Acid-base hydrolytic chemistry route to thin films containing terminal donor ligands and organometallic complexes for heterogenization of metal complex catalysis

Article abstract of DOI:10.1021/om970923b

A general synthetic approach based on the hydrolysis of R′₃Si-NR₂ with organic compounds containing acidic protons, to construct thin films of donor ligands on inorganic oxide surfaces that are subsequently used to support a variety of organometallic complexes, is reported. The reaction of surface hydroxyl groups on silica, glass, quartz, and single-crystal silicon with SiCl₄, followed by NEt₂H, affords surface-anchored Si-NEt₂ moieties which, upon simple acid-base hydrolysis with HO-(CH₂)_n-XR₂ (n = 3, X = N, R = C₂H₅; n = 3, X = P, R = C₆H₅; n = 4, X = P, R = C₂H₅), HO-C₆H₄-XR2 (X = P, R = C₆H₅; X = N, R = C₂H₅), and HO-CH(CH₃)-(CH₂)₃-N(C₂H ₅)₂ at ambient temperature, yield thin films containing terminal phosphine and amine donor ligands. These ligands are then used to covalently anchor organometallic complexes of Ni(0), Rh(I), Ru(II), and Pd(0) via bridge-splitting or ligand-displacement reactions. The synthesis of solution models to the surface-bound species and the characterization of the latter using numerous surface analytical techniques have proven useful in determining the conditions for the deposition process and in the evaluation of the structure of the supported metal complexes. A thin film of [Si]-O-(CH₂)₃PPh₂Ni-(CO)₂PPh ₃ on glass catalyzes the oligomerization of phenylacetylene resulting in a product distribution different from that of a similar reaction in solution. The enhanced activity and selectivity of the organometallic Ni(0) thin films suggests that a positive role is played by the orientation of the surface-bound organometallic species in catalysis.

Full text of DOI:10.1021/om970923b

1798
Organometallics 1998, 17, 1798-1811
Acid -Ba se Hyd r olytic Ch em istr y Rou te to Th in F ilm s
Con ta in in g Ter m in a l Don or Liga n d s a n d Or ga n om eta llic
Com p lexes for Heter ogen iza tion of Meta l Com p lex
Ca ta lysis
Maria G. L. Petrucci and Ashok K. Kakkar*
Department of Chemistry, McGill University, 801 Sherbrooke Street West,
Montreal, Quebec H3A 2K6, Canada
Received October 22, 1997
A general synthetic approach based on the hydrolysis of R′3Si-NR2 with organic compounds
containing acidic protons, to construct thin films of donor ligands on inorganic oxide surfaces
that are subsequently used to support a variety of organometallic complexes, is reported.
The reaction of surface hydroxyl groups on silica, glass, quartz, and single-crystal silicon
with SiCl4, followed by NEt2H, affords surface-anchored Si-NEt2 moieties which, upon simple
acid-base hydrolysis with HO-(CH2)n-XR2 (n ) 3, X ) N, R ) C2H5; n ) 3, X ) P, R )
C6H5; n ) 4, X ) P, R ) C2H5), HO-C6H4-XR2 (X ) P, R ) C6H5; X ) N, R ) C2H5), and
HO-CH(CH3)-(CH2)3-N(C2H5)2 at ambient temperature, yield thin films containing
terminal phosphine and amine donor ligands. These ligands are then used to covalently
anchor organometallic complexes of Ni(0), Rh(I), Ru(II), and Pd(0) via bridge-splitting or
ligand-displacement reactions. The synthesis of solution models to the surface-bound species
and the characterization of the latter using numerous surface analytical techniques have
proven useful in determining the conditions for the deposition process and in the evaluation
of the structure of the supported metal complexes. A thin film of [Si]-O-(CH2)3PPh2Ni-
(CO)2PPh3 on glass catalyzes the oligomerization of phenylacetylene resulting in a product
distribution different from that of a similar reaction in solution. The enhanced activity and
selectivity of the organometallic Ni(0) thin films suggests that a positive role is played by
the orientation of the surface-bound organometallic species in catalysis.
In tr od u ction
thetic routes for the preparation of thin films containing
donor ligands utilize the weakly acidic surface of silica,
which permits condensation reactions of trialkoxy-
silanes containing terminal donor molecules.4 This type
of surface modification of silica has recently been the
subject of much debate.4a,b,e It has been shown that the
reaction of (C2H5O)3Si(CH2)nPPh2 (n ) 3, 4) with the
surface hydroxyl groups on silica leads to significant
amounts of side products containing anchored phospho-
rus oxide species, as well as the oligomerization of
trialkoxysilanes in solution.4a,b Surface immobilized PV
groups that do not bind tightly to the transition metals
contribute to leaching of metals from the surface. We
have recently developed a new synthetic methodology5,6
based on simple acid-base hydrolysis that utilizes
commercially available reagents to construct thin films
containing amine and phosphine donor ligands on the
The study of supported transition-metal complexes
continues to attract widespread interest. The im-
mobilization of transition-metal catalysts on solid sup-
ports has been shown to possess numerous advantages,
including the ease of separation of the catalyst from the
reaction products, and is expected to enhance catalytic
activity and selectivity over their homogeneous coun-
terparts.1 From an industrial viewpoint, supported
metal catalysis offers potential for the design of efficient
catalytic systems with an advantageous combination of
specific properties of homogeneous and heterogeneous
phases.2 Silica is a commonly employed anchor for
heterogenizing homogeneous catalysis, since its surface
hydroxyl groups offer rich chemistry3 to covalently
attach donor ligands which can then be used to intro-
duce transition-metal complexes. The traditional syn-
(4) (a) Blumel, J . J . Am. Chem. Soc. 1995, 117, 2112-2113. (b)
Blumel, J . Inorg. Chem. 1994, 33, 5050-5056. (c) Capka, M.; Czakoova,
M.; Wlodzimierz, U.; Schubert, U. J . Mol. Catal. 1992, 74, 335. (d)
Deschler, U.; Kleinschmit, P.; Panster, P. Angew. Chem., Int. Ed. Engl.
1986, 25, 236-252. (e) Bemi, L.; Clark, H. C.; Davies, J . A.; Fyfe, C.
A.; Wasylishen, R. E. J . Am. Chem. Soc. 1982, 104, 438-445. (f) Allum,
K. G.; Hancock, R. D.; Mckenzie, S.; Pitkethly, R. C. Catal. Proc. Int.
Congr., 5th 1972, 1, 477-486. (g) Smith, A. K.; Basset, J . M.; Maitlis,
P. M. J . Mol. Catal. 1977, 2, 223-226.
(1) (a) Iwasawa, Y.; Gates, B. C. Chemtech 1989, 3, 173-181 and
references therein. (b) Hartley, F. R. Supported Metal Complexes, A
New Generation of Catalysts; D. Reidel Publishing: Dordrecht, Neth-
erlands, 1985. (c) Surface Organometallic Chemistry: Molecular Ap-
proaches to Surface Catalysis; Basset, J . M., Gates, B. C., Candy, J .-
P., Choplin, A., Leconte, M., Quignard, F., Santini, C., Eds.; Kluwer:
Dordrecht, Netherlands, 1988.
(2) (a) Iwasawa, Y. Tailored Metal Catalysts; D. Reidel Publishing:
Dordrecht, Netherlands, 1986. (b) J acobs, P. A.; Bein, T.; De Vos, D.
E.; Subba Rao, Y. V. J . Chem. Soc., Chem. Commun. 1997, 355-356.
(3) Elmer, T. H. In Silylated Surfaces; Leyden, D. E., Collins, W.
T., Eds.; Gordon and Breach Science Publishers: New York, 1978; p
1.
(5) (a) Petrucci, M. G. L.; Kakkar, A. K. J . Chem. Soc., Chem.
Commun. 1995, 1507-1508. (b) Petrucci, M. G. L.; Kakkar, A. K. Adv.
Mater. 1996, 8 (3), 251-253.
(6) Yam, C. M.; Kakkar, A. K. J . Chem. Soc., Chem. Commun. 1995,
907-909.
S0276-7333(97)00923-0 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/31/1998

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1799
Sch em e 1
surfaces of silica, glass, quartz, and single-crystal Si and
avoids many of the common side reactions of the silane
condensation methodology mentioned above. It leads
to thin films containing terminal phosphine ligands
without any surface-bound phosphine oxide species. The
anchored donor ligands are subsequently used to carry
out ligand-displacement or bridge-splitting reactions to
afford covalently surface-bound transition-metal com-
plexes. The flat surfaces of glass, quartz, and single-
crystal Si allow for the build up of robust thin films of
oriented organometallic moieties. Increasing the num-
ber of available metallic sites oriented in a specific
direction may significantly enhance catalytic activity
and selectivity.7 In addition, flat surfaces offer op-
portunities to elucidate the molecular structure of the
anchored species by probing the environment of the
active metal center involved in catalysis. There are a
variety of experimental techniques that can be employed
to characterize, identify, and estimate the nature of the
surface species, leading to new information for the
design of future tailor-made catalysts.
similarly gave Me3Si-O-(CH2)3-PPh2RhCl(CO)PPh3
(12), Me3Si-O-(CH2)3-PPh2RhCl(CO)2 (13), Me3SiNEt2-
RhCl(PPh3)2 (14), Me3Si-O-(CH2)3-NEt2RhCl(CO)-
PPh3 (15), Me3Si-O-CH(CH3)-(CH2)3-NEt2RhCl(CO)-
PPh3 (16), and Me3Si-O-C6H4-NEt2RhCl(CO)PPh3
(17). The complexes Me3Si-O-(CH2)3-PPh2Pd(PPh3)3
(18) and Me3Si-O-(CH2)3-PPh2RuCl2(CO)2PPh3 (19)
were accordingly prepared by reacting the appropriate
ligand with Pd(PPh3)4 or RuCl2(CO)2(PPh3)2, respec-
tively.
The solution 31P{1H} NMR and the FT-IR data for
the above-mentioned Ni, Rh, Pd, and Ru complexes are
shown in Table 1. The 31P{1H} NMR spectra are similar
to those for their starting complexes with some excep-
tions. The compound Me3Si-O-(CH2)3-NEt2Ni(CO)2-
PPh3 produced a singlet at 26.7 ppm in its 31P{1H} NMR
spectrum which is similar to that for Me3SiNEt2Ni-
(CO)2PPh3 (singlet at 27.3 ppm) and Me3Si-O-CH-
(CH3)(CH2)3-NEt2Ni(CO)2PPh3 (27.3 ppm, s) and, in-
triguingly, is shifted upfield compared to the bis(phos-
phine) complex Ni(CO)2(PPh3)2 (35.2 ppm). Such a shift
in the 31P{1H} NMR spectrum is generally observed
upon replacing a triarylphosphine with a more electron-
donating trialkylphosphine at the metal center. For
example, replacement of one of the PPh3 ligands on Ni-
(CO)2(PPh3)2 with a trialkylphosphine, Me3Si-O-
(CH2)4-PEt2Ni(CO)2PPh3, leads to an upfield shift (26.3
ppm). A similar shift is also observed upon comparing
Me3Si-O-(CH2)3-PPh2Pd(PPh3)3 (13.72 ppm) with the
starting complex Pd(PPh3)4 (19.6 ppm).
Resu lts a n d Discu ssion
Solu tion Ch em istr y. Aminosilanes, (CH3)3Si-NR2
(R ) CH3, C2H5), which are generally prepared from
organosilicon halides and excess NR2H, react almost
quantitatively via acid-base hydrolysis with molecules
containing acidic protons, affording the corresponding
silylated alcohols with the elimination of amine (Scheme
1).8 For example, Me3Si-NEt2 reacts with terminal
alcohols such as HO-(CH2)n-XR2, HO-(C6H4)-XR2,
and HO-CH(CH3)-(CH2)3-XR2 (X ) N, P) at ambient
temperature to yield Me3Si-O-C6H4-N(C2H5)2 (1),
Me3Si-O-(CH2)3-N(C2H5)2 (2), Me3Si-O-CH(CH3)-
(CH2)3-N(C2H5)2 (3), Me3Si-O-(CH2)n-PR2 (n ) 4, R
) C2H5, 4; n ) 3, R ) C6H5, 5), and Me3Si-O-C6H4-
P(C6H5)2 (6) in almost quantitative yields. These ter-
tiary phosphine and amine donor ligands react with
organometallic complexes via ligand-displacement or
bridge-splitting processes. For example, a phosphine
ligand on Ni(CO)2(PPh3)2 can be exchanged with Me3-
Si-O-(CH2)n-XR2 or Me3Si-NEt2 to give Me3Si-O-
(CH2)3-PPh2Ni(CO)2PPh3 (7), Me3Si-O-(CH2)4-PEt2-
Ni(CO)2PPh3 (8), Me3SiNEt2Ni(CO)2PPh3 (9), Me3Si-
O-(CH2)3-NEt2Ni(CO)2PPh3 (10), and Me3Si-O-
CH(CH3)-(CH2)3-NEt2Ni(CO)2PPh3 (11). The displace-
ment or bridge-splitting reactions of the above ligands
with RhCl(CO)(PPh3)2, RhCl(PPh3)3, or [RhCl(CO)2]2
The compound Me3SiNEt2RhCl(PPh3)2, which was
prepared by the reaction of RhCl(PPh3)3 with Me3-
SiNEt2, showed only a doublet at 54.5 ppm (J Rh-P ) 195
Hz) in its 31P{1H} NMR spectrum, suggesting a square-
planar geometry for this complex with two equivalent
phosphines.
A comparison of the FT-IR spectra of the Ni(0)
complexes also showed some intriguing results. The
bisphosphine complexes Me3Si-O-(CH2)4-PEt2Ni-
(CO)2PPh3 and Me3Si-O-(CH2)3-PPh2Ni(CO)2PPh3
exhibit two νCO stretching frequencies similar to those
for Ni(CO)2(PPh3)2 (Table 1). However, it is interesting
to note that for the complexes in which one of the
phosphines is replaced with an amine ligand, Me3-
SiNEt2Ni(CO)2PPh3, Me3Si-O-(CH2)3-NEt2Ni(CO)2-
PPh3, and Me3Si-O-CH(CH3)(CH2)3-NEt2Ni(CO)2PPh3,
the νCO stretching frequencies move to lower wavenum-
bers. This trend is not observed for the Rh(I) complexes.
The 31P{1H} NMR and FT-IR spectra for the above
solution models are valuable in evaluating and compar-
ing the structures of the surface-immobilized transition-
(7) Tollner, K.; Popovitz-Biro, R.; Lahav, M.; Milstein, D. Science
1997, 278, 2100.
(8) Fessenden, R.; Fessenden, J . S. Chem. Rev. 1961, 61, 361.

1800 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar
Ta ble 1. High -Resolu tion Solu tion 31P {1H} NMR a n d F T-IR Da ta for Or ga n om eta llic Com p lexes
Con ta in in g Nitr ogen a n d P h osp h or u s Don or Liga n d s
complex
31P{1H}, C6D6 δ (ppm)
FT-IR, νCO (cm-1) Nujol
(CH3)3Si-O-(CH2)4PEt2 (4)
(CH3)3Si-O-(CH2)3PPh2 (5)
(CH3)3Si-O-C6H4PPh2 (6)
-21.7
-14.1
25.6
Ni(CO)2(PPh3)2
35.2
34.0 (d), 25.1 (d)
27.1 (d), 26.3 (d)
27.3
26.7
26.9
1998, 1935
1999, 1938
1996, 1934
1981, 1934
1982, 1936
1975, 1916
(CH3)3Si-O-(CH2)3PPh2Ni(CO)2PPh3 (7)
(CH3)3Si-O-(CH2)4PEt2Ni(CO)2PPh3 (8)
(CH3)3SiNEt2Ni(CO)2PPh3 (9)
(CH3)3Si-O-(CH2)3NEt2Ni(CO)2PPh3 (10)
(CH3)3Si-O-CH(CH3)(CH2)3NEt2Ni(CO)2PPh3 (11)
RhCl(PPh3)3
33.3 (d), 54.6 (dd)
[RhCl(CO)2]2
RhCl(CO)(PPh3)2
2105, 2085, 2031
1960
31.9 (d)
(CH3)3Si-O-(CH2)3PPh2RhCl(CO)PPh3 (12)
(CH3)3Si-O-(CH2)3PPh2RhCl(CO)2 (13)
(CH3)3SiNEt2RhCl(PPh3)2 (14)
(CH3)3Si-O-(CH2)3NEt2RhCl(CO)PPh3 (15)
(CH3)3Si-O-CH(CH3)(CH2)3NEt2RhCl(CO)PPh3 (16)
(CH3)3Si-O-C6H4NEt2RhCl(CO)PPh3 (17)
23.7 (d), 24.4 (d)
27.2 (d)
54.5 (d)
46.7 (d)
46.4 (d)
1964
2080, 2010
1968
1961
1964
47.9 (d)
Pd(PPh3)4
19.6
(CH3)3Si-O-(CH2)3PPh2Pd(PPh3)3 (18)
13.72 (br)
RuCl2(CO)2(PPh3)2
(CH3)3Si-O-(CH2)3PPh2RuCl2(CO)2PPh3 (19)
18.5
20.5, 19.2
2054, 1996
2062, 1982
Sch em e 2
metal complexes. Solution models also provide essential
information concerning the reaction conditions for sur-
face deposition. The above-described acid-base hydro-
lytic chemistry of aminosilanes with species containing
terminal acidic protons, if easily transferred to inorganic
oxide surfaces, can provide a simple and efficient
method for anchoring phosphine and amine donor
ligands and subsequently building covalently immobi-
lized organometallic thin films.
Su r fa ce Ch em istr y a n d Ch a r a cter iza tion . It is
well-known that the surfaces of silica, glass, quartz, and
single-crystal silicon consist of Si-OH groups with a
packing density of approximately 4.70 OH/100 Å2.9a
Before any deposition process, the inorganic oxide
substrates used in this study were cleaned9b,c by (i)
soaking in soap solution and sonicating for 30 min; (ii)
treating with piranha solution (70% H2SO4, 30% H2O2)
[Ca u tion : The piranha solution is highly corrosive and
explosive. Care should be taken while using this
mixture]; (iii) rinsing with deionized water; and, finally,
(iv) drying over a stream of nitrogen. Thin films
containing terminal donor ligands were deposited by
treating the substrates with toluene solutions of (i)
SiCl4, (ii) dry NEt2H, and (iii) the appropriate donor
ligands (Scheme 2). These thin films containing termi-
nal phosphine and amine ligands were then utilized to
covalently anchor transition-metal complexes by dis-
placement4f or bridge-splitting10-13 reactions similar to
the solution chemistry described above.
(9) (a) Zhuravlev, L. T. Colloids and Surf. 1993, 74 (1), 71. (b) Lloyd,
T. B.; Li, J .; Fowkes, F. M.; Brand, J . R.; Dizikes, L. J . J . Coat. Technol.
1992, 64, (813), 91-99. (b) Pintchovski, F.; Pricew, J . B.; Tobin, P. J .;
Peavey, J .; Kobold, K. J . Electrochem. Soc. 1979, 1428. (c) Wasserman,
S. R.; Yu-Tai, T.; Whitesides, G. M. Langmuir 1990, 6, 1074.
(10) Ugo, R.; Bonati, F.; Fiore, M. Inorg. Chim. Acta 1968, 2, 463.

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1801
Some of the commonly used techniques for the char-
acterization and estimation of the structure of the newly
prepared thin films containing surface-immobilized
species include contact angle goniometry, X-ray photo-
electron, solid-state NMR, and FT-IR (transmission and
attenuated total reflection modes) spectroscopies. The
results from a combination of these techniques provide
a useful estimation of the surface composition as well
as the environment of the surface-bound metal center
involved in catalysis. A summary of the techniques
employed in this study is given below.
nm. A similar blue shift (∼50 nm) in the UV-vis
absorption spectra has also been observed upon im-
mobilizing a cobalt(II) acetate complex.15c An estima-
tion of the surface coverage in a thin film of [Si]-O-
(CH2)3-PPh2Ni(CO)2(PPh3) on quartz by UV-vis absorp-
tion spectroscopy gives a surface packing density of 3
× 10-9 mol/cm2, which is comparable to coverages
reported previously for covalently anchored monolayers
of metal complexes,15a-c and suggests a densely packed
thin film.
X-r a y P h otoelectr on Sp ectr oscop y (XP S). XPS
is known to be a very good technique for the determi-
nation of the surface composition of the anchored
species, and it can provide useful information about the
elements present on the surface. In addition, changing
the substituents on the metal center results in an
increase or decrease in the binding energies of the metal
and the elements of the donor ligands attached to it.
We applied this technique for the analytical evaluation
of various organometallic complexes immobilized on
glass slides (Table 2b). For a comparative study, XPS
spectra of the model complexes were also collected and
the results are presented in Table 2a.
We first attempted an evaluation of the efficiency of
the reactions of SiCl4 with surface hydroxyl groups,
followed by the reaction with NEt2H, and finally with
the appropriate phosphine or amine donor molecules
(steps 1-3, Scheme 2). No residual chlorine or amine
was found from a detailed XPS analysis of these thin
films, which suggests high conversion of the surface-
bound chlorine to amine and, finally, phosphine/amine
donor moieties.
There is a slight increase in the binding energies of
the elements in the thin films as compared to their solid-
state analogues (Table 2). For example, the P 2s line
positions for the thin films range between 197.9 and
204.6 eV. These binding energies are slightly shifted
from the model complexes (188-197 eV) as well as from
the known value of 191 eV for free PPh3.16 An increase
in the binding energies is also apparent for the Si 2p,
O 1s, and C 1s peaks of the surface-immobilized metal
complexes. This increase in the binding energies of the
respective elements in the thin films may be due to
charging effects. Since electrons are leaving the sample
by photoemission, an electrical equilibrium can only be
established if electrons can readily flow from ground to
neutralize the residual positive charge. For insulators
such as glass, the conductivity may not be sufficient to
prevent positive charge build up, thereby resulting in
an increase in the binding energies. The Si 2p binding
energies for the thin films are greatly affected by
charging, resulting in the largest difference in binding
energies from the model complexes.
Con ta ct An gle Gon iom etr y. To gain some insight
into the structure and packing of the surface-bound
species, thin films containing terminal amine and
phosphine donor ligands on flat surfaces were charac-
terized by surface-wettability measurements. Contact
angle goniometry measures the angle that the drop of
a liquid makes on a flat substrate and is dependent on
the relative hydrophobicity or hydrophilicity of the thin
film surface and the liquid.14a For example, a clean and
unfunctionalized glass surface produces a contact angle
of ∼18° with water. When a nonpolar liquid such as
hexadecane is deposited onto a hydrophilic surface such
as an unfunctionalized glass slide, an increase in the
forces of repulsion at the solid-liquid interface results
in a higher contact angle (∼85°). Conversely, when
hexadecane is deposited onto an organic monolayer, an
increase in the forces of attraction results in the
lowering of the contact angle. Thin films containing
tertiary phosphines (phenyl-, propyl-, and butylphos-
phines) exhibited contact angles of around 7° with
hexadecane and an average of 95° with a polar probe
liquid such as deionized H2O. These values are consis-
tent with, for example, anchored structures exposing
phenyl groups or short chain alkanes to the surface14b-d
and suggest that these surface-bound phosphines are
densely packed. We were unable to examine the contact
angle for the surface-anchored [Si]-NEt2 moieties, since
the Si-N bond can be easily hydrolyzed. The thin films
containing long alkane chain nitrogen-donor ligands
(phenyl-, propyl-, and pentylamines) produced contact
angles ranging between 68° and 74° with water, which
are lower than for the phosphine-terminated surfaces.
Such lower contact angles have also been observed for
surface-bound 4′-(4-methylphenyl)-2,2′:6′,2′′-terpyridine
ligand14e and may, probably, be due to the more polar
nature of the nitrogen atom of the terminal amine
ligands.
UV-Vis Absor p tion Sp ectr oscop y. UV-Vis ab-
sorption spectroscopy has been used in the past for the
evaluation of the packing density in newly developed
thin film structures.15a,b The UV-vis absorption spec-
trum of Ni(CO)2(PPh3)2 in solution shows a peak at 236
nm, and a similar spectrum for the anchored Ni(0)
complex [Si]-O-(CH2)3-PPh2Ni(CO)2(PPh3) gives the
absorption maxima at 208 nm with a blue shift of ∼28
One should be cautious in interpreting XPS spectra,
however, besides charging, there are other effects
(15) (a) Sullivan, P. B.; Morris, K.; Paulson, S. J . Chem. Soc., Chem.
Commun. 1992, 1615. (b) Li, D.; Swanson, B. I.; Robinson, J . M.;
Hoffbauer, M. A. J . Am. Chem. Soc. 1993, 155, 6975. (c) Butterworth,
J . H.; Clark, J . H.; Walton, P. H.; Barlow, S. J . J . Chem. Soc., Chem.
Commun. 1996, 1859. (d) Arkles, B. Silane Coupling Agent Chemistry.
In Silane Compounds: Register and Review; Arkles, B., Anderson, P.,
Larsen, G. L., Petrach Systems, Bristol, PA, 1987. (e) The surface
coverage (3 × 10-9 mol/cm2) was calculated using UV-vis absorption
spectroscopy: [Si]-O-(CH2)3PPh2Ni(CO)2PPh3, λmax ) 208 nm, A )
0.20; Ni(CO)2(PPh3)2, λmax 236 nm), A ) 2.55.
(11) Heiber, W.; Heusinger, H.; Vohler, J . Chem. Ber. 1957, 90, 2425.
(12) Lawson, D. N.; Wilkinson, G. J . Chem. Soc. 1965, 1900.
(13) Rollman, L. D. Inorg. Chim. Acta 1972, 6, 137.
(14) (a) Ulman, A. Introduction to Ultrathin Films. From Langmuir
Blodgett to Self-Assembly; Academic: New York, 1991. (b) Dhirani, A.-
A.; Zehner, R. W.; Hsung, R. P.; Guyot-Sionnest, P.; Sita, L. R. J . Am.
Chem. Soc. 1996, 118, 3319. (c) Sabatini, E.; Cohen- Boulakio, J .;
Bruening, M.; Rubinstein, I. Langmuir 1993, 9, 2974. (d) Fox, H. W.;
Hare, E. F.; Zisman, W. A. J . Colloid Sci. 1953, 8, 194. (e) Schmehl,
R. H.; Liang, Y. J . Chem. Soc., Chem. Commun. 1995, 1007.
(16) Tolman, C. A.; Riggs, W. M.; Linn, W. J .; King, C. M.; Wendt,
R. C. Inorg. Chem. 1973, 12 (12), 2770.

1802 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1803
Ta ble 3. CP /MAS 31P {1H} NMR a n d F T-IR Da ta for
An ch or ed Com p lexes Con ta in in g P h osp h or u s a n d
Nitr ogen Don or Liga n d s
(CH2)4PEt2 (δ -21.7) and the 31P{1H} CP/MAS NMR of
the surface-immobilized P(III) species e.g., [Si]-O-
(CH2)3PPh2 (-16.3 ppm), prepared by condensation of
(EtO)3Si(CH2)3PPh2 on silica.4b As mentioned earlier,
the preparation of thin films by the condensation of
(EtO)3Si-(CH2)nPPh2 (n ) 2, 3) on silica results in the
formation of two chemically distinct phosphorus moi-
eties on the surface of the support, specifically the
desired phosphine ligand and anchored pentacoordinate
phosphine oxide Ph2P(-O-[SiO2]2)2(CH2)3Si-O-[SiO2]
(25.9 ppm).4b A major concern in the study of im-
mobilized catalysts is their tendency to leach from the
support, and it has been suggested that the formation
of P(V) species may be a contributing factor for the
leaching process4a,b The presence of only the surface-
bound phosphorus(III) ligand in the acid-base hydro-
lytic method described here suggests that the new
surface functionalization technique is an efficient pro-
cedure in preparing phosphine-oxide-free supports un-
der mild reaction conditions.
The solid-state 31P{1H} NMR spectra of the covalently
anchored Ni(0) organometallic thin films [Si]-O-(CH2)3-
PPh2Ni(CO)2PPh3, [Si]-O-(CH2)4-PEt2Ni(CO)2PPh3,
and [Si]-NEt2Ni(CO)2PPh3 with isotropic chemical
shifts of δ 29.5 (br), 28.8 and 28.1, and 32.2 ppm,
respectively, are comparable to their solution models Ni-
(CO)2(PPh3)2 (35.2 ppm), (CH3)3Si-O-(CH2)3-PPh2Ni-
(CO)2PPh3 (36.0, 26.4 ppm), (CH3)3Si-O-(CH2)4-PEt2-
Ni(CO)2PPh3 (27.1, 26.3 ppm), and (CH3)3Si-NEt2Ni-
(CO)2PPh3 (27.2 ppm) and to the 31P{1H} CP/MAS NMR
spectra of (CH3)3Si-O-(CH2)3NEt2Ni(CO)2PPh3 (28.3
ppm) and (CH3)3Si-O-CH(CH3)(CH2)3NEt2Ni(CO)2PPh3
(31.1 ppm). Similar observations can be made for the
Rh(I), Pd(II), and Ru(II) complexes (Tables 1, 3, and 4).
Following surface reactions with the organometallic
complexes, the isotropic chemical shifts belonging to the
bound ligands were no longer observed. The latter
implies high efficiency of the displacement and bridge-
splitting reactions.
The isotropic chemical shifts and the coupling con-
stant values for the surface-bound species can be
compared with those obtained from solution measure-
ments and can assist in assigning the geometry of the
surface-bound species. For example, the CP/MAS 31P-
{1H} NMR spectrum of [Si]-O-(CH2)3-PPh2RhCl(CO)-
PPh3 results in an ABX spin system (where A and B
are the magnetically nonequivalent, mutually trans
phosphorus nuclei and X is Rh), exhibiting coupling of
phosphorus to rhodium and between inequivalent phos-
phines. The magnitude of J Rh-P coupling of 132 Hz is
comparable to that in solution for the RhCl(CO)(PPh3)2
complex (J Rh-P ) 127 Hz) and for the (CH3)3Si-O-
(CH2)3PPh2RhCl(CO)PPh3 complex in the solid state
(J Rh-P ) 125 Hz) and is indicative of the silica-bound
trans isomer. In contrast, the chelate type phosphine
complex would result in a very different J Rh-P coupling,
typically 158 Hz (cis-[RhCl(CO){PPh2(CH2)2PPh2}]).20
The chemical shift anisotropies (∆σ) similarly provide
important structural information for the surface-bound
complexes of Ni(0), Rh(I), and Ru(II). Chemical shift
anisotropies are sensitive enough to differentiate be-
tween the chemical environments and bonding arrange-
ments of the phosphorus(III) nuclei.4b,e,18,19 The chemi-
31P{1H}
thin film
([Si] ) ground glass silica)
CP/MAS FT-IR, KBr
δ (ppm) νCO (cm-1
)
[Si]-O-C6H4PPh2 (20)
[Si]-O-(CH2)3PPh2 (21)
[Si]-O-(CH2)4PEt2 (22)
26.7
-16.01
-23.2
[Si]-O-(CH2)3PPh2Ni(CO)2PPh3 (26)
[Si]-O-(CH2)4PEt2Ni(CO)2PPh3 (27)
[Si]-NEt2Ni(CO)2PPh3 (28)
[Si]-O-(CH2)3NEt2Ni(CO)2PPh3 (29)
[Si]-O-CH(CH3)(CH2)3NEt2Ni(CO)2-
PPh3 (30)
29.5 (br)a 1998, 1934
28.1, 28.8 1996, 1932
31.2
28.8
28.4
1980, 1936
1982, 1935
1975, 1911
[Si]-O-(CH2)3PPh2Rh(CO)2Cl (31)
23.4
2079, 2001
[Si]-O-(CH2)3PPh2RhCl(CO)PPh3 (32) 28.2, 33.2 1964
[Si]-NEt2RhCl(PPh3)2 (33)
51.1, 58.3
[Si]-O-(CH2)3NEt2RhCl(CO)PPh3 (34) 47.5
[Si]-O-CH(CH3)(CH2)3NEt2RhCl(CO)- 48.6
PPh3 (35)
1958
1954
[Si]-O-C6H4NEt2RhCl(CO)PPh3 (36)
47.5
1956
[Si]-O-(CH2)3PPh2Pd(PPh3)3 (37)
14.6 (br)a
[Si]-O-(CH2)3PPh2RuCl2(CO)2PPh3 (38) 17.5 (br)a 2054, 1996
a
br ) broad.
related to coordination of the ligands to the metal and
the presence of electron-withdrawing elements on the
metal center that might cause shifts in binding energies.
We observe that as poor donor ligands such as amines
replace phosphines at the metal center, there is an
increase in the binding energies of P 2s (Table 2). For
the surface-anchored complexes containing only the
phosphine donor ligands, the Rh binding energies
ranged between 307.7 and 310.3 eV, which are compa-
rable to the binding energies for the solution model
complexes (308-309 eV) as well as the known value of
309 eV for RhCl(CO)(PPh3)2.17 However, a similar
increase in the binding energies as that observed for P
2s energies was also evident for the Rh 3d5/2 binding
energies of complexes containing amine donor ligands.
The Cl 1s energies were found to be in the range of
268.7-271.0 eV for the surface-bound species. The
higher value of 271.0 eV for [Si]-O-(CH2)3PPh2-
RuCl2(CO)2PPh3 may also be due to the presence of two
chloride ligands on the metal center. This is also seen
for the model complex, RuCl2(CO)2PPh3[PPh2(CH2)3-
OSiMe3] (16).
Solid -Sta te 31P {1H} NMR. The application of cross-
polarization18 and magic-angle spinning19 techniques in
the solid-state 31P{1H} NMR spectroscopy is extremely
valuable when studying surface-immobilized transition
metal complexes containing phosphorus(III) donors.4a,b,e
For instance, thin films containing terminal phosphines
on ground glass [Si]-O-(CH2)3PPh2 and [Si]-O-(CH2)4-
PEt2 exhibit single resonances at δ -16.01 and -23.2
ppm, respectively, in their cross-polarized 31P{1H} NMR
spectra (Table 3). These resonances are comparable
with the high-resolution solution 31P{1H} NMR spectra
of Me3Si-O-(CH2)3PPh2 (δ -14.05) and Me3Si-O-
(17) Grimblot, J .; Bonnelle, J . P.; Montreux, A.; Petit, F. Inorg. Chim.
Acta 1979, 34, 29.
(18) Schaefer, J .; Stejskal, E. O. J . Am. Chem. Soc. 1976, 98, 1031.
(19) (a) Pines, A.; Gibby, M. G.; Waugh, J . S. J . Chem. Phys. 1972,
56, 1776; 1973, 59, 569. (b) Harris, R. K.; Merwin, L. H.; Hagele, G. J .
Chem. Soc., Faraday Trans 1 1989, 85 (6), 1409-1434. (c) Herzfeld,
J .; Berger, A. E. J . Chem. Phys. 1980, 73, 6021. (d) Harge´, J . C.;
Abdallaoui, H. E.; Rubini, P. Magn. Reson. Chem. 1993, 31, 752-757.
(20) Sanger, A. R. J . Chem. Soc., Chem. Commun. 1995, 907-909.

1804 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar
Ta ble 4. 31P {1H} NMR Ch em ica l Sh ift Ten sor s for Com p lexes Con ta in in g P h osp h or u s a n d Nitr ogen Don or
Liga n d s Ca lcu la ted fr om CP -MAS a n d Sp in n in g Sid eba n d An a lysisa
31P{1H}
CP/MAS δ (ppm)
complex
δ11 (ppm)
δ22 (ppm)
δ33 (ppm)
∆σb (ppm)
a. Nonanchored Complexes
(CH3)3Si-O-(CH2)4PEt2Ni(CO)2PPh3 (8)
(CH3)3Si-O-(CH2)3NEt2Ni(CO)2PPh3 (10)
(CH3)3Si-O-CH(CH3)(CH2)3NEt2Ni(CO)2PPh3 (11)
31.1, 25.8
28.3
31.1
67.8
66.4
78.3
54.1
53.9
45.2
-27.35
-35.5
-30.7
88.3
95.7
92.5
(CH3)3Si-O-(CH2)3PPh2RhCl(CO)PPh3 (12)
(CH3)3Si-O-(CH2)3PPh2Rh(CO)2Cl (13)
(CH3)3Si-NEt2RhCl(PPh3)2 (14)
27.5, 23.4
24.9
56.2
62.3
78.0
112.5
72.8
43.8
33.5
66.8
30.6
-29.8
-37.8
-10.6
-30.6
82.9
93.6
100.3
82.3
(CH3)3Si-O-CH(CH3)(CH2)3NEt2RhCl(CO)PPh3 (16)
43.0
(CH3)3Si-O-(CH2)3PPh2RuCl2(CO)2PPh3 (19)
19.8, 17.0
70.2
19.4
-35.8
80.6
b. Anchored Complexes
[Si]-O-C6H4PPh2c (20)
[Si]-O-(CH2)3PPh2c (21)
26.7
-16.6
62.3
13.8
28.4
-21.3
-10.2
-42.2
55.6
49.7
[Si]-O-(CH2)4PEt2Ni(CO)2PPh3c (27)
[Si]-O-(CH2)3NEt2Ni(CO)2PPh3c (29)
[Si]-O-CH(CH3)(CH2)3NEt2Ni(CO)2PPh3c (30)
28.1, 28.8
28.8
28.4
75.8
83.4
72.0
41.2
44.5
50.4
-30.8
-41.6
-37.2
89.3
105.6
98.4
[Si]-O-(CH2)3PPh2Rh(CO)2Clc (31)
[Si]-O-(CH2)3PPh2RhCl(CO)PPh3c (32)
[Si]-NEt2RhCl(PPh3)2c (33)
23.4
74.8
84.4
104.9
87.8
31.7
37.1
72.4
61.7
-36.8
-27.1
-13.2
-5.5
90.1
87.8
101.9
80.3
28.2, 31.5
51.1, 58.3
48.6
[Si]-O-CH(CH3)(CH2)3NEt2RhCl(CO)PPh3c (35)
[Si]-O-(CH2)3PPh2RuCl2(CO)2PPh3c (38)
17.5 (br)d
69.2
22.5
-32.7
78.6
a
b
1
Uncertainties are (1.5 and (2.5 ppm for the chemical shift tensors and ∆σ, respectively. Anisotropy parameter ∆δ ) δ33 - /2(δ11
+ δ22), where |δ33 - δiso| > |δ11 - δiso| > |δ22 - δiso|, δ ) -σ. c [Si] ) ground glass silica. br ) broad.
d
cal shift anisotropies (CSAs) in the 31P{1H} CP/MAS
NMR spectra of tertiary phosphine ligands have been
reported to be in the range of 35-50 ppm.4e In the
present study, CSAs for the immobilized phosphines
[Si]-O-C6H4-PPh2 (20) and [Si]-O-(CH2)3PPh2 (21)
were found to be 56 and 50 ppm, respectively. The
phosphorus(V) nuclei generally exhibit greater deshield-
ing in comparison to the phosphorus(III) nuclei and,
thus, result in a larger anisotropy (190 ppm for OP-
(C14H29)3 and 200 ppm for OPPh3).4e
The chemical shifts and chemical shift anisotropies
of the supported metal complexes are similar to those
for the unbound complexes (Table 4), suggesting that
the organometallic complexes retain their structures on
the surface. The CSAs of the surface-immobilized
organometallic species range between 76 and 106 ppm,
which indicates that there are no P(V)-anchored species
on the surface. Transition-metal complexes bound by
phosphorus ligands generally exhibited lower anisotro-
pies than metal complexes covalently bound to amine
donor ligands. Since amine ligands are weaker donors
than phosphines, they have a much more profound
F igu r e 1. FT-IR-ATR spectrum (1850-2100 cm-1 region)
deshielding effect on the anisotropic chemical shift of
phosphorus.
F T-IR Sp ect r oscop y. Fourier transform infrared
spectroscopy in the transmission and attenuated total
of a thin film of [Si]-O-(CH2)3PPh2Ni(CO)2PPh3 (A) on a
single-crystal silicon wafer (one side polished), and FT-IR
spectrum (1850-2100 cm-1 region) of (CH3)3Si-O-(CH2)3-
PPh2Ni(CO)2PPh3 in Nujol (B).
reflection (ATR) modes was applied to characterize the
structure of bound organometallic moieties containing
carbonyl ligands. FT-IR-ATR, in particular, is very
useful in characterizing thin film structures.5b This
sensitive surface technique provides insight into the
environment of the active metal center, the ligands
present, and the packing arrangement onto the flat
silicon substrates. The organometallic thin films of
{Si}-O-(CH2)3-PPh2Ni(CO)2PPh3 and {Si}-O-(CH2)3-
PPh2RhCl(CO)PPh3 were grown on the 111 surface of
the single-side polished Si wafers. A KRS crystal was
sandwiched between the reflective faces of two silicon
wafers, and the angle of the incident light (θ) was set
at 45° at a resolution of 2 cm-1
. The FT-IR-ATR
spectrum of the thin film, {Si}-O-(CH2)3-PPh2Ni-
(CO)2PPh3 on single-crystal Si (A) and an FT-IR spec-
trum of (CH3)3Si-O-(CH2)3-PPh2Ni(CO)2PPh3 in Nujol
(B) are shown in Figure 1. The similarities in νCO
stretching frequencies between the IR spectra of the
solution model and the supported metal complex indi-
cate that the complexes are electronically unchanged
when bound to the silylated surface. The monolayer
structure on the flat silicon wafer produces two νCO
stretching frequencies which are of roughly equal
intensities.21a The intensity and the number of bands

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1805
using the solution model complex Ni(CO)2(PPh3)-
[PPh2(CH2)3OSi(CH3)3] in monomer-to-catalyst ratios of
250:1 and 24000:1. The latter ratio is approximately
equal to the catalyst concentration of the covalently
anchored organometallic complex on a 1 in. × 1 in. glass
slide. Similar to earlier studies,22a,e both solution reac-
tions resulted in the formation of 1,2,4-triphenylbenzene
as the major product and 1,3,6-triphenyl-1-yne-3,5-diene
and 1,3,5-triphenylbenzene as the minor products.
Although the product distributions are similar, the most
significant difference is in their catalytic efficiencies.
The monomer-to-catalyst ratio of 24000:1 was found to
be highly inefficient in oligomerizing phenylacetylene.
This study indicates that the polymerization of pheny-
lacteylene diminishes significantly between the ratios
of 250:1 to 24000:1, as suggested earlier by Meriwether.22e
A similar catalytic reaction using a thin film of [Si]-
O-(CH2)3PPh2-Ni(CO)2PPh3 supported on a 1 in. × 1
in. glass slide produced a mixture with a product
distribution of symmetric 1,3,5-triphenylbenzene at
56%, the unsymmetrical 1,2,4-triphenylbenzene at 23%,
and a linear isomer 1,4,6-triphenyl-1-yne-3,5-diene at
21%. This is considerably different from the product
distribution in the homogeneous catalysis and suggests
selectivity of the surface-immobilized Ni complex in the
oligomerization of phenylacetylene. The turnover ef-
ficiency of the catalyst, which was determined based on
the concentration of the Ni complex found experimen-
tally by UV-vis absorption spectroscopy, was found to
F igu r e 2. FT-IR-ATR spectrum (1700-2200 cm-1 region)
of a thin film of [Si]-O-(CH2)3PPh2RhCl(CO)PPh3 (A) on
a single-crystal silicon wafer (one side polished), and FT-
IR spectrum (1700-2200 cm-1 region) of (CH3)3Si-O-
(CH2)3PPh2RhCl(CO)PPh3 in Nujol (B).
in the FT-IR spectrum depend on the symmetry of the
molecule.21b For the complex in solution, two unequal
carbonyl stretching frequencies are due to the sym-
metric and asymmetric dipole moment changes in the
tetrahedral Ni(0) complex. Since the intensities of the
carbonyl stretching frequencies are equivalent for the
surface-bound complex, it might suggest that due to the
packing arrangement in the thin film, the Ni complex
is forced to orient itself in a distorted tetrahedral
geometry.
be 1656 h-1 15e,23
The turnover rate of the cyclooligo-
.
merization using the Ni complex in solution with a
monomer-to-catalyst ratio similar to the surface reaction
was found to be 1.16 × 10-3 h-1. Although one should
be cautious in comparing surface turnover efficiency,
which is based on the concentration of catalyst esti-
mated from UV-vis spectra, with the turnover rate in
solution, it seems that the catalytic activity is signifi-
cantly enhanced upon supporting the complex on glass.
This suggests that the support may not be merely an
inert backbone but may take a positive role in promoting
catalyst activity and selectivity.
The thin film of {Si}-O-(CH2)3-PPh2RhCl(CO)PPh3
on single-crystal silicon showed a single νCO stretching
frequency at 1964 cm-1 in its FT-IR-ATR spectrum
(Figure 2) which is identical to its solution analogue
(CH3)3Si-O-(CH2)3-PPh2RhCl(CO)PPh3 (νCO ) 1964
cm-1). The FT-IR-ATR spectra of these thin films also
depict the asymmetric stretching mode of the alkyl
chain in the above complex at 2950 cm-1 and the phenyl
A detailed examination22a,e of the polymerization
reaction of numerous acetylenes with Ni(CO)2(PPh3)2 in
solution has established that the “active catalyst” in
these reactions is obtained by the loss of both CO ligands
followed by a possible oxidative addition of acetylene
to this Ni(0) coordinatively unsaturated complex. As
discussed above, polymerization of phenylacetylene with
the surface-anchored [Si]-O-(CH2)3PPh2Ni(CO)2PPh3
complex afforded a different product ratio than a similar
reaction in solution with Ni(CO)2(PPh3)2 or Me3SiO-
(CH2)3-PPh2Ni(CO)2(PPh3). We were intrigued by the
possibility of an alternative pathway which may be
operative in the former reaction. To evaluate this
hypothesis, we undertook a time-evolved FT-IR study
of this reaction. The Ni(0) complex was supported on a
stretching mode at 3039 cm-1
.
Ca ta lytic Oligom er iza tion of P h en yla cetylen e.
It is well-known that phenylacetylene can be oligomer-
ized using a Ni(0) catalyst, Ni(CO)2(PPh3)2, in a mono-
mer-to-catalyst ratio of 250:1, resulting in cyclic and
linear trimeric products, 1,2,4-triphenylbenzene (70%),
1,3,6-triphenyl-1-yne-3,5-diene (30%), and 1,3,5-tri-
phenylbenzene (in less than 1% yield).22a,e To accurately
compare the catalytic properties of the thin film [Si]-
O-(CH2)3PPh2Ni(CO)2PPh3 with a solution model com-
plex, we carried out oligomerization of phenylacetylene
(22) (a) Meriwether, L. S.; Colthup, E. C.; Kennerly, G. W.; Reusch,
R. N. J . Org. Chem. 1961, 26, 5155. (b) Heimback, P.; J olly, P. W.;
Wilke, G. Adv. Organomet. Chem. 1970, 8, 29. (c) Semmelhack, M. F.
Org. React. 1972, 19, 115. (d) Heimback, P. Angew. Chem., Int. Ed.
Engl. 1973, 12, 975. (e) Meriwether, L. S.; Colthup, E. C.; Kennerly,
G. W.; Leto, M. F. J . Org. Chem. 1962, 27, 3930.
(21) (a) The peak integration analysis was performed using an OPUS
V2.2 program and Levenberg-Marquardt algorithm: Ni(CO)2(PPh3)-
(PPh2(CH2)3OSiMe3), νCO 1938 (intensity ) 0.1992, width ) 15.529,
and integral ) 4.554), νCO 1999 (intensity ) 0.1408, width ) 14.973,
and integral ) 2.923); [Si]-O-(CH2)3PPh2Ni(CO)2PPh3 νCO 1936
(intensity ) 0.1964, width ) 12.599, and integral ) 2.634), νCO 1996
(intensity ) 0.1968, width ) 8.980, and integral ) 2.416). (b) Cotton,
F. A.; Wilkinson, G. Advanced Inorganic Chemistry, 3rd ed., Inter-
science Publishing: New York, 1972; pp 695-697.
(23) Turnover efficiency was determined using the surface coverage
estimated from UV-vis absorption spectroscopy: 3 × 10-9 mol cm-2
× 6.25 cm2 × 2 ) 3.75 × 10-8 mol of Ni complex present on both sides
of the glass slide: 2.4837 × 10-4 mol of product/3.75 × 10-8 mol of Ni
catalyst/4 h ) 1656 h-1
.

1806 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar
Ta ble 5. XP Sa of Th in F ilm s of [Si]-O-(CH2)3P P h 2Ni(CO)2P P h 3 Befor e (1) a n d After (2) th e Ca ta lytic Cycle
c
d
element
binding energy (eV)
FWHM
Concs. (%)b
peak area
Ix/Sx
Cx
Thin Film 1
6.95
Ni2p3/2
O1s
C1s
P2p3/2
Si2p
855.0
533.0
286.0
132.0
103.0
9.00
7.00
6.00
8.00
6.00
242 257.27
60 067.747
50 794.174
38 113.875
12 964.81
80 752.425
91 011.738
203 176.699
105 871.876
48 017.810
0.1527
0.1721
0.3842
0.2002
0.0908
17.62
60.25
6.27
8.91
Thin Film 2
4.71
Ni2p3/2
O1s
C1s
P2p3/2
Si2p
858.0
534.0
288.0
134.0
102.0
10.00
8.00
6.00
8.00
6.00
106 187.399
48 210.465
26 478.846
15 631.952
10 805.510
35 395.797
73 046.159
105 915.384
43 422.089
40 020.407
0.1189
0.2453
0.3557
0.1458
0.1344
22.59
57.26
4.14
11.30
a
b
XPS carried out on VG Escalab MKII instrument using Mg KR radiation. Calculation of peak areas and integration performed
using the program Surfsoft version 1.4. c Ix/Sx ) peak area/atomic sensitivity factor. Integration: Cx ) [Ix/Sx]/[∑Ii/Si].
d
may be an initial loss of a triphenylphosphine and a
carbonyl ligand from the surface-bound {Si}-O-
(CH2)3PPh2Ni(CO)2PPh3 complex, followed by attack
with phenylacetylene. Anchoring of the Ni complex to
the surface may create a specific environment almost
like a reactive pocket where, for steric reasons, the
addition of phenylacetylene occurs in an orientation that
favors the formation of symmetric 1,3,5-triphenylben-
zene.
XP S Stu d y of Th in F ilm s of [Si]-O-(CH2)3P P h 3-
Ni(CO)2P P h 3 Befor e a n d After Ca ta lysis. A quan-
titative evaluation of the thin films of [Si]-O-(CH2)3-
PPh2Ni(CO)2PPh3 before and after catalysis using XPS
was undertaken in order to establish whether there is
any leaching of the Ni complex during the catalytic
process. Two different slides from the same batch were
used for this experiment. Table 5 contains the XPS data
including peak positions, concentrations, and integra-
tions of each element present on the surface before and
after catalysis.
The Ni 2p3/2, P 2p3/2, and C 1s peaks show a decrease
in atomic concentration by 32%, 34%, and 5%, respec-
tively. The O 1s and Si 2p atomic concentration
increased by 22% and 21%. The relative integration of
the Ni peak similarly results in a decrease from 0.1527
to 0.1189. A decrease in peak integration is likewise
seen for the phosphorus and carbon peaks, and the
silicon and oxygen peaks showed an increase in their
integration. In addition to the possibility of leaching
of the Ni complex during the catalytic cycle, we must
also take into account varying degrees of radiation
damage which could cause peak intensities to diminish.
The peak positions of Ni, P, and C are also shifted to
higher binding energies, which suggests that these
elements are not in the same environment as they were
prior to the catalytic reaction. As discussed above, a
carbonyl and a phosphine ligand may have been lost in
the formation of the active catalyst, resulting in the
modification of the electronics at the metal center. This
is perhaps also the reason for the 3 eV shift in the Ni
2p3/2 binding energy. There is also an increase in the
C 1s binding energy, which suggests the presence of an
unsatured carbon center.
F igu r e 3. FT-IR spectra (1575-2275 cm-1 region) of a thin
film of [Si]-O-(CH2)3PPh2Ni(CO)2PPh3 on a borosilicate
glass slide (thickness ) 0.16 mm) at time (t) ) 0 (A), 15
(B), 30 (C), 60 (D), 120 (E), and 240 min (F).
thin glass slide (24 × 24 mm, 0.16 nm thick) using the
deposition chemistry described above. Unfunctionalized
glass slides of such thickness are transparent in the IR
region of interest and are invaluable in monitoring
surface reactions. The FT-IR spectra of a thin film of
{Si}-O-(CH2)PPh2Ni(CO)2PPh3 before placing it in the
reaction mixture (A) and after 15 (B), 30 (C), 60 (D),
120 (E) and 240 (F) min of its reaction with pheny-
lacetylene at 90 °C in benzene are shown in Figure 3.
As expected, a thin film of {Si}-O-(CH2)3PPh2Ni-
(CO)2PPh3 before any reaction shows two νCO stretching
frequencies at 1996 and 1935 cm-1. The most signifi-
cant changes in the FT-IR spectra take place after 15
min of the reaction (B), where the original peaks are
replaced with the peaks at 3102 (br), 3049 (br), 2210
(w, br), 1967 and 1954 (s, br), and 1812 (br) cm-1 (Figure
3). It indicates that during this time, the active catalyst
is formed on the surface which proceeds with the
oligomerization of phenylacetylene. The above peaks
in the FT-IR spectra may be assigned as follows: 3102
and 3049 cm-1 to the aromatic ring and 2210 (νCtC),
1967 Ni-H, 1954 (νCO), and 1812 cm-1 to the π-bound
phenylacetylene. These observations suggest that there
Con clu sion s
The new surface modification technique based on
simple acid-base hydrolytic chemistry is a versatile
approach to functionalize inorganic oxide surfaces under

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1807
minimize the intensity of the O 1s line, the line widths of the
P 2s, Ni 2s, and Rh 3d5/2 lines, and the base line slope in the
Ni 2s region. The solid-state 31P{1H} NMR spectra were
recorded on a Chemagnetics CMX-300 MHz spectrometer
using ammonium phosphate as an internal standard and
operating at 121.279 MHz, with high-power decoupling, using
a recycle time of 6 s and a contact time of 2 ms. Different
spinning rates, ranging from 1.5 to 4.5 kHz, were used to
identify the isotropic peaks. Calculation of the shielding
tensors was achieved with the aid of a computational package
developed by Kentgens et al.24 Infrared spectra were recorded
on a Bruker IFS-48 Fourier transform infrared spectropho-
tometer using a standard resolution of 4 cm-1 for transmission
and 2 cm-1 for attenuated total reflection experiments. The
organometallic thin films were studied using FT-IR in the
transmission and ATR modes, and in the latter case, a KRS
crystal was placed between the reflective sides of 111 Si
wafers. A miniature pressure device was employed in order
to maximize optical contact. A critical incidence angle of θ )
45° was used, since this geometry yields a maximum signal of
6000 counts/s.
P r ep a r a t ion of Solu t ion Mod els: (CH 3)3SiOC6H 4N-
(C2H5)2 (1). 3-(Diethylamino)phenol (87.4 mg, 0.53 mmol) was
dissolved in toluene (30 mL) to which (CH3)3Si-N(C2H5)2 (100
µL, 0.53 mmol) was added. The mixture was stirred at room
temperature for 18 h under an atmosphere of N2. There was
a distinct color change from deep brown to red. Removing the
solvent under vacuum gave a red oily product. Yield: 0.12 g
(96%). 1H NMR (C6D6, 270 MHz): δ 0.10 (9H, s, (CH3)3Si),
0.89 (6H, t, J H-H ) 7 Hz, NCH2CH3), 2.97 (4H, q, J H-H ) 7.2
Hz, N-CH2), 6.29, 6.39, 7.09 (4H, m, C6H4-N). EI-MS: m/z
237. Anal. Calcd for C13H23NOSi (237.4): C, 65.77; H, 9.76;
N, 5.89. Found: C, 65.45; H, 9.79; N, 5.88.
(CH3)3SiO(CH2)3N(C2H5)2 (2). To a solution of 3-(diethyl-
amino)-1-propanol (78.5 µL, 0.53 mmol) in 20 mL of benzene,
(CH3)3Si-N(C2H5)2 (100 µL, 0.53 mmol) was added, resulting
in an immediate color change from colorless to yellow. The
mixture was allowed to stir at room temperature for 10 h. The
solvent and diethylamine were distilled, leaving behind a
yellow oil with a yield of 0.11 mL (90%). 1H NMR (C6D6, 270
MHz): δ 0.09 (9H, s, (CH3)3Si), 0.86 (6H, t, J H-H ) 7.2 Hz,
CH3CH2N), 1.65 (2H, m, J H-H ) 7 Hz, CH2CH2CH2), 2.19 (4H,
q, J H-H ) 7.2 Hz, N-CH2CH3), 2.26 (2H, t, J H-H ) 6 Hz,
N-CH2), 3.79 (2H, t, J H-H ) 6.5 Hz, O-CH2). EI-MS: m/z
203. Anal. Calcd for C10H25SiON (203.4): C, 59.05; H, 12.39;
N, 6.88. Found: C, 58.76; H, 11.77; N, 7.01.
(CH3)3SiOCH(CH3)(CH2)3N(C2H5)2 (3). To a solution of
5-(diethylamino)-2-pentanol (97.3 µL, 0.53 mmol) in benzene
(20 mL), (CH3)3Si-N(C2H5)2 (100 µL, 0.53 mmol) was added,
and the mixture was left to stir at room temperature for 24 h.
The solvent and diethylamine were distilled in vacuo, affording
a yellow oil. Yield: 0.10 mL (82%). 1H NMR (C6D6, 270
MHz): δ 0.11 (9H, s, (CH3)3Si), 0.88 (6H, t, J H-H ) 7.2 Hz,
N-CH2CH3), 1.27 (3H, d, J H-H ) 6.8 Hz, CH(CH3)), 1.38 (2H,
m, J H-H ) 6.8 Hz, CH2CH2CH2), 1.55 (2H, t, J H-H ) 6.4 Hz,
N-CH2CH2), 2.16 (4H, q, J H-H ) 6.5 Hz, N-CH2CH3), 2.35
(2H, q, J H-H ) 6.7 Hz, CH2CH(CH3)), 3.73 (1H, m, J H-H ) 6.9
Hz, CH(CH3)). EI-MS: m/z 231. Anal. Calcd for C12H29SiON
(231.45): C, 62.27; H, 12.63; N, 6.05. Found: C, 62.63; H,
12.83; N, 6.24.
mild reaction conditions and using commercially avail-
able reagents. Compared with the original silane
condensation methods, this deposition process leads to
phosphine-oxide-free thin films when tertiary phos-
phines are employed as chromophores. These thin films
containing amine and phosphine donor ligands co-
valently bind a variety of transition-metal complexes.
Characterization of the bound species by a variety of
techniques has helped evaluate their actual environ-
ment on the surface. Such a thin film of a Ni(0)
complex, [Si]-O(CH2)3PPh2-Ni(CO)2PPh3, on glass oli-
gomerizes phenylacetylene with a product ratio that is
different from that of its solution analogues, (CH3)3Si-
O(CH2)3PPh2-Ni(CO)2PPh3 and Ni(CO)2(PPh3)2. Evalu-
ation of this catalytic reaction suggests that the forma-
tion of the products can be explained by considering an
initial loss of a phosphine and a carbonyl ligand, instead
of the loss of both carbonyl ligands in the catalytic
reaction in solution. Thus, catalytic activity and selec-
tivity can be enhanced by anchoring organometallic
complexes on flat surfaces, leading to tailored metal
catalysis by molecular self-assembly. We are currently
evaluating the role of this type of molecular order in
catalysis.
Exp er im en ta l Section
Ma ter ia ls a n d Mea su r em en ts. All experiments were
performed using appropriately sized Schlenk flasks and mo-
lecular self-assembly apparatus, under a nitrogen atmosphere.
Toluene, benzene, THF, diethyl ether, and hexanes were stored
under nitrogen after being distilled over sodium. Diethyl-
amine, 3-(diethylamino)-1-propanol, and 5-(diethylamino)-2-
pentanol were dried over KOH and distilled prior to use. NMR
spectra were recorded on either a Gemini 200 MHz or a J EOL
270 MHz spectrometer. All NMR samples were prepared
under a nitrogen atmosphere in either C6D6 or CDCl3. Chemi-
cal shifts reported are relative to tetramethylsilane as an
internal standard for 1H NMR spectra and to H3PO4 for 31P-
{1H} NMR spectra. Electron impact (EI) and fast atom
bombardment (FAB) mass spectra were obtained using a low-
resolution KRATOS MS25RSA spectrometer with xenon as the
ionizing gas and nitrobenzyl alcohol as the matrix. Elemental
analyses were performed by either Microanalytical Service Ltd.
(Chemical Engineering), Montreal, Quebec, or Guelph Chemi-
cal Laboratories Ltd., Guelph, Ontario. Gas chromatography
analysis was performed on a Hewlett-Packard 6840 instru-
ment using He as the carrier gas. Samples for GC-MS were
analyzed on a Hewlett-Packard 5988A instrument using He
as the carrier gas, with an injector temperature of 250 °C,
source temperature of 200 °C, and electron-impact energy of
70 eV at 300 µA trap current.
The static contact angles for the thin films were measured
using a Rame-Hart NRL100 goniometer using deionized water
and hexadecane as probe liquids. X-ray photoelectron spectra
were measured either on a INRS 220i XL spectrometer,
Varenne, Quebec, or on a VG Escalab MKII instrument, EÄ cole
Polytechnique, Universite´ de Montreal. Binding energies,
peak intensities, and peak widths at half-height were recorded
using Al KR or Mg KR radiation to produce the photoemission
of electrons from the core levels of the surface atoms. About
60 Å of depth was probed for a detector perpendicular to the
surface. The analyzed surface was 2 × 3 mm. All peak
positions were corrected for carbon at 285.0 eV in binding
energy to adjust for charging effects. The power of the source
was 300 W and a pressure of 1 × 10-9 Torr. Lines were
measured for Si 2p1/2, O 1s, C 1s, P 2s, P 2p3/2, N 1s, Cl 2s, Ni
2s1/2, Ni 2p3/2, Rh 3d5/2, Ru 3p1/2, and Pd 3d5/2. Air-sensitive
films were usually run a number of times, attempting to
(CH3)3SiO(CH2)4P (C2H5)2 (4). A mixture of (4-hydoxybut-
yl)diethylphosphine (100 mg, 0.62 mmol) and (CH3)3Si-
N(C2H5)2 (117 µL, 0.62 mmol) in 25 mL of benzene were stirred
at room temperature for 21 h. Diethylamine and benzene were
distilled under vacuum, resulting in a pale yellow oil. Yield:
0.13 mL (94%). 1H NMR (C6D6, 270 MHz): δ 0.09 (9H, s,
(CH3)3Si), 0.95 (4H, m, J H-H ) 7 Hz, CH2CH2), 1.19 (6H, t,
(24) Kentgens, A. P.; Power, W.; Wasylishen, R. E. HBLQFIT
Sideband Analysis, version 2.2; Dalhousie University: Halifax, Nova
Scotia, Canada, 1991.

1808 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar
J H-H ) 8 Hz, PCH2CH3), 1.56 (2H, m, J H-H ) 7 Hz, PCH2-
CH2), 2.48 (4H, q, J H-H ) 8 Hz, PCH2CH3), 3.50 (2H, t, J H-H
) 6 Hz, O-CH2). 31P{1H} (C6D6, 270 MHz): δ -21.7 (s). EI-
MS: m/z 234. Anal. Calcd for C11H27POSi (234.4): C, 56.37;
H, 11.61. Found: C, 56.18; H, 11.72.
[(CH3)3SiO(CH2)3N(C2H5)2]Ni(CO)2(P (C6H5)3) (10). Ni-
(CO)2(P(C6H5)3)2 (208 mg, 0.33 mmol) and compound 2 (75 µL,
0.33 mmol) were dissolved in toluene (20 mL), and the mixture
was set to reflux at 85 °C for 14 h. The solution was
evaporated to dryness under vacuum, and the pale yellow
residue was washed with 20 mL of diethyl ether to give a pale
yellow flaky solid. Yield: 170 mg (90.4%). 1H NMR (270 MHz,
C6D6): δ 0.15 (9H, s, (CH3)3Si), 1.06 (6H, t, J H-H ) 8 Hz,
NCH2CH3), 1.78 (2H, m, J H-H ) 7.8 Hz CH2CH2CH2), 2.56 (4H,
q, J H-H ) 8 Hz, NCH2CH3), 3.39 (2H, t, J H-H ) 7.9 Hz, NCH2-
CH2), 4.72 (2H, t, J H-H ) 8 Hz, OCH2), 7.25, 7.80 (15H, m,
P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6): δ 26.7 (s). IR
(Nujol): νCO 1982, 1936 cm-1. Anal. Calcd for C30H40O3NPSiNi
(580.40): C, 62.08; H, 6.94; N, 2.41. Found: C, 62.65; H, 6.65;
N, 2.46. 31P{1H} NMR (cross polarization): δ 28.3 (s). XPS
(Al KR): Si (2p, 97 eV), P (2s, 192 eV), C (1s, 280 eV), O (1s,
528 eV), N (2s, 394 eV), Ni (2p, 850 eV).
[(CH3)3SiOCH(CH3)(CH2)3N(C2H5)2]Ni(CO)2P (C6H5)3 (11).
To a solution of 3 (75 µL, 0.28 mmol) in 25 mL of toluene, Ni-
(CO)2(P(C6H5)3)2 (179 mg, 0.28 mmol) was added, and the
mixture was allowed to reflux at 70 °C for 15 h under an
atmosphere of nitrogen. The solvent was evaporated under
vacuum, and the pale yellow residue was recrystallized from
a toluene/hexane mixture to yield a pale yellow solid. Yield:
155 mg (91%). 1H NMR (270 MHz, C6D6): δ 0.12 (9H, s, (CH3)3-
(CH3)3SiO(CH2)3P (C6H5)2 (5). (3-Hydroxypropyl)diphen-
ylphosphine (55 mg, 0.23 mmol) was dissolved in benzene (25
mL), and (CH3)3Si-N(C2H5)2 (42.6 µL, 0.23 mmol) was added.
The mixture was stirred at room temperature for 22 h under
a stream of N2. Distillation in vacuo afforded a colorless oil.
Yield: 0.065 mL (91.5%). 1H NMR (C6D6, 200 MHz): δ 0.09
(9H, s, (CH3)3Si), 1.72 (2H, m, J H-H ) 6 Hz, CH2CH2CH2), 2.09
(2H, m, J H-H ) 6 Hz, P-CH2), 3.52 (2H, t, J H-H ) 6 Hz,
O-CH2), 7.10, 7.46 (10H, m (br), P(C6H5)2). 31P{1H} (C6D6,
270 MHz): δ -14.05 (s). EI-MS: m/z 316. Anal. Calcd for
C
18H25POSi (316.45): C, 68.32; H, 7.96. Found: C, 68.31; H,
7.88.
(CH3)3SiOC6H4P (C6H5)2 (6). To a solution of (2-hydroxy-
phenyl)diphenylphosphine (35 mg, 0.124 mmol) in 10 mL of
benzene, (CH3)3Si-N(C2H5)2 (23 µL, 0.124 mmol) was added,
and the mixture was stirred at ambient temperature for 24 h
under nitrogen. The solvent and diethylamine were distilled
off under vacuum to give a pale yellow oil. Yield: 0.04 mL,
(91%). 1H NMR (C6D6, 200 MHz): δ 0.06 (9H, s, (CH3)3Si),
6.70, 7.05, 7.88 (14H, m, C6H4P(C6H5)2). 31P{1H} (270 MHz,
Si), 0.80 (6H, t, J H-H ) 8 Hz, NCH2CH3), 1.25 (3H, d, J H-H
)
C6D6): δ 25.6 (s). EI-MS: m/z 351. Anal. Calcd for C21H23
POSi (350.5): C, 71.97; H, 6.61. Found: C, 71.80; H, 6.42.
-
7 Hz, CH(CH3)), 1.36 (2H, m, J H-H ) 7 Hz, CH2CH2CH2), 2.20
(4H, q, J H-H ) 6 Hz, NCH2CH3), 2.40 (2H, m, J H-H ) 6.5 Hz,
CH2CH(CH3)), 3.20 (2H, t, J H-H ) 6 Hz, CH2CH2N), 3.70 (1H,
m, (CH3)CH), 7.24, 7.92 (15H, m, P(C6H5)3). 31P{1H} NMR (270
MHz, C6D6): δ 26.9 (s). IR (Nujol): νCO 1975, 1916 cm-1. EI-
MS: m/z 609. Anal. Calcd for C32H44O3PNSiNi (608.44): C,
63.17; H, 7.29; N, 2.30. Found: C, 63.39; H, 7.15; N, 2.09.
Solid-state 31P{1H} NMR (cross polarization): δ 31.1 (s). XPS
(Al KR): Si (2p, 97 eV), P (2s, 192 eV), C (1s, 279 eV), O (1s,
527 eV), N (2s, 394 eV), Ni (2p, 849.0 eV).
[(CH3)3SiO(CH2)3P (C6H5)2]Ni(CO)2P (C6H5)3 (7). Ni(CO)2-
(P(C6H5)3)2 (0.20 g, 0.31 mmol) was dissolved in 20 mL of
toluene to which 100 µL (0.31 mmol) of 5 was added, and the
mixture was set to reflux at 90 °C for 21 h. The solvent was
evaporated to dryness under vacuum, and the pale yellow
residue was washed with diethyl ether (10 mL), followed by
recrystallization from a toluene/hexane mixture to give a pale
yellow flaky solid. Yield: 0.20 g (91%). 1H NMR (270 MHz,
C6D6): δ 0.07 (9H, s, (CH3)3Si), 1.71 (2H, m, J H-H ) 5 Hz,
CH2CH2CH2), 2.10 (2H, t, J H-H ) 5 Hz, PCH2), 3.52 (2H, t,
J H-H ) 5 Hz, OCH2), 7.07, 7.41 (10H, m, P(C6H5)2), 7.32, 7.87
(15H, m, P(C6H5)3). 31P{1H} NMR (C6D6, 270 MHz): δ 34.0
(d, J P-P ) 82 Hz), 25.1 (d, J P-P ) 82 Hz). IR (Nujol): νCO 1999,
1938 cm-1. EI-MS: m/z 693. Anal. Calcd for C38H40O3P2SiNi
(693.46): C, 65.82; H, 5.81. Found: C, 66.57; H, 5.89.
[(CH3)3SiO(CH2)4P (C2H5)2]Ni(CO)2(P (C6H5)3) (8). A mix-
ture of Ni(CO)2(P(C6H5)3)2 (273 mg, 0.43 mmol) and compound
4 (100 µL, 0.43 mmol) in 25 mL of toluene was set to reflux at
80 °C for 24 h. The solvent was evaporated to dryness under
vacuum, and the beige residue was crystallized from a toluene/
hexane mixture affording a beige powder. Yield: 248 mg
(95%). 1H NMR (270 MHz, C6D6): δ 0.12 (9H, s, (CH3)3Si), 0.83
(4H, m, J H-H ) 7.2 Hz, CH2CH2), 1.21 (6H, t, J H-H ) 6.9 Hz,
PCH2CH3), 1.57 (2H, m, J H-H ) 6.8 Hz, PCH2CH2), 3.24 (4H,
q, J H-H ) 6.9 Hz, PCH2CH3), 3.66 (2H, t, J H-H ) 7 Hz, OCH2),
7.42, 7.68 (15H, m, P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6):
δ 27.1 (d, J P-P ) 75 Hz), 26.3 (d, J P-P ) 75 Hz) ppm. IR
(Nujol): νCO 1996, 1934 cm-1. EI-MS: m/z 614. Anal. Calcd
for C31H42O3P2SiNi (611.4): C, 60.90; H, 6.92. Found: C,
60.23; H, 6.19. XPS (Al KR): Si (2p, 98 eV), P (2s, 188 eV), C
(1s, 280 eV), O (1s, 531 eV), Ni (2p, 852 eV).
[(CH3)3SiN(C2H5)2]Ni(CO)2P (C6H5)3 (9). Ni(CO)2(P(C6H5)3)2
(0.250 g, 0.39 mmol) and (CH3)3SiN(C2H5)2 (74 µL, 0.39 mmol)
were dissolved in 30 mL of toluene. The mixture was stirred
for 2 h at room temperature and was then set to reflux at 70
°C for 18 h. The solvent was concentrated to 5 mL and layered
with hexane. A white solid precipitated, which was filtered
and dried under vacuum. Yield: 185 mg (91%). 1H NMR (270
MHz, C6D6): δ 0.11 (9H, s, (CH3)3Si), 1.12 (6H, t, J H-H ) 7 Hz,
NCH2CH3), 3.02 (4H, q, J H-H ) 7 Hz, NCH2CH3), 7.05, 7.87
(15H, m, P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6): δ 27.3
(s). IR (Nujol): νCO 1981, 1934 cm-1. EI-MS: m/z 522. Anal.
Calcd for C27H34O2NPSiNi (522.3): C, 62.09; H, 6.56; N, 2.68.
Found: C, 61.05; H, 6.05; N, 2.66.
[(CH3)3SiO(CH2)3P (C6H5)2]Rh Cl(CO)(P (C6H5)3) (12). To
a solution of RhCl(CO)(P(C6H5)3)2 (50 mg, 0.072 mmol) in
benzene (20 mL), compound 5 (23 µL, 0.072 mmol) was added,
and the mixture was heated to 50 °C for 20 h. The solvent
was evaporated to dryness under vacuum to afford a yellow
residue, which was washed with ether (10 mL) and hexane
(15 mL) and then dried under vacuum. Yield: 38 mg (73%).
1H NMR (270 MHz, C6D6): δ 0.06 (9H, s, (CH3)3Si), 1.76 (2H,
m, J H-H ) 6.7 Hz, CH2CH2CH2), 2.28 (2H, m, J H-H ) 7.2 Hz,
PCH2), 3.51 (2H, t, J H-H ) 6 Hz, OCH2), 7.37, 7.73 (10H, m,
P(C6H5)2), 7.07, 7.52 (15H, m, P(C6H5)3). 31P{1H} NMR (270
MHz, C6D6): δ 24.4 (d, J Rh-P ) 116 Hz), 23.7 (d, J Rh-P ) 116
Hz). IR (Nujol): νCO 1964 cm-1
Calcd for
.
FAB-MS: m/z 754. Anal.
C
37H40O2P2ClSiRh (745.11): C, 59.64; H, 5.41.
Found: C, 61.35; H, 5.52. 31P{1H} NMR (cross polarization):
δ 27.5 (d), 23.4 (d). XPS (Al KR): Si (2p, 97 eV), P (2s, 192
eV), C (1s, 281 eV), O (1s, 528 eV), Cl (2s, 269 eV), Rh (3d,
309 eV).
[(CH3)3SiO(CH2)3P (C6H5)2]Rh (CO)2Cl (13). A 20 mg
solution of [Rh(CO)2Cl]2 (0.051 mmol) and compound 5 (32 µL,
0.102 mmol) was dissolved in benzene (15 mL). There was
an immediate color change from red to yellow. The mixture
was left to stir at room temperature for 3 h under an
atmosphere of nitrogen. The solvent was evaporated to
dryness under vacuum to leave behind a bright yellow residue,
which was recrystallized from a toluene/hexane mixture.
Yield: 25 mg (96%). 1H NMR (270 MHz, C6D6): δ 0.16 (9H, s,
(CH3)3Si), 1.86 (2H, m, J H-H ) 7 Hz, CH2CH2CH2), 2.21 (2H,
m, J H-H ) 6.9 Hz, PCH2), 3.70 (2H, t, J H-H ) 6.4 Hz, OCH2),
7.03, 7.69 (10H, m, P(C6H5)2). 31P{1H} NMR (270 MHz, C6D6):
δ 27.2 (d, J Rh-P ) 121 Hz). IR (Nujol): νCO 2080, 2010 cm-1
.
Anal. Calcd for C20H25O3PClSiRh (510.82): 47.03; H, 4.93.
Found: C, 48.12; H, 4.98. 31P{1H} NMR (cross polarization):
δ 24.9 (d). XPS (Al KR): Si (2p, 97 eV), P (2s, 193 eV), C (1s,
280 eV), O (1s, 527 eV), Cl (2s, 264 eV), Rh (3d, 308 eV).

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1809
[(CH3)3SiN(C2H5)2]Rh Cl(P (C6H5)3)2 (14). RhCl(P(C6H5)3)3
(60 mg, 0.065 mmol) was dissolved in 20 mL of benzene, to
which 12.2 µL (0.065 mmol) of (CH3)3SiN(C2H5)2 was added.
The mixture was left to react at room temperature for 24 h,
followed by 5 h at 65 °C, which resulted in a color change from
deep red to orange. The solvent was evaporated to dryness
under vacuum, and the orange residue was washed with
diethyl ether followed by recrystallization from a toluene/
hexane mixture to afford an orange powder. Yield: 45 mg
(86.5%). 1H NMR (270 MHz, CDCl3): δ 0.19 (9H, s, (CH3)3Si),
1.11 (6H, t, J H-H ) 6.9 Hz, NCH2CH3), 3.27 (4H, q, J H-H ) 7.2
Hz, NCH2CH3), 7.02, 7.75 (30H, m, P(C6H5)3). 31P{1H} NMR
(270 MHz, CDCl3): δ 54.5 (d, J Rh-P ) 195 Hz). FAB-MS: m/z
809. Anal. Calcd for C43H49P2NClSiRh (808.26): C, 63.89; H,
6.11; N, 1.73. Found: C, 63.06; H, 6.05; N, 1.80. 31P{1H} NMR
(cross polarization): δ 56.2 (d). XPS (Al KR): Si (2p, 97 eV),
P (2s, 193 eV), C (1s, 280 eV), O (1s, 528 eV), N (2s, 395 eV),
Cl (2s, 264 eV), Rh (3d, 309 eV).
concentrated to 5 mL and layered with 15 mL of diethyl ether.
A pale yellow microcrystalline solid that precipitated was
filtered in vacuo, washed with diethyl ether, and dried under
vacuum. Yield: 47.5 mg (91%). 1H NMR (270 MHz, C6D6): δ
0.04 (9H, s, (CH3)3Si), 1.75 (2H, m, J H-H ) 6 Hz, CH2CH2CH2),
2.13 (2H, m, J H-H ) 6 Hz, PCH2), 3.38 (2H, t, J H-H ) 5 Hz,
OCH2), 6.97, 7.48, (10H, m, P(C6H5)2), 7.02, 7.78 (45H, m,
P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6): δ 13.72 (br, s).
FAB-MS: m/z 1208. Anal. Calcd for
C72H70P4OSiPd
(1209.75): C, 71.48; H, 5.83. Found: C, 71.35; H, 5.76. XPS
(Al KR): Si (2p, 98 eV), P (2s, 188 eV), C (1s, 280 eV), O (1s,
528 eV), Pd (3d, 337 eV).
[(CH3)3SiO(CH2)3P (C6H5)2]Ru Cl2(CO)2(P (C6H5)3) (19). A
mixture of RuCl2(CO)2(P(C6H5)3)2 (200 mg, 0.27 mmol) and
compound 5 (84 µL, 0.27 mmol) in 30 mL of THF was set to
reflux at 70 °C for 20 h. The solution was concentrated to 10
mL and layered with hexane (20 mL). A white crystalline solid
was filtered, washed with hexanes, and dried in vacuo.
Yield: 185 mg (88.5%). 1H NMR (270 MHz, C6D6): δ 0.05 (9H,
s, (CH3)3Si), 1.89 (2H, m, J H-H ) 6.2 Hz, CH2CH2CH2), 2.17
(2H, m, J H-H ) 6.2 Hz, PCH2), 3.57 (2H, t, J H-H ) 6 Hz, OCH2),
7.02, 7.38 (10H, m, P(C6H5)2), 7.75, 8.22 (15H, m, P(C6H5)3).
31P{1H} NMR (270 MHz, C6D6): δ 20.5, 19.2 ppm. IR (Nujol):
νCO 2062, 1982 cm-1 FAB-MS: m/z 806. Anal. Calcd for
[(CH 3)3SiO(CH 2)3N(C2H 5)2]R h Cl(CO)(P (C6H 5)3) (15).
RhCl(CO)(P(C6H5)3)2 (35 mg, 0.051 mmol) and compound 2
(10.3 µL, 0.051 mmol) were dissolved in 20 mL of benzene.
The mixture was refluxed at 70 °C for 5 h under a stream of
nitrogen, resulting in a color change from yellow to red. The
solvent was removed in vacuo, affording a red solid that was
recrystallized from a toluene/hexane mixture. Yield: 22 mg
(69%). 1H NMR (270 MHz, C6D6): δ 0.11 (9H, s, (CH3)3Si), 0.94
(6H, t, J H-H ) 7.2 Hz, NCH2CH3), 1.71 (2H, t, J H-H ) 7.2 Hz,
NCH2CH2), 2.19 (2H, m, J H-H ) 7.2 Hz, CH2CH2CH2), 2.27
(4H, q, J H-H ) 6 Hz, NCH2CH3), 3.79 (2H, t, J H-H ) 6 Hz,
OCH2), 7.02, 7.92 (15H, m, P(C6H5)3). 31P{1H} NMR (270 MHz,
C
38H40P2O3Cl2SiRu (806.73): C, 56.57; H, 4.99. Found: C,
56.58; H, 4.53. 31P{1H} NMR (cross polarization): δ 19.8, 17.0
(s). XPS (Al KR): Si (2p, 98 eV), P (2s, 197 eV), C (1s, 280
eV), O (1s, 529 eV), Cl (2s, 271 eV), Ru (3p, 482 eV).
Su r fa ce R ea ct ion s a n d Ch a r a ct er iza t ion . Gen er a l
P r oced u r e. Clean substrates of glass, quartz, single-crystal
silicon, and ground glass silica were first treated with a toluene
solution of SiCl4 (10% v/v) at room temperature for 18 h. They
were then washed with copious amounts of dry toluene, placed
in a solution of fresh toluene containing 5% v/v HN(C2H5)2,
and left to stir at 70 °C for 14 h. The substrates were washed
with toluene, then immersed in a toluene solution containing
appropriate ligands, and left to react at room temperature for
24 h. They were washed with toluene and dried under a
stream of nitrogen. The ligands deposited on silica and flat
glass surfaces include: HO-C6H4PPh2 (20), HO-(CH2)3PPh2
(21), HO-(CH2)4PEt2 (22), HO-C6H4NEt2 (23), HO-(CH2)3-
NEt2 (24), and HO-CH(CH3)(CH2)3NEt2 (25). Solid-state 31P-
{1H} CP/MAS experiments were performed on functionalized
ground glass silica, and the contact angle measurements were
carried out on flat glass surfaces.
C6D6): δ 46.7 (d, J Rh-P ) 174 Hz). IR (C6H6): νCO 1968 cm-1
FAB-MS: m/z 632. Anal. Calcd for 29H40O2PClNSiRh
.
C
(632.06): C, 55.11; H, 6.38; N, 2.22. Found: C, 55.32; H, 6.26;
N, 2.23.
[(C H 3 )3 S i O C H (C H 3 )(C H 2 )3 N (C 2 H 5 )2 ]R h C l(C O )(P -
(C6H5)3) (16). A solution of RhCl(CO)(P(C6H5)3)2 (40 mg, 0.058
mmol) in 30 mL of benzene and compound 3 (13.4 µL, 0.058
mmol) was allowed to reflux at 70 °C for 18 h, resulting in a
color change from yellow to orange. Solvent was removed in
vacuo, resulting in an orange residue, which was recrystallized
from a toluene/hexane mixture affording an orange powder.
Yield: 24 mg (63%). 1H NMR (270 MHz, C6D6): δ 0.14 (9H, s,
(CH3)3Si), 0.98 (6H, t, J H-H ) 7.2 Hz, NCH2CH3), 1.26 (3H, d,
J H-H ) 6.2 Hz, CH(CH3)), 1.42 (2H, m, J H-H ) 5.4 Hz, CH2CH2-
CH2), 1.57 (2H, q, J H-H ) 5.4 Hz, CH2CH(CH3)), 2.32 (4H, q,
J H-H ) 5.4 Hz, NCH2CH3), 2.42 (2H, t, J H-H ) 5.7 Hz, NCH2-
CH2), 3.74 (1H, m, J H-H ) 5.9 Hz, CH(CH3)), 6.98, 7.96 (15 H,
m, P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6): δ 46.4 (d, J Rh-P
[Si]-O-C6H4-P (C6H5)2 (20). Solid-state 31P{1H} NMR
(cross polarization with xmtr blanking): δ 26.7 ppm. Contact
angles: θH ) 91°; θHexadecane ) 8°.
O
2
[Si]-O-(CH2)3P (C6H5)2 (21). Solid-state 31P{1H} NMR
(cross polarization with xmtr blanking): δ -16.01 ppm.
Contact angles: θH ) 94°; θHexadecane ) 7°.
) 158 Hz). IR (C6H6): νCO 1961 cm-1
. FAB-MS: m/z 661.
Anal. Calcd for C31H44O2PNClSiRh (660.11): C, 56.40; H, 6.72;
N, 2.12. Found: C, 56.21; H, 6.65; N, 2.16. 31P{1H} NMR
(cross polarization): δ 43.0 (d). XPS (Al KR): Si (2p, 97 eV),
P (2s, 193 eV), C (1s, 280 eV), O (1s, 528 eV), N (2s, 395 eV),
Cl (2s, 267 eV), Rh (3d, 312 eV).
O
2
[Si]-O-(CH2)4P (C2H5)2 (22). Solid-state 31P{1H} NMR
(cross polarization with xmtr blanking): δ -23.2 ppm. Contact
angles: θH ) 96°; θHexadecane ) 7°.
O
2
[Si]-O-C6H4N(C2H5)2 (23). Contact angles: θH ) 68°;
[(CH3)3SiOC6H4N(C2H5)2]Rh Cl(CO)(P (C6H5)3) (17). RhCl-
(CO)(P(C6H5)3)2 (25 mg, 0.036 mmol) and compound 1 (8.62
µL, 0.036 mmol) were dissolved in benzene (20 mL) and
allowed to reflux at 70 °C for 15 h. The solvent was then
removed in vacuo, and recrystallization from a toluene/hexane
mixture yielded an orange solid. Yield: 0.022 g (89.6%). 1H
NMR (270 MHz, C6D6): δ 0.14 (9H, s, (CH3)3Si), 0.92 (6H, t,
J H-H ) 7.2 Hz, NCH2CH3), 3.02 (4H, q, J H-H ) 7.2 Hz, NCH2-
CH3), 6.32, 6.43, 7.12 (4H, m, C6H4N), 7.09, 7.70 (15H, m,
O
2
θHexadecane ) 15°.
[Si]-O-(CH2)3N(C2H5)2 (24). Contact angles: θH O ) 73°;
2
θHexadecane ) 12°.
[Si]-O-CH(CH3)(CH2)3N(C2H5)2 (25). Contact angles:
θH ) 74°; θHexadecane ) 12°.
O
2
Or ga n om eta llic Th in F ilm s. A general procedure for
functionalizing inorganic oxide surfaces such as ground glass
silica, glass, quartz, and single-crystal silicon with transition-
metal complexes is described below.
Gr ou n d Gla ss Silica : [Si]-O-(CH2)3P (C6H5)2Ni(CO)2-
(P (C6H5)3) (26a ). Ni(CO)2(P(C6H5)3)2 (250 mg) was dissolved
in 50 mL of toluene. Ground glass silica functionalized with
22 was added, and the mixture was set to reflux at 90 °C for
24 h. It was then filtered and washed with copious amounts
of toluene and dried in vacuo, resulting in the formation of
the surface-anchored complex 26a .
P(C6H5)3). 31P{1H} NMR (270 MHz, C6D6): δ 47.9 (d, J Rh-P
)
177 Hz). IR (C6H6): νCO 1964 cm-1. FAB-MS: m/z 667. Anal.
Calcd for C32H38O2PNClSiRh (666.08): C, 57.70; H, 5.75; N,
2.10. Found: C, 57.06; H, 5.46; N, 2.24.
[(CH3)3SiO(CH2)3P (C6H 5)2]P d (P (C6H 5)3)3 (18). Pd(P-
(C6H5)3)4 (50 mg, 0.043 mmol) was dissloved in 30 mL of THF,
to which compound 5 (13.7 µL 0.043 mmol) was added, and
the mixture was refluxed at 75 °C for 20 h. The solution was

1810 Organometallics, Vol. 17, No. 9, 1998
Petrucci and Kakkar
F la t Gla ss/Qu a r tz/Sin gle-Cr ysta l Si (26b). Ni(CO)2-
(P(C6H5)3)2 (25-50 mg) was dissolved in 30 mL of toluene in a
self-assembly apparatus containing a glass slide functionalized
with 21 positioned in a Teflon carrousel. The solution was
refluxed at 90 °C for 24 h, followed by washing of the glass
slide with toluene (3 × 30 mL) and drying under a nitrogen
atmosphere.
with transmitter blanking): δ 48.6 (d, J Rh-P ) 164 Hz). FT-
IR (KBr): νCO 1954 cm-1. XPS (Al KR): Si (2p, 105.5 eV), P
(2s, 200.3 eV), C (1s, 286.6 eV), N (1s, 400.1 eV), Cl (2s, 270.9
eV), O (1s, 531.3 eV), Rh (3d, 311.8 eV).
[Si]-O-C6H 4-N(C2H 5)2R h Cl(CO)(P (C6H 5)3) (36). The
conditions of deposition were similar to that for 35. Solid-
state 31P{1H} NMR (cross polarization with transmitter
blanking): δ 47.5 (br). FT-IR (KBr): νCO 1956 cm-1. XPS (Al
KR): Si (2p, 105.3 eV), P (2s, 200.3 eV), C (1s, 286.4 eV), N
(1s, 398.9 eV), Cl (2s, 269.7 eV), O (1s, 531 eV), Rh (3d, 311.6
eV).
[Si]-O-(CH2)3P (C6H5)2P d (P (C6H5)3)3 (37). Pd(P(C6H5)3)4
(25 mg) dissolved in THF and the substrates functionalized
with 21 were refluxed at 75 °C for 20 h to result in the
formation of a thin film of 37. Solid-state 31P{1H} NMR (cross
polarization with transmitter blanking): δ 14.6 (br s). XPS
(Al KR): Si (2p, 104.2 eV), P (2s, 195.2 eV), C (1s, 286 eV), O
(1s, 534.3 eV), Pd (3d, 338.2 eV).
[26a ,b]. Solid state 31P{1H} NMR (cross polarization via
spinlock): δ 29.5 (br s). FT-IR (KBr): νCO 1998, 1934 cm-1
.
FT-IR-ATR (KRS): νCO 1996, 1935, cm-1. XPS (Al KR): Si (2p,
102.6 eV), P (2s, 199 eV), C (1s, 284.9 eV), O (1s, 532 eV), Ni
(2p, 859.0 eV). UV-vis (quartz): monolayer coverage 3 × 10-9
mol/cm2.
[Si]-O-(CH2)4P (C2H5)2Ni(CO)2(P (C6H5)3) (27). Solid-
state 31P{1H} NMR (single pulse with decoupling xmtr blank-
ing): δ 28.1, 28.8 ppm. FT-IR (KBr): νCO 1996, 1932 cm-1
.
XPS (Al KR): Si (2p, 102.5 eV), P (2s, 198.2 eV), C (1s, 287
eV), O (1s, 530.2 eV), Ni (2p, 858.0 eV).
[Si]-N(C2H5)2Ni(CO)2(P (C6H5)3) (28). Solid-state 31P{1H}
NMR (cross polarization via spinlock): δ 31.2 ppm. FT-IR
(KBr): νCO 1980, 1936 cm-1. XPS (Al KR): Si (2p, 105.9 eV),
P (2s, 199.5 eV), C (1s, 286.2 eV), N (1s, 401.5 eV), O (1s, 531
eV), Ni (2p, 858.0 eV).
[Si]-O-(CH2)3P (C6H5)2Ru Cl2(CO)2P (C6H5)3 (38). The
conditions of deposition were similar to that for 37. Solid-
state 31P{1H} NMR (cross polarization with transmitter
blanking): δ 17.6 (br s). FT-IR (KBr): νCO 2054, 1996 cm-1
.
XPS (Al KR): Si (2p, 105.3 eV), P (2s, 201.1 eV), C (1s, 287.2
eV), Cl (2s, 271 eV), O (1s, 531 eV), Ru (3p, 489 eV).
[Si]-O-(CH2)3N(C2H5)2Ni(CO)2(P (C6H5)3) (29). Solid-
state 31P{1H} NMR (cross polarization with transmitter
Cyclooligom er iza tion of P h en yla cetylen e Usin g Ni-
(CO)2P P h 3[(P P h 2(CH2)3OSi(CH3)3] in a Ca ta lyst-to-Mon o-
m er R a t io of 1:250. Gen er a l P r oced u r e. Ni(CO)2P-
(C6H5)3[P(C6H5)2(CH2)3OSi(CH3)3] (200 mg, 0.29 mmol) was
added under a nitrogen atmosphere to 25 mL of C6H6 contain-
ing 7.90 mL (7.35 g, 72.5 mmol) of phenylacetylene, and the
mixture was set to reflux at 80 °C for 3 h, during which time
the solution went from pale yellow to reddish-brown in color.
The benzene and unreacted phenylacetylene (185 µL) were
distilled from the reaction mixture. The residue was extracted
into petroleum ether, and the insoluble portion was filtered
and washed with ether (10 mL) and hexanes (10 mL). The
orange filtrate was cooled to -20 °C overnight, resulting in
the recrystallization of colorless needles. Evaporating the
solvent from the orange filtrate, followed by crystallization in
diethyl ether, afforded an orange powder. Total yield of three
fractions: 5.88 g (79.9%).
blanking): δ 28.8 ppm. FT-IR (KBr): νCO 1982, 1935 cm-1
.
XPS (Al KR): Si (2p, 109.3 eV), P (2s, 203.5 eV), C (1s, 288.2
eV), N (1s, 400.7 eV), O (1s, 531.6 eV), Ni (2p, 856.0 eV).
[Si]-O-CH(CH3)(CH2)3N(C2H5)2Ni(CO)2(P (C6H5)3) (30).
Solid-state 31P{1H} NMR (cross polarization with transmitter
blanking): δ 28.4 ppm. FT-IR (KBr): νCO 1975, 1911 cm-1
.
XPS (Al KR): Si (2p, 106.6 eV), P (2s, 200.6 eV), C (1s, 286.9
eV), N (1s, 400.2 eV), O (1s, 530.9 eV), Ni (2p, 856.0 eV).
[Si]-O-(CH2)3P (C6H5)2Rh (CO)2Cl (31). [Rh(CO)2Cl]2 (25
mg) and the substrates functionalized with 21 in toluene were
stirred for 4 h at ambient temperature to afford (31). Solid-
state 31P{1H} NMR (cross polarization with transmitter
blanking): δ 23.4 (d, J Rh-P ) 93 Hz). FT-IR (KBr): νCO 2079,
2001 cm-1. XPS (Al KR): Si (2p, 103.4 eV), P (2s, 198.2 eV),
C (1s, 285.1 eV), Cl (2s, 269.6 eV), O (1s, 531.7 eV), Rh (3d,
310.4 eV).
[Si]-O-(CH2)3P (C6H5)2Rh Cl(CO)(P (C6H5)3) (32). RhCO-
(Cl)(P(C6H5)3)2 (25 mg) dissolved in toluene and the susbstrates
functionalized with 21 were stirred at 50 °C for 20 h to give a
thin film of (32). Solid-state 31P{1H} NMR (cross polarization
with transmitter blanking): δ 28.1 (d, J Rh-P ) 132 Hz), 31.5
(t, J P-P ) 366 Hz), 34.9 (d, J Rh-P ) 132 Hz). FT-IR (KBr):
1,2,4-Tr ip h en ylben zen e. Yield: 5.35 g (91%). 1H NMR
(270 MHz, C6D6): δ 7.16 (s), 7.41 (m). IR (KBr): ν 2945, 1839,
. Mp: 101 °C. GC (C6H6): 5.73
min. GC-MS (C6H6): 40.87 min, m/z 306. UV-vis (C6H12):
λmax 248, 272 (sh) nm.
1,3,5-Tr ip h en ylben zen e. Yield: 0.37 g (6.30%). 1H NMR
(270 MHz, C6D6): δ 7.77 (s), 7.51 (d), 7.23 (m). IR (KBr): ν
4051, 3056, 1949, 1884, 1758, 1602, 1111, 999, 872 cm-1. Mp:
171 °C. GC (C6H6): 7.81 min. GC-MS (C6H6): 44.34 min, m/z
306. UV-vis (C6H12): λmax 250 nm.
1,3,6-Tr iph en yh ex-1-yn e-3,5-dien e. Yield: 0.16 g (2.72%).
1H NMR (270 MHz, C6D6): δ 8.00, 6.34, 5.88 (s), 7.20 (m). IR
(KBr): ν 3024, 1951, 916 cm-1. Mp: 108 °C. GC (C6H6): 3.39
min. GC-MS (C6H6): 29.42 min, m/z 306. UV-vis (C6H12):
λmax 206, 281 nm.
Cyclooligom er iza tion of P h en yla cetylen e Usin g Ni-
(CO)2P P h 3[(P P h 2(CH2)3OSi(CH3)3] in a Ca ta lyst-to-Mon o-
m er Ra tio of 1:24000. Gen er a l P r oced u r e. Ni(CO)2P-
(C6H5)3[P(C6H5)2(CH2)3OSi(CH3)3] (3.8 mg 0.005 mmol) was
dissolved in 20 mL of C6H6, to which 14.27 mL of phenylacety-
lene (13.4 g, 0.131 mol) was added. The reaction mixture was
set to reflux at 80 °C for 3 h, followed by distillation of benzene
and phenylacetylene. Total yield of three fractions: 0.48 g
(3.65%).
1630, 1515, 1219, 805 cm-1
ν
CO 1964 cm-1. FT-IR-ATR (KRS): νCO ) 1964 cm-1. XPS (Al
KR): Si (2p, 103.7 eV), P (2s, 199.8 eV), C (1s, 284.9 eV), Cl
(2s, 269.2 eV), O (1s, 530.8 eV), Rh (3d, 307.7 eV).
[Si]-N(C2H5)2Rh Cl(P (C6H5)3)2 (33). RhCl(P(C6H5)3)3 (25
mg) dissolved in benzene and the substrates functionalized
with diethylamine were left to stir at ambient temperature
for 24 h, followed by refluxing at 65 °C for 5 h to result in the
formation of a thin film of 33. Solid-state 31P{1H} NMR (cross
polarization with transmitter blanking): δ 51.1 (d, J Rh-P ) 185
Hz), 58.3 (d, J Rh-P ) 185 Hz). XPS (Al KR): Si (2p, 109.5 eV),
P (2s, 204.6 eV), C (1s, 289.7 eV), N (1s, 401.8 eV), Cl (2s, 270.8
eV), O (1s, 533 eV), Rh (3d, 315.2 eV).
[Si]-O-(CH2)3N(C2H5)2Rh Cl(CO)(P (C6H5)3) (34). RhCO-
(Cl)(P(C6H5)3)2 dissolved in benzene and the substrates func-
tionalized with 24 were stirred at 70 °C for 5 h to afford a
thin film of 34. Solid-state 31P{1H} NMR (cross polarization
with transmitter blanking): δ 47.5 (d, J Rh-P ) 163 Hz). FT-
IR (KBr): νCO 1958 cm-1. XPS (Al KR): Si (2p, 103 eV), P (2s,
197.9 eV), C (1s, 285.7 eV), N (1s, 399.5 eV), Cl (2s, 268.7 eV),
O (1s, 531 eV), Rh (3d, 310.8 eV).
1,2,4-Tr ip h en ylben zen e. Yield: 0.425 g (87.9%). 1H NMR
(270 MHz, C6D6): δ 7.15 (s), 7.48 (m). IR (KBr): ν 2945, 1839,
1653, 1515, 1219, 805 cm-1. Mp: 102 °C. GC (C6H6): 5.687
min. GC-MS (C6H6): 40.75 min, m/z 306. UV-vis (C6H12):
λmax 249, 272 (sh) nm.
[Si]-O-CH(CH3)(CH2)3N(C2H5)2Rh Cl(CO)(P (C6H5)3) (35).
RhCO(Cl)(P(C6H5)3)2 dissolved in toluene and the substrates
functionalized with 25 were stirred at 70 °C for 18 h to give a
thin film of 35. Solid-state 31P{1H} NMR (cross polarization

Acid-Base Hydrolytic Chemistry Route to Thin Films
Organometallics, Vol. 17, No. 9, 1998 1811
1,3,5-Tr ip h en ylben zen e. Yield: 0.025 g (5.18%). 1H NMR
(270 MHz, C6D6): δ 7.77 (s), 7.51 (d), 7.23 (m). IR (KBr): ν
4051, 3057, 1949, 1884, 1757, 1593, 1111, 998, 872 cm-1. Mp:
172 °C. GC (C6H6): 7.459 min. GC-MS (C6H6): 44.31 min,
m/z 306. UV-vis (C6H12): λmax 250 nm.
1,3,6-Tr iph en yh ex-1-yn e-3,5-dien e. Yield: 0.03 g (6.21%).
1H NMR (270 MHz, C6D6): δ 8.00, 6.34, 5.88 (s), 7.20 (m). IR
(KBr): ν 3031, 2250 (w), 1951, 916 cm-1. Mp: 108 °C. GC
(C6H6): 3.411 min. GC-MS (C6H6): 29.02 min, m/z 306. UV-
vis (C6H12): λmax 206, 281 nm.
Mech a n istic Stu d ies Usin g F T-IR. A glass slide contain-
ing the supported metal complex [Si]-O-(CH2)3P(C6H5)2Ni-
(CO)2PPh3 was placed in benzene in an apparatus equipped
with KBr windows. A 100 µL amount of dry and distilled
phenylacetylene was added, and the reaction vessel was
lowered in an oil bath set at 90 °C. After a period of 15, 30,
and 45 min, etc., the reaction vessel was removed from the oil
bath. Benzene, phenylacetylene, and any organic products
were syringed out, and the glass slide was washed with 2 ×
50 mL of benzene followed by drying the glass slide under a
stream of nitrogen. The FT-IR spectra of the thin film were
taken, and this procedure was repeated after 30, 60, 120, and
240 min. Benzene and unreacted phenylacetylene were
distilled under vacuum, leaving behind a yellow residue, which
was recrystallized from diethyl ether and characterized by 1H
NMR, FT-IR, UV-vis, melting points, GC, and GC-MS.
Qu a n tita tive XP S Stu d y of th e Th in F ilm s of [Si]-O-
(CH2)3P P h 3Ni(CO)2P P h 3 Befor e a n d After Ca ta lysis. Two
glass slides (1 in. × 1 in.) were functionalized with the Ni
complex, [Si]-O-(CH2)3PPh2Ni(CO)2PPh3, as previously de-
scribed. One of the slides was removed and used for the
quantitative XPS study, and the second slide was subjected
to catalytic oligomerization of phenylacetylene. After 4 h, the
slide was removed from the self-assembly apparatus, washed
copiously with toluene, dried under a stream of nitrogen, and
its X-ray photoelectron spectra was recorded. Benzene and
unreacted phenylacetylene from the organic portion were
distilled under vacuum, leaving behind a yellow residue, which
was recrystallized from diethyl ether and characterized by 1H
NMR, FT-IR, UV-vis, melting points, GC, and GC-MS.
Cyclooligom er iza t ion of P h en yla cet ylen e Usin g
a
Su p p or ted Ni(0) Com p lex: [Si]-O-(CH2)3P P h 2Ni(CO)2-
P P h 3. The catalytic reaction was performed using the Ni(0)
complex [Si]-O-(CH2)3P(C6H5)2Ni(CO)2P(C6H5)3 surface-im-
mobilized on a 1 in. × 1 in. glass slide. The slide was placed
in a self-assembly apparatus equipped for stirring and heating.
Benzene (10 mL) was added to cover the slide, and 100 µL of
dry and distilled phenylacetylene was also introduced. The
mixture was set to reflux at 90 °C for 4 h, resulting in a color
change from colorless to bright yellow. The resulting solution
was distilled to remove benzene and excess phenylacetylene,
leaving behind an orange-brown oily residue characterized by
1H NMR, FT-IR, UV-vis, melting points, GC, and GC-MS. The
percentage of the trimers are based on GC-MS results. Total
yield: 0.075 g (80.65%).
1,3,5-Tr ip h en ylben zen e. 1H NMR (270 MHz, C6D6): δ
7.77 (s), 7.51 (m), 7.23 (m). IR (CH2Cl2): ν 2974, 1602, 1096,
996, 860 cm-1. Mp: 172 °C. GC (C6H6): 7.879 min, 58.84%.
GC-MS (C6H6): 44.71 min, m/z 306, 56.01%. UV-vis (C6H12):
λmax 250 nm.
1,2,4-Tr ip h en ylben zen e. 1H NMR (270 MHz, C6D6): δ
7.15 (s), 7.24 (m). IR (CH2Cl2): ν 2932 cm-1
. Mp: 102 °C.
Ack n ow led gm en t . This work was performed
through the financial support of NSERC of Canada and
FCAR of Quebec (Canada). We thank Mr. F. G. Morin
for his help in acquiring the solid-state NMR spectra.
M.G.L.P. thanks NSERC of Canada and FCAR of
Quebec (Canada) for a postgraduate scholarship.
GC (C6H6): 5.808 min, 23.13%. GC-MS (C6H6): 40.76 min,
m/z 306, 20.64%. UV-vis (C6H12): λmax 250, 272 (sh) nm.
1,4,6-Tr ip h en yh ex-1-yn e-3,5-d ien e. 1H NMR (270 MHz,
C6D6): δ 8.09 (d, J H-H ) 16 Hz), 6.82 (d, J H-H ) 16 Hz), 5.89
(s), 7.24 (m). IR (CH2Cl2): ν 3024, 1950, 835 cm-1. Mp: 109
°C. GC (C6H6): 3.426 min, 18.03%. GC-MS (C6H6): 28.75 min,
m/z 306, 23.01%. UV-vis (C6H12): λmax 280 nm.
OM970923B