Rhombic dodecahedral Ag8M6 (M = Cu, Ag, Au) cluster complexes of ferrocenylethynyl prepared by reaction of (AgC≡CFc) n with [M2(Ph2PNHPh2) 2(MeCN)2]2+ (M =

Article abstract of DOI:10.1021/om0607346

Reaction of the polymeric silver ferrocenylacetylide (AgC≡CFc) _n with [M₂(Ph₂PNHPPh₂h(MeCN) ₂]²⁺ (M = Cu, Ag, Au) gave rise to the isolation of rhombic dodecahedral Ag₈^I

Full text of DOI:10.1021/om0607346

Organometallics 2006, 25, 4941-4944
4941
Rhombic Dodecahedral Ag8M6 (M ) Cu, Ag, Au) Cluster
Complexes of Ferrocenylethynyl Prepared by Reaction of
(AgCtCFc)n with [M2(Ph2PNHPh2)2(MeCN)2]2+ (M ) Cu, Ag, Au)
Qiao-Hua Wei,† Gang-Qiang Yin,† Li-Yi Zhang,† and Zhong-Ning Chen*,†,‡
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter,
Chinese Academy of Sciences, Fuzhou, Fujian 350002, People’s Republic of China, and State Key
Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, the Chinese Academy
of Sciences, Shanghai 200032, People’s Republic of China
ReceiVed August 13, 2006
Summary: Reaction of the polymeric silVer ferrocenylacetylide
(AgCtCFc)n with [M2(Ph2PNHPPh2)2(MeCN)2]2+ (M ) Cu,
Ag, Au) gaVe rise to the isolation of rhombic dodecahedral
AgI8MI6 cage complexes together with the unusual 1,2,5-
azadiphospholium product [FcCdCH(Ph2PNPPh2)](BF4) by the
cyclic addition of FcCtC to Ph2PNHPPh2. Distinct redox waVe
splitting occurs in the AgI8CuI6 cage complex with ∆E1/2 ) 0.15
V due to successiVe oxidation of the Fc groups, induced
probably by electronic interactions between iron centers in the
ferrocenylacetylides.
CuI3, and MII cluster units in the complexes [Pt2(dppm)2(Ct
3
CFc)2] (dppm ) bis(diphenylphosphino)methane),5 [Ru2(Y-
DMBA)4(CtCFc)2] (Y-DMBA ) meta-substituted dimethyl-
benzamidinates),6 [Cu3(µ-dppm)3(µ3-η1-CtCFc)2](PF6),7 and
[M3(dpa)4(CtCFc)2] (dpa ) 2,2′-dipyridylamide, M ) Co,8
Ru9), respectively. It has been demonstrated that the electronic
nature of the [M] connectors, including metal centers and their
ancillary ligands, plays a vital role in the electronic coupling
and, hence, electron delocalization in these species.3-10 Recently,
the bis(ferrocenylethynyl)-capped hexanuclear platinum com-
pound [Pt6(µ-PtBu2)4(CO)4(CtCFc)2] has been reported,11
which reveals the presence of intramolecular electron transfer
from the {Pt6} cluster to the peripheral ferrocenyl subunits.
Great effort has been devoted to the chemistry of metal
alkynyl complexes because of their intriguing spectroscopic,
redox, and optical properties and their potential applications in
molecular electronics.1,2 As a redox-active alkynyl ligand,
ferrocenylethynyl (FcCtCH) has been used widely in the design
of [D]-[M]-[A] ([D] ) donor, [M] ) metal or cluster, [A] )
acceptor) compounds to explore electronic communication
between ferrocenyl groups across a metal or cluster-containing
spacer.3-10 The [M] spacers are mononuclear RuII and PtII
components in the complexes trans-[RuII(P-P)2(CtCFc)2] (P-P
) diphosphine)3 and trans-[PtII(PR3)2(CtCFc)2] (R ) aryl,
alkyl).4 They can also be binuclear PtI2 and RuIII2, trinuclear
During our studies on group 11 metal alkynyl chemistry, a
series of AgI-CuI and AgI-AuI heterometallic cluster com-
plexes with various nuclearities have been prepared by reaction
of [M2(Ph2PXPPh2)2(MeCN)2]2+ (X ) CH2, NH; M ) CuI, AgI,
AuI) with polymeric silver acetylides,12 which exhibit rich
spectroscopic and luminescent properties. These studies prompted
us to attempt the depolymerization of polymeric silver ferro-
cenylacetylide (AgCtCFc)n with [M2(Ph2PXPPh2)2(MeCN)2]2+
.
Interestingly, while the reactions gave octahedral hexanuclear
AgI6 and CuI6 complexes when X ) CH2,13 rhombic dodeca-
hedral AgI8MI6 (M ) Cu, Ag, Au) cage complexes and a 1,2,5-
azadiphospholium product were isolated when X ) NH (Scheme
1).
* To whom correspondence should be addressed at the Fujian Institute
of Research on the Structure of Matter. E-mail:czn@ms.fjirsm.ac.cn.
† Fujian Institute of Research on the Structure of Matter.
‡ Shanghai Institute of Organic Chemistry.
(1) (a) Szafert, S.; Gladysz, J. A. Chem. ReV. 2003, 103, 4175. (b) Ren,
T. Organometallics 2005, 24, 4854. (c) Rosenthal, U. Angew. Chem., Int.
Ed. 2003, 42, 1791.
(2) (a) Yam, V. W.-W. Acc. Chem. Res. 2002, 35, 555. (b) Long, N. J.;
Williams, C. K. Angew. Chem., Int. Ed. 2003, 42, 2586.
(3) (a) Jones, N. D.; Wolf, M. O.; Giaquinta, D. M. Organometallics
1997, 16, 1352. (b) Zhu, Y.; Clot, O.; Wolf, M. O.; Yap, G. P. A. J. Am.
Chem. Soc. 1998, 120, 1812. (c) Colbert, M. C. B.; Lewis, J.; Long, N. J.;
Raithby, P. R.; White, A. J. P.; Williams, D. J. J. Chem. Soc., Dalton Trans.
1997, 99.
(4) (a) Lebreton, C.; Touchard, D.; Pichon, L. L.; Daridor, A.; Toupet,
L.; Dixneuf, P. H. Inorg. Chim. Acta 1998, 272, 188. (b) Osella, D.;
Gambino, O.; Nervi, C.; Ravera, M.; Russo, M. V.; Infante, G. Inorg. Chim.
Acta 1994, 225, 35. (c) Osella, D.; Gobetto, R.; Nervi, C.; Ravera, M.;
D’Amato, R.; Russo, M. V. Inorg. Chem. Commun. 1998, 1, 239.
(5) Yip, J. H. K.; Wu, J.; Wong, K.-Y.; Ho, K. P.; So-Ngan Pun, C.;
Vittal, J. J. Organometallics 2002, 21, 5292.
(6) (a) Xu, G.-L.; DeRosa, M. C.; Crutchley, R. J.; Ren, T. J. Am. Chem.
Soc. 2004, 126, 3728. (b) Xu, G.-L.; Crutchley, R. J.; DeRosa, M. C.; Pan,
Q.-J.; Zhang, H.-X.; Wang, X.; Ren, T. J. Am. Chem. Soc. 2005, 127, 13354.
(7) Yip, J. H. K.; Wu, J.; Wong, K.-Y.; Yeung, K.-W.; Vittal, J. J.
Organometallics 2002, 21, 1612.
Slow addition of 2 equiv of polymeric (AgCtCFc)n to a 1,2-
dichloroethane-methanol-dichloromethane (2/2/1 v/v/v) solu-
tion of [M2(Ph2PNHPPh2)2(MeCN)2](BF4)2 with stirring gave
a clear red solution, from which the purple product 1 and red
Ag8M6 cluster complex (M ) Cu (2), Ag (3), Au (4)) were
separated by silica gel column chromatography.14 These com-
pounds have been characterized by ESI-MS spectrometry,
microanalyses, 1H NMR and IR spectroscopy (Supporting
Information), and X-ray crystallography.15
The compound [FcCdCH(Ph2PNPPh2)](BF4) (1) (Figure 1)
is a 1,2,5-azadiphospholium species originating probably from
a cyclic addition reaction of PPh2NHPPH2 with ferrocenylethy-
nyl. The curved array FcCdCH (C3-C2-C1 ) 126.6(4)°)
(11) Albinati, A.; de Biani, F. F.; Leoni, P.; Marchetti, L.; Pasquali, M.;
Rizzato, S.; Zanello, P. Angew. Chem., Int. Ed. 2005, 44, 5701.
(12) (a) Wei, Q.-H.; Yin, G.-Q.; Zhang, L-Y.; Shi, L.-X.; Mao, Z.-W.;
Chen, Z.-N. Inorg. Chem. 2004, 43, 3484. (b) Wei, Q.-H.; Zhang, L-Y.;
Yin, G.-Q.; Shi, L.-X.; Chen, Z.-N. J. Am. Chem. Soc. 2004, 126, 9940.
(c) Wei, Q.-H.; Zhang, L-Y.; Yin, G.-Q.; Shi, L.-X.; Chen, Z.-N.
Organometallics 2005, 24, 3818.
(8) Berry, J. F.; Cotton, F. A.; Murillo, C. A. Organometallics 2004,
23, 2503.
(9) Kuo, C.-K.; Chang, J.-C.; Yeh, C.-Y.; Lee, G.-H.; Wang, C.-C.; Peng,
S.-M. Dalton Trans. 2005, 3696.
(10) Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; Somers, N.; White,
A. H. Aust. J. Chem. 2003, 56, 509.
(13) Wei, Q.-H.; Zhang, L.-Y.; Shi, L.-X.; Chen, Z.-N. Inorg. Chem.
Commun. 2004, 7, 286.
10.1021/om0607346 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 09/15/2006

4942 Organometallics, Vol. 25, No. 21, 2006
Scheme 1. Synthetic Routes to Complexes 1-4
Communications
instead of linearity in FcCtCH suggests sp2-hybridized char-
acter for C1 and C2 atoms. The C1-C2 length (1.341(6) Å) is
typical of a CdC double bond, which was also confirmed by
the IR spectrum, with a strong ν(CdC) band occurring at 1618
cm-1. The P-N (1.601(4) and 1.612(4) Å) distances are close
to those in the deprotonated [Ph2PNPPh2]- 16 but obviously
shorter than those in PPh2NHPPH2.17 The related bonding
parameters are comparable to those in the phenyl counterpart
[PhCdCH(Ph2PNPPh2)]Br, which was formed by direct reaction
of PPh2NHPPh2 with PhCtCBr.18
The Ag8M6 cluster complexes exhibit a cage structure
composed of 8 AgI and 6 MI (M ) Cu (2), Ag (3), Au (4))
centers linked by 12 ferrocenylacetylides, in which a chloride
ion is located at the center of the cage. The Ag8M6 cluster
(Figure 2) forms a rhombic dodecahedron19 made up of 14
Ag2M2 quadrangles. Eight AgI centers are arranged at the 8
apices of a cube, whereas 6 MI centers are oriented at the 6
apices of an octahedron. Interestingly, each of the 6 square
planes in the AgI8 cube is capped with a MI atom.19 Likewise,
each of the 8 triangular planes in the MI6 octahedron is capped
with a AgI atom (Figure 2). The Ag-Cu (2.82-3.07 Å for 2),
Ag-Ag (2.89-3.086 Å for 3), and Ag-Au (2.92-3.31 Å for
4) distances lie within the ranges found in other AgI-CuI, AgI-
AgI, and AgI-AuI alkynyl complexes.2,12,19,20 These distances
are shorter than the sum of AgI and MI van der Waals radii
(3.06 Å for AgI-CuI and 3.40 Å for AgI-AgI and AgI-AuI),
indicating unambiguously the presence of metal-metal con-
tacts.12,20 It is noteworthy that each AgI atom is associated with
3 adjacent MI atoms, whereas each MI atom is connected to 4
adjacent AgI atoms via AgI-MI contacts. The acetylides adopt
an asymmetric µ3-η1 or µ3-η1:η1:η2 bonding mode to link one
MI and two/three AgI centers, in which the M-C length is much
shorter than those of the Ag-C bonds. The M-CtC-Fc arrays
are quasi-linear, whereas those of Ag-CtC-Fc are curved.
(14) Synthetic procedure for 1 and 2: to 10 mL of a 1,2-dichloroethane-
methanol-dichloromethane (2/2/1 v/v/v) solution of [Cu2(Ph2PNHPPh2)2-
(MeCN)2](BF4)2 (115.3 mg, 0.10 mmol) was added slowly (AgCtCFc)n
(63.3 mg, 0.20 mmol) with stirring for 12 h to give a clear deep red solution.
The solvents were removed in vacuo to afford a red residue, which was
dissolved in 5 mL of dichloromethane. The solution was then chromato-
graphed on a silica gel column (100-200 mesh). The first band was eluted
using dichloromethane-acetone (50/3) to afford a small quantity of
unidentified species. Elution of the second band using dichloromethane-
acetone (5/1) gave the mauve compound 1. Yield: 18% (based on AgCt
CFc). The third band was eluted using dichloromethane-acetone (1/1),
affording compound 2 as a red product. Yield: 47% (based on AgCtCFc).
Detailed characterization data for compounds 1-4 is provided in the the
Supporting Information.
(15) Crystal data for 1: C36H30BF4FeNP2, Mr ) 681.21, triclinic, space
group P1h, a ) 10.3467(3) Å, b ) 10.9956(1) Å, c ) 14.9663(4) Å, R )
96.362(1)°, â ) 107.810(1)°, γ ) 93.639(1)°, V ) 1602.54(6) Å3, Z ) 2,
F
calcd ) 1.412 g cm-3, µ ) 0.621 mm-1, T ) 293(2) K, R1 ) 0.0637, wR2
) 0.1554 for 3984 reflections with I > 2σ(I), GOF ) 1.091. Crystal data
for 2‚CH2Cl2‚8H2O: C145H127Ag8Cl3Cu6Fe12O9, Mr ) 4034.22, triclinic,
space group P1h, a ) 16.261(5) Å, b ) 18.153(7) Å, c ) 27.627(9) Å, R )
87.950(11)°, â ) 75.424(10)°, γ ) 74.763(7)°, V ) 7611(5) Å3, Z ) 2,
F
calcd ) 1.760 g cm-3, µ ) 3.025 mm-1, T ) 293(2) K, R1 ) 0.0867, wR2
) 0.2629 for 15 304 reflections with I > 2σ(I), GOF ) 1.078. Crystal data
for 3‚10H2O: C144H129Ag14ClFe12O11, Mr ) 4251.3, triclinic, space group
P1h, a ) 15.6539(3) Å, b ) 16.7787(2) Å, c ) 17.6979(2) Å, R ) 79.829-
(1)°, â ) 69.036(1)°, γ ) 62.276(1)°, V ) 3842.09(10) Å3, Z ) 1, Fcalcd
)
1.837 g cm-3, µ ) 2.897 mm-1, T ) 293(2) K, R1 ) 0.1053, wR2 )
0.2644 for 7426 reflections with I > 2σ(I), GOF ) 1.292. Crystal data for
4‚10H2O: C144H129Ag8Au6ClFe12O11, Mr ) 4785.88, triclinic, space group
P1h, a ) 15.6892(1) Å, b ) 16.7712(3) Å, c ) 17.7327(3) Å, R ) 81.126-
(1)°, â ) 68.883(1)°, γ ) 62.678(1)°, V ) 3866.7(1) Å3, Z ) 1, Fcalcd
)
2.055 g cm-3, µ ) 7.803 mm-1, T ) 293(2) K, R1 ) 0.0986, wR2 )
0.2530 for 7146 reflections with I > 2σ(I), GOF ) 1.228.
(16) (a) Wei, Q.-H.; Yin, G.-Q.; Ma, Z.; Shi, L.-X.; Chen, Z.-N. Chem.
Commun. 2003, 2188. (b) Ellermann, J.; Utz, J.; Knoch, F. A.; Moll, M. Z.
Anorg. Allg. Chem. 1996, 622, 1871.
(17) Sekabunga, E. J.; Smith, M. L.; Webb, T. R.; Hill, W. E. Inorg.
Chem. 2002, 41, 1205.
(18) (a) Trofimenko, S.; Rheingold, A. L.; Incarvito, C. D. Angew. Chem.,
Int. Ed. 2003, 42, 3506. (b) Schmidpeter, A.; Polborn, K. Heteroat. Chem.
1997, 8, 347.
(19) (a) Rais, D.; Yau, J.; Mingos, D. M. P.; Vilar, R.; White, A. J. P.;
Williams, D. J. Angew. Chem., Int. Ed. 2001, 40, 3464. (b) Rais, D.; Mingos,
D. M. P.; Vilar, R.; White, A. J. P.; Williams, D. J. J. Organomet. Chem.
2002, 652, 87. (c) Abu-Salah, O. M.; Ja’far, M. H.; Al-Ohaly, A. R.; Al-
Farhan, K. A.; Al-Enzi, H. S.; Dolomanov, O. V.; Howard, J. A. K. Eur.
J. Inorg. Chem. 2006, 2353.
(20) (a) Abu-Salah, O. M. J. Organomet. Chem. 1998, 565, 211. (b)
Schuster, O.; Monkowius, U.; Schmidbaur, H.; Ray, R. S.; Kruger, S.;
Rosch, N. Organometallics 2006, 25, 1004. (c) de la Riva, H.; Nieuwhuyzen,
M.; Fierro, C. M.; Raithby, P. R.; Male, L.; Lagunas, M. C. Inorg. Chem.
2006, 45, 1418.
Figure 1. ORTEP drawing of the cation of 1 with atom-labeling
scheme showing 30% thermal ellipsoids.

Communications
Organometallics, Vol. 25, No. 21, 2006 4943
Figure 3. Cyclic and differential pulse voltammograms (CV and
DPV) of 2 in a 0.1 M dichloromethane solution of (Bu4N)(PF6).
The scan rate is 100 mV s-1 for CV and 20 mV s-1 for DPV.
OH)2](BF4)2 (11.85 Å)13 but obviously longer than those in Cu6-
(dppm)2(CtCFc)4(ClO4)2 (11.08 Å).13 It is noticeable that, for
the Ag8Cu6 complex 2, the Fe‚‚‚Fe separations in the gauche-
oriented (average 11.45 Å) Fc-CtC-Cu-CtC-Fc arrays are
obviously shorter than those in the cis-arranged (average 11.75
Å) ones.
Redox properties of 1-4 were investigated by cyclic and
pulse differential voltammetry in a 0.1 M dichloromethane
solution of (Bu4N)(PF6). A reversible redox wave occurs at E1/2
) 0.34 V (vs Fc+/Fc) for 1 due to the oxidation of ferrocenyl,
which is more positive compared with that for ferrocenylethynyl
(0.14 V),4b indicating that cyclic formation of 1,2,5-azadiphos-
pholium makes oxidation of the iron center much more difficult.
As shown in Figure 3, 2 exhibits two separate reversible redox
waves at 0.29 and 0.14 V, respectively, ascribed to the
successive oxidation of ferrocenyls. The wave separation ∆E1/2
of two stepwise redox processes is 0.15 V, which corresponds
to the comproportionation constant Kc ) 343. The distinct redox
wave splitting indicates that intramolecular electronic com-
munication is likely operative between ferrocenyls and is
mediated across the quasi-linear pathway Fc-CtC-Cu-Ct
C-Fc.22,23 It is noteworthy that redox wave splitting in 2 (∆E1/2
) 0.15 V, Fe‚‚‚Fe ) 11.60 Å) is more obvious than that in the
triangular trinuclear complex [CuI3(µ-dppm)3(µ3-η1-CtCFc)2]+
Figure 2. (a) Perspective view of the complex cation of 2. (b)
Ag8Cu6 cluster core showing a rhombic dodecahedral structure.
While the Ag center is located in a distorted-triangular-planar
environment built from three C donors, the M center exhibits a
quasi-linear arrangement, with the C-M-C angle being close
to 180°. As depicted in Scheme S1 (Supporting Information),
Fc-CtC-M-CtC-Fc arrays are likely oriented in three
different conformations, of which the trans mode is most
frequently found in the [D]-[M]-[A] compounds of ferroce-
nylethynyl.3,4,6,7,9,11 The cis and gauche orientations, however,
occur only in a few cases. Four examples with cis conformations
are Cu6(dppm)2(CtCFc)4(ClO4)2,13 Pt2(dppm)2(CtCFc)2,5 Co3-
(dpa)4(CtCFc)2,8 and Ir2Cu4(CtCFc)8.10 Two examples with
gauche orientations are [Ag6(dppm)2(CtCFc)4(CH3OH)2]-
(BF4)213 and trans-Mn(dmpe)2(CtCFc)2.21 In contrast with the
all-trans orientations in Ag14 complex 3 and Ag8Au6 complex
4, of the six Fc-CtC-Cu-CtC-Fc arrays in Ag8Cu6
complex 2, three are cis-oriented and other three are gauche-
arranged. Average intramolecular Fe‚‚‚Fe separations in the
bridging Fc-CtC-M-CtC-Fc arrays are 11.55, 12.28, and
12.25 Å for compounds 2 (M ) Cu), 3 (M ) Ag), and 4 (M )
Au), respectively, which are comparable to those in the trinuclear
complex [CuI3(dppm)3(µ3-η1-CtCFc)2](PF6) (11.78 Å)7 and
octahedral hexanuclear complex [Ag6(dppm)2(CtCFc)4(CH3-
(∆E1/2 ) 0.11 V, Fe‚‚‚Fe ) 11.78 Å)7 and octahedral hexa-
13
nuclear complexes Cu6(dppm)2(CtCFc)4(ClO4)2 (∆E1/2
<
0.07 V, Fe‚‚‚Fe ) 11.85 Å) and [Ag6(dppm)2(CtCFc)4(CH3-
OH)2](BF4)213 (∆E1/2 < 0.07 V, Fe‚‚‚Fe ) 11.08 Å), although
their Fe‚‚‚Fe separations in the Fc-CtC-M-CtC-Fc arrays
are similar. This is likely elucidated by the better linearity in
the Fc-CtC-M-CtC-Fc arrays for 2 compared with those
for tri- and hexanuclear CuI or AgI complexes.7,13 In striking
contrast with the reversible redox properties of 2, the electro-
chemical behavior of 3 and 4 is irreversible, with a broad
oxidation peak (0.42 V for 3 and 0.40 V for 4) in the anodic
region and a small reduction peak (0.07 V for 3 and 0.08 V for
4) on the cathodic side, probably because of their instability in
the electrochemical measurement, which induces dissociation
of the Ag8M6 (M ) Ag, Au) cluster species.
In summary, depolymerization of silver ferrocenylacetylide
(AgCtCFc)n with [M2(Ph2PNHPh2)2(MeCN)2]2+ (M ) Cu, Ag,
(22) Adams, R. D.; Qu, B.; Smith, M. D. Inorg. Chem. 2001, 40, 2932.
(23) Fabrizi de Biani, F.; Corsini, M.; Zanello, P.; Yao, H.; Bluhm, M.
E.; Grimes, R. N. J. Am. Chem. Soc. 2004, 126, 11360.
(21) Belenkaya, A. G.; Dolgushin, F. M.; Peterleitner, M. G.; Petrovskii,
P. V.; Krivykh, V. V. Russ. Chem. Bull. 2002, 160.

4944 Organometallics, Vol. 25, No. 21, 2006
Communications
Supporting Information Available: Text giving experimental
details, figures giving additional views of the compounds prepared
and additional characterization data, and CIF files giving crystal
data for 1-4. This material is available free of charge via the
Internet at http://pubs.acs.org.
Au) induced isolation of rhombic dodecahedral heteronuclear
AgI8MI6 cage complexes together with the unusual 1,2,5-
azadiphospholium product [FcCdCH(Ph2PNPPh2)](BF4) by a
cyclic addition reaction of FcCtC with Ph2PNHPPh2. Intramo-
lecular electronic communication is likely operative between
Fc groups and is mediated by the pathways Fc-CtC-M-
CtC-Fc (M ) Cu, Ag) in the AgI8CuI6 cage complex.
OM0607346