Ferrocenyldiselenolate-stabilized copper-selenium clusters

Article abstract of DOI:10.1021/ic061111n

The silylated ferrocenyl selenium reagent 1,1′-Fe(η⁵- C₅H₄SeSiMe₃)₂ has been used for the high yield formation of the phosphine-ligated copper complexes Cu ₂(fcSe₂)(P/Pr₃)₂ (1) and Cu ₄(fcSe₂)₂(PnPr₃)₄ (2) from solublilized CuOAc, as determined by single-crystal X-ray diffraction. The incorporation of a source of Se^2- into the reaction scheme with the reagent Se(SiMe₃)₂ yields the mixed selenide/ ferrocenyldiselenolate cluster [Cu₂₀Se₆(Se ₂fc)₄(PnPr₃)10] (3). Partial substitution of the PnPr₃ ligand shell in 3 with the phosphinothiol Ph ₂P(CH₂)₃SH leads to an expansion of the framework and the high yield formation of the crystallographically characterized cluster Cu₃₆(fcSe₂)₆Se₁₂(PnPr ₃)₁₀(Ph₂P(CH₂)₃SH) ₂ (5), which contains surface alkylthiol groups on a copper-selenium core.

Full text of DOI:10.1021/ic061111n

Inorg. Chem. 2006, 45, 9394−9401
Ferrocenyldiselenolate-Stabilized Copper−Selenium Clusters
Christian Nitschke,† Dieter Fenske,*,†,‡ and John F. Corrigan*,§
Institut fu¨r Anorganische Chemie der UniVersita¨t Karlsruhe (TH), 76133 Karlsruhe, Germany,
Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, 76344 Eggenstein-Leopoldshafen,
Germany, and Department of Chemistry, The UniVersity of Western Ontario,
London, N6A 5B7 Canada
Received June 20, 2006
The silylated ferrocenyl selenium reagent 1,1′-Fe(η
5-C5H4SeSiMe3)2 has been used for the high yield formation of
the phosphine-ligated copper complexes Cu2(fcSe2)(PiPr3)2 (1) and Cu4(fcSe2)2(PnPr3)4 (2) from solublilized CuOAc,
-
as determined by single-crystal X-ray diffraction. The incorporation of a source of Se2 into the reaction scheme
with the reagent Se(SiMe3)2 yields the mixed selenide/ferrocenyldiselenolate cluster [Cu20Se6(Se2fc)4(PnPr3)10] (3).
Partial substitution of the PnPr3 ligand shell in 3 with the phosphinothiol Ph2P(CH2)3SH leads to an expansion of
the framework and the high yield formation of the crystallographically characterized cluster Cu36(fcSe2)6Se12(PnPr3)10-
(Ph2P(CH2)3SH)2 (5), which contains surface alkylthiol groups on a copper−selenium core.
Introduction
ferrocenyl reagent Fe(C5H4SeSiMe3)2,4 which serves as a
soluble source of [Fe(C5H4Se)2]2- (fcSe22-) during cluster-
forming reactions. Although ferrocenydiselenolate complexes
of late transition metal complexes are well documented,5
there are few reports describing the coordination of these
ligands to group 11 metals.4,6 Importantly, fcSe22--passivated
copper-selenide semiconductor nanoclusters are relatively
stable with respect to ligand dissociation/framework con-
densation reactions in solution, as the bidentate nature of
the fcSe2 ligands assists in preventing random condensation
The utility and importance of silylated chalcogen reagents
for the assembly of metal-chalcogenide and -chalcogeno-
late clusters continue to spur the development of this
area of inorganic chemistry.1 Investigations detailing the
assembly of chalcogen-bridged nanometer-sized copper
clusters (“nanoclusters”) have been described by using
bis(trimethylsilyl)chalcogen reagents for the delivery of
interstitial “E2-” (E ) S, Se, Te).2 By varying the nature of
the surface-stabilizing chalcogenolate (RE-) and phosphine
ligands together with reaction conditions, one can isolate a
large variety of core sizes ranging from the molecular to the
nanoscale in single-crystalline form3 and the optical and
electronic properties of these Cu2E clusters can be tuned by
controlling the assembly of these monodisperse systems.2 It
was recently communicated that the surfaces of such clusters
can be passivated and functionalized through the use of the
(3) (a) Fuhr, O.; Fernandez-Recio, L.; Fenske, D. Eur. J. Inorg. Chem.
2005, 2306-2314. (b) Eichho¨fer, A.; Beckmann, E.; Fenske, D.;
Herein, D.; Krautscheid, H.; Schloegl, R. Isr. J. Chem. 2001, 41, 31-
37. (c) Zhu, N.; Fenske, D. J. Chem. Soc., Dalton Trans. 1999, 1067-
1076. (d) Bettenhausen, M.; Eichho¨fer, A.; Fenske, D.; Semmelmann,
M. Z. Anorg. Allg. Chem. 1999, 625, 593-601. (e) Eichho¨fer, A.;
Fenske, D. J. Chem. Soc., Dalton Trans. 1998, 2969-2972. (f)
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1997, 4491-4498. (g) Corrigan, J. F.; Fenske, D. Angew. Chem., Int.
Ed. Engl. 1997, 36, 1981-1983. (h) Dehnen, S.; Fenske, D. Chem.s
Eur. J. 1996, 2, 1407-1416. (i) Corrigan, J. F.; Balter, S.; Fenske, D.
J. Chem. Soc., Dalton Trans. 1996, 729-738. (j) Krautscheid, H.;
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1993, 32, 1303-1305. (k) Fenske, D.; Krautscheid, H. Angew. Chem.,
Int. Ed. Engl. 1990, 29, 1452-1454.
* To whom correspondence should be addressed. E-mail: dieter.fenske@
chemie.uni-karlsruhe.de (D.F.), corrigan@uwo.ca (J.F.C.). Phone: (+49)-
721-608-2086 (D.F.), (+1)519-661-2111 ext. 86387 (J.F.C.).
† Institut fu¨r Anorganische Chemie der Universita¨t Karlsruhe.
‡ Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft.
§ The University of Western Ontario.
(4) (a) Wallbank, A. I.; Corrigan, J. F. Chem. Commun. 2001, 377-378.
(b) Wallbank, A. I.; Borecki, A.; Taylor N, J.; Corrigan, J. F.
Organometallics 2005, 24, 788-790.
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Chemistry 2; Fujita, M., Powell, A. K., Creutz, C., Eds.; Elsevier:
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J. F. In The Chemistry of Nanomaterials: Synthesis, Properties, and
Applications; Rao, C. N. R. A., Mu¨ller, A., Cheetham, A. K., Eds.;
Wiley-VCH: Weinheim, Germany, 2004; pp 418-451.
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279-317.
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2872-2879. (b) Herberhold, M.; Jin, G.-X.; Rheingold, A. L. Z. Anorg.
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9394 Inorganic Chemistry, Vol. 45, No. 23, 2006
10.1021/ic061111n CCC: $33.50
© 2006 American Chemical Society
Published on Web 10/11/2006

Ferrocenyldiselenolate Stabilized Cu-Se Clusters
Table 1. Crystallographic Data for the Structure Determination of 1-6
param
1
2
3
4
5
6
chem formula Cu2Se2FeP2C28H50 Cu4Se4Fe2P4C56H100 Cu20Se14Fe4P10C130H242.C7H16 Cu2S4P4C60H66 Cu36Se24S1.7 Fe6P12C178.2 H293.2 Cu36Se24Fe6P12C204H276
fw
789.5
P21/n
-100
1578.9
P1h
-173
4814.8
P1h
-173
1166.3
P21/c
-123
12.9530(7)
22.320(2)
10.4615(5)
90
112.431(4)
90
7479.5
P21/n
-173
19.763(3)
21.774(2)
61.137(8)
90
91.660(10)
90
7617.5
P21/n
-173
19.878(3)
21.494(2)
61.897(10)
90
92.280(10)
90
space group
temp (°C)
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
10.5499(7)
12.443(1)
25.042(2)
90
99.12(2)
90
3245.7(4)
4.097
13.211(3)
15.683(3)
17.868(4)
79.98(3)
79.34(3)
67.29(3)
3334.6(11)
3.988
16.325(1)
18.020(1)
18.004(1)
79.962(5)
78.015(5)
68.331(5)
4787.5(5)
5.242
2795.7(3)
1.063
26297(6)
6.605
26425(6)
6.562
µ (Mo KR1,
mm-1
)
Z
4
2
1
2
4
4
F (g cm-3
)
1.616
7697:316
R1 ) 0.0555
1.572
1.670
1.386
6661:320
R1 ) 0.0442
1.859
21914:1423
R1 ) 0.0907
1.915
data:params
R indices
14663:626
R1 ) 0.0466
wR2 ) 0.1271
15845:821
R1 ) 0.0691
wR2 ) 0.1879
39264:1427
R1 ) 0.0911
wR2 ) 0.2472
[I > 2σ(I)] wR2 ) 0.1461
wR2 ) 0.1089 wR2 ) 0.2538
reactions from occurring when the clusters are dissolved in
organic solvents, which can lead to amorphous products.
Such systems could thus lend themselves to selective
substitution reactions of the ancillary PR3 ligands. The
introduction of phosphine ligands containing thioether groups
has been demonstrated;7 however, to date, the introduction
of a thiol group into the phosphine shell around such
nanoclusters, which might allow covalent bonding onto a
variety of metal surfaces via metal-thiolate bond formation,8
has yet to be achieved. Herein, we describe the general
assembly of high nuclearity ferrocenyldiselenolate clusters
and nanoclusters of copper(I). We demonstrate that partial
substitution of the ancillary phosphine ligand shell on Cu-
Se frameworks is possible, leading to surface alkylthiol
groups on a copper-selenide core.
Figure 1. Molecular structure of Cu2(µ2-η2-fcSe2)(PiPr3)2 (1) (isopropyl
groups are omitted for clarity). The cyclopentadienyl rings of the ferrocenyl
unit display an eclipsed arrangement.
Table 2. Selected Bond Distances (Å) and Angles (deg) for
Cu2(µ2-η2-fcSe2)(PiPr3)2 (1)
Experimental Section
Se1-C1
1.895(4)
Se1-Cu1
2.3904(6)
2.4816(8)
1.898(4)
2.4067(7)
2.4567(7)
2.2167(11)
2.2081(11)
104.86(12)
100.26(12)
64.91(2)
99.95(12)
104.45(12)
65.06(2)
135.06(4)
117.81(4)
103.69(3)
136.24(4)
119.82(4)
102.47(2)
132.8(2)
General Data. All reactions were performed under an inert
atmosphere of purified nitrogen using standard Schlenk techniques.
Reagent grade solvents were dried by standard procedures and were
freshly distilled prior to use. Deuterated solvents were dried over
either potassium (C7D8, C6D6) or P2O5 (CDCl3) under N2. CuOAc,9
Ph2P(CH2)3SH,10 PR3,11 Se(SiMe3)2,12 and fc(SeSiMe3)2 were
prepared according to literature procedures.
Se1-Cu2
Se2-C6
Se2-Cu2
Se2-Cu1
Cu1-P1
Cu2-P2
4a
C1-Se1-Cu1
C1-Se1-Cu2
Cu1-Se1-Cu2
C6-Se2-Cu2
C6-Se2-Cu1
Cu2-Se2-Cu1
P1-Cu1-Se1
P1-Cu1-Se2
Se1-Cu1-Se2
P2-Cu2-Se2
P2-Cu2-Se1
Se2-Cu2-Se1
Se1-C1-Fe1
Se2-C6-Fe1
The selection of single crystals suitable for X-ray diffraction was
carried out by immersing the air-sensitive samples in perfluoropoly-
(7) Fuhr, O.; Meredith, A.; Fenske, D. J. Chem. Soc., Dalton Trans. 2002,
4091-4094.
(8) Love, J. C.; Estroff, L. A.; Kriebel, J. K.; Nuzzo, R. G.; Whitesides,
G. M. Chem. ReV. 2005, 105, 1103-1169.
(9) Edwards, D. A.; Richards, R. J. Chem. Soc., Dalton Trans. 1973,
2463-2468.
(10) White, G. S.; Stephan, D. W. Organometallics 1987, 6, 2169-2175.
(11) (a) Cowley, A. H.; Mills, J. L. J. Am. Chem. Soc. 1969, 91, 2915-
2919. (b) Cumper, C. W. N.; Foxton, A. A.; Read, J.; Vogl, A. I. J.
Chem. Soc. 1964, 430-434. (c) Grim, S. O.; McFarlane, W.; Davidoff,
E. F. J. Org. Chem. 1967, 32, 781-784.
133.0(2)
ether oil (Riedel de Ha¨en) and mounting the oil-coated crystal on
a glass pin set in a goniometer head. The oil freezes upon cooling
in a flow of nitrogen protecting the crystal from oxidation. The
structural analyses were carried out at low temperatures (-100 to
-173 °C) on a STOE IPDS II diffractometer (Mo KR, λ ) 0.710 73
Å) equipped with an imaging plate area detector (3, 4, 6) and on a
STOE STADI 4 diffractometer (Mo KR, λ ) 0.710 73 Å) equipped
with a four-circle CCD detector (1, 2, 5). Structure solution and
refinement against F2 were carried out using SHELXS and
(12) DeGroot, M. W.; Taylor, N. J.; Corrigan, J. F. J. Mater. Chem. 2004,
14, 654-660.
(13) (a) Sheldrick, G. M. SHELXS-97: Program for Crystal Structure
Solution. University of Go¨ttingen, 1997. (b) Sheldrick, G. M.
SHELXL-97: Program for Crystal Structure Refinement. University
of Go¨ttingen, 1997. (c) Sheldrick, G. M. SHELXP 5.05: Program for
Molecular Graphics. University of Go¨ttingen, 1994.
(14) Brandenburg, K.; Putz, H. DIAMOND Version 3.1: Crystal and
Molecular Structure Visualization. Crystal Impact GbR: Bonn,
Germany, 2005.
Inorganic Chemistry, Vol. 45, No. 23, 2006 9395

Nitschke et al.
Figure 2. Molecular structure of Cu4(µ3-η2-fcSe2)2(PnPr3)4 (2) (n-propyl groups are omitted for clarity). The cyclopentadienyl rings around Fe1 are in a
near-eclipsed arrangement (deviation ) 3°), whereas the rings about Fe2 are staggered by 51°.
Figure 3. Molecular structure of Cu20Se6(fcSe)4(PnPr3)10 (3) (propyl groups and H atoms are omitted for clarity).
SHELXL software.13 Molecular diagrams were prepared using the
DIAMOND 3.0 program.14 The crystallographic data of 1-6 are
summarized in Table 1. The weakly diffracting nature of crystals
of 5 and 6 resulted in high R1 values. For 5, site occupation
(substitution) disorder was observed for one of the Ph2P(CH2)3SH
ligands (P6). A two-site Ph2P(CH2)3SH:PnPr3 model (70:30) gave
a satisfactory refinement.
1H and 31P{1H} NMR spectra were recorded on either a Bruker
AMX 300 or an AV 400 spectrometer. Spectra are referenced
internally to residual protio-solvent (1H) or externally (31P) and are
9396 Inorganic Chemistry, Vol. 45, No. 23, 2006

Ferrocenyldiselenolate Stabilized Cu-Se Clusters
Table 3. Selected Bond Distances (Å) and Angles (deg) for
Cu4(fcSe2)2(PnPr3)4 (2)
Table 4. Selected Bond Distances (Å) and Angles (deg) for
Cu20Se6(fcSe2)4(PnPr3)10 (3)
Se1-Cu1
2.3462(11)
2.3716(13)
2.3477(13)
2.3689(12)
2.3521(11)
2.3892(11)
2.3338(12)
2.3987(11)
2.2341(17)
2.2381(18)
2.2088(17)
2.217(2)
102.77(17)
103.69(18)
94.20(4)
110.03(16)
107.76(17)
104.75(5)
109.85(18)
100.01(17)
75.78(4)
Cu1-Se3
2.5895(16)
2.6791(16)
2.3987(14)
2.4206(14)
2.4242(15)
2.3940(14)
2.4010(14)
2.4301(15)
2.3987(15)
2.3991(14)
2.4391(15)
2.4037(16)
2.4834(14)
2.5228(14)
2.4768(13)
2.6034(14)
2.6222(15)
2.3943(14)
2.4561(14)
2.5243(16)
2.3556(16)
2.5826(14)
2.5146(17)
2.5176(15)
2.6095(14)
2.6711(15)
2.3691(17)
2.5989(16)
2.3991(14)
2.6034(14)
2.3940(14)
2.6222(15)
122.82(11)
105.13(9)
105.75(8)
110.28(8)
102.24(9)
110.34(5)
115.26(5)
127.46(6)
114.83(6)
118.14(6)
113.82(5)
114.96(5)
120.75(6)
112.70(6)
109.81(5)
117.47(6)
118.75(5)
116.57(5)
119.56(6)
117.48(5)
117.41(5)
134.58(10)
P3-Cu8-Se2
106.03(9)
119.10(6)
108.69(10)
112.39(10)
97.24(5)
117.66(9)
109.22(5)
109.66(5)
135.05(10)
105.92(10)
117.81(6)
70.16(5)
60.42(4)
122.12(5)
65.52(4)
123.26(5)
60.20(4)
69.03(5)
61.47(4)
123.44(6)
64.58(5)
122.91(6)
60.31(4)
104.41(5)
116.24(5)
114.40(5)
77.65(4)
73.81(5)
67.95(4)
64.50(4)
66.01(4)
178.82(5)
113.21(5)
74.51(5)
63.84(4)
79.05(5)
120.43(5)
124.69(5)
66.38(5)
116.48(5)
63.31(4)
63.25(4)
62.89(4)
79.79(5)
64.47(5)
81.73(5)
118.35(6)
124.33(5)
65.09(4)
118.58(5)
62.83(4)
63.43(4)
62.59(4)
Se1-Cu2
Cu1-Se1
Se6-Cu8-Se2
P5-Cu9-Se6
Se2-Cu4
Cu2-Se1
Se2-Cu2
Cu2-Se5
P5-Cu9-Se7
Se6-Cu9-Se7
P5-Cu9-Se5
Se3-Cu3
Cu2-Se3
Se3-Cu2
Cu3-Se7a
Se4-Cu3
Cu3-Se2
Se6-Cu9-Se5
Se7-Cu9-Se5
P4-Cu10-Se7
P4-Cu10-Se4
Se7-Cu10-Se4
Cu2-Se1-Cu3
Cu2-Se1-Cu1
Cu3-Se1-Cu1
Cu3-Se2-Cu5
Cu3-Se2-Cu8
Cu5-Se2-Cu8
Cu2-Se3-Cu4
Cu2-Se3-Cu1
Cu4-Se3-Cu1
Cu4-Se4-Cu7
Cu4-Se4-Cu10
Cu7-Se4-Cu10
Cu7-Se5-Cu5
Cu7-Se5-Cu2
Cu5-Se5-Cu2
Cu7-Se5-Cu6
Cu5-Se5-Cu6
Cu2-Se5-Cu6
Cu7-Se5-Cu9
Cu5-Se5-Cu9
Cu2-Se5-Cu9
Cu6-Se5-Cu9
Cu8-Se6-Cu4a
Cu8-Se6-Cu5
Cu4a-Se6-Cu5
Cu8-Se6-Cu9
Cu4a-Se6-Cu9
Cu5-Se6-Cu9
Cu8-Se6-Cu6a
Cu4a-Se6-Cu6a
Cu5-Se6-Cu6a
Cu9-Se6-Cu6a
Cu10-Se7-Cu3a
Cu10-Se7-Cu7
Cu3a-Se7-Cu7
Cu10-Se7-Cu9
Cu3a-Se7-Cu9
Cu7-Se7-Cu9
Cu10-Se7-Cu6a
Cu3a-Se7-Cu6a
Cu7-Se7-Cu6a
Cu9-Se7-Cu6a
Se4-Cu4
Cu3-Se1
Cu1-P2
Cu4-Se4
Cu1-P1
Cu4-Se6a
Cu3-P4
Cu4-Se3
Cu4-P3
Cu5-Se5
C1-Se1-Cu1
C1-Se1-Cu2
Cu1-Se1-Cu2
C6-Se2-Cu4
C6-Se2-Cu2
Cu4-Se2-Cu2
C16-Se3-Cu3
C16-Se3-Cu2
Cu3-Se3-Cu2
C11-Se4-Cu3
C11-Se4-Cu3
Cu3-Se4-Cu4
P2-Cu1-P1
P2-Cu1-Se1
P1-Cu1-Se1
Se2-Cu2-Se1
Se2-Cu2-Se3
Se1-Cu2-Se3
P4-Cu3-Se4
P4-Cu3-Se3
Se4-Cu3-Se3
P3-Cu4-Se2
P3-Cu4-Se4
Se2-Cu4-Se4
Se1-C1-Fe1
Se2-C6-Fe1
Se4-C11-Fe2
Se3-C16-Fe2
Cu5-Se6
Cu5-Se2
Cu6-Se5
Cu6-Se6a
Cu6-Se7a
Cu7-Se5
Cu7-Se7
Cu7-Se4
Cu8-Se6
108.14(17)
107.63(18)
71.24(4)
Cu8-Se2
Cu9-Se6
Cu9-Se7
123.41(7)
117.03(5)
117.61(6)
116.27(4)
120.11(5)
123.29(4)
125.83(6)
110.36(6)
120.83(4)
125.90(6)
120.20(7)
111.88(5)
126.5(3)
Cu9-Se5
Cu9-Cu6a
Cu10-Se7
Cu10-Se4
Se6-Cu4a
Se6-Cu6a
Se7-Cu3a
Se7-Cu6a
P1-Cu1-P2
P1-Cu1-Se3
P2-Cu1-Se3
P1-Cu1-Se1
P2-Cu1-Se1
Se3-Cu1-Se1
Se1-Cu2-Se5
Se1-Cu2-Se3
Se5-Cu2-Se3
Se7a-Cu3-Se2
Se7a-Cu3-Se1
Se2-Cu3-Se1
Se4-Cu4-Se6a
Se4-Cu4-Se3
Se6a-Cu4-Se3
Se5-Cu5-Se6
Se5-Cu5-Se2
Se6-Cu5-Se2
Se5-Cu7-Se7
Se5-Cu7-Se4
Se7-Cu7-Se4
P3-Cu8-Se6
123.6(3)
135.5(3)
134.0(3)
reported relative to tetramethylsilane (1H) or 85% phosphoric acid
(31P). Chemical shifts are quoted in δ (ppm) and coupling constants
in Hertz.
UV-vis spectra were recorded with a Perkin-Elmer UV/VIS/
NIR Spectrometer Lambda 900 at room temperature as solutions
in dichloromethane. Elemental analysis was performed with a Vario
EL-Analysenautomaten “elementar Vario EL” by ELEMENTAR-
Analysensysteme.
Synthesis of Cu2(fcSe2)(PiPr3)2 (1). PiPr3 (1.33 mL, 7.05 mmol)
was added to a suspension of CuOAc (0.42 g, 3.4 mmol) in 20 mL
of THF to yield a clear, colorless solution. The reaction was cooled
to -65 °C, and a solution of fc(SeSiMe3)2 (0.82 g, 1.7 mmol,
dissolved in 7 mL of THF) was added. Slow warming to room
temperature over 4 days afforded a light brown solution. Layering
with n-pentane afforded yellow-orange blocks of 1 in 65% yield
based on Cu. Anal. Calcd for 1: C, 42.60; H, 6.38. Found: C,
a Symmetry transformations used to generate equivalent atoms:
-x, -y, -z.
42.60; H, 6.38. Found: C, 42.83; H, 6.38. 1H NMR (C7D8, 193 K,
δ): 5.18 (1H), 4.94 (1H), 4.73 (1H), 4.58 (1H), 4.53 (1H), 4.50
(1H), 4.42 (1H), 4.34 (1H), 4.29 (1H), 4.27 (1H), 4.09 (1H), 4.03
(1H), 3.94 (1H), 3.87 (1H), 3.82 (1H), 3.68 (1H), 1.50-1.07 (br,
84H). 31P{1H}-NMR (C7D8, 223 K, δ): -20.5 (s), -21.0 (s), -22.4
(s) (intensity 1:1:2). UV-vis: 460 nm (sh, ꢀ ) 673 L mol-1 cm-1).
Synthesis of Cu20Se6(fcSe2)4(PnPr3)10 (3). CuOAc (0.76 g, 6.2
mmol) was dissolved with PnPr3 (2.44 mL, 12.4 mmol) in 25 mL
of THF. The solution was cooled to -65 °C, and Se(SiMe3)2 (0.52
mL, 2.1 mmol) and a solution of fc(SeSiMe3)2 (0.50 g, 1.0 mmol,
dissolved in 4 mL of THF) were added. Slow warming to room
temperature over 4 days afforded a brown solution, and removal
of the solvent under reduced pressure led to a brown powder. The
1
42.31; H, 6.33. H NMR (C6D6, 298 K, δ): 4.21 (t, JHH ) 2 Hz,
4H), 4.11 (t, JHH ) 2 Hz, 4H), 1.80 (m, 6H, P-CH-), 1.12 (m,
36H, -CH3). 31P{1H}-NMR (C6D6, δ): -22.2 (br s, W1/2 ) 53
Hz). UV-vis: 453 nm (sh, ꢀ ) 170 L mol-1 cm-1).
Synthesis of Cu4(fcSe2)2(PnPr3)4 (2). CuOAc (0.20 g, 1.6 mmol)
was dissolved with PnPr3 (0.65 mL, 3.56 mmol) in 15 mL of THF.
The solution was cooled to -65 °C, and a solution of fc(SeSiMe3)2
(0.42 g, 0.85 mmol, dissolved in 3 mL of THF) was added. Slow
warming to room temperature over 4 days afforded a brown
solution. Layering with n-pentane led to X-ray-quality orange-red
crystals of 2 in 70% yield based on Cu. Anal. Calcd for 2: C,
Inorganic Chemistry, Vol. 45, No. 23, 2006 9397

Nitschke et al.
Table 5. Selected Bond Distances (Å) and Angles (deg) for
Cu2(Ph2P(CH2)3S)2(Ph2P(CH2)3SH)2 (4)
Cu1-P2
2.2605(7)
2.2636(9)
2.3756(8)
2.3776(7)
1.831(3)
Cu1-P1
Cu1-S1
Cu1-S1a
S1-C3
S1-Cu1a
2.3776(7)
1.784(4)
S2-C18
P2-Cu1-P1
P2-Cu1-S1
P1-Cu1-S1
P2-Cu1-S1a
P1-Cu1-S1a
S1-Cu1-S1a
C3-S1-Cu1
C3-S1-Cu1a
Cu1-S1-Cu1a
115.57(3)
111.56(3)
102.25(3)
112.51(3)
112.09(3)
101.46(3)
111.99(12)
112.82(11)
78.54(2)
a Symmetry transformations used to generate equivalent atoms: -x, -y
+ 1, -z + 1.
Figure 4. Molecular structure of Cu2(µ2-η2-Ph2P(CH2)3S)2(Ph2P-
(CH2)3SH)2 (4).
the solution at 0 °C yielded crystalline 6 as yellow crystals in 90%
yield based on Cu. Anal. Calcd for 4: C, 61.78; H, 5.70. Found:
C, 61.96; H, 5.78. H NMR (C6D6, δ): 7.57 (br s, 16H), 7.03 (br
1
powder was redissolved in n-heptane, and the resulting solution
was filtered. Cluster 3 crystallized out of saturated solutions at room
temperature as X-ray-quality brown blocks in 75% yield based on
Cu. Anal. Calcd for 3: C, 33.12; H, 5.17. Found: C, 32.85; H,
s, 24 H), 2.04 (br s, 12H, CH2), 1.70 (br s, 12H, CH2), 1.07 (br s,
2H, SH). 31P{1H}-NMR (C6D6, δ): -15.5 (s). UV-vis: 279 nm
(ꢀ ) 2290 L mol-1 cm-1).
Synthesis of Cu36(fcSe2)6Se12(PnPr3)10(Ph2P(CH2)3SH)2 (5). 3
(0.12 g, 0.025 mmol) was dissolved in a mixture of 15 mL diethyl
ether:THF (2:1). To the resulting dark brown solution was added
at room temperature a large excess of Ph2P(CH2)3SH (0.12 mL,
0.51 mmol). The reaction mixture was allowed to stir overnight.
After slow diffusion of 10 mL of pentane into the mixture, the
reaction was stored at -35 °C. After 1 week, cluster 5 was retrieved
1
5.12. H NMR (CDCl3, ferrocenyl region, δ): 4.83 (s, 4H), 4.67
(s, 4H), 4.07-3.90 (m, 24 H). 31P{1H}-NMR (C7D8, δ): -23.7
ppm (br, s).
Synthesis of Cu2(Ph2P(CH2)3S)2(Ph2P(CH2)3SH)2 (4).
Ph2P(CH2)3SH (1.31 mL, 5.64 mmol) was added to a suspension
of CuOAc (0.23 g, 1.9 mmol) in 10 mL of diethyl ether. Storing
Figure 5. Molecular structure of Cu36Se12(fcSe2)6(PnPr3)10(Ph2P(CH2)3SH)2 (5) (propyl groups and H atoms are omitted for clarity).
9398 Inorganic Chemistry, Vol. 45, No. 23, 2006

Ferrocenyldiselenolate Stabilized Cu-Se Clusters
bonded (0.2 Å). The two selenolate bridges are somewhat
asymmetrically ligated to the two metals (Table 2) with the
Cu‚‚‚Cu distance (2.6155(8) Å) in accord with the +1
1
oxidation states. The solution H NMR spectra for 1 are
consistent with the observed solid-state structure, with two
sharp signals observed in the ferrocenyl region at room
temperature (δ ) 4.21, 4.11 ppm), similar to those reported
for ferrocenyldichalcogenolates bridging two metal centers.15
The reaction of CuOAc solubilized with the smaller
trialkylphosphine PnPr3 and fc(SeSiMe3)2 led to the selective
formation of the cluster Cu4(fcSe2)2(PnPr3)4 (2) (Figure 2).
As observed in 1, each copper center displays a distorted
trigonal planar coordination geometry, with angles varying
from 110.5° (P4-Cu3-Se3) to 125° (P4-Cu3-Se4) (Table
3). In 2, however, this is achieved with an asymmetric
distribution of the phosphine ligands and bridging selenolate
bonds. Whereas Cu1 and Cu4 are each coordinated to two
Se and one phosphine ligand, Cu2, which is located in the
center of the cluster, is bonded to three selenium atoms (Se1,
Se2, Se3) and the trigonal coordination about Cu3 is achieved
with one selenium (Se1) and two phosphine ligands. The
structure of 2 can be described as a dimerization of 1 (with
a different distribution of the PR3 ligands), likely due to the
reduced steric requirements of PnPr3 versus PiPr3.16 At 223
Figure 6. Three subunits of the surface of Cu36Se12(fcSe2)6(PnPr3)10-
(Ph2P(CH2)3SH)2 (5) emphasizing the relationship to the arrangement of
atoms observed on the surface of cluster 3 (phosphorus substituents and all
H atoms are omitted for clarity).
1
K, H NMR spectra of 2 display 16 well-resolved signals
as dark brown X-ray-quality needles in 78% yield. Anal. Calcd for
5: C, 29.00; H, 4.00. Found: C, 29.25; H, 3.92
for the inequivalent C5H4 protons. 1 and 2 represent rare
examples of copper-ferrocenylselenolate complexes.4
Using a combination of fc(SeSiMe3)2 together with Se-
(SiMe3)2 allows for the formation of larger frameworks, due
to the formation and availability of Se2- for the generation
of a copper-selenide core, which can then be passivated
via the introduction of surface selenolate ligands.1,2 Thus,
the reaction of CuOAc‚2PnPr3 with a mixture of fc-
(SeSiMe3)2 and Se(SiMe3)2 (6:1:2) leads to the high yield
formation of the mixed selenide/ferrocenyldiselenolate nano-
cluster Cu20Se6(fcSe2)4(PnPr3)10 (3). The Cu-Se framework
of 3 (Table 4) is similar to that which was previously
communicated for the complexes Cu20Se6(fcSe2)4(PnBu3)10
and Cu20Se6(fcSe2)4(PEt2Ph)10, with only minor deviations
due to the different tertiary phosphine ligands employed.4b
The selenium framework consists of six µ5-selenide ligands
(Se5, Se6, Se7, and their symmetry equivalents) arranged
to form an (nonbonded) octahedron at the center of the
clusters, which, in addition to the central ring of the four
Synthesis of Cu36Se12(fcSe2)6(PnPr2Ph)12 (6). CuOAc (0.40 g,
3.3 mmol) was dissolved with PnPr2Ph (1.40 mL, 6.50 mmol) in
25 mL of THF. The solution was cooled to -65 °C, and Se(SiMe3)2
(0.22 mL, 0.98 mmol) and a solution of fc(SeSiMe3)2 (0.31 g, 0.64
mmol, dissolved in 4 mL THF) were added. The solution was
warmed to room temperature over a period of 3-4 days to give a
brown solution. Slow diffusion of n-pentane into the solution
afforded 6 as X-ray-quality dark brown needles in 32% yield based
on Cu. Anal. Calcd for 6: C, 32.16; H, 3.65. Found: C, 32.29;
H, 3.58.
Results and Discussion
Copper(I) acetate is dissolved in common organic solvents
with the use of tertiary phosphine ligands and reacts readily
with trimethsilyl-selenium reagents via the formation of
metal-selenium bonds and the formation of trimethysilyl
acetate.2 The silane byproduct of these reactions does not
interfere with the crystallization process of the formed cluster
and, most importantly, nanocluster complexes. Thus, when
CuOAc was dissolved in THF with PiPr3 and reacted with
fc(SeSiMe3)2, the dimeric complex Cu2(µ2-η2-fcSe2)(PiPr3)2
(1) was isolated in good yield after the addition of pentane.
The structure of 1 is illustrated in Figure 1, and selected
bond lengths are presented in Table 2. The two copper atoms
show a distorted trigonal planar arrangement (sum of the
angles 357° (Cu1) and 359° (Cu2), each bonded to two
selenium centers of the ferrocenyl unit and one PiPr3 ligand.
The selenolate centers each asymmetrically bridge the two
copper sites, and the two cyclopentadienyl ligands adopt an
eclipsed arrangement. Although the two C5 rings about iron
are nearly parallel (deviation ) 2.0°), the two Se centers lie
slightly above the cyclopentadienyl rings to which they are
2-
fcSe2 groups, are bonded to the copper(I) centers (Figure
3). The ferrocenylselenolate ligands are each bonded to three
copper sites, and the copper centers display both trigonal
and tetrahedral coordination geometries.
We observe that solutions of 3 are kinetically stable under
ambient conditions, as shown by NMR spectroscopy and
(15) (a) Takemoto, S.; Kuwata, S.; Nishibayashi, Y.; Hidai, M. Organo-
metallics 2000, 19, 3249-3252. (b) Takemoto, S.; Kuwata, S.;
Nishibayashi, Y.; Hidai, M. Inorg. Chem. 1998, 37, 6428-6434. (c)
Herberhold, M.; Jin, G.-X.; Rheingold, A. L. Angew. Chem., Int. Ed.
Engl. 1995, 34, 656-657. (d) Heberhold, M.; Jin, G.-X.; Rheingold,
A. L.; Sheats, G. F. Z. Naturforsch., B 1992, 47, 1091-1098. (e)
Cullen, W. R.; Talaba, A.; Rettig, S. J. Organometallics 1992, 11,
3152-3156. (f) Seyferth, D.; Hames, B. W. Inorg. Chim. Acta 1983,
77, L1-L2.
(16) Tolman, C. A. Chem. ReV. 1977, 77, 312-348.
Inorganic Chemistry, Vol. 45, No. 23, 2006 9399

Nitschke et al.
Cu(I) salts due to the reactive nature of the S-H bond.10,17
For example, CuOAc reacts smoothly in solution with 2
equiv of the phosphinothiol Ph2P(CH2)3SH to form Cu2(Ph2P-
(CH2)3S)2(Ph2P(CH2)3SH)2 (4) in 95% yield via activation
of the S-H bond (and the elimination of HOAc). The
dimeric complex 4 (Table 5) consists of two copper centers
(Cu1 and the symmetry equivalent Cu1′) each arranged in a
pseudotetrahedral coordination geometry. Each copper is
bonded to two thiolates (S1 and S1′) and two phosphine
ligands (Figure 4). One of the phosphine ligands (P1 and
P1′) acts as a bridging ligand, building a six-membered Cu-
S-(CH2)3-P ring. The other phosphine ligands (P2, P2′)
complete the coordination about the metals, but retain a free
thiol group. The copper-thiolate distances in 4 (2.3756(8)-
2.3776(7) Å) are slightly longer than those reported for the
related trinuclear complex [CpFe{η5-C5H3(1-PPh2)(2-CH-
(CH3)S)}Cu]3 (Cu-S ) 2.178(6)-2.251(6) Å).17a
Table 6. Selected Bond Distances (Å) for
Cu36(fcSe2)6Se12(PPr3)10(Ph2P(CH2)3SH)2 (5)
Cu1-Se3
2.544(4)
2.573(4)
2.425(4)
2.424(4)
2.438(4)
2.390(4)
2.402(4)
2.415(4)
2.404(4)
2.410(4)
2.415(5)
2.432(4)
2.458(4)
2.566(4)
2.404(5)
2.552(4)
2.815(5)
2.424(4)
2.452(4)
2.585(4)
2.503(5)
2.565(5)
2.704(5)
2.343(5)
2.355(4)
2.686(5)
2.481(5)
2.566(5)
2.706(4)
2.329(4)
2.522(5)
2.734(4)
2.332(4)
2.465(4)
2.713(4)
2.536(5)
2.582(5)
2.420(4)
2.424(4)
2.433(4)
2.388(4)
2.415(4)
2.424(4)
2.399(4)
2.402(5)
2.422(4)
2.444(4)
2.457(4)
2.537(4)
2.392(4)
2.534(4)
2.413(4)
2.423(4)
Cu19-Se18
Cu20-Se6
Cu20-Se22
Cu20-Se17
Cu21-Se18
Cu21-Se17
Cu21-Se16
Cu22-Se8
Cu22-Se18
Cu22-Se24
Cu23-Se17
Cu23-Se22
Cu23-Se23
Cu24-Se18
Cu24-Se24
Cu24-Se23
Cu25-Se11
Cu25-Se9
Cu26-Se19
Cu26-Se11
Cu26-Se9
Cu27-Se10
Cu27-Se9
Cu27-Se14
Cu28-Se12
Cu28-Se11
Cu29-Se19
Cu29-Se10
Cu29-Se20
Cu30-Se19
Cu30-Se23
Cu31-Se19
Cu31-Se12
Cu31-Se21
Cu32-Se10
Cu32-Se20
Cu32-Se22
Cu33-Se21
Cu33-Se20
Cu33-Se19
Cu34-Se12
Cu34-Se24
Cu34-Se21
Cu35-Se20
Cu35-Se22
Cu35-Se23
Cu36-Se21
Cu36-Se24
Cu36-Se23
S1-C84
2.624(5)
2.443(5)
2.586(5)
2.897(5)
2.335(5)
2.360(4)
2.687(5)
2.522(5)
2.556(4)
2.602(4)
2.316(4)
2.395(4)
2.882(4)
2.359(4)
2.507(4)
2.709(4)
2.566(4)
2.566(4)
2.423(4)
2.429(4)
2.437(4)
2.398(4)
2.402(4)
2.414(4)
2.392(4)
2.406(4)
2.403(4)
2.457(4)
2.594(4)
2.407(4)
2.548(4)
2.415(4)
2.444(4)
2.605(4)
2.490(4)
2.592(4)
2.599(5)
2.329(4)
2.343(5)
2.714(5)
2.514(4)
2.594(5)
2.666(5)
2.345(4)
2.506(4)
2.674(4)
2.326(4)
2.457(4)
2.757(4)
1.79(3)
Cu1-Se1
Cu2-Se13
Cu2-Se3
Cu2-Se1
Cu3-Se2
Cu3-Se1
Cu3-Se17
Cu4-Se4
Cu4-Se3
Cu4-Se18
Cu5-Se13
Cu5-Se2
Cu5-Se14
Cu6-Se13
Cu6-Se23
Cu6-Se17
Cu7-Se13
Cu7-Se4
Cu7-Se15
Cu8-Se2
Using the preformed Cu-Se cluster 3, however, we found
that it is possible to incorporate thiol phosphine ligands as
partial substitution of the PnPr3 ligand shell with Ph2P(CH2)3-
SH, with the controlled, concomitant formation of a larger
cluster framework. When cluster 3 was dissolved in mixture
of diethyl ether and THF and treated with an excess of
Ph2P(CH2)3SH, a gradual lightening of the reaction solution
was observed from which X-ray-quality dark brown needles
of Cu36(Se2fc2)6Se12(PnPr3)10(Ph2P(CH2)3SH)2 (5) were iso-
lated in 78% yield. The introduction of excess ligand resulted
in a cluster expansion reaction, and there are clear structural
relationships between the framework in 5 (Figure 5) and that
displayed in 3. The structure of Cu36 cluster 5 is best viewed
as an expansion of the original Cu20 framework in 3, albeit
with a more condensed central core. Cluster 3 resides on a
crystallographic inversion center and can be described as
consisting of two Cu10(Se2fc)2Se3 units (Figure 6), and the
larger framework in 5 can be viewed as being composed of
three of these units (Figure 6) centered about a Cu6Se3 core.
The reduction in the PR3:Cu ratio together with an increased
Cu8-Se22
Cu8-Se14
Cu9-Se15
Cu9-Se14
Cu9-Se13
Cu10-Se4
Cu10-Se24
Cu10-Se15
Cu11-Se14
Cu11-Se22
Cu11-Se23
Cu12-Se15
Cu12-Se24
Cu12-Se23
Cu13-Se7
Cu13-Se5
Cu14-Se5
Cu14-Se7
Cu14-Se16
Cu15-Se6
Cu15-Se5
Cu15-Se20
Cu16-Se8
Cu16-Se7
Cu16-Se21
Cu17-Se16
Cu17-Se6
Cu17-Se17
Cu18-Se16
Cu18-Se23
Cu19-Se16
Cu19-Se8
2-
ratio of Se2- to surface fcSe2 on going from 3 to 5
contributes to a more condensed core in 5, with nine
interstitial copper atoms coordinated by a µ9-Se ion (Se23)
and two µ6-Se2- centers (Se22 and Se24; Tables 6; Figure
5). As illustrated in Figure 5, two of the twelve phosphine
ligands present are Ph2P(CH2)3SH (bonded to Cu1 and
Cu13), containing a free thiol group pointing out from the
cluster surface. For the Ph2P(CH2)3SH ligand P6, there is
crystallographic evidence for a two-site Ph2P(CH2)3SH:PnPr3
disorder, and a model with 70:30 occupancy of the two
ligands gave a satisfactory refinement. The other tripropyl-
phosphine ligands were ultimately not substituted.
S2-C126
1.73(3)
2.624(5)
2.443(5)
Cu19-Se18
Cu20-Se6
dynamic light scattering experiments, and we attribute this
to the bidentate ferrocenyldiselenolate ligands, as Cu-Se
nanocluster complexes whose surfaces are passivated exclu-
sively with phosphine ligands commonly display random
condensation reactions when redissolved in organic solvents.7
The good solubility and relative stability of cluster 3 in
common organic solvents thus lends itself to an investigation
of whether selective substitution reactions of the ancillary
PnPr3 shell on such clusters could be performed, as the
introduction of reactive groups via the phosphine ligand shell
surrounding the cluster core may allow for covalent bonding
of these clusters onto a metal surface.
(17) See for example: (a) Togni, A.; Rihs, G.; Blumer, R. E. Organome-
tallics 1992, 11, 613-621. (b) Chen, C.-H.; Lee, G.-H.; Liaw, W.-F.
Inorg. Chem. 2006, 45, 2307-2316. (c) Hsu, Hua-Fen; Peng, Wan-
Yu; Li, Zung-Ying; Wu, Ru-Rong; Liao, Ju-Hsiou; Wang, Yu; Liu,
Yi-Hung; Shieh, Minghuey; Kuo, Ting-Shen. Inorg. Chim. Acta 2005,
358, 2149-2154. (d) Matsuzaki, K.; Kawaguchi, H.; Voth, P.; Noda,
K.; Itoh, S.; Takagi, H. D.; Kashiwabara, K.; Tatsumi, K. Inorg. Chem.
2003, 42, 5320-5329. (e) Ortner, K.; Hilditch, L.; Zheng, Y.; Dilworth,
J. R.; Abram, U. Inorg. Chem. 2000, 39, 2801-2806. (f) Maina, T.;
Pecorale, A.; Dolmella, A.; Bandoli, G.; Mazzi, U. J. Chem. Soc.,
Dalton Trans. 1994, 2437-2443.
Free thiol groups would be one of the most suitable
candidates because their bonding behavior onto Au surfaces
has been well studied.8 Thiol phosphines, however, cannot
be used directly in the preparation of Cu-Se clusters from
9400 Inorganic Chemistry, Vol. 45, No. 23, 2006

Ferrocenyldiselenolate Stabilized Cu-Se Clusters
The direct assembly of the Cu36Se12(fcSe2)6 framework
observed in 5 can also be achieved using a combination of
CuOAc‚PnPr2Ph, Se(SiMe3)2, and fc(SeSiMe3)2. The struc-
turally related nanocluster Cu36Se12(fcSe2)6(PnPr2Ph)12 (6) can
be prepared in crystalline form in good yield under low-
temperature conditions (Supporting Information; Figure S1).
This is perhaps not surprising, as the Tollman cone angles16
for PhPnPr2 and Ph2P(CH2)3SH are expected to be similar.
In summary, the ferrocenyldiselenide reagent fc(SeSiMe3)2
phosphinothiol ligands and the first step en route to the
assembly of copper-selenide nanoclusters that may be
amenable to anchoring onto metal surfaces.
Acknowledgment. J.F.C. gratefully acknowledges the
Natural Sciences and Engineering Research Council (NSERC)
of Canada and the Government of Ontario Premier’s
Research Excellence Awards (PREA) program for financial
support. J.F.C. also thanks the Forschungszentrum Karlsruhe
for a visiting research fellowship. D.F. thanks the DFG
Centre for Functional Nanostructures, the Fonds der Che-
mischen Industrie, and the Forschungszentrum Karlsruhe for
financial support.
2-
is a convenient source for the delivery of fcSe2 in the
synthesis of Cu-Se cluster and nanocluster complexes. The
bridging selenolate ligands impart a certain amount of kinetic
stability to Cu20Se6(fcSe2)4(PnPr3)10 (3). In the presence of
excess Ph2P(CH2)3SH, however, the cluster framework is
selectively expanded to yield Cu36(Se2fc2)6Se12(PPr3)10-
(Ph2P(CH2)3SH)2 (5), in which partial substitution of the PPr3
ligand shell has been achieved. This represents the first
example of a structurally characterized nanocluster containing
Supporting Information Available: X-ray crystallographic files
in CIF format for complexes 1-6 including a representation of
cluster 6 (Figure S1). This material is available free of charge via
the Internet at http://pubs.acs.org.
IC061111N
Inorganic Chemistry, Vol. 45, No. 23, 2006 9401