synthesized cyanometalate boxes and de-
fect boxes possessed non-displaceable ligands such as Cp
–
ing, non-displaceable co-ligand such as C5H5 . The face-
capping co-ligand inhibits the formation of polymers, by
minimizing cross-linking, but still allows the formation of
three-dimensional structures, which resemble subunits of
PB.[7,8]
Our first attempt at molecular cyanometalate cages af-
forded the cationic cage [CpCo(CN)3]4[Cp*Rh]4
and Cp*. Isolable cyanometalate cages with displaceable li-
z
gands L, e.g. Csʚ[CpCo(CN)3]4[Cp*Ru]3MLn (L
=
MeCN, n = 1, 3), represent intriguing targets, which would
enable the generation of ensembles of greater complexity
and enhanced reactivity. For example, one could envision a
modular approach to the preparation of “boxes-of-boxes.”
Few cyanometalates of nuclearity Ͼ8 have been well-char-
acterized in solution.[11] We previously described the
“double boxes” {[CsʚCo4Ru3]2M}z, and we anticipate that
still higher nuclearity cages can be achieved. The construc-
tion of such oligo-cages will require boxes with one or more
vertices that contain labile terminal ligands. This paper out-
lines our initial efforts toward this goal (Scheme 1).
4+ [7]
.
Re-
placing the dicationic tritopic Lewis acid with a monoca-
tionic analog results in charge-neutral ionophilic molecular
cages.[9]
Specifically,
the
reaction
[CpCo(CN)3]–,
[a] Department of Chemistry, University of Illinois at Urbana-
Champaign,
Urbana, IL 61801, USA
E-mail: rauchfuz@uiuc.edu
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Scheme 1. Box-completion reactions of CsʚCo4Ru3 described in this report.
Results and Discussion
Solution Properties of the CsʚCo4Ru3 Metallo-Ligand
Prior to examining the complexation properties of
CsʚCo4Ru3, we conducted experiments aimed at elucidat-
ing the solution behavior of this “defect box.” Four isomers
are possible, depending on the relative stereochemistry of
the three CpCo(CN)3 units situated on the “rim”
(Scheme 2). Two Cs isomers are observed by 1H NMR spec-
troscopy.[10] The interconversion of these two Cs isomers is
hypothesized to occur through the scission of one Ru–N
bond, rotation of the unidentate [CpCo(CN)3]– subunit,
and reformation of the Ru–N bond to a different cyano
group of the same [CpCo(CN)3]– subunit (Scheme 2).
The stereochemical nonrigidity of the rim [CpCo(CN)3]–
groups is indicated by the effect of solvent on the endo2exo1/
endo1exo2 isomer ratio. In THF solution, the ratio is 3:1,
whereas addition of 10% MeCN shifts this ratio to 9:1 (Fig-
ure 1). The presence of MeCN favors the Cs isomer with
two endo CNt ligands (see Scheme 2). Furthermore, small
amount of MeCN cause the chemical shifts of the Cp sig-
nals to shift downfield, possibly due an apparent interaction
of the Cp protons with the triple bond of the MeCN. The
interaction between the MeCN protons and the cyanide lin-
kers of the cage framework was previously indicated with
the solid-state structure of CsʚCo4Ru3.[2]
Labeling studies provided further evidence that the
CsʚCo4Ru3 cage undergoes partial disassembly in solution.
Scheme 2. Schematic depiction of isomers for the M7 defect cages
(top), and pathway that interconverts the two Cs isomers (bottom).
Two Ru–N bonds must break to dissociate a “rim”
–
CpCo(CN)3
subunit. As monitored by ESI-MS,
CsʚCo4Ru3 was shown to exchange with K[(MeC5H4)- did not increase the rate vertex exchange, suggesting that
Co(CN)3] (CoЈ) to give CsʚCo4–xCoЈxRu3 over the course vertex exchange is dissociative, being dependent only on
of days. Altering the amount of CoЈ from one to four equiv. [CsʚCo4Ru3]. In a similar experiment, we found that the
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Cyanometalate Cages with Exchangeable Terminal Ligands
FULL PAPER
tape” motif, constructed from strong hydrogen bonds con-
necting the acidic protons and the basic cyanide ligands
(Figure 2). The ammonium cyanide distances (N···NC–Co)
range from 2.747 to 2.999 Å indicating strong hydrogen
bonds.[13]
Figure 2.
Structure
of
the
hydrogen-bonded
polymer
PhNH3CpCo(CN)3 (top). Schematic illustrating the bonding in the
tape polymer (bottom).
Figure 1. Schematic of the two detected isomers of CsʚCo4Ru3
(top), 1H NMR spectra of CsʚCo4Ru3 in various solvents (bot-
tom).
Although the defect box CsʚCo4Ru3 does undergo par-
tial disassembly in solution, it displayed greater stability
than the analogous Co4Rh32+, which lacks a centrally “glu-
ing” Cs+ center. The Co4Rh32+ +[Cp*Ru(NCMe)3]+ reac-
tion afforded a mixture of Co4Rh44+, Co4Rh3Ru3+, and
Co4Rh2Ru22+. These products, especially Co4Rh44+, indicate
2+
defect box [CpCo(CN)3]4[Cp*Rh]3 (Co4Rh32+) underwent
2+
rapid exchange with CoЈ to give Co4–xCoЈxRh3 in under
5 h.
Treatment of a solution of CsʚCo4Ru3 with CO resulted
in rapid degradation as indicated by the appearance of a
νCO band at 1943 cm–1. ESI-MS of the reaction mixture
featured peaks corresponding to {[CpCo(CN)3]2[Cp*Ru-
(CO)]3}+. We propose {[CpCo(CN)3]2[Cp*Ru(CO)]3}+ is a
trigonal-bipyramidal cage, other examples of which are
known in cyanometalate chemistry.[12]
2+
that the starting Co4Rh3 disassembles followed by reas-
sembly of [Cp*Rh(NCMe)3]2+, [Cp*Ru(NCMe)3]+, and
[CpCo(CN)3]– in a nearly statistical manner. Slightly
different
products
are
obtained
when
the
Co4Rh32+ +[Cp*Ru(NCMe)3]+ reaction was conducted in
4+
the presence of Cs+. Again, the main products are Co4Rh4
and Co4Rh3Ru3+, but we also obtained small amounts of
–
Further evidence for the mobility of the CpCo(CN)3
3+
CsʚCo4Rh2Ru2 and CsʚCo4Rh3Ru4+. These latter two
vertices in CsʚCo4Ru3 came from vertex extraction reac-
tions involving ammonium ions. Thus treatment of this cage
with PhNH3OTf afforded the coordination polymer
PhNH3CpCo(CN)3 [Equation (1)].
species are unprecedented examples of cationic receptors
binding Cs+. In contrast to the behavior of the Cs-free
cages, CsʚCo4Ru3 remained intact upon complexation to
[Cp*Rh(NCMe)3]2+ to produce CsʚCo4Ru3Rh2+ quantita-
tively.
+
4
CsʚCo4Ru3
+
4
PhNH3
Ǟ
4
PhNH3CpCo(CN)3
+
3
(1)
[CsʚCo4Ru4]+ + Cs+
This polymeric species was independently synthesized by
treating an MeCN solution of PPN[CpCo(CN)3] with
PhNH3OTf (PPN+ = Ph3PNPPh3+). The yellow solid was
soluble only in polar solvents, i.e. those expected to com-
pete for hydrogen bonds. The polymer adopts a “folded
Boxes with Lewis-Acidic Tetrahedral Vertices: Copper(I)
and Silver(I)
Treatment of a MeCN solution of [Cu(NCMe)4]PF6 with
a
THF solution of CsʚCo4Ru3 at 0 °C gave red
Eur. J. Inorg. Chem. 2007, 2721–2728
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1
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{Csʚ[CpCo(CN)3]4[Cp*Ru]3Cu(NCMe)}PF6 ([CsʚCo4- characterized by H NMR and IR spectroscopy, as well as
Ru3Cu(NCMe)]PF6). The 1H NMR spectrum confirmed ESI-MS.
the C3v symmetry with two Cp resonances in a 3:1 ratio and
single resonance for Cp*. The IR spectrum of [CsʚCo4Ru3-
Boxes Completed with Lewis-Acidic Octahedral Vertices:
Ruthenium
Cu(NCMe)]PF6 featured a single broad νCN band at
2144 cm–1, which is higher in energy vs. νCN for the terminal
cyanides of CsʚCo4Ru3 (2129 cm–1). The ESI-MS of the
product solution supported the formulation. The red-col-
ored silver derivative [CsʚCo4Ru3Ag(NCMe)]+ was pre-
pared analogously from AgPF6 and CsʚCo4Ru3.
The metallo-ligand CsʚCo4Ru3 was shown to bind a
variety of ruthenium PPh3 complexes. Thus, RuCl2(PPh3)3
and RuHCl(PPh3)3 afforded the corresponding eight-vertex
1
cages (Scheme 1). The H NMR spectra of [CsʚCo4Ru3-
The MeCN ligands in [CsʚCo4Ru3M(NCMe)]+ (M =
Ag, Cu) exchange readily. Treatment of these cages with
PPh3 yielded the expected adducts [CsʚCo4Ru3MPPh3]-
PF6, which were characterized spectroscopically. We at-
tempted to generate higher nuclearity cyanometalates by ex-
ploiting the Lewis acidities of [CsʚCo4Ru3M(NCMe)]+ by
their condensation with (18-crown-6K)3[Co(CN)6] or
Et4NCN. Such reactions only regenerated CsʚCo4Ru3, sug-
gesting that the metallo-ligand CsʚCo4Ru3 is only weakly
bound to the coinage metal.
Ru(PPh3)2Cl]Cl and [CsʚCo4Ru3Ru(PPh3)2H]Cl are con-
sistent with Cs symmetry (Figure 3). Treatment of [CsʚCo4-
Ru3Ru(PPh3)2H]Cl with an MeCN solution of AgPF6 gave
[CsʚCo4Ru3Ru(PPh3)2(NCMe)](PF6)2, concomitant with
formation of Ag. This MeCN-containing product was char-
acterized by proton NMR spectroscopy and X-ray crystal-
lography.
Boxes with Lewis-Acidic Octahedral Vertices: Nickel
Condensation of CsʚCo4Ru3 with [Ni(NCMe)6](BF4)2
gave the trimetallic cage {Cs[CpCo(CN)3]4[Cp*Ru]3Ni-
(NCMe)3}2+ ([CsʚCo4Ru3Ni(NCMe)3]2+). To prevent the
generation of the {{Cs[CpCo(CN)3]4[Cp*Ru]3}2Ni}2+ by-
product, the CsʚCo4Ru3 cage was added as an MeCN
slurry to a concentrated solution of [Ni(NCMe)6](BF4)2.
1
The H NMR spectrum of the red product indicated C3v
symmetry. The signals, especially those of the “rim” CpCo
centers, are broadened due to their adjacency to the para-
magnetic octahedral NiII center. The IR spectrum of
[CsʚCo4Ru3Ni(NCMe)3](BF4)2 featured a single broad νCN
band at 2170 cm–1; absent was the νCNt band at 2129 cm–1
for CsʚCo4Ru3. The ESI-MS of the product solution sup-
ported the formation of [CsʚCo4Ru3Ni(NCMe)3]2+ (m/z =
855); signals corresponding to {(CsʚCo4Ru3)2Ni}2+ were
not detected. The metalation route enjoys some generality:
a slurry of CsʚCo4Ru3 was found to react with [Fe-
(NCMe)6](PF6)2 to afford [CsʚCo4Ru3Fe(NCMe)3](PF6)2,
which was identified by ESI-MS.
Figure 3. 1H NMR spectrum of {Csʚ[CpCo(CN)3]4[Cp*Ru]3-
[Ru(PPh3)2Cl]}Cl in C6D6 solution.
A cage containing one Ru(C6H6)2+ vertex was prepared
from the reaction of CsʚCo4Ru3 and [(C6H6)Ru(NCMe)3]-
(PF6)2. Photolysis of [CsʚCo4Ru3Ru(C6H6)](PF6)2 was an-
ticipated to afford the corresponding [Ru(NCMe)3] deriva-
tive, which would be promising building block. Unfortu-
nately, photolysis of [CsʚCo4Ru3Ru(C6H6)](PF6)2 was a
slow process. Only 30% conversion to [CsʚCo4Ru3Ru-
(NCMe)3](PF6)2 was observed after four days.[14]
The MeCN ligands of [CsʚCo4Ru3Ni(NCMe)3]2+ ex-
change with a variety of Lewis bases. Qualitative tests using
ESI-MS showed that 9-ane-S3 formed adducts (9-ane-S3 is
1,4,7-trithiacyclononane). Preparative-scale reaction gave
the red crystalline species [CsʚCo4Ru3Ni(9-ane-S3)](BF4)2,
which was characterized crystallographically (see below).
Attempts were made to generate higher nuclearity cages
X-ray Crystallographic Results on New Molecular Boxes
Single crystal X-ray structure of [CsʚCo4Ru3Ni(9-ane-
by exploiting the Lewis acidity of [CsʚCo4Ru3Ni- S3)](BF4)2 confirmed the structure of the completed box.
(NCMe)3]2+. Treatment of these cages, however, with The CsʚCo4Ru3 subunit remains intact and binds the Ni(9-
K[(C5R5)M(CN)3] [(C5R5)M = Cp*Rh, CpCo] or Et4NCN ane-S3) subunit in a tridentate fashion forming the trimetal-
generated the double box {(CsʚCo4Ru3)2Ni}2+, as indi- lic cube framework, analogous to previously reported com-
cated by ESI-MS analysis. Apparently, scission of the Ni– pleted boxes (Figure 4).[15] In the case of [CsʚCo4Ru3-
N(cage) bonds is facile. A sample {[CsʚCo4Ru3]2Ni}- Ru(PPh3)2(NCMe)](PF6)2, the dicationic cage consists of a
(BF4)2 was generated independently by treatment of Co4Ru4(µ-CN)12 cube with a Ru(PPh3)2(NCMe)2+ vertex
CsʚCo4Ru3 with 0.5 equiv. of [Ni(NCMe)6](BF4)2 and and three Cp*Ru vertices. The cyanide linkages in both the
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Cyanometalate Cages with Exchangeable Terminal Ligands
FULL PAPER
[CsʚCo4Ru3Ni(9-ane-S3)](BF4)2 and [CsʚCo4Ru3Ru-
(PPh3)2(NCMe)](PF6)2 cages are ordered, as indicated by
characteristically short Co-C distances. The cage frame-
works conform well to the geometry of a cube with ca. 90°
N–M–N and C–M–C angles (Table 1 and Table 2).
Conclusions
The cage CsʚCo4Ru3 is a versatile metallo-ligand, de-
spite its stereochemical complications. Neither of the two
isomers of this cage are poised to serve as a tridentate li-
gand: reorientation of the terminal cyanide ligands is re-
quired. Metalation of CsʚCo4Ru3 is complete upon ad-
dition of the electrophile. The isomerization of the terminal
cyanides would appear to require the scission of at least one
intra-cage Ru–NC–Co linkage, which allows it to exchange
sites with the terminal cyanide ligand. Various chemical
tests – cage degradation with CO and PhNH3+, as well as
quasi-degenerate exchange reactions – show that vertex ex-
change occurs, however, more slowly than complexation.
The metallo-ligand CsʚCo4Ru3 exhibits exceptional af-
finity for binding to diverse metal centers. This work sub-
stantially extends this range to include a range of metal
centers that bear reactive ligands. We show that these site-
differentiated cages can undergo selective substitution reac-
tions without disruption of the M8(µ-CN)12 framework. It
appears that this first generation of reactive cages are insuf-
ficiently robust, so further work is merited on the design
of new cyanometalate cage-ligands. The CsʚCo4Ru3 ligand
functions as a facially capping tridentate ligand akin to tris-
(pyrazolyl)borate (Tp) and triazacyclononane (TACN).
Complexes of the type Tp2Mz and (TACN)2Mz are com-
mon, whereas the half-sandwich complexes are rarer.[16]
Figure 4. Molecular structures from left to right: {Csʚ[CpCo-
(CN)3]4[Cp*Ru]3Ni(9-ane-S3)}(BF4)2 and {Csʚ[CpCo(CN)3]4-
[Cp*Ru]3[Ru(NCMe)(PPh3)2]}(PF6)2. Cp and Cp* rings, phenyl
groups, and counterions were omitted for clarity. Thermal ellip-
soids are set at the 50% level.
Table 1. Selected bond lengths [Å] and angles [°] for [CsʚCo4-
Ru3Ni(9-ane-S3)](BF4)2.
Experimental Section
Ni–N(10)
2.0035
2.0786
2.0005
2.0963
2.0698
2.0409
1.8224
1.8830
1.9023
N(10)–Ni–N(11)
N(10)–Ni–N(12)
N(11)–Ni–N(12)
N(2)–Ru(2)–N(6)
N(2)–Ru(2)–N(7)
N(6)–Ru(2)–N(7)
C(4)–Co(2)–C(6)
C(4)–Co(2)–C(10)
C(6)–Co(2)–C(10)
93.97
93.68
92.33
88.10
85.53
83.34
88.27
92.99
87.48
Reactions and manipulations were performed under nitrogen, using
standard Schlenk-line techniques. Solvents were dried and deoxy-
genated prior to use K(MeC5H4)Co(CN)3,[17] [Cu(NCMe)4]PF6,[18]
Ni–N(11)
Ni–N(12)
Ru(2)–N(2)
Ru(2)–N(6)
Ru(2)–N(7)
Co(2)–C(4)
Co(2)–C(6)
Co(2)–C(10)
[Ni(NCMe)6](BF4)2,[19] [Fe(NCMe)6](PF6)2,[20] Ru(PPh3)3Cl2,[21]
[22]
[(C6H6)Ru(NCMe)3](PF6)2
and {Csʚ[CpCo(CN)3]4[Cp*Ru]3}[10]
were prepared according to literature methods. Elemental analyses
were conducted by the School of Chemical Sciences Microanalyti-
1
cal Laboratory. H and 31P NMR spectra were acquired with Var-
ian Unity 400 and 500. Electrospray ionization-mass spectra (ESI-
MS) and MS-MS measurements were acquired with a Micromass
Quattro QHQ quadrupole-hexapole-quadrupole instrument. Infra-
red spectra were obtained with a Mattson Galaxy Series FT-IR
3000 on pressed KBr pellets.
Table 2. Selected bond lengths [Å] and angles [°] for
{Csʚ[CpCo(CN)3]4[Cp*Ru]3[Ru(NCMe)(PPh3)2]}(PF6)2.
Ru(2)–N(2)
Ru(2)–N(4)
Ru(2)–N(6)
Co(1)–C(3)
Co(1)–C(4)
Co(1)–C(5)
Ru(1)–N(1)
Ru(1)–N(3)
Ru(1)–N(12)
Ru(1)–N(13)
Ru(1)–P(1)
Ru(1)–P(2)
2.0920
2.0954
2.0829
1.8644
1.8833
1.8739
2.0841
2.0423
2.0781
2.0841
2.3403
2.3475
N(2)–Ru(2)–N(4)
N(2)–Ru(2)–N(6)
N(4)–Ru(2)–N(6)
C(3)–Co(1)–C(4)
C(3)–Co(1)–C(5)
C(4)–Co(1)–C(5)
N(1)–Ru(1)–N(3)
N(1)–Ru(1)–N(12)
N(3)–Ru(1)–N(12)
85.72
85.81
87.81
91.23
92.62
89.96
88.49
86.94
87.22
Crystallography: Crystals were mounted to a thin glass fiber using
oil (Paratone-N, Exxon). Data were filtered to remove statistical
outliers. The integration software (SAINT) was used to test for
crystal decay as a bilinear function of X-ray exposure time and sine
(θ). Data were collected with a Siemens Platform/CCD automated
diffractometer. Crystal and refinement details are given in supple-
mentary material. The structures were solved using SHELXTL by
direct methods; correct atomic positions were deduced from an E
map or by an unweighted difference Fourier synthesis. H atom U
values were assigned as 1.2 times the Ueq values of adjacent C
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FULL PAPER
atoms. Non-H atoms were refined with anisotropic thermal coeffi-
cients. Successful convergence of the full-matrix least-squares re-
finement of F2 was indicated by the maximum shift/error for the
last cycle.
EtOH and DMSO. Single crystals were grown by vapor diffusion
of Et2O into an EtOH solution.
{Csʚ[CpCo(CN)3]4[Cp*Ru]3[Cu(NCMe)]}PF6,
[CsʚCo4Ru3Cu-
(NCMe)]PF6: A solution of Csʚ[CpCo(CN)3]4[Cp*Ru]3 (413 mg,
0.25 mmol) in THF (30 mL) was added dropwise to a stirred solu-
tion of [Cu(MeCN)4]PF6 (93 mg, 0.25 mmol) in MeCN (15 mL) at
0 °C over 1 h. The resulting dark red solution was stirred for 5 h,
and the solvent was removed under vacuum. Yield: 394 mg (83%).
1H NMR (CD3CN): δ = 1.68 (s, 45 H, Cp*), 5.53 (s, 15 H, Cp),
5.60 (s, 5 H, Cp) ppm. ESI-MS: m/z = 1714 [M+ – MeCN]. IR
CCDC-632474 for {Csʚ[CpCo(CN)3]4[Cp*Ru]3Ni(9-ane-S3)}-
(BF4)2, -632475 for PhNH3CpCo(CN)3, and -632476 for
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru(NCMe)(PPh3)2}(PF6)2) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from the Cambridge Crystallo-
graphic Data Centre at www.ccdc.cam.ac.uk/data_request/cif.
1H NMR Properties of CsʚCo4Ru3: THF (Cp signals only): δ =
5.43 [s, 10 H, Cp, for (endo)2(exo)1], 5.45 [s, 5 H, Cp, for (endo)2-
(exo)1], 5.59 [s, 5 H, Cp, for (endo)2(exo)1], 5.38 [s, 10 H, Cp, for
(endo)1(exo)2], 5.50 [s, 5 H, Cp, for (endo)1(exo)2], 5.62 [s, 5 H, Cp,
for (endo)1(exo)2] ppm. THF/MeCN, 9:1 (Cp signals only): δ = 5.51
[s, 10 H, Cp, for (endo)2(exo)1], 5.44 [s, 5 H, Cp, for (endo)2(exo)1],
5.64 [s, 5 H, Cp, for (endo)2(exo)1], 5.40 [s, 10 H, Cp, for (endo)1-
(exo)2], 5.53 [s, 5 H, Cp, for (endo)1(exo)2], 5.67 [s, 5 H, Cp, for
(endo)1(exo)2] ppm.
(KBr): ν = 2144 (νCN) cm–1. C64H68Co4CsCuF6N13PRu3 (1898.94):
˜
calcd. C 40.46, H 3.61, N 9.59; found C 40.93, H 3.75, N 10.07.
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Cu(PPh3)}PF6, [CsCo4Ru3Cu(PPh3)]-
PF6: An MeCN stock solution of PPh3 (1 mL, 0.0012 m) was
added dropwise to a stirred solution of [CsʚCo4Ru3Cu(NCMe)]
1
PF6 (2.2 mg, 0.0012 mmol) in MeCN (5 mL). H NMR (CD3CN):
δ = 1.68 (s, 45 H), 5.51 (s, 15 H), 5.61 (s, 5 H), 7.55 (m, 15 H)
ppm. 31P NMR (CD3CN): δ = 21.89 ppm. ESI-MS: m/z = 1977
[{Cs[CpCo(CN)3]4[Cp*Ru]3[CuPPh3]}+].
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ag(NCMe)}PF6,
[CsʚCo4Ru3Ag-
Vertex Exchange in CsʚCo4Ru3: A mixture of K[MeC5H4Co-
(CN)3] (20.5 mg, 0.08 mmol) and Csʚ[CpCo(CN)3]4[Cp*Ru]3
(33 mg, 0.02 mmol) was stirred in MeCN (5 mL) and THF (5 mL)
for 5 h. A 0.1-mL sample of reaction mixture was diluted with
3 mL MeCN/THF (1:1) and analyzed by ESI-MS over the course
of 96 h.
(NCMe)]PF6: A solution of AgPF6 (33.4 mg, 0.13 mmol) in MeCN
(10 mL) was added dropwise to a slurry of CsʚCo4Ru3 (218 mg,
0.13 mmol) in MeCN (15 mL) at 0 °C. The deep red solution was
warmed to room temperature. After stirring for 1 h, the solvent was
1
evaporated. Yield: 87% (220 mg). H NMR (CD3CN): δ = 1.68 (s,
45 H, Cp*), 1.96 (s, 3 H, MeCN), 5.54 (s, 15 H, Cp), 5.62 (s, 5 H,
43 h: m/z (%) = 1678 (100) [{Cs[CpCo(CN)3]2[MeC5H4Co(CN)3]2-
Cp) ppm. ESI-MS: m/z
=
ν
˜
1758 [{Cs[CpCo(CN)3]4-
[Cp*Ru]3}+].
[Cp*Ru]3Ag}+]. IR (KBr):
=
2141 (νCN
)
cm–1.
C64H68AgCo4CsN13F6PRu3 (1943.26): calcd. C 39.52, H 3.53, N
9.37; found C 39.13, H 3.55, N 9.60.
67 h: m/z (%) = 1678 (74) [{Cs[CpCo(CN)3]2[MeC5H4Co(CN)3]2-
[Cp*Ru]3}+], 1692 (100) [{Cs[CpCo(CN)3][MeC5H4Co(CN)3]3-
[Cp*Ru]3}+] and 1706 (28) [{Cs[MeC5H4Co(CN)3]4[Cp*Ru]3}+].
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ag(PPh3)}PF6, [CsʚCo4Ru3Ag(PPh3)]-
PF6: A solution of PPh3 (12.8 mg, 0.05 mmol) in MeCN (10 mL)
96 h: m/z (%) = 1678 (56) [{Cs[CpCo(CN)3]2[MeC5H4Co(CN)3]2-
[Cp*Ru]3}+], 1692 (100) [{Cs[CpCo(CN)3][MeC5H4Co(CN)3]3-
[Cp*Ru]3}+] and 1706 (52) [{Cs[MeC5H4Co(CN)3]4[Cp*Ru]3}+].
Vertex Exchange in Co4Rh32+: A mixture of PPN[MeC5H4Co-
(CN)3] (59.8 mg, 0.08 mmol) and {[CpCo(CN)3]4[Cp*Rh]3}(PF6)2
(35.9 mg, 0.02 mmol) was stirred in MeCN (10 mL ) for 5 h. A 0.1-
mL sample of the reaction mixture was diluted with 3 mL MeCN
and analyzed by ESI-MS.
was added dropwise to
a stirred solution of [CsʚCo4Ru3-
Ag(NCMe)]PF6 (95.2 mg, 0.05 mmol) in MeCN (20 mL). The sol-
1
vent was removed under vacuum. H NMR (CD3CN): δ = 1.68 (s,
45 H, Cp*), 5.51 (s, 15 H, Cp), 5.62 (s, 5 H, Cp), 7.54–7.53 (m, 15
H, Ph) ppm. 31P NMR (CD3CN): δ = 10.7 [d, 1J(P, 107Ag) =
577 Hz], 10.70 [d, 1J(P, 109Ag) = 651.9 Hz] ppm. ESI-MS: m/z =
2021 [{Cs[CpCo(CN)3]4[Cp*Ru]3AgPPh3}+].
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ni(NCMe)3}(BF4)2, [CsʚCo4Ru3Ni-
(NCMe)3](BF4)2: A slurry of CsʚCo4Ru3 (224 mg, 0.14 mmol) in
MeCN (90 mL) was added dropwise to a solution of [Ni(NCMe)6]-
(BF4)2 (65.2 mg, 0.14 mmol) in MeCN (10 mL) at 0 °C. The deep
red solution was warmed to room temperature. After stirring for
1 h, the solvent was removed in vacuo. Yield: 227 mg (85%). 1H
NMR (CD3CN): δ = 1.70 (s, 45 H, Cp*), 1.96 (s, 9 H, MeCN),
5 h: m/z (%) = 761 [{[CpCo(CN)3]4[Cp*Rh]3}2+], 768 [{[CpCo-
(CN)3]3[MeC5H4Co(CN)3][Cp*Rh]3}2+], 775 [{[CpCo(CN)3]2-
[MeC5H4Co(CN)3]2[Cp*Rh]3}2+], 782 [{[CpCo(CN)3][MeC5H4Co-
(CN)3]3[Cp*Rh]3}2+], 789 [{[MeC5H4Co(CN)3]4[Cp*Rh]3}2+].
Degradation of CsʚCo4Ru3 with CO:
A
solution of
Csʚ[CpCo(CN)3]4[Cp*Ru]3 (50.3 mg, 0.031 mmol) in CH2Cl2
(20 mL) was purged with CO for 7 h. The solvent was then removed
in vacuo and the red residue was extracted into MeCN and CH2Cl2
and analyzed by mass spectrometry and IR spectroscopy, respec-
tively ESI-MS: (m/z) = 1198 [{[CpCo(CN)3]2[Cp*RuCO]3}+]. IR
4.99 (br. s, 15 H, Cp), 5.63 (s, 5 H, Cp) ppm. IR (KBr): ν = 2170
˜
(νCN
)
cm–1. ESI-MS: m/z
1796
[{Cs[CpCo(CN)3]4[Cp*Ru]3Ni}BF4+].
=
855 [{Cs[CpCo(CN)3]4-
[Cp*Ru]3Ni}2+],
C68H74B2Co4CsF8N15NiRu3 (2005.16): calcd. C 40.69, H 3.72, N
10.48; found C 41.05, H 3.96, N 10.77.
(CH Cl ): ν = 1947 (νCO), 2165 (νCN), 2126 cm–1.
˜
2
2
Degradation with PhNH3+. Generation of PhNH3CpCo(CN)3: A
THF stock solution of PhNH3OTf (1 mL, 0.004 m) was added to
7.4 mg (0.004 mmol) of Csʚ[CpCo(CN)3]4[Cp*Ru]3. After 7 d, a
yellow-colored precipitate, PhNH3[CpCo(CN)3], formed. This spe-
cies was independently prepared by addition of a solution of
PhNH3OTf (97.2 mg, 0.4 mmol) in MeCN (50 mL) to a solution
of PPN[CpCo(CN)3] (294.7 mg, 0.4 mmol) in MeCN (20 mL) to
[{Csʚ[CpCo(CN)3]4[Cp*Ru]3}2Ni](BF4)2: A solution of CsʚCo4Ru3
(197.1 mg, 0.12 mmol) in CH2Cl2/MeCN (40 mL, 1:1) was treated
with a solution of [Ni(NCMe)6](BF4)2 (28.6 mg, 0.06 mmol) in
MeCN (10 mL). The solvent was removed in vacuo. Yield: 169 mg
1
(80%). H NMR (CD3CN): δ = 1.68 (s, 90 H, Cp*), 5.09 (br. s, 30
H, Cp), 5.62 (s, 10 H, Cp) ppm. ESI-MS: m/z
= 1680
[[{Cs[CpCo(CN)3]4[Cp*Ru]3}2Ni]2+]. C124H130B2Co88Cs2N24NiRu6
(3531.48): calcd. C 42.14, H 3.71, N, 9.52; found C 42.56, H 3.74,
N 9.80.
afford yellow microcrystals. Yield: 0.0761 g (64%). IR (KBr): ν =
˜
2129 (νCN) cm–1, 2603 (νNH) cm–1. C14H13CoN4 (296.05): calcd. C
56.75, H 4.43, N 18.92; found C 56.38, H 4.36, N 18.53. The salt
was insoluble in acetone, CH2Cl2, THF, MeCN but dissolved in
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Fe(NCMe)3}(PF6)2:
A
slurry of
CsʚCo4Ru3 (168.5 mg, 0.1 mmol) in MeCN (70 mL) was added
2726
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 2721–2728

Cyanometalate Cages with Exchangeable Terminal Ligands
FULL PAPER
dropwise to a stirred solution of [Fe(NCMe)6](PF6)2 (60.5 mg, m/z
=
915 [M2+
,
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru(C6H6)}2+].
0.1 mmol) in MeCN (8 mL) at 0 °C. The deep red solution was
warmed to room temperature. After a further 1 h, the solvent was
C98H96ClCo4CsN12P2Ru4·CH3CN·Et2O: calcd. C 39.78, H 3.79, N
8.15; found C 40.42, H 3.64, N 8.36. A solution of {Csʚ[CpCo-
(CN)3]4[Cp*Ru]3Ru(C6H6)}(PF6)2 (9 mg) in CD3CN (0.7 mL) in a
NMR tube was subjected to photolysis using a mercury lamp. After
96 h, the ESI-MS and NMR spectra of the reaction mixture
showed a 30% conversion to {Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru-
(NCCD3)3}(PF6)2.
removed in vacuo. Yield: 170 mg (80%). IR (KBr): ν = 2153 (ν
)
˜
CN
cm–1. ESI-MS: m/z
=
854 [{Cs[CpCo(CN)3]4[Cp*Ru]3Fe}2+].
C68H74Co4CsF12FeN15P2Ru3 (2118.26): calcd. C 38.52, H, 3.52, N,
9.92; found C 39.03, H 3.56, N 9.81.
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ni(9-ane-S3)}(BF4)2, [CsCo4Ru3Ni(9-
ane-S3)](BF4)2: A solution of 9-ane-S3 (7.3 mg, 0.04 mmol) in
MeCN(10 mL)wasaddedtoasolutionof[CsʚCo4Ru3Ni(NCMe)3]-
(BF4)2 (81.5 mg, 0.04 mmol) in of MeCN (10 mL). The red solution
was stirred for 1 h, and the solvent was removed in vacuo. ESI-
MS: m/z = 945 [{Cs[CpCo(CN)3]4[Cp*Ru]3Ni(9-ane-S3)}2+]. Single
crystals were grown by vapor diffusion of Et2O into a CH2Cl2/
acetone solution of [CsʚCo4Ru3Ni(9-ane-S3)](BF4)2.
Acknowledgments
This research was supported by the US Department of Energy
(DEFG02-90ER 14146).
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{Csʚ[CpCo(CN)3]4[Cp*Ru]3RuCl(PPh3)2}Cl:
CsʚCo4Ru3 (440 mg, 0.266 mmol) in THF (40 mL) was added
dropwise to stirred solution of RuCl2(PPh3)3 (256 mg,
A
solution of
a
0.266 mmol) in THF (40 mL) at 0 °C over the course of 1 h. After
stirring the resulting dark red solution for 16 h, the solvent was
removed under vacuum. The residue was extracted with Et2O
(60 mL), and this extract was concentrated under vacuum. Ad-
dition of hexane gave a dark red solid. Yield: 390 mg (63%). 1H
NMR ([D8]THF): δ = 1.69 (s, 15 H, Cp*), 1.73 (s, 30 H, Cp*), 4.83
(s, 5 H, Cp), 4.96 (s, 10 H, Cp), 5.54 (s, 5 H, Cp), 7.08 (m, 12 H,
Ph), 7.45 (m, 6 H, Ph), 7.73 (m, 12 H, Ph) ppm. ESI-MS:
m/z = 2312 [M+, (Csʚ{[CpCo(CN)3]4[Cp*Ru]3RuCl(PPh3)2})+].
C98H95Cl2Co4CsN12P2Ru4 (2345.56): calcd. C 50.16, H 4.08, N
7.16; found C 50.33, H 3.21, N 7.27.
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{Csʚ[CpCo(CN)3]4[Cp*Ru]3RuH(PPh3)2}Cl:
A
solution of
CsʚCo4Ru3 (330 mg, 0.2 mmol) in THF (30 mL) was added drop-
wise to a stirred solution of RuHCl(PPh3)3 (185 mg, 0.2 mmol) in
THF (30 mL) at 0 °C over the course of 1 h. After stirring the dark
red solution for 16 h, it was concentrated under vacuum to ca.
10 mL. Addition of 50 mL of hexane gave a dark red precipitate,
which was washed with hexane, dried under vacuum to give a dark
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1
red solid. Yield: 348 mg (75%). H NMR (CD3CN): δ = –15.24 (t,
JRu-H = 27 Hz, 1 H, Ru-H), 1.68 (s, 15 H, Cp*), 1.73 (s, 30 H,
Cp*), 4.83 (s, 10 H, Cp), 5.01 (s, 5 H, Cp), 5.60 (s, 5 H, Cp), 7.20
(m, JH-H = 7 Hz, 12 H, Ph), 7.27 (m, JH-H = 7 Hz, 6 H, Ph), 7.52
(m, JH-H = 7 Hz, 12 H, Ph) ppm. ESI-MS: m/z = 2278 [M+,
(Csʚ{[CpCo(CN)3]4[Cp*Ru]3RuH(PPh3)2})+]. C98H96ClCo4CsN12-
P2Ru4 (2311.12): calcd. C 50.91, H, 4.18, N, 7.27; found C 51.03,
H 4.23, N 8.62.
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{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru(NCMe)(PPh3)2}(PF6)2: A mixture
of
{Csʚ[CpCo(CN)3]4[Cp*Ru]3RuH(PPh3)2}Cl
(46 mg,
0.02 mmol) and AgPF6 (5 mg, 0.0.02 mmol) in THF (5 mL) was
stirred overnight. After the solvent was removed under vacuum,
the residue was extracted with MeCN (5 mL), which was concen-
trated to ca. 1 mL. Dilution of this extract with Et2O (5 mL ) gave
a red-colored solid. The product was crystallized by dissolution in
MeCN followed by the slow addition of Et2O. Crystals were grown
by liquid diffusion of diethyl ether into acetonitrile solution. ESI-
MS: m/z
=
1139 [M+, {Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru-
(NCMe)(PPh3)2}2+].
{Csʚ[CpCo(CN)3]4[Cp*Ru]3Ru(C6H6)}(PF6)2:
A
solution of
CsʚCo4Ru3 (330 mg, 0.2 mmol) in THF (15 mL) was added drop-
wise to solution of [(C6H6)Ru(NCMe)3](PF6)2 (119 mg,
a
0.2 mmol) in MeCN (25 mL) at 0 °C over 1 h. After stirring for
16 h, the resulting dark red solution was evaporated. Yield: 340 mg
1
(80%). H NMR (CD3CN): δ = 1.66 (s, 45 H, Cp*), 5.58 (s, 5 H,
Cp), 5.73 (s, 15 H, Cp), 6.17 (s, 6 H, C6H6) ppm. ESI-MS:
Eur. J. Inorg. Chem. 2007, 2721–2728
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2727

J. L. Boyer, H. Yao, M. L. Kuhlman, T. B. Rauchfuss, S. Wilson
FULL PAPER
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Received: January 1, 2007
Published Online: March 27, 2007
2728
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Eur. J. Inorg. Chem. 2007, 2721–2728