Covalent rigid-rod organometallic polymers with alternating transition metal clusters and conjugated spacers in the main chain

Article abstract of DOI:10.1021/om0604021

The first rigid-rod cluster-containing σ-alkynyl polymers E-[({Pt₆}-CC-Ar-CC)]_x-{Pt6}-E [(3), {Pt₆} = Pt₆(μ-PBu₂^t)₄(CO)₄, E = end group; M_n = 22 000-38 000] have been prepared by step-growth polycondensation of {Pt₆}-Cl₂ and 1,4-didodecyl-2,5-diethynylbenzene (HCC-Ar-CCH) under Sonogashira-type conditions. The monodisperse oligomers HCC-Ar-CC-({Pt₆}CC-Ar-CC) _x-{Pt₆}-CC-Ar-CCH [(4) x = 0; (11) x = 2; (15) x = 4] were also prepared by stepwise procedures, still based on Cu(I)-catalyzed dehydrohalogenation reactions. A red-shift of the UV-vis absorption centered at ca. 470 nm, on increasing chain length, suggests some degree of electron delocalization along the backbone.

Full text of DOI:10.1021/om0604021

4226
Organometallics 2006, 25, 4226-4230
Covalent Rigid-Rod Organometallic Polymers with Alternating
Transition Metal Clusters and Conjugated Spacers in the Main
Chain
Piero Leoni,*,† Lorella Marchetti,† Swagat Kumar Mohapatra,† Giacomo Ruggeri,†,‡ and
Lucia Ricci†,‡
Dipartimento di Chimica e Chimica Industriale, UniVersita` di Pisa, and Consorzio InteruniVersitario
Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Pisa Research Unit,
Via Risorgimento 35, I-56126 Pisa, Italy
ReceiVed May 10, 2006
The first rigid-rod cluster-containing σ-alkynyl polymers E-[({Pt6}-CC-Ar-CC)]x-{Pt6}-E [(3), {Pt6}
) Pt6(µ-PBut2)4(CO)4, E ) end group; Mn ) 22 000-38 000] have been prepared by step-growth
polycondensation of {Pt6}Cl2 and 1,4-didodecyl-2,5-diethynylbenzene (HCC-Ar-CCH) under Sono-
gashira-type conditions. The monodisperse oligomers HCC-Ar-CC-({Pt6}CC-Ar-CC)x-{Pt6}-CC-
Ar-CCH [(4) x ) 0; (11) x ) 2; (15) x ) 4] were also prepared by stepwise procedures, still based on
Cu(I)-catalyzed dehydrohalogenation reactions. A red-shift of the UV-vis absorption centered at ca.
470 nm, on increasing chain length, suggests some degree of electron delocalization along the backbone.
exceedingly rare,5,6 even though it is considered a remarkable
task.1d To our knowledge only two examples of soluble polymers
have been reported: {Ru6(µ6-C)(CO)15(Ph2P-CC-PPh2)}n
Introduction
The incorporation of transition metals into oligomeric or
polymeric frameworks has been subjected to intense scrutiny,
and the interest is rapidly growing further after the discovery
of new synthetic procedures and of the valuable properties and
technological potential of these materials.1,2 An important class
of such derivatives includes the one-dimensional metal-alkynyls
or -polyynyls [(-LnM-CC-R-CC-)x; R ) none, -(CC)y-,
aromatic or heteroaromatic-diyl rings],2 where the metal centers
are embedded into the main chain of the polymer by virtue of
robust M-CC covalent σ-bonds, not involving the π-electrons
of the CC triple bond. The third-order nonlinear optical, liquid-
crystalline, and electro-optic properties of these materials have
been recently reviewed.2a Analogous polymers, containing
transition metal cluster units [(-LnMz-CC-R-CC-)x; z g 3],
are presently unknown;3,4 indeed, the inclusion of polyhedral
metal clusters into a macromolecular organometallic chain is
5c
and the polyurethane [-O(CH2)mC5H4{Mo2Ir2(CO)10}C5H4-
(CH2)mOC(O)N(H)-R-N(H)C(O)-]n.5d The latter appears to
be the unique example where the cluster-spacer connection is
made with strong covalent M-C bonds, although the spacer
itself is clearly nonconjugated. Additionally, the insoluble
diisocyanide-bridged polymers {[Pt3(µ-dppm)3(µ-1,4-CN-
C6R4-NC)][PF6]2}n (R ) H, Me) were found5e to dissolve with
breakdown of the oligomeric structure, and a few interesting
soluble polymers with Pt35f or M4 (M ) Pd, Pt) linear chains5g-h
in the repeating units have been reported. It is worth noting the
potential relevance of cluster-containing conjugated structures
(4) Some nonalkynyl polymers with metal-metal bonded M2 moieties
in the repeating unit have been reported in: (a) Xue, W. M.; Ku¨hn, F. E.;
Herdtweck, E.; Li, Q. Eur. J. Inorg. Chem. 2001, 213. (b) Chisholm, M.
H. Acc. Chem. Res. 2000, 33, 53. (c) Cotton, F. A.; Kim, Y.; Ren, T. Inorg.
Chem. 1992, 31, 2723. (d) Handa, M.; Matsumoto, H.; Yashioka, D.;
Nukada, R.; Mikuriya, M.; Hiromitsu, I.; Kusage, K. Bull. Chem. Soc. Jpn.
1998, 71, 1811. (e) Harvey, P. D. Coord. Chem. ReV. 2001, 219-221, 17.
(f) Irwin, M. J.; Jia, G.; Vittel, J. J.; Puddephatt, R. J. Organometallics
1996, 15, 5321. (g) Miyasaka, H.; Clerac, R.; Campos-Fernandez, C. S.;
Dunbar, K. R. Inorg. Chem. 2001, 40, 1663.
(5) (a) For a recent review on oligomeric cluster-containing systems (quite
generally short oligomers) see ref 4b. (b) Humphrey, M. G. Macromol.
Symp. 2004, 209, 1-22. (c) Johnson, B. F. G.; Sanderson, K. M.; Shephard,
D. S.; Ozkaya, D.; Zhou, W.; Ahmed, H.; Thomas, M. D. R.; Gladden, L.;
Mantle, M. Chem. Commun. 2000, 1317-1318. (d) Lucas, N. T.; Humphrey,
M. G.; Rae, A. D. Macromolecules 2001, 34, 6188-6195. (e) Bradford,
A. M.; Kristof, E.; Rashidi, M.; Yang, D.-S.; Payne, N. C.; Puddephatt, R.
J. Inorg. Chem. 1994, 33, 2355-2363. (f) Tanase, T.; Goto, E.; Begum, R.
A.; Hamaguchi, M.; Zhan, S.; Iida, M.; Sakai, K. Organometallics 2004,
23, 5975. (g) Zhang, T.; Crouin, M.; Harvey, P. D. Inorg. Chem. 1999, 38,
1305. (h) Zhang, T.; Crouin, M.; Harvey, P. D. Inorg. Chem. 1999, 38,
957.
* To whom correspondence should be addressed. Phone: +39 050
2219217. Fax: +39 050 2219246. E-mail: leoni@dcci.unipi.it.
† Dipartimento di Chimica e Chimica Industriale.
‡ INSTM.
(1) (a) Nguyen, P.; Go´mez-Elipe, P.; Manners, I. Chem. ReV. 1999, 99,
1515-1548. (b) Manners, I. Science 2001, 294, 1664-1666. (c) Abd-El-
Aziz, A. S. Macromol. Rapid. Commun. 2002, 23, 995-1031. (d) Manners,
I. Synthetic Metal-Containing Polymers; Wiley-VCH: Weinheim, 2004.
(e) Bunz, U. H. F. J. Organomet. Chem. 2003, 683, 269.
(2) (a) Long, N. J.; Williams, C. K. Angew. Chem., Int. Ed. 2003, 42,
2586-2617. (b) Khan, M. S.; Al-Mandhary, M. R. A.; Al-Suti, M. K.; Al-
Battashi, F. R.; Al-Saadi, S.; Ahrens, B.; Bjernemose, J. K.; Mahon, M. F.;
Raithby, P. R.; Younus, M.; Chawdhury, N.; Ko¨hler, A.; Marseglia, E. A.;
Tedesco, E.; Feeder, N.; Teat, S. J. Dalton Trans. 2004, 2377-2385. (c)
Wong, W.-Y.; Liu, L.; Poon, S.-Y.; Choi, K.-H.; Cheah, K.-W.; Shi, J.-X.
Macromolecules 2004, 37, 4496-4504. (d) Bunten, K. A.; Kakkar, A. K.
Macromolecules 1996, 29, 2885-2893. (e) La Groia, A.; Ricci, A.; Bassetti,
M.; Masi, D.; Bianchini, C.; Lo Sterzo, C. J. Organomet. Chem. 2003, 683,
406-420. (f) Haskins-Glusac, K.; Pinto, M. R.; Tan, C.; Schanze, K. S. J.
Am. Chem. Soc. 2004, 126, 1496.
(6) A few examples of soluble polymers with non-metal-metal-bonded
polyoxometalates or main group clusters (C60, carboranes) embedded in
the main chain are reported in: (a) Peng, Z. Angew. Chem., Int. Ed. 2004,
43, 930. (b) Roncali, J. Chem. Soc. ReV. 2005, 34, 483. (c) Herzog, A.;
Jalisatgi, S. J.; Knobler, C. B.; Wedge, T. J.; Hawthorne, M. F. Chem. Eur.
J. 2005, 11, 7155. (d) Pakhomov, S.; Kaszynski, P.; Young, V. G., Jr. Inorg.
Chem.2000, 2243.
(3) Short oligomers containing bimetallic Pt2 or Ru2 units have been
described in: (a) Irwin, M. J.; Jia, G.; Vittal, J. J.; Puddephatt, R. J.
Organometallics 1996, 15, 5321-5329. (b) Wong, K. T.; Lehn, J. M.; Peng,
S. M.; Lee, G. H. Chem. Commun. 2000, 2259-2260. Ren, T. Organo-
metallics 2005, 24, 4854-4870.
10.1021/om0604021 CCC: $33.50 © 2006 American Chemical Society
Publication on Web 07/19/2006

Cluster-Containing Organometallic Polymers
Organometallics, Vol. 25, No. 17, 2006 4227
(CCPh)2 and 328.9 ppm in 1],8b this sample should mainly
contain Pt-Cl terminations (E ) Cl).
Scheme 1. Preparation of Polymers 3
A further amount of the dialkyne 2 (2/3a = 2) was added to
the mother solution and, after 3 days of stirring, a portion of
the solution was separated and treated as described before,
yielding polymer 3b. Noticeably, the GPC measurements
showed that the degree of polymerization (DP) is unchanged
with respect to 3a (Table 1), indicating that only the substitution
of the Cl end groups with the CC-Ar-CCH moieties occurred.
1
As a consequence, the H NMR spectrum of 3b showed the
signal of the CCH moiety at 3.23 ppm, and only one 31P{1H}
NMR resonance was observed at 335.5 ppm for the P-Pt-CC
(both terminal and internal) nuclei. Finally, the reaction mixture
was treated with 1 (1/3b molar ratio = 1) and, after 3 days of
stirring, polymer 3c was recovered as described above [overall
yield for 3a-c: >80% with respect to 1]. The GPC analysis
of sample 3c confirmed a substantial increase of the Mn and
Mw values (Mn ) 37 555, Table 1), in accord with the step-
growth polycondensation character of the polymerization. A
residual, small resonance in the 31P{1H} NMR at 328.0 ppm,
overlapping the main signal at 335.5 ppm and the absence of a
1H NMR signal at ca. 3.2 ppm, confirmed that, similar to 3a,
polymer 3c mainly contains Pt-Cl end groups. The IR spectra
of 3a-c showed the expected absorptions at 2093 (m, br, νCt
C) and 2010 (s, br, νCtO) cm-1, and limited to 3b, a very weak
absorption at 3302 cm-1 was observed for the terminal CCH
Table 1. Molecular Weights from GPC and NMR Analyses
a
a
a
b
c
polymer
Mw
Mn
Mw/Mn
DPGPC(PS)
DPNMR
3a
3b
3c
64 700
68 156
148 887
22 500
23 272
37 555
2.9
2.9
4.0
9
9
15
8
8
16
a Monodispersed polystyrene as GPC standard. b DPGPC(PS) ) (Mn
-
M({Pt6}E2)/M({Pt6}CC-Ar-CC) (E ) Cl, 3a, 3c; CC-Ar-CCH, 3b).
c Calculated from NMR spectroscopy.
1
moiety. The H NMR spectra of 3a-c exhibited, besides the
aforementioned peaks, a slightly broadened singlet (7.13 ppm)
for the aromatic protons, the tert-butyl signal (virtual triplet at
1.51 ppm), and the n-dodecyl resonances (2.76-0.87 ppm), with
integral ratios that conform to the proposed structures. The
chemical shifts of the 195Pt{1H} resonances [δPt ) -4684
(Ptapical), -2980 (Pttetrahedron) ppm] are similar to those reported
for {Pt6}(CCR)2 [-4674 (2 Pt), -2996 (4Pt) ppm];8b the
complex shape of these resonances9 is diagnostic for the {Pt6}
unit symmetrically substituted at the two “apical” positions8,10
and strictly resembles those previously observed for {Pt6}X2
in the field of molecular electronics, as suggested by recent
studies on single-electron tunneling transistors working reliably
at room temperature and based on a single molecular metal-
lorganic cluster.7 On these grounds, in previous communications8a,b
we reported that the dichloride {Pt6}Cl2 (1) [{Pt6} ) Pt6(µ-
PBut2)4(CO)4] is a useful synthon for the introduction of the
{Pt6} cluster unit in complex structures. Herein we describe the
synthesis of the first cluster-containing σ-alkynyl polymers; pure
and monodisperse shorter oligomers were also prepared.
(X ) halogen,8a,b CCR,8b CHO10) and [{Pt6}(CO)2]2+ 8c
for
,
Results and Discussion
many of which the structure was elucidated by X-ray analysis.
σ-Alkynyl polymers were prepared via the CuCl-catalyzed
coupling between complex 1 and 1,4-didodecyl-2,5-diethynyl-
benzene [(2), HCC-Ar-CCH] (Scheme 1). The course of the
polymerization was investigated by taking portions of the
reaction mixture and characterizing the polymeric material via
GPC and spectroscopic measurements. Indeed, after 16 h of
stirring, a first portion of the reaction mixture was taken and
evaporated, and the residue was analyzed by IR and NMR (1H,
31P) spectroscopy, showing that the starting materials 1 and 2
were absent. Column chromatography of this residue yielded a
single fraction of the σ-alkynyl polymer [E-({Pt6}-CC-Ar-
CC)x-{Pt6}-E], 3a (Scheme 1, E ) end group, Ar ) 1,4-C6H2-
(2,5-C12H25)2, Mn ) 22 500 by GPC, see Table 1). Since (i) no
signal for the CCH moiety was observed in the 1H NMR
spectrum of 3a, and (ii) the only two complex and overlapped
resonances, observed at 335.5 and 328.0 ppm in its 31P{1H}
NMR spectrum, were respectively assigned to the P-Pt-CC
and to the terminal P-Pt-Cl groups [δP ) 335.7 in {Pt6}-
The DP values were calculated also from NMR spectroscopy,
namely, from the ratios between (i) the 31P{1H} NMR reso-
nances of the P-Pt-CC and P-Pt-Cl nuclei (for 3a and 3c)
1
and (ii) the H NMR resonances of the CCH (3.23 ppm) and
ArCH2 (2.79 ppm) groups (for 3b); importantly, they were found
to be very close to the ones from GPC measurements.11 Finally,
to assess the electronic conjugation along the {Pt6}/arylalkynyl
chains, we prepared the monodisperse shorter oligomers HCC-
Ar-CC-({Pt6}CC-Ar-CC)x-{Pt6}-CC-Ar-CCH [(4) x )
0; (11) x ) 2; (15) x ) 4], with precisely controlled lengths.
Complex 4 was prepared as previously described8b by the
dehydrohalogenation of the dichloride 1 with a 3-fold excess
(9) Each Pt6 cluster is constituted by 22 groups of nonequivalent
isotopomers (total number of isotopomers: 26 ) 64), nearly all giving
subspectra that cannot be interpreted with simple first-order approximations,
and a meaningful accurate simulation of the total spectrum is not accessible
with our programs. However, the main features of the complex shape of
the signals remain constant and may be taken as a footprint of the
hexanuclear {Pt6}X2 structure.8,10
(7) Gubin, S. P.; Gulayev, Yu. V.; Khomutov, G. B.; Kislov, V. V.;
Kolesov, V. V.; Soldatov, E. S.; Sulaimankulov, K. S.; Trifonov, A. S.
Nanotechnology 2002, 13, 185-194.
(8) (a) Albinati, A.; Leoni, P.; Marchetti, L.; Rizzato, S. Angew. Chem.,
Int. Ed. 2003, 42, 5990-5993. (b) Leoni, P.; Marchetti, F.; Marchetti, L.;
Pasquali, M. Chem. Commun. 2003, 2372-2373. (c) de Biani, F. F.; Ienco,
A.; Laschi, F.; Leoni, P.; Marchetti, F.; Marchetti, L.; Mealli, C.; Zanello,
P. J. Am. Chem. Soc. 2005, 127, 3076-3089.
(10) Leoni, P.; Marchetti, F.; Marchetti, L.; Pasquali, M.; Quaglierini,
S. Angew. Chem., Int. Ed. 2001, 40, 3617-3618.
(11) It is known that overestimated molecular weights are generally
obtained by GPC measurements on rigid-rod metal-alkynyl polymers.
Nevertheless, Lo Sterzo and co-workers have reported that, in the presence
of octyloxy side-chains, the rigid rodlike polymers of general formula
[-(Bu3P)2M-CC-Ar-CC-]n [M ) Pd, Pt; Ar ) C6H2(OC8H17)2]2e give
reliable GPC results.

4228 Organometallics, Vol. 25, No. 17, 2006
Scheme 2. Preparation of the Monodisperse Oligomers 11 and 15
Leoni et al.
CC-R-CC-)x, on their interesting and well-established2 pho-
tophysical properties.
Table 2. Selected UV-Vis Data for 4, 11, 15, and Polymers
3a-c
compound
λ
max (nm)
4
11
15
3a-c
449
466
470
476
Experimental Section
General Data. The reactions were carried out under a nitrogen
atmosphere, by using standard Schlenk techniques. [Pt6(µ-PBut2)4-
(CO)6](CF3SO3)2 (5),10 Pt6(µ-PBut2)4(CO)4Cl2 (1),8 and 1,4-didode-
cyl-2,5-diethynylbenzene (2)12 were prepared as previously de-
scribed. Solvents were dried by conventional methods and distilled
under nitrogen prior to use. NMR spectra were acquired using a
of the dialkyne 2, while 11 and 15 were obtained according to
the stepwise method shown in Scheme 2.
The key intermediate in this procedure is the unsymmetrical
dihalide {Pt6}ICl, (6), which undergoes selective dehydroha-
logenation with terminal alkynes at the chloride ligand, thus
allowing a controlled growth of the chain length. Reactive
dichlorides can be restored from the intermediate diiodides (8/
12) in two steps (substitution with CO, assisted by Tl+, followed
by reaction with tetra-n-butylammonium chloride).
1
Varian Gemini 200 BB spectrometer (200 MHz for H) at room
temperature (about 293 K) on CDCl3 solutions; frequencies are
referenced to the residual resonances of the deuterated solvent (H,
13C), 85% H3PO4 (31P), and H2PtCl6 (195Pt). The symbol is used
#
to label 1H, 13C, and 31P peaks with 195Pt satellites. UV-vis spectra
were recorded on a Perkin-Elmer Lambda 9 spectrophotometer. IR
spectra were (Nujol mulls, KBr) were recorded on a Perkin-Elmer
FT-IR 1725X spectrophotometer. Molecular weights were deter-
mined (relative to PS standard) on a Waters 2487 equipped with a
set of PL gel columns (CHCl3 as the eluent, flow rate 1 mL min-1).
Preparation of Polymer 3. A NHEt2/CH2Cl2 (150/50 mL)
solution of 1 (500 mg, 0.258 mmol) was treated with 1,4-didodecyl-
2,5-diethynylbenzene (120 mg, 0.258 mmol) and CuCl (1 mg, 5.2
µmol). After stirring for 16 h at room temperature, 10 mL of the
mixture was taken (fraction A) and all the volatiles were removed
in vacuo. The resulting residue was washed with H2O/acetone (1:
1) and eluted with CH2Cl2 on a silica gel chromatographic column,
yielding a red solid (3a, 25 mg). The reaction mixture was treated
with 1,4-didodecyl-2,5-diethynylbenzene (25.2 mg, 54.5 µmol) and
stirred for 60 h at room temperature. A portion of the mixture was
taken (10 mL, fraction B) and handled as detailed for fraction A,
yielding 3b (red, 26 mg). Finally, the dichloride 1 (49.9 mg, 25.8
µmol) was added to the reaction mixture. After 3 days stirring, all
Indeed, the absorption at ca. 450 nm, observed in the UV-
vis spectrum of “monomer” 4, is red-shifted for the “tri-” and
“pentamers” 11 and 15, respectively at 466 and 470 nm, and is
further shifted at 476 nm for the polymers 3a-c (Table 2).
Similar effects have been observed previously in many oligo-
meric platinum(II) or palladium(II) polyynes of general formula
[-LmM-CC-Ar-CC-]n [(M ) Pt, Pd)] and have been
attributed to an increased delocalization of π-electrons along
the polymer backbone, which extends through the metal sites.2
In summary, this work describes the step-growth polycon-
densationof the dichloride {Pt6}Cl2 and the dialkyne HCC-
Ar-CCH, giving the first cluster-containing σ-alkynyl polymers,
which exhibit (nonoptimized) high molecular weights. Presently,
work is in progress in order to (i) synthesize analogous oligo-
and polymers with different dialkynyl spacers (both organic and
organometallic) and (ii) elucidate the influence of the replace-
ment of single platinum centers with cluster units in the
repeating unit of alkynyl polymers of general formula [(-LnMz-
(12) Kloppenburg, L.; Jones, D.; Bunz, U. H. F. Macromolecules 1999,
32, 4194.

Cluster-Containing Organometallic Polymers
Organometallics, Vol. 25, No. 17, 2006 4229
the volatiles were removed in vacuo, and the residue was washed
with H2O/acetone (1:1) and passed over a silica gel chromatographic
column (CH2Cl2 as the eluent), yielding a red solid (3c, 535 mg).
3a. Anal. Calcd for C596H1064Cl2O36P36Pt54, Cl{[Pt6(PtBu2)4(CO)4]-
CCC6H2(C12H25)2CC}8[Pt6(PtBu2)4-(CO)4]Cl:13 C, 34.9; H, 5.22.
(0.38 mg, 0.002 mmol) were added to a diethylamine (75 mL)
solution of complex 6 (405 mg, 0.20 mmol). After 24 h the solvent
was evaporated and the orange residue was extracted with Et2O to
give, after chromatography (silica gel, eluent CH2Cl2/n-hexane, 1:5),
420 mg of 7 (86%). Anal. Calcd for C70H125IO4P4Pt6: C, 34.3; H,
1
1
Found: C, 35.1; H, 5.18. H NMR: δ 7.13 (s, CH), 2.79 (br s,
5.1. Found: C, 34.4; H, 5.0. H NMR: δ 7.21 (s, Ar, 1 H), 7.15
3
ArCH2), 1.65 (br, CH2 dodecyl), 1.51 (vt, JHP+5JHP ) 6.0 Hz,
(s, Ar, 1 H), 3.26 (s, CCH, 1 H) 2.76 (br m, ArCH2, 2 H), 2.67 (br
3
PtBu), 1.27 (br s, CH2 dodecyl), 0.87 (t, CH3 dodecyl, JHH ) 6.4
m, ArCH2, 2 H), 1.65 (br, CH2 dodecyl, 8 H), 1.50 (vt, 3JHP+5JHP
Hz). 13C{1H} NMR: δ 216.6 (CO), 139.4 (CCH2, Ar), 131.0 (CH,
Ar), 125.4 (C-CtC, Ar), 123.0 (CCPt), 103.0 (CCPt), 43.7 (PC),
3
) 7 Hz, 36 H), 1.47 (vt, JHP+5JHP ) 7 Hz, 36 H), 1.25, 1.23 (s,
br, CH2 dodecyl, 32 H), 0.86 ppm (t, CH3 dodecyl, 6 H). 13C{1H}
NMR: δ 215.6, 207.6 (CO), 142.4, 140.6, 132.7, 131,7, 129.6 (Ar)
122.3 (CCPt), 117.7 (Ar), 102.3 (CCPt), 83.9 (CCH), 80.6 (CCH),
t
34.1, 32.0 (dodecyl), 31.6 (CH3, Bu), 30.4, 29.8, 29.4, 22.7, 14.2
(dodecyl). 31P{1H} NMR: δ 335.5 (P-Pt-CC, m), 328.0 (weak
m, P-Pt-Cl). 195Pt{1H} NMR: δ -4684.5 (m, 1 Pt), -2979.8
t
t
45.4, 44.2 (C, Bu), 34.4, 34.2 (dodecyl), 32.5 (CH3, Bu), 32.4
(m, 2 Pt). IR (CH2Cl2): 2093 (CtC), 2010 (CO) cm-1
.
(dodecyl), 31.8 (CH3, tBu), 31.1, 30.8, 30.1, 29.9, 29.8, 23.1, 14.3
ppm (dodecyl). 31P{1H} NMR: δ 336.1# (s), 330.7# ppm (s).
-
195
3b. Anal. Calcd for C664H1170Cl2O36P36Pt54, HCCC6H2(C12H25)2-
CC{[Pt6(PtBu2)4(CO)4]CCC6H2(C12H25)2-CC}8[Pt6(PtBu2)4(CO)4]-
CCC6H2(C12H25)2CCH:4 C, 37.3; H, 5.52. Found: C, 37.5; H, 5.54.
Pt{1H} NMR: δ -3030 (m, 2 Pt), -3326 (m, 2 Pt), -4711 (m, 1
Pt), -4896 ppm (m, 1 Pt). IR (CH2Cl2): 3302 (νCtCH), 2091 (νCt
C), 2014 cm-1 (νCO).
1
The H NMR spectrum is similar to that of 3a, except for the
presence of a weak singlet at 3.23 ppm (s, CCH). The 13C and
195Pt NMR spectra are virtually identical to those of 3a. 31P{1H}
NMR: δ 335.5 (m, P-Pt-CC). IR (CH2Cl2): 3302 (CtCH), 2093
Preparation of I{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}2[Pt6(µ-
PBut2)4(CO)4]I (8). Complex 7 (400 mg, 0.163 mmol) and CuI
(0.31 mg, 1.6 × 10-3 mmol) were added to a diethylamine (75
mL) solution of complex 1 (155 mg, 0.080 mmol). After 24 h
stirring at room temperature, all the volatiles were removed in vacuo
and the resulting red residue was extracted with Et2O and
chromatographed on silica gel (eluent CH2Cl2/n-hexane, 1:2),
yielding 406 mg of 8 (75%). Anal. Calcd for C176H320I2O12P12Pt18:
(CtC), 2010 (CO) cm-1
.
3c. Anal. Calcd for C1086H1932Cl2O64P64Pt96, Cl{[Pt6(PtBu2)4-
(CO)4]CCC6H2(C12H25)2CC}15[Pt6(PtBu2)4(CO)4]Cl:4 C, 35.4; H,
1
5.29. Found: C, 35.2; H, 5.32. The H, 13C, 31P, and 195Pt NMR
and IR spectra are virtually identical to those of 3a.
Preparation of Pt6(µ-PBut2)4(CO)4(CC-Ar-CCH)2 (4). 1,4-
Didodecyl-2,5-diethynylbenzene (86 mg, 0.186 mmol) and CuI
(0.28 mg, 0.0015 mmol) were added to a diethylamine (50 mL)
solution of complex 1 (120 mg, 0.062 mmol). After 24 h the solvent
was evaporated and the red oil residue was chromatographed on
silica gel. The unreacted dialkyne was eluted with CH3CN, while
the subsequent elution with Et2O provided a red solution of 4.
Solvent removal followed by drying under vacuum afforded 4 as a
red oil (152 mg, 88%). Anal. Calcd for C104H178O4P4Pt6: C, 44.8;
1
C, 31.2; H, 4.77. Found: C, 31.1; H, 4.9. H NMR: δ 7.14 (br s,
Ar, 4 H), 2.77 (br m, ArCH2, 8 H), 1.65 (br, CH2 dodecyl, 16 H),
3
1.52 (vt, JHP+5JHP ) 7 Hz, 216 H), 1.27 (br s, CH2 dodecyl, 64
H), 0.88 ppm (t, CH3 dodecyl, 12 H). 13C{1H} NMR: δ 217.1,
215.8, 207.5 (CO), 139.9, 131.3, 125.8, 125.5 (Ar) 123.0 (CCPt),
104.6, 103.7 (CCPt), 45.3, 44.0 (C, tBu), 34.4 (dodecyl), 32.4 (CH3,
tBu), 32.3 (dodecyl), 31.7 (CH3, tBu), 31.0, 30.2, 30.1, 30.0, 29.8,
23.1, 14.3 ppm (dodecyl). 31P{1H} NMR: δ 336.2# (s, 4 P), 333.5#
(s, 4 P), 330.2# ppm (s, 4 P). 195Pt{1H} NMR: δ -2979 (m, 4 Pt),
-3052 (m, 4 Pt), -3322 (m, 4 Pt), -4685 (m, 2 Pt), -4697 (m, 2
Pt), -4899 ppm (m, 2 Pt). IR (CH2Cl2): 2096 (νCtC), 2012 cm-1
(ν CO).
1
H, 6.44. Found: C, 44.5; H, 6.6. H NMR: δ 7.12 (s, Ar, 2 H),
7.18 (s, Ar, 2 H), 3.23 (s, CCH, 2 H), 2.79 (br m, ArCH2, 4 H),
2.70 (br m, ArCH2, 4 H), 1.64 (br, CH2 dodecyl, 16 H), 1.50 (vt,
3JHP+5JHP ) 7 Hz, 72 H), 1.26 (br s, CH2 dodecyl, 64 H), 0.89
ppm (t, CH3 dodecyl, 12 H). 13C{1H} NMR: δ 216.6 (CO), 142.2,
140.4, 132.6, 131.6, 129.6 (Ar) 122.1 (CCPt), 117.6 (Ar), 108.4,
Preparation of [OC{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}2[Pt6-
(µ-PBut2)4(CO)4]CO] (PF6)2 (9). TlPF6 (120 mg, 0.343 mmol) was
added to a THF (100 mL) solution of complex 8 (400 mg, 0.059
mmol). The flask was filled with CO (1 atm) and the reaction
mixture stirred for 24 h at room temperature. The solvent was
evaporated and the residue was washed with hexane and then
dissolved in acetone. Filtration of the resulting red solution followed
by solvent removal afforded complex 9 as a red solid (285 mg,
70%). Anal. Calcd for C178H320F12O14P14Pt18: C, 31.2; H, 4.70.
Found: C, 31.1; H, 4.6. 1H NMR: δ 7.19 (br s, Ar, 4 H), 2.79 (m,
br, ArCH2, 8 H), 1.66 (br, CH2 dodecyl, 16 H), 1.51 (vt, 3JHP+5JHP
) 7 Hz, 216 H), 1.28 (br s, CH2 dodecyl, 64 H), 0.89 ppm (t, CH3
dodecyl, 12 H). 13C{1H} NMR: δ 218.7, 216.9, 204.5 (CO), 139.8,
131.4, 126.6, 124.4 (Ar) 122.9 (CCPt), 105.0 (CCPt), 46.1, 45.6,
t
(CCPt), 83.4 (HCC), 80.1 (CCH), 43.9 (C, Bu), 34.2, 32.3, 32.2
(dodecyl), 31.6 (CH3, tBu), 30.9, 30.7, 29.9, 29.8, 29.6, 22.9, 14.2
ppm (dodecyl). 31P{1H} NMR: δ 334.0# ppm (s). 195Pt{1H}
NMR: δ -2986 (m, 4 Pt), -4693 ppm (m, 2 Pt). IR (CH2Cl2):
3300 (νCtCH), 2090 (νCtC), 2010 cm-1 (νCO).
Preparation of Pt6(µ-PBut2)4(CO)4ICl (6). n-Bu4NCl (62.5 mg,
0.225 mmol) was added to a red solution of complex 5 (500 mg,
0.225 mmol) in CH2Cl2 (10 mL). After a few minutes all the
volatiles were removed in vacuo and the resulting red residue was
dissolved in acetone/H2O (20:1) and treated with KI (50 mg, 0.301
mmol). Complex 6 precipitated out as an orange solid and was
filtered and vacuum-dried (433 mg, 95%). Anal. Calcd for C36H72-
ClIO4P4Pt6: C, 21.3; H, 3.6. Found: C, 21.4; H, 3.8. 1H NMR: δ
1.52 ppm (vt, 3JHP + 5JHP ) 7.5 Hz). 13C{1H} NMR: δ 206.0 (s,
CO), 203.8 (s, CO), 45.2, 44.7 (s, C, tBu), 32.4, 31.5 ppm (s, CH3).
31P{1H} NMR: δ 333.2# (s), 328.7# ppm (s). 195Pt{1H} NMR: δ
-3356 (m, 2 Pt), -3453 (m, 2 Pt), -4149 (m, 1 Pt), -4941 ppm
(m, 1 Pt). IR (CH2Cl2): 2016 cm-1 (ν CO).
t
t
44.0 (C, Bu), 34.4 (dodecyl), 31.9 (CH3, Bu), 30.7, 30.1, 30.1,
29.7, 23.0, 14.5 ppm (dodecyl). 31P{1H} NMR: δ 357.1# (s, 4 P),
354.5# (s, 4 P), 333.5# (s, 4 P), -142.6 ppm (sept, JPF ) 705 Hz).
195Pt{1H} NMR: δ -2985 (m, 8 Pt), - 3074 (m, 4 Pt), 4494 (m,
2 Pt), -4689 (m, 2 Pt), -4991 ppm (m, 2 Pt). IR (CH2Cl2): 2126
(vw) (νCtC), 2078 (s), 2057 (m), 2045 (s), 2031 (m), 2018 (vs),
2011 (s) cm-1 (νCO).
Preparation of I[Pt6(µ-PBut2)4(CO)4](CC-Ar-CCH) (7). 1,4-
Didodecyl-2,5-diethynylbenzene (140 mg, 0.30 mmol) and CuI
Preparation of Cl{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}2[Pt6-
(µ-PBut2)4(CO)4]Cl (10). NH4Cl (9.6 mg, 0.18 mmol) was added
to a red solution of complex 9 (285 mg, 0.042 mmol) in acetone
(10 mL). Addition of H2O (5 mL) caused the precipitation of a red
solid, which was filtered and chromatographed on silica gel (eluent
CH2Cl2/n-hexane, 1:2), yielding 250 mg of 10 (90%). Anal. Calcd
for C176H320Cl2O12P12Pt18: C, 32.1; H, 4.90. Found: C, 32.2; H,
(13) The average molecular weight agrees with integral ratios of 1H NMR
spectra. In the 31P NMR spectra of 3a and 3c, the integral ratios between
the resonances of the P-Pt-CC and P-Pt-Cl nuclei have been estimated
by comparison with the weighed sum of the spectra of the monomer
derivatives {Pt6}X2 (X ) Cl, CC[(1,4-n-C12H25)2-2,5-C6H2]CCH). 1H and
31P NMR spectra for quantitative evaluations were acquired with a 60 s
delay between each transient.
1
4.8. H NMR: δ 7.19 (br s, Ar, 4 H), 2.80 (br m, ArCH2, 8 H),

4230 Organometallics, Vol. 25, No. 17, 2006
Leoni et al.
1.64 (br, CH2 dodecyl, 16 H), 1.52 (vt, 3JHP+5JHP ) 7 Hz, 216 H),
1.28 (br s, CH2 dodecyl, 64 H), 0.89 ppm (t, CH3 dodecyl, 12 H).
13C{1H} NMR: δ 216.9, 215.8, 204.7 (CO), 139.7, 131.3, 125.8,
125.4 (Ar), 123.4, 123.0 (CCPt), 119 (Ar), 103.8, 102.9 (CCPt),
44.9, 44.2, 44.0 (C, Bu), 34.4, 32.3 (dodecyl), 31.9 (CH3, Bu),
30.7, 30.2, 30.1, 23.0, 14.3 ppm (dodecyl). 31P{1H} NMR: δ 336.1#
(s, 4 P), 333.0# (s, 4 P), 325.7# ppm (s, 4 P). 195Pt{1H} NMR: δ
-2980 (m, 4 Pt), -3033 (m, 4 Pt), -3426 (m, 4 Pt), -4120 (m, 2
Pt), -4686 (m, 2 Pt), -4700 ppm (m, 2 Pt). IR (CH2Cl2): 2097
(νCtC), 2013 cm-1 (νCO).
Calcd for C318H568F12O22P22Pt30: C, 33.2; H, 4.98. Found: C, 33.1;
1
H, 4.9. H NMR: δ 7.18 (br s, Ar, 8 H), 2.79 (br m, ArCH2, 16
3
H), 1.66 (br, CH2, dodecyl, 32 H), 1.51 (vt, JHP+5JHP ) 7 Hz,
360 H), 1.28 (br s, CH2 dodecyl, 128 H), 0.89 ppm (t, CH3 dodecyl,
24 H). 13C{1H} NMR: δ 218.7, 216.9, 216.7, 204.4 (CO), 139.7,
131.3, 126.6, 125.6, 124.4 (Ar) 123.1 122.7, 120.8 (CCPt), 119.1,
t
t
t
118.7 (Ar), 104.5, 103.8 (CCPt), 46.1, 45.6, 44.0 (C, Bu), 34.4,
t
32.2 (dodecyl), 31.9 (CH3, Bu), 30.7, 30.1, 30.0, 29.7, 23.0, 14.5
ppm (dodecyl). 31P{1H} NMR: δ 357.5.1# (s, 4 P), 353.8# (s, 4 P),
332.9# (s, 12 P), -142.4 ppm (sept, JPF ) 705 Hz). 195Pt{1H}
NMR: δ -2979 (m, 16 Pt), -3068 (m, 4 Pt), -4493 (m, 2 Pt),
-4686 (m, 6 Pt), -4994 ppm (m, 2 Pt). IR (CH2Cl2): 2126 (vw)
(νCtC), 2095 (sh), 2078 (w), 2056 (w), 2046 (w), 2031 (sh), 2011
(br, vs) cm-1 (νCO).
Preparation of HCC-Ar-CC-{[Pt6(µ-PBut2)4(CO)4](CC-
Ar-CC)}2[Pt6(µ-PBut2)4(CO)4]-CC-Ar-CCH (11). 1,4-Di-
dodecyl-2,5-diethynylbenzene (55 mg, 0.119 mmol) and CuI (0.38
mg, 0.002 mmol) were added to a diethylamine (75 mL) solution
of complex 10 (250 mg, 0.038 mmol). After 24 h the solvent was
evaporated and the red residue was extracted with Et2O to give,
after chromatography (silica gel, eluent CH2Cl2/n-hexane, 1:2), 240
mg of 11 (85%). Anal. Calcd for C244H426O12P12Pt18: C, 39.4; H,
5,78. Found: C, 39.3; H, 5.9. 1H NMR: δ 7.21 (s, Ar, 2 H), 7.19
(s, Ar, 6 H), 3.24 (s, CCH, 2 H), 2.80 (br m, ArCH2, 16 H), 1.66
(br, CH2 dodecyl, 32 H), 1.52 (vt, 3JHP+5JHP ) 7 Hz, 216 H), 1.29
(s, br, CH2 dodecyl, 128 H), 0.89 ppm (t, CH3 dodecyl, 24 H).
13C{1H} NMR: δ 217.0, 216.5 (CO), 142.1, 140.4, 139.7, 132.6,
131.7, 131.3, 129.7, 125.6 (Ar) 123.2 (CCPt), 122.1, 117.6 (Ar),
108.1, 103.7 (CCPt), 83.9 (CCH), 80.1 (CCH), 44.0 (C, tBu), 34.4,
32.3 (dodecyl), 31.9 (CH3, tBu), 30.7, 30.1, 30.0, 29.9, 29.7, 23.0,
14.5 ppm (dodecyl). 31P{1H} NMR: δ 339.3# (s, 4 P), 333.0# ppm
(s, 8 P). 195Pt{1H} NMR: δ -2983 (m, 12 Pt), -4683 ppm (m, 6
Pt). IR (CH2Cl2): 3300 (νCtCH), 2091 (νCtC), 2010 cm-1 (νCO).
Preparation of I{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}4[Pt6(µ-
PBut2)4(CO)4]I (12). Complex 5 (201 mg, 0.027 mmol) and CuI
(0.10 mg, 5.4 × 10-4 mmol) were added to a diethylamine (60
mL) solution of complex 6 (126 mg, 0.062 mmol). After 24 h
stirring at room temperature, all the volatiles were removed in vacuo
and the resulting red residue was extracted with Et2O and
chromatographed on silica gel (eluent CH2Cl2/n-hexane, 1:2),
yielding 240 mg of 12 (78%). Anal. Calcd for C316H568I2O20P20-
Pt30: C, 33.25; H, 5.02. Found: C, 33.2; H, 5.1. 1H NMR: δ 7.18
(s, br, Ar, 8 H), 2.80 (br m, ArCH2, 16 H), 1.65 (br, CH2 dodecyl,
32 H), 1.51 (vt, 3JHP+5JHP ) 7 Hz, 360 H), 1.28 (br s, CH2 dodecyl,
128 H), 0.89 ppm (t, CH3 dodecyl, 24 H). 13C{1H} NMR: δ 216.9,
215.6, 207.2 (CO), 139.7, 131.4, 125.6 (Ar) 123.1 (CCPt), 119.2
(Ar), 103.8 (CCPt), 45.3, 44.2 (C, tBu), 34.4, 32.6, 32.3 (dodecyl),
Preparation of Cl{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}4[Pt6-
(µ-PBut2)4(CO)4]Cl (14). NH4Cl (7 mg, 0.13 mmol) was added to
a red solution of complex 13 (150 mg, 0.013 mmol) in acetone (10
mL). Addition of H2O (5 mL) caused the precipitation of a red
solid, which was filtered and chromatographed on silica gel (eluent
CH2Cl2/n-hexane, 1:2), yielding 128 mg of 14 (88%). Anal. Calcd
for C316H568Cl2O20P20Pt30: C, 33.8; H, 5.10. Found: C, 33.7; H,
1
5.2. H NMR: δ 7.18 (br s, Ar, 8 H), 2.79 (br m, ArCH2, 16 H),
1.64 (br, CH2 dodecyl, 32 H), 1.51 (vt, 3JHP+5JHP ) 7 Hz, 360 H),
1.27 (br s, CH2 dodecyl, 128 H), 0.89 ppm (t, CH3 dodecyl, 24 H).
13C{1H} NMR: δ 216.9, 215.8, 204.7 (CO), 139.7, 131.3, 125.6
t
(Ar) 123.1 (CCPt), 119.2 (Ar), 103.7 (CCPt), 44.9, 44.0 (C, Bu),
34.4, 32.3 (dodecyl), 31.9 (CH3, tBu), 30.7, 30.1, 30.0, 29.7, 23.0,
14.5 ppm (dodecyl). 31P{1H} NMR: δ 336.1# (s, 4 P), 333.0# (s,
12 P), 325.7# ppm (s, 4 P). 195Pt{1H} NMR: δ -2979 (m, 12 Pt),
-3039 (m, 4 Pt), -3426 (m, 4 Pt), -4119 (m, 2 Pt), -4684 ppm
(m, 8 Pt). IR (CH2Cl2): 2096 (νCtC), 2012 cm-1 (νCO).
Preparation of HCC-Ar-CC {[Pt6(µ-PBut2)4(CO)4](CC-
Ar-CC)}4[Pt6(µ-PBut2)4(CO)4]CC-Ar-CCH (15). 1,4-Didode-
cyl-2,5-diethynylbenzene (13 mg, 0.028 mmol) and CuI (0.03 mg,
1.8 × 10-4 mmol) were added to a diethylamine (50 mL) solution
of complex 14 (101 mg, 0.009 mmol). After 24 h the solvent was
evaporated and the red residue was extracted with Et2O to give,
after chromatography (silica gel, eluent CH2Cl2/n-hexane, 1:2), 88
mg of 15 (81%). Anal. Calcd for C384H674O20P20Pt30: C, 38.2; H,
1
5.62. Found: C, 38.1; H, 5.7 H NMR: δ 7.20 (s, Ar, 2 H), 7.18
(s, Ar, 10 H), 3.23 (s, CCH, 2 H) 2.79 (br m, ArCH2, 24 H), 1.66
(br, CH2 dodecyl, 48 H), 1.51 (vt, 3JHP+5JHP ) 7 Hz, 360 H), 1.28
(br s, CH2 dodecyl, 192 H), 0.89 ppm (t, CH3 dodecyl, 36 H). 13C-
{1H} NMR: δ 216.9, 216.5 (CO), 142.1, 140.4, 139.7, 132.6, 131.7,
131.3, 129.7, 125.6 (Ar) 123.1 (CCPt), 119.1, 117.7 (Ar), 103.7
(CCPt), 83.9 (CCH), 80.1 (CCH), 44.0 (C, tBu), 34.4, 32.3
t
31.9 (CH3, Bu), 30.7, 30.1, 30.0, 29.7, 23.0, 14.5 ppm (dodecyl).
31P{1H} NMR: δ 335.9# (s, 4 P), 333.0# (s, 12 P), 329.7# ppm (s,
4 P). 195Pt{1H} NMR: δ -2983 (m, 16 Pt), -3322 (m, 4 Pt), -4686
(m, 8 Pt), -4901 ppm (m, 2 Pt). IR (CH2Cl2): 2095 (νCtC), 2011
cm-1 (νCO).
t
(dodecyl), 31.9 (CH3, Bu), 30.7, 30.1, 30.2, 29.7, 23.0, 14.5 ppm
(dodecyl). 31P{1H} NMR: δ 333.9.1# (s, 4 P), 333.0# ppm (s, 16
P). 195Pt{1H} NMR: δ -2979 (m, 20 Pt), -4684 ppm (m, 10 Pt).
IR (CH2Cl2): 3299 (νCtCH), 2092 (νCtC), 2010 cm-1 (νCO).
Preparation of [OC{[Pt6(µ-PBut2)4(CO)4](CC-Ar-CC)}4[Pt6-
(µ-PBut2)4(CO)4]CO](PF6)2 (13). TlPF6 (70 mg, 0.200 mmol) was
added to a THF (80 mL) solution of complex 12 (240 mg, 0.021
mmol). The flask was filled with CO (1 atm) and the reaction
mixture stirred for 24 h at room temperature. The solvent was
evaporated and the residue was washed with hexane and then
dissolved in acetone. Filtration of the resulting red solution followed
by solvent removal afforded complex 13 (170 mg, 70%). Anal.
Acknowledgment. This work was supported by the Minis-
tero dell’Istruzione, dell’Universita` e della Ricerca (MIUR),
Programmi di Rilevante Interesse Nazionale, PRIN 2004-2005.
OM0604021