Polarized complexes obtained by regiospecific substitution of a CN group in Ru{C≡CC(CN)=C(CN)2}(dppe)Cp* (Cp* = η-C 5Me5)

Article abstract of DOI:10.1021/om300059q

The complex Ru{C≡CC(CN)=C(CN)₂}(dppe)Cp* (1), containing the new tricyanovinylethynyl (3,4,4-tricyanobut-3-en-1-ynyl) ligand, undergoes ready substitution of the 3-cyano group by nucleophiles (Nu) such as H, Me, Prⁱ, Bu, Bu^t, mesityl, OMe, OBu^t, OCH₂CH=CH₂, NHEt, NEt₂, and PPh₂ to give Ru{C≡CC(Nu)=C(CN)₂}(dppe)Cp. The X-ray diffraction structures of several of the resulting complexes are reported and, for the mesityl and PPh₂ products, show that isomerization to the 3,5-dimethylbenzyl and oxidation to the phosphine oxide have respectively occurred.

Full text of DOI:10.1021/om300059q

Article
pubs.acs.org/Organometallics
Polarized Complexes Obtained by Regiospecific Substitution of a CN
Group in Ru{CCC(CN)C(CN)2}(dppe)Cp* (Cp* = η-C5Me5)
Michael I. Bruce,*,† Alexandre Burgun,† Brian K. Nicholson,‡ Christian R. Parker,† Brian W. Skelton,§,∥
and Allan H. White§
†School of Chemistry & Physics, University of Adelaide, Adelaide, South Australia 5005, Australia
‡Department of Chemistry, University of Waikato, Hamilton, New Zealand
§Chemistry M313, SBBCS, University of Western Australia, Crawley, Western Australia 6009, Australia
S
* Supporting Information
ABSTRACT: The complex Ru{CCC(CN)C(CN)2}-
(dppe)Cp* (1), containing the new tricyanovinylethynyl
(3,4,4-tricyanobut-3-en-1-ynyl) ligand, undergoes ready sub-
stitution of the 3-cyano group by nucleophiles (Nu) such as H,
Me, Pri, Bu, But, mesityl, OMe, OBut, OCH2CHCH2,
NHEt, NEt2, and PPh2 to give Ru{CCC(Nu)C(CN)2}-
(dppe)Cp*. The X-ray diffraction structures of several of the
resulting complexes are reported and, for the mesityl and PPh2
products, show that isomerization to the 3,5-dimethylbenzyl and oxidation to the phosphine oxide have respectively occurred.
ruthenium complex Ru{CCC(CN)C(CN)2}(dppe)Cp*
INTRODUCTION
■
(1) was obtained in essentially quantitative yield, and we have
Although reactions of tetracyanoethene ((NC)2CC(CN)2,
commenced a study of its reactions. In an earlier account, we
TCNE) with alkynyl−transition-metal complexes generally
described complexes formed by addition of a proton or other
proceed by [2 + 2] cycloaddition reactions to give
metal−ligand fragments.2b In this paper, we direct our attention
tetracyanocyclobutenyls with subsequent ring opening to afford
tetracyanobutadienyls,1 we recently found that facile sub-
to the facile substitution of the CN group gem to the metal
center by other nucleophiles, which provides a route for tuning
the electronic properties of these molecules. While the negative
charge can be accommodated by the dicyanomethylene group,
the CN group gem to the metal substituent is labilized thereby,
stitution of a CN group in TCNE by the ethynyl groups of
complexes M(CCH)(PP)Cp′ (M = Ru, (PP)Cp′ =
(PPh3)2Cp, (dppe)Cp*; M = Os, (PP)Cp′ = (dppe)Cp*),
with concomitant elimination of HCN, afforded the unusual
as shown by the longer C−CN distance (1.477(8) Å) in
tricyanovinylethynyl (tricyanobutenynyl) complexes M{C
CC(CN)C(CN)2}(PP)Cp′.2 The CC triple bonds in
these complexes are strongly polarized by virtue of their linking
an electron-rich M(PP)Cp′ fragment to the powerfully
accepting C(CN)2 group. Such materials, which can be
considered to contain an electron-rich metal donor (D) linked
by a π-conjugated bridge (π) to a strongly electron-accepting
group (A) (D−π−A systems), are of contemporary interest
because their strong polarization leads to efficient nonlinear
optical properties, which may have a role in the construction of
various molecular-scale electronic devices.3 Their structural
features are consistent with a significant contribution from the
zwitterionic mesomer, and we decided to examine the
chemistry of these systems in more detail.
Part of the extensive chemistry of tetracyanoethene is
characterized by substitution of one or two CN groups by
other nucleophiles.4,5 For example, alcohols such as MeOH and
HOCH2CH2OH react under basic conditions to give
respectively methyl tricyanovinyl ether, MeOC(CN)C-
(CN)2, and dicyanoketene acetal, (NC)2CC(OCH2CH2O).
Similarly, arylamines and phosphorus ylides afford tricyano-
vinyl−anilines and −phosphorylides, respectively.4−7 The
comparison with those of the C(CN)2 group (1.441,
1.449(2) Å). A brief account of some of these reactions has
appeared.2a
RESULTS
■
Substitution Reactions of Ru{CCC(CN)C(CN)2}-
(dppe)Cp* (1). The propensity for substitution of the CN
group gem to the metal center was discovered accidentally from
a reaction between 1 and the putative LiCC{Ru(dppe)Cp*}
derivative8 (obtained from LiBu and Ru(CCH)(dppe)Cp*),
designed to give the binuclear complex {Cp*(dppe)Ru}2C
C(CN)2. In fact, only the dicyanobutenynyl Ru{CCCBu
C(CN)2}(dppe)Cp* (2), as shown by a single-crystal X-ray
diffraction study (see below), was obtained. Earlier work by
others had described a reaction between the analogous indenyl
complex Ru(CCH)(PP)(η5-C9H7) (PP = (PPh3)2, dppe)
and LiBu to give a lithiated alkynyl intermediate which could be
converted to Ru(CCR)(PP)(η5-C9H7) when treated with
Received: January 24, 2012
Published: May 22, 2012
© 2012 American Chemical Society
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Scheme 1. Reactions of Ru{CCC(CN)C(CN)2}(dppe)Cp* (1) with Nucleophiles
RX (RX = SnClPh3, [I(py)2]BF4).8 We then realized that the
formation of 2 might proceed via substitution of the CN group
gem to the metal center in 1 by unreacted LiBu with elimination
of LiCN. This hypothesis was supported by the direct reaction
between 1 and LiBu, which gave 2 in 32% yield.
the expected signals. ES-MS generally contain M+ or [M + H]+,
[M + Na]+, and [Ru(dppe)(C5Me5)]+ ions, together with
aggregate ions formed by clustering of two molecules around a
Na+ cation: e.g., [2 M + Na]+.
Reactions between 1 and the organolithium reagents
LiMe.LiBr and LiBut, or the Grignard reagent PriMgBr,
afforded the analogous complexes Ru{CCCRC(CN)2}-
(dppe)Cp* (R = Me (3; 76%), But (4; 27%), Pri (5; 48%),
respectively). In contrast, reactions with LiPh or PhMgCl each
gave several products, none of which could be obtained pure.
However, with (mes)MgBr, the complex with R =
CH2C6H3Me2-3,5 (6; 11%) could be isolated. This rearrange-
ment of the mesityl (2,4,6-trimethylphenyl) group to the 3,5-
dimethylbenzyl substituent was revealed by a single-crystal X-
ray diffraction structure determination (see below). The 3,5-
dimethylbenzyl group gives characteristic resonances for the
two Me groups at δ 1.26, the CH2 at δ 3.21, and the C6H3
protons at δ 6.39 and 6.76 (intensity 2/1). This unusual,
although not unprecedented, isomerization is probably driven
by steric pressures around C(3). Previous organometallic
examples include conversion of Ir(mes)(CO)(dppe) to Ir-
(CH2C6H3Me2-3,5)(η-C2H4)(CO)(dppe) on heating in the
presence of C2H4 and the formation of an equilibrium mixture
of Ir{C(O)mes}(CO)2(dppe) and cis- and trans-IrH-
{CH2C6H2Me2-3,5-C(O)-2}(CO)(dppe) by heating the C-
(O)mesityl complex in CO.9
We have now found that 1 readily reacts with a range of
nucleophiles to give similar products 2−14 (Scheme 1), many
of which have been characterized by single-crystal X-ray
diffraction studies. All compounds described herein gave
satisfactory elemental analyses. Spectroscopic properties, de-
tailed in the Experimental Section, are also in accord with the
assigned structures, IR spectra containing characteristic
absorptions assigned to ν(CN) between 2170 and 2214 (two
bands) and a ν(CC) band between 1979 and 1995 cm−1
(except for 7 and 8, where the absorption is at 2019 and 2014
cm−1, respectively, and 13, where it is found at 1958 cm−1).
Unusually strong ν(CC) bands were found, resulting from
the polarization of the CC triple bond by the electron-
donating and -accepting substituents. At lower frequencies,
ν(CC) bands occur at ca. 1485 cm−1. In the NMR spectra,
the metal−ligand fragment showed the usual Cp* (δH 1.55, δC
10.25, 95.5) and dppe (δH ca. 2.25, 2.90, δC ca. 29.5−30.5, δP
81.0−84.6) resonances. The cyanocarbon fragment gives rise to
two closely spaced 13C resonances at δ ca. 116−120. Carbon
atoms in the C4 chain were found at δ ca. 75, 120, 150, and 200,
the last signal being a triplet (J(CP) ca. 23 Hz) and arising from
C(1). It is likely that the signal at δ ca. 150 arises from the
C(CN)2 carbon, so that the other resonances can be assigned to
C(2) and C(3). The various substituents at C(3) gave rise to
Attempts to use alkynyl anions to displace the CN(3) group
were unsuccessful, several complexes containing heterocyclic
ligands having been isolated instead. These are probably
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formed by attack at a CN group and will be described
elsewhere.
Electrochemistry and UV−Vis Spectroscopy. The redox
properties of some of these compounds, which are summarized
in Table 1, are also of interest. For 1 and 13, reduction events
Nitrogen nucleophiles also displace the CN group, a reaction
between 1 and NHEt2 affording the two products Ru{C
CC(NREt)C(CN)2}(dppe)Cp* (R = H (7; 23%), Et (8;
34%)). These complexes were readily separated by preparative
TLC and were characterized on the basis of their 1H NMR and
ES-MS spectra. Of note are the IR ν(CC) bands at relatively
high frequencies (2019 and 2014 cm−1, respectively; cf. 1979
cm−1 in 1), a result of the strong electron-donor property of the
amino groups. Compound 7 has the NH resonance at δH 5.36.
In particular, the ES-MS of these complexes (obtained from
solutions containing NaOMe) contained [M + Na]+ ions at m/
z 802 and 830, respectively, while confirmation of the structure
of 7 by an X-ray diffraction structure determination is reported
below. Loss of an ethyl group from NHEt2 during this reaction
may result from activation of the NEt2 group in 8 by the cyano
carbon, perhaps resulting in a reaction similar to a β-
elimination.
Table 1. Electrochemical and UV−Vis Data
electrochemistry (V)
1
2
R
Ered
Eox
Eox
λmax/nm (ε/M−1 cm−1
)
i
i
i
i
i
i
NEt2 (8)
But (4)
+0.53
+0.58
+0.64
+0.70
+0.72
+0.69
+0.91
+1.35
+1.23
+1.08
+1.17
+1.38
+1.17
315 (14 600), 386 (17 600)
456 (23 000)
H (14)
460 (26 900)
OMe (9)
OBut (11)
416 (n.a.)
426 (22 000)
P(O)Ph2 (13) −1.40
CN (1) −1.06
527 (18 900)
p
557 (26 200)
i
p
Irreversible. Partially reversible (ia/ic = 0.8). n.a. = not available. All
values in V vs SCE, referenced to FeCp*2/[FeCp*2]+ = −0.02 V.
Electrochemical samples (1 mM) were dissolved in CH2Cl2 containing
0.1 M [NBu4]PF6 as supporting electrolyte.
Addition of sodium to a solution of 1 in a mixture of THF
and MeOH smoothly afforded Ru{CCC(OMe)C(CN)2}-
(dppe)Cp* (9; 36%), while a similar procedure using allyl
alcohol afforded Ru{CCC(OCH2CHCH2)C(CN)2}-
(dppe)Cp* (10; 22%). The OBut analogue 11 was obtained
in 21% yield from 1 and KOBut. Addition of LiBr or LiCl to the
reaction mixture, or using LiMe·LiBr, increased the yields of 10
and 11 to 42 and 54%, respectively, possibly by increasing the
rate of substitution by stabilizing the negative charge in the
transition state.10−12 A further example of an alkoxy derivative
was obtained from the reaction between 1 and HCCCO2Et/
Na[N(SiMe3)2], which afforded Ru{CCC(OEt)C(CN)2}-
(dppe)Cp* (12), possibly because the alkynyl ester is
converted to the stronger nucleophile NaOEt more rapidly
than reaction with 1 can occur. As mentioned above, complex
products were obtained from reactions involving other
(simpler) alkynyl anions. The NMR spectra of these complexes
showed the expected signals for the OR groups.
are found at −1.06 and −1.40 V vs SCE, respectively, which
may reflect the presence of electron-withdrawing groups on
C(3). The redox potentials (+0.53 V (NEt2) to +0.91 V (CN))
correlate well with the UV−vis λmax values (Table 1). At higher
potentials, a second, irreversible, process is found at potentials
which appear to be inversely related to the electron-donor
power of the gem substituent: e.g., +1.08 (H) to +1.35 V
(NEt2). This process is not found for 1 within the solvent range
employed.
These complexes are notable for the strong variation in their
colors, through yellow (OR, NR2), orange (alkyl), red-orange
(H), and pink (P(O)Ph2) to violet (CN), with differing
substituents (Figure 1). A feature of the UV−vis spectra (Table
Extension of these substitutions to a phosphorus nucleophile
was achieved in the reaction between 1 and LiPPh2.
Conventional workup afforded a deep pink compound in
40% yield, which was identified as the phosphoryl derivative
Ru{CCC[P(O)Ph2]C(CN)2}(dppe)Cp* (13) by an X-
ray structure determination. IR bands at 1958 cm−1 (ν(CC))
and a weak ν(PO) absorption at 1195 cm−1 in the IR spectrum
also supported this formulation. It is likely that air oxidation of
an initial PPh2 product, whose presence was suggested by 31P
resonances at δ 30.5 and 81.0 (1/2) in the reaction mixture,
which also contained signals at δ 23.6 and 83.3 (1/2) from the
phosphoryl derivative 13, occurs during reaction or workup.
Substitution of the CN(3) group by hydride was initially
achieved in a reaction between 1 and Na[Fe(CO)2Cp], and
orange-red Ru{CCCHC(CN)2}(dppe)Cp* (14) was
obtained in 89% yield. The direct reaction between 1 and
Li[BHEt3] in THF at −78 °C afforded 14 in 45% yield. The
−CH− group gives resonances at δH 6.75 and δC 142.22. The
unusual replacement of CN by H during the reaction between
1 and Na[Fe(CO)2Cp] cannot be easily explained. There are
analogous reactions in the formation of Fe{CH(CN)2}-
(CO)2Cp in the reaction of the same carbonylmetal anion
Figure 1. UV−vis spectra of Ru{CCC(R)C(CN)2}(dppe)Cp* in
CH2Cl2; R = CN (1; blue trace), But (4; red trace), NEt2 (8; green
trace), P(O)Ph2 (13; magenta trace).
1) is an intense absorption (ε ca. 20 000 M−1.cm−1), with λmax
ranging between 386 to 557 nm. This results from the
polarization conferred by the presence of an electron-rich metal
center and the strongly electrophilic cyanocarbon fragment
linked by the CC core (D−π−A sytems). Changes in λmax
with different substituents at C(3) relate to the stronger
electron-withdrawing substituent having the higher λmax value,
from 557 nm (for 1) to 386 nm (in 8). The latter has a second
13
with CBr2(CN)2 and of Fe(C6F4H-4)(CO)2Cp from similar
reactions of C6F5X (X = F, Cl, Br, I).14 In all cases, the
byproduct is {Fe(CO)2Cp}2, suggesting that radical reactions
may be involved.
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absorption band at 315 nm, perhaps because of the presence of
a second strong electron donor (NEt2).
2.234(2)−2.304(2) Å and Ru−P = 2.2665(4)−2.3093(6) Å
and angles at Ru between 82.60(2) and 84.66(2)° (P(1)−Ru−
P(2)) and between 81.17(7) and 92.97(6)° (P(1,2)−Ru−
C(1)) (extreme values found in molecule 1 of 13).
As found for 1,2 complex 4 displays marked solvatochrom-
ism, the main absorption shifting from 456 nm (CH2Cl2) to
438 nm (hexane/CH2Cl2, 24/1). This feature supports the
assignment of the strong absorption band to an M→L CT, as
substantiated for 1 by the DFT calculations described
elsewhere.2b Partial spatial overlap of the HOMO and
LUMO allows a facile transition to occur. Similar effects
found for other “push−pull” molecules, including some related
substituted alkynyl−ruthenium complexes,15 have been attrib-
uted to the stability of the excited state in more polar
solvents.16 In such molecules, optical properties are related to
the polarizability of the π-bonding electrons in the bridging
core.17,18 However, unlike some related compounds, including
cyano(ethynyl)ethenes, our complexes do not fluoresce,
possibly because the metal center quenches any emissions.
Molecular Structures. The molecular structures of several
of the complexes described above have been determined by
single-crystal X-ray diffraction methods, our preliminary
communication containing details for compounds 1 and 9.2a
Figure 2 depicts a single molecule of 3 (as representative of
The alkynyl group is attached to Ru by a single bond
(1.925(2)−1.977(6) Å, average 1.955(13) Å), the M−CC−
C fragment being approximately linear (angles at C(1)
170.5(3)−178.8(6)° (average 175.7(24)°), angles at C(2)
167.9(2)−177.8(4)° (average 173.0(32)°), the short C(1)−
C(2) separation (1.215(5)−1.234(8) Å, average 1.232(8) Å)
confirming the retention of the CC triple bond. The
similarity of the C(2)−C(3) (1.371(3)−1.428(4) Å, average
1.396(16) Å) and C(3)C(4) bond lengths (1.368(8)−
1.412(4) Å, average 1.386(18) Å) suggests considerable
electron delocalization within this fragment (see below). The
substituted vinyl group bears two CN groups on C(4) (C(4)−
C(41,42) = 1.409(4)−1.437(8) Å, average 1.428(11) Å), while
the second substituent on C(3), which reflects the substitution
chemistry of 1, is gem to the M−CC fragment. The
substituents on C(3) are attached by C(3)−X bonds, where X
= C (1.494(9)−1.541(5) Å, average 1.516(18) Å), N(3)
(1.344(4), 1.345(4) Å), O(3) (1.349(3) Å, cf. 1.347(3) Å for
92a), P(3) (1.837(2), 1.845(2) Å). There are generally no
significant differences in the Ru−C(1)−C(2)−C(3)−C(4)
bond lengths (Table 2) as the substituent X attached to C(3)
is changed, with the exception of 1 and 13, in which X is
strongly electron accepting. The geometrical parameters of
these substituents are normal and do not merit further
discussion.
DISCUSSION
■
The chemistry of TCNE is dominated by nucleophilic
displacement of one or two CN groups,4,5 a feature which we
were able to use in the synthesis of compounds such as
Ru{CCC(CN)C(CN)2}(dppe)Cp* (1) when sterically
demanding alkynyl−group 8 metal complexes are used.2 This
reaction is an alternative to the [2 + 2] cycloaddition reactions
which are usually found.1 The likely mechanism involves
stabilization of an intermediate charged species by the 
C(CN)2 group, followed by elimination of the CN(3) group as
cyanide.
Figure 2. Projection of molecule 1 of Ru{CCCMeC(CN)2}-
(dppe)Cp* (3) as representative of complexes 2, 4, 6, 7, 13, and 14
(projections of these molecules are given as Figures S1−S6 in the
Supporting Information).
The present work has been concerned with the synthesis of a
range of 3-substituted dicyanobutenynyl complexes from
reactions between 1 and various nucleophiles. Thus, we have
been able to replace the gem CN group by H, alkyl, amino,
alkoxy, and phosphorus groups under mild conditions. In the
last reaction, we suggest that the expected phosphine complex,
containing an uncoordinated P(III) atom, is readily oxidized
during the workup. The resulting complexes have been
molecules of 2, 4, 6, 7, 13, and 14, similar plots of which are to
be found in the Supporting Information as Figures S1−S6;
selected structural data for all complexes studied are collected
in Table 2 and Table S1 (Supporting Information)).
Common features for all molecules include the Ru(dppe)-
Cp* group, which has been described on many earlier
occasions.19 The present determinations confirm the presence
of this pseudo-octahedral fragment, with Ru−C(cp*) =
Table 2. Bond Distances (Å) for Ru−C(1)C(2)−C(3)XC(4)(CN)2 Chains
X
Ru−C(1)
1.926(6)
C(1)−C(2)
C(2)−C(3)X
C(3)C(4)
ref
CN (1)
Bu (2)
Me (3)
But (4)
1.243(7)
1.388(8)
1.368(8)
2
1.959, 1.977(6)
1.951, 1.957(2)
1.966(4)
1.234, 1.218(8)
1.234, 1.232(2)
1.215(5)
1.395, 1.390(8)
1.388, 1.391(2)
1.395(5)
1.393, 1.392(8)
1.387, 1.379(2)
1.393(5)
this work
this work
this work
this work
this work
this work
this work
2a
CH2C6H3Me (6)
NHEt (7)
1.958(2)
1.229(3)
1.393(3)
1.376(3)
1.966, 1.965(3)
1.925, 1.936(2)
1.952(2)
1.232, 1.234(4)
1.244, 1.241(3)
1.231(3)
1.418, 1.428(4)
1.371, 1.376(3)
1.387(3)
1.404, 1.412(4)
1.402, 1.397(3)
1.383(3)
P(O)Ph2 (13)
H (14)
OMe (9)
1.950(2)
1.237(3)
1.391(3)
1.388(3)
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spectrometer via a 10 mL injection loop. Nitrogen was used as the
drying and nebulizing gas. Peaks listed are the most intense of the
isotopic clusters. CVs were recorded using a PAR Model 263A
potentiostat, with a saturated calomel electrode. The cell contained a
Pt-disk working electrode and Pt-wire counter and pseudoreference
electrodes. Electrochemical samples (1 mM) were dissolved in CH2Cl2
containing 0.1 M [NBu4]PF6 as supporting electrolyte. Potentials are
given in V vs SCE, referenced to FeCp*2/[FeCp*2]+ (−0.02 V) as
internal calibrant. Elemental analyses were by CMAS, Belmont,
Victoria, Australia, and by Campbell Microanalytical Centre,
University of Otago, Dunedin, New Zealand.
characterized spectroscopically and, in many cases, by single-
crystal X-ray diffraction structure determinations. Their
spectroscopic properties, in particular the NMR and UV−vis
spectra, reflect the presence of the various substituents and
their varying electron donor powers.
This chemistry is paralleled by the substitution chemistry of
TCNE itself, e.g., in the reaction with 1,2-dihydroxyethane
(ethylene glycol) to give (NC)2CC(OCH2CH2O),4,5 and is
a result of the presence of good leaving groups on the alkene.
Notable features of this chemistry include the enhanced yields
obtained when alkylation reactions, for example, are carried out
in the presence of metal halides10−12 and the unusual, although
not unprecedented,9 isomerization of the expected mesityl
complex to the 3,5-dimethylbenzyl derivative, perhaps driven
by the steric requirements around C(3). In addition, the C(3)−
CN bond in 1 (1.477(8) Å) is significantly longer than the
other two C−CN bonds, a property consistent with the ready
cleavage of the C(3)−CN bond during the reactions described
above. The formation of both 7 and 8 from the reaction
between 1 and NHEt2 may result from competitive elimination
of (HCN + C2H4) and EtCN during the course of the reaction;
we could not detect any NH2Et in our sample of NHEt2. The
unusual replacement of CN by H during the reaction between
1 and Na[Fe(CO)2Cp] cannot be easily explained, although
conversion of the anion to {Fe(CO)2Cp}2 suggests that radical
reactions may be involved.
Reagents. The complex Ru{CCC(CN)C(CN)2}(dppe)Cp*
(1) was obtained as described previously.2 All other reagents were
obtained from Sigma-Aldrich or Fluka and used as received without
further purification.
Preparation of Ru{CCCRC(CN)2}(dppe)Cp*. (a). R = Bu
(2). (i) A stirred solution of Ru{CCC(CN)C(CN)2}(dppe)Cp*
(1; 50 mg, 0.066 mmol) in thf (15 mL) was cooled to −78 °C and
treated with LiBu (2.5 M in hexane, 29 μL, 0.073 mmol). The purple
solution turned dark orange and was warmed to room temperature.
Solvent was removed, and the residue was purified by preparative TLC
(acetone/hexane, 3/7) to give some recovered starting material (Rf =
0.39; 5 mg, 10%). An orange band (Rf = 0.48) contained bright orange
Ru{CCCBuC(CN)2}(dppe)Cp* (2; 15 mg, 30%, conversion
33%). X-ray-quality crystals were grown from hexane. Anal. Calcd
(C46H48N2P2Ru): C, 69.77; H, 6.11; N, 3.54; Mr, 792. Found: C,
69.95; H, 6.32; N, 3.55. IR/cm−1: ν(CN) 2210 w, ν(CC) 1989
vs, ν(CC) 1483 m. 1H NMR: δ 0.75 (t, J = 7 Hz, 3H, Me), 1.10 (m,
4H, 2 × CH2), 1.56 (s, 15H, Cp*), 2.09 (t, J = 7 Hz, 2H, CH2) 2.26,
2.88 (2m, 2 × CH2, CH2−P), 7.19−7.54 (m, 20H, Ph). 13C NMR
(C6D6): δ 10.05 (s, C5Me5), 14.08, 22.30, 31.15, 39.26 (4s, Bu),
29.41−30.20 (m, CH2−P), 77.45, 124.45, 160.81 (3s, C), 95.40 (s,
C5Me5), 117.44, 117.57 (2s, CN), 127.74−138.37 (Ph), 198.31 (m,
Ru−C). 31P NMR: δ 82.4 (s, dppe). ES-MS (m/z): 635, [Ru(dppe)-
Cp*]+; 792, M+; 815, [M + Na]+; 1427, [M + Ru(dppe)Cp*]+; 1607,
[2 M + Na]+.
(ii) To a stirred solution of Ru(CCH)(dppe)Cp* (50 mg, 0.08
mmol) in thf (12 mL) at −78 °C was added BuLi (2.5 M in hexane, 45
μL, 0.11 mmol). After 40 min Ru{CCC(CN)C(CN)2}(dppe)-
Cp* (64 mg, 0.08 mmol) was added to the solution. The solution
gradually changed from deep purple to yellow-purple. Solvent was
removed, and the residue was purified by preparative TLC (acetone/
hexane, 3/7) to afford some starting material and bright orange
Ru{CCCBuC(CN)2}(dppe)Cp* (2; 13 mg, 22%).
These complexes are further examples of “push−pull”
compounds, in which an electron-rich center is linked via a
conjugated carbon chain to a strongly electrophilic group
(D−π−A systems).16−18,20 As mentioned above, considerable
work is currently directed toward the synthesis of purely
organic molecules that fall into this category, which have
potential as components in molecular electronics (optoelec-
21,22
tronics, nonlinear optics).198,
Their absorptions across the
visible region provide a measure of the HOMO−LUMO
energy gap as a function of the electron-donor power of the 3-
substituent, and the variations observed here indicate that
subtle tuning of this gap is possible. The redox potentials,
which decrease as the donor power of the 3-substituent
increases, also provide a measure of these changes.
(b). R = Me (3). A stirred solution of 1 (60 mg, 0.079 mmol) in thf
(10 mL) was cooled to −78 °C and treated with LiMe·LiBr (1.5 M in
hexane, 60 μL, 0.09 mmol). The solution acquired an orange tinge,
and a further 1 equiv of MeLi·LiBr solution (75 μL) was added, upon
which the solution turned orange. The solution was warmed to room
temperature, and solvent was removed. The residue was purified by
preparative TLC (acetone/hexane, 3/7), an orange band (Rf = 0.44)
affording bright orange Ru{CCC(Me)C(CN)2}(dppe)Cp* (3;
45 mg, 76%). X-ray-quality crystals were grown from CDCl3/MeOH
or CH2Cl2/hexane. Anal. Calcd (C43H42N2P2Ru): C, 68.78; H, 5.64;
N, 3.73; Mr, 750. Found: C, 68.87; H, 5.63; N, 3.74. IR/cm−1: ν(C
N) 2212 w, 2196 w, ν(CC) 1993 vs, ν(CC) 1487 m, 1435 w. 1H
NMR: δ 1.56 (s, 15H, Cp*), 1.75 (s, 3H, Me), 2.19, 2.84 (2m, 2 × 2H,
CH2−P), 7.17−7.58 (m, 20H, Ph). 13C NMR: δ 10.18 (s, C5Me5),
25.77 (s, Me), 28.88−30.02 (m, CH2−P), 73.56, 124.83, 155.79 (3s,
C), 95.51 (s, C5Me5), 117.16, 117.38 (2s, CN), 127.86−136.92 (Ph),
199.20 (m, Ru−C). 31P NMR: δ 81.6 (s, dppe). ES-MS (m/z): 750,
M+; 773, [M + Na]+.
EXPERIMENTAL SECTION
■
General Considerations. All reactions were carried out under dry
nitrogen, although normally no special precautions to exclude air were
taken during subsequent workup. Common solvents were dried,
distilled under nitrogen, and degassed before use. Separations were
carried out by preparative thin-layer chromatography on glass plates
(20 × 20 cm2) coated with silica gel (Merck, 0.5 mm thick) or by flash
chromatography (Davisil 40−63 μm).
Instruments. IR spectra were obtained using a Bruker IFS28 FT-
IR spectrometer. Unless otherwise stated, spectra in CH2Cl2 were
obtained using a 0.5 mm path length solution cell with NaCl windows.
Nujol mull spectra were obtained from samples mounted between
NaCl disks. NMR spectra were recorded on a Varian 2000 (1H at
300.13 MHz, 13C at 75.47 MHz, 31P at 121.503 MHz) or Unity Inova
600 instrument, the latter being equipped with a cryoprobe (1H at
599.653 MHz, 13C at 150.796 MHz). Samples were dissolved in
CDCl3 contained in 5 mm sample tubes. Chemical shifts are given in
ppm relative to internal tetramethylsilane for 1H and 13C NMR spectra
and external H3PO4 for 31P NMR spectra. UV−vis−near-IR spectra
were obtained with a Varian-Cary 5000 UV−vis−near-IR spectropho-
tometer. Samples were contained in fused quartz cells, path length 1
cm. Electrospray mass spectra (ES-MS) were obtained from samples
dissolved in MeOH; in some cases, NaOMe was used as an aid to
ionization.23 Solutions were injected into a Fisons VG Platform II
(c). R = But (4). A stirred solution of 1 (81 mg, 0.106 mmol) in thf
(12 mL) was cooled to −78 °C. To the solution was added LiBut (1.6
M solution in pentane, 80 μL, 0.128 mmol) to give an instant color
change to orange. The solution was warmed to room temperature,
solvent was removed, and the residue was purified by preparative TLC
(acetone/hexane, 3/7) to give an orange band (Rf = 0.48) containing
Ru{CCCBut=C(CN)2}(dppe)Cp* (4; 23 mg, 27%). X-ray-quality
crystals were grown from CH2Cl2/MeOH. Anal. Calcd
4178
dx.doi.org/10.1021/om300059q | Organometallics 2012, 31, 4174−4181

Organometallics
Article
(C46H48N2P2Ru): C, 69.77; H, 6.11; N, 3.54; Mr, 792. Found: C,
69.69; H, 6.14; N, 3.66. IR/cm−1: ν(CN) 2204 w, 2190 (sh), ν(CC)
Hz, Ru−C). 31P NMR: δ 83.9 (s, dppe). ES-MS (m/z): 635,
[Ru(dppe)Cp*]+; 808, [M + H]+; 830, [M + Na]+.
1
1980 vs, ν(CC) 1456 m, 1437 m. H NMR: δ 0.88 (s, 9H, But),
(g). R = OMe (9). Na (15 mg, 0.670 mmol) was dissolved in a
mixture of thf and MeOH (15 mL, 2/1), and 1 (170 mg, 0.223 mmol)
was added to the solution. The reaction was monitored by spot TLC,
and starting material was consumed after 6 h to give a pink-red
solution. Solvent was removed, and the residue was purified by column
chromatography (flash silica, acetone/hexane, 3/7). The first fraction
afforded Ru{CCC(OMe)C(CN)2}(dppe)Cp* (9; 61 mg, 36%)
as a yellow solid. X-ray-quality crystals were obtained from CDCl3/
MeOH. Anal. Calcd (C43H42N2OP2Ru): C, 67.44; H, 5.53; N, 3.66;
Mr, 766. Found: C, 67.40; H, 5.57; N, 3.70. IR/cm−1: ν(CN) 2212
w, 2197 w, ν(CC) 1994 vs, ν(CC) 1487 m, 1435 w. 1H NMR: δ
1.56 (s, 15H, Cp*), 2.30, 2.78 (2m, 2 × H, CH2−P), 3.17 (s, 3H,
OMe), 7.17−7.59 (m, 20H, Ph). 13C NMR: δ 10.25 (s, C5Me5),
29.62−30.54 (m, CH2−P), 57.37 (s, OMe), 95.58 (s, C5Me5), 108.05,
159.98 (2s, C), 116.44, 117.50 (2s, CN), 128.01−137.89 (m, Ph),
192.26 (m, Ru−C). 31P NMR (CDCl3): δ 82.3 (s, dppe). ES-MS (m/
z): 635, [Ru(dppe)Cp*]+; 767, [M + H]+.
(h). R = OCH2CHCH2 (10). Na (23 mg, 1.00 mmol) and LiBr (17
mg, 0.197 mmol) were dissolved in a mixture of thf and allyl alcohol
(9.5 mL, 16/3). 1 (75 mg, 0.099 mmol) was then added to the
solution. After 2.5 h, starting material was no longer present in the
now red solution. Solvent was removed, and the residue was purified
by column chromatography (flash silica, acetone/hexane, 3/7), the
first yellow fraction giving Ru{CCC(OCH2CHCH2)C-
(CN)2}(dppe)Cp* (10; 32 mg, 42%) as a yellow solid. Anal. Calcd
(C45H44N2OP2Ru): C, 68.16; H, 5.60; N, 3.54; Mr, 792. Found: C,
68.12; H, 5.71; N, 3.59. IR/cm−1: ν(CN) 2213 m, 2199 w, ν(C
C) 1995 vs, ν(CC) 1487 s, 1436 m. 1H NMR: δ 1.55 (s, 15H, Cp*),
2.27, 2.75 (2m, 2 × 2H, CH2−P), 3.93 (d, J = 4.8 Hz, 2H, OCH2),
4.99 (m, 1H, HT; HC, HG, HT = protons cis, gem, trans to OCH2), 5.27
(m, 1H, HC), 5.44 (m, 1H, HG), 7.16−7.59 (m, 20H, Ph). 13C NMR: δ
10.22 (s, C5Me5), 29.56−30.31 (m, CH2−P), 58.48, 107.99, 158.82
(3s, C), 70.41 (s, OCH2), 95.51 (s, C5Me5), 116.30, 117.51 (2s, CN),
117.37 (CH2), 128.13−137.65 (Ph), 191.64 (t, J(CP) = 23 Hz, Ru−
C). 31P NMR: δ 82.4 (s, dppe). ES-MS (m/z) 635, [Ru(dppe)Cp*]+;
815, [M + Na]+; 1607, [2 M + Na]+.
1.55 (s, 15H, Cp*), 2.35, 2.89 (2m, 2 × 2H, CH2−P), 7.17−7.59 (m,
20H, Ph). 13C NMR: δ 10.22 (s, C5Me5), 29.66 (s, CMe3), 28.50−
31.02 (m, CH2−P), 39.46 (s, CMe3), 73.40, 125.59, 167.92 (3s, C),
95.61 (s, C5Me5), 118.74, 118.94 (2s, CN), 127.66−138.98 (Ph),
200.28 (m, Ru−C). 31P NMR: δ 84.6 (s, dppe). ES-MS (m/z): 792,
M+.
(d). R = Pri (5). MgClPri (0.5 M solution in thf, 41 μL, 0.081 mmol)
was added to a solution of 1 (41 mg, 0.054 mmol) in thf (7 mL) at 0
°C, resulting in an instant color change to orange. After the mixture
was warmed to room temperature, solvent was removed and the
residue was purified by preparative TLC (acetone/hexane, 3/7) to give
an orange band (Rf = 0.48) containing Ru{CCCPri=C(CN)2}-
(dppe)Cp* (5; 20 mg, 48%). Anal. Calcd C45H46N2P2Ru): C, 69.48;
H, 5.96; N, 3.60; Mr, 778. Found: C, 69.62; H, 6.07; N, 3.66. IR/cm−1:
ν(CN) 2211 w, 2197 w, ν(CC) 1987 vs, ν(CC) 1480 m, 1435
w. 1H NMR: δ 0.68 (d, J = 6.6 Hz, 6H, 2 × Me), 1.55 (s, 15H, Cp*),
2.30, 2.95 (2m, 2 × 2H, CH2−P), 2.77 (sept, J = 6.6 Hz, 1H, CHMe2),
7.15−7.58 (m, 20H, Ph). 13C NMR: δ 10.26 (s, C5Me5), 21.64 (s,
Me), 29.47−31.08 (m, CH2−P), 36.54 (s, CH), 73.20, 121.39, 165.94
(3s, C), 95.45 (s, C5Me5), 117.40, 117.48 (2s, CN), 127.65−138.72
(Ph), 197.90 (m, Ru−C). 31P NMR: δ 83.7 (s, dppe). ES-MS (m/z):
801, [M + Na]+.
(e). R = CH2C6H3Me2-3,5 (6). MgBr(mes) (1.0 M solution in Et2O,
80 μL 0.08 mmol) was added to a solution of 1 (40 mg, 0.053 mmol)
in thf (7 mL) at 0 °C. After 24 h at room temperature, solvent was
removed and purification of the residue by preparative TLC (acetone/
hexane, 3/7) afforded Ru{CCC(CH2C6H3Me2-3,5)C(CN)2}-
(dppe)Cp* (6; 5 mg, 11%) contained in an orange band (Rf =
0.48). X-ray-quality crystals were grown from CH2Cl2/hexane. Anal.
Calcd (C51H50N2P2Ru): C, 71.73; H, 5.90; N, 3.28; Mr, 854. Found:
C, 71.51; H, 6.65; N, 3.10. IR/cm−1: ν(CN) 2209 w, ν(CC) 1990
1
vs, ν(CC) 1485 m, 1433 w, 1420 w. H NMR: δ 1.26 (s, 6H, 2 ×
Me), 1.50 (s, 15H, Cp*), 1.93, 2.33 (2m, 2 × 2H, CH2−P), 3.21 (s,
2H, CH2), 6.39, 6.76 (2s, 2H + 1H, o- and p-C6H3), 7.12−7.45 (m,
20H, Ph). 13C NMR: δ 9.90 (s, C5Me5), 22.68 (s, Me2C6H3), 29.21−
29.69 (m, CH2−P), 44.24 (s, C−CH2−C6), 75.18, 124.84, 157.00 (3s,
C), 95.23 (s, C5Me5), 116.98, 117.57 (2s, CN), 126.57−137.55 (Ph +
C6H3), 199.47 (m, Ru−C). 31P NMR: δ 81.6 (s, dppe). ES-MS (m/z):
877, [M + Na]+.
(i). R = OBut (11). KOBut (37 mg, 0.329 mmol) was added to a
solution of 1 (47 mg, 0.062 mmol) and LiCl (14 mg, 0.329 mmol) in
thf (8 mL). After 30 min, solvent was removed and the residue was
purified on a column of flash silica (acetone/hexane, 3/7) to give a
bright yellow fraction containing Ru{CCC(OBut)C(CN)2}-
(dppe)Cp* (11; 27 mg, 54%). Anal. Calcd (C46H48N2OP2Ru): C,
68.39; H, 5.99; N, 3.47; Mr, 808. Found: C, 67.18; H, 6.42; N, 3.16.
IR/cm−1: ν(CN) 2211 w, 2196 w, ν(CC) 1982 vs, ν(CC) 1489
m, 1449 w, 1438 w. 1H NMR: δ 1.11 (s, 9H, But), 1.55 (s, 15H, Cp*),
2.35, 2.91 (2m, 2 × 2H, CH2−P), 7.14−7.65 (m, 20H, Ph). 13C NMR:
δ 10.34 (s, C5Me5), 28.31 (s, OCMe3), 29.08−30.82 (m, CH2−P),
63.16, 111.89, 158.04 (3s, C), 83.24 (s, OCMe3), 95.49 (s, C5Me5),
117.21, 117.83 (2s, CN), 127.94−138.85 (Ph), 187.49 (m, Ru-C). 31P
NMR: δ 84.5 (s, dppe). ES-MS (m/z): 831, [M + Na]+.
(j). R = OEt (12). A solution of ethyl propiolate (193 mg, 1.97
mmol) in thf (10 mL) was treated with Na[N(SiMe3)2] (1.96 mL of
1.0 M solution in toluene, 1.97 mmol) at −78 °C. After the mixture
was stirred for 30 min, 1 (100 mg, 0.131 mmol) was added, and the
mixture was slowly warmed to room temperature over 8 h. Solvent was
removed, and the residue was purified by column chromatography
(acetone/hexane, 3/7). The first yellow fraction contained Ru{C
CC(OEt)C(CN)2}(dppe)Cp* (12; 33 mg, 32%). Anal. Calcd
(C44H44N2OP2Ru): C, 67.77; H, 5.69; N, 3.59; Mr, 780. Found: C,
67.32; H, 5.68; N, 3.57. IR/cm−1: ν(CN) 2211 w, 2195 w, ν(CC)
1995 vs, ν(CC) 1485 s, 1436 w. 1H NMR (C6D6): δ 0.67 (t, J = 7.2
Hz, 3H, OCH2Me), 1.50 (s, 15H, Cp*), 2.00, 2.72 (2m, 2 × CH2,
dppe), 3.42 (q, J = 7.2 Hz, 2H, OCH2Me), 7.02−7.62 (m, 20H, Ph).
13C NMR (CDCl3): δ 10.20 (s, C5Me5), 14.82, 66.30 (2s, OEt),
29.57−30.48 (m, dppe), 95.43 (s, C5Me5), 107.94, 159.27 (2s, C),
116.47, 117.61 (2s, CN), 127.94−137.92 (m, Ph), 189.89 (t, J(CP) =
22 Hz, Ru−C). 31P NMR (C6D6): δ 82.5 (s, dppe). ES-MS (m/z):
781, [M + H]+; 803, [M + Na]+; 1583, [2 M + Na]+.
(f). R = NHR′ (R′ = H (7), Et (8)). A solution of 1 (25 mg, 0.033
mmol) in NHEt2 was stirred at room temperature for 5 days, after
which time the color had changed to golden yellow. Solvent was
removed, and the residue was purified by preparative TLC (CH2Cl2/
hexane, 9/1) to give two yellow compounds identified as Ru{C
CC(NHEt)C(CN)2}(dppe)Cp* (7; 6 mg, 23%, Rf = 0.5) and
Ru{CCC(NEt2)C(CN)2}(dppe)Cp* (8; 9 mg, 34%, Rf = 0.4).
Crystals of 7 suitable for X-ray diffraction were grown from hexane.
Ru{CCC(NHEt)C(CN)2}(dppe)Cp* (7). Anal. Calcd
(C44H45N3P2Ru): C, 67.85; H, 5.82; N, 5.40; Mr, 779. Found: C,
68.13; H, 5.90; N, 5.52. IR/cm−1: ν(NH) 3394 w, ν(CN) 2202 w,
1
2175 w, ν(CC) 2019 vs, ν(CC) 1542 m, 1436 w, 1421 w. H
NMR: δ 0.73 (t, J = 7.5 Hz, NCH2Me), 1.56 (s, 15H, Cp*), 2.30, 2.75
(2m, 2 × CH2, CH2−P), 2.75 (m, CH2, NEt), 5.36 (m, NHEt), 7.19−
7.59 (m, 20H, Ph). 13C NMR: δ 10.01 (s, C5Me5), 15.13 (s, CH3,
NEt), 29.34−29.95 (m, CH2−P), 39.17 (s, CH2, NEt), 48.32, 105.12,
151.04 (3s, C), 94.54 (s, C5Me5), 118.56, 119.25 (2s, CN), 127.56−
138.06 (Ph), 178.84 (t, J(CP) = 22 Hz, Ru−C). 31P NMR: δ 82.9 (s,
dppe). ES-MS (m/z): 635, [Ru(dppe)Cp*]+; 802, [M + Na]+.
Ru{CCC(NEt2)C(CN)2}(dppe)Cp* (8). Anal. Calcd
(C46H49N3P2Ru): C, 68.47; H, 6.12; N, 5.21; Mr, 807. Found: C,
68.69; H, 6.43; N, 5.20. IR/cm−1: ν(CN) 2197 w, 2170 w, ν(CC)
2014 s, ν(CC) 1510 w, 1435 w, 1404 m. 1H NMR: δ 0.88 (t, J = 7.1
Hz, 2 × Me, NEt), 1.55 (s, 15H, Cp*), 2.25, 2.84 (2m, 2 × 2H, CH2−
P), 3.25 (q, J = 7.1 Hz, 2 × CH2, NEt), 7.16−7.64 (m, 20H, Ph). 13
C
NMR: δ 10.09 (C5Me5), 13.58 (s, Me, NEt), 29.67−30.22 (m, CH2−
P), 45.32 (CH2, NEt), 47.12, 108.08, 149.37 (3s, C), 94.35 (br,
C5Me5), 120.62 (s, CN), 127.47−138.52 (Ph), 169.89 (t, J(CP) = 23
4179
dx.doi.org/10.1021/om300059q | Organometallics 2012, 31, 4174−4181

Organometallics
Article
Table 3. Crystal Data and Refinement Details
a
2
3
4
formula
mol wt
cryst syst
space group
a/Å
C46H48N2P2Ru
791.87
C43H42N2P2Ru
749.80
C46H48N2P2Ru. CH4O
823.92
triclinic
monoclinic
P21/c
monoclinic
P21/n
P1
̅
13.081(3)
16.335(3)
18.677(4)
97.080(3)
94.993(4)
98.620(3)
3893
24.1070(3)
15.5408(1)
21.5254(3)
12.9749(1)
16.3939(1)
19.8075(2)
b/Å
c/Å
α/deg
β/deg
112.974(2)
100.480(1)
γ/deg
V/Å3
ρc/g cm−3
7425
4143
1.351
1.342
1.321
Z
4
8
4
2θmax/deg
μ(Mo Kα)/mm−1
Tmin/max
crystal dimens/mm3
Ntot
58
72
128
0.52
0.54
4.1 [μ(Cu Kα)]
0.86
0.90
0.71
0.63 × 0.43 × 0.06
40 918
0.43 × 0.21 × 0.06
170 886
0.20 × 0.11 × 0.015
19 286
N (Rint)
No
17 648 (0.054)
11 119
34 131 (0.053)
19 311
6410 (0.032)
4926
R1
0.063
0.037
0.035
wR2 (a, b)
T/K
0.18 (0.036, 26)
150
0.091 (0.040, −)
100
0.099 (0.060, −)
100
6
7
13
14
formula
C51H50N2P2Ru
853.94
C44H45N3P2Ru
778.84
C54H49N2OP3Ru. CH2Cl2
1020.86
C42H40N2P2Ru
735.77
mol wt
cryst syst
space group
a/Å
monoclinic
P21/c
monoclinic
P21/c
triclinic
monoclinic
P21/n
P1
̅
11.5378(3)
15.8074(4)
23.9009(6)
23.5091(8)
16.3084(6)
21.2864(9)
13.8361(3)
14.1441(3)
26.9670(4)
90.796(2)
104.115(2)
108.390(2)
4833
12.2366(7)
15.1830(8)
19.613(2)
b/Å
c/Å
α/deg
β/deg
101.215(3)
112.715(4)
96.766(6)
γ/deg
V/Å3
ρc/g cm−3
4276
7528
3618
1.351
4
1.327
1.374
1.403
Z
4
8
4
2θmax/deg
μ(Mo Kα)/mm−1
Tmin/max
crystal dimens/mm3
Ntot
68
60
66
63
0.48
0.54
0.58
0.55
0.95
0.94
0.96
0.93
0.37 × 0.12 × 0.12
71 342
0.17 × 0.08 × 0.04
85 845
0.43 × 0.17 × 0.14
78 310
0.34 × 0.30 × 0.12
60 803
N (Rint)
No
16 791 (0.045)
8979
20 429 (0.10)
9910
34 287 (0.039)
22 613
12 854 (0.039)
8120
R1
0.039
0.041
0.044
0.036
wR2 (a, b)
T/K
0.096 (0.045, −)
100
0.073 (0.0183, −)
100
0.121 (0.065, −)
100
0.092 (0.047, −)
100
a
Data measured with monochromatic Cu Kα radiation; λ = 1.541 84 Å.
(k). R = P(O)Ph2 (13). To a stirred solution of 1 (60 mg, 0.079
δ 1.59 (s, 15H, Cp*), 2.12, 3.65 (2m, 2 × 2H, CH2−P), 6.95−7.16 (m,
30H, Ph). 13C NMR: δ 9.93 (s, C5Me5), 29.25−30.14 (m, CH2−P),
78.46 (d, J(CP) = 20 Hz, C(CN)2), 97.03 (s, C5Me5), 117.11 (s, CN),
118.24 (d, J(CP) = 16 Hz, C), 128.01−137.89 (Ph), 146.37 (d, J(CP)
= 83 Hz, C−P), 227.85 (m, Ru−C). 31P NMR: δ 23.6 (s, 1P,
P(O)Ph2), 83.3 (s, 2P, dppe). ES-MS (m/z): 937, [M + H]+; 959, [M
+ Na]+; 1895, [2 M + Na]+.
(l). R = H (14). (i) To a stirred solution of 1 (70 mg, 0.092 mmol) in
thf (10 mL) at room temperature was added a solution of
Na[Fe(CO)2Cp] (0.12 M, 0.84 mL, 1.1 equiv, from {Fe(CO)2Cp}2
(207 mg, 0.577 mmol) and 3% Na/Hg (2.1 g) in thf (10 mL)). The
reaction was monitored by spot TLC and showed that starting material
mmol, 1 equiv) in thf (8 mL) was added 1 mL of a solution of LiPPh2
(1 mL of the red solution obtained from the reaction between Li (6
mg, 0.087 mmol) and PPh3 (228 mg, 0.87 mmol) in thf (10 mL) over
1 day). After 2 h, solvent was removed and the residue was purified by
preparative TLC (acetone/hexane, 3/7) to give a band (Rf = 0.39)
containing purple Ru{CCC[P(O)Ph2]C(CN)2}(dppe)Cp* (13;
29 mg, 40%). X-ray-quality crystals were grown from CH2Cl2/hexane.
Anal. Calcd (C54H49N2OP3Ru.CH2Cl2): C, 64.70; H, 5.04; N, 2.75; Mr
(unsolvated), 936. Found: C, 65.22; H, 5.31; N, 2.80. IR/cm−1: ν(C
N) 2209 w, 2191 (sh), ν(CC) 1958 vs, ν(CC) 1437 m, 1425 w;
in Nujol ν(CN) 2201 m, ν(CC) 1948v s, ν(PO) 1195 w. 1H NMR:
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Organometallics
Article
remained after 16 h. A further 3 equiv of Na[Fe(CO)2Cp] solution
(2.3 mL) was added. After 1 h, all the starting material had been
consumed and the solution had changed from purple to orange-brown.
Solvent was removed, and the residue was purified by column
chromatography (flash silica, acetone/hexane, 1/4). The first brown-
red fraction contained {Fe(CO)2Cp}2 (15 mg, 91%). The second red-
orange fraction afforded Ru{CCCHC(CN)2}(dppe)Cp* (14; 60
mg, 89%) as a dark red solid. X-ray-quality crystals were obtained from
CDCl3/hexane. Anal. Calcd (C42H40N2P2Ru): C, 68.56; H, 5.48; N,
3.80; Mr, 736. Found: C, 68.61; H, 5.53; N, 3.78. IR/cm−1: ν(CN)
2214 w, 2199 w, ν(CC) 1988 vs, ν(CC) 1509 m, 1483 w, 1435
w. 1H NMR (CDCl3): δ 1.56 (s, 15H, Cp*), 2.19, 2.87 (2m, 2 × CH2,
CH2−P), 6.75 (s, 1H, CCH), 7.20−7.53 (m, 20H, Ph), 13C NMR
(CDCl3): δ 9.99 (s, C5Me5), 28.92−29.86 (m, CH2−P), 75.30, 125.52,
(2s, C), 95.66 (s, C5Me5), 116.32, 118.35 (2s, CN), 127.38−137.33
(Ph), 142.22 (s, CHC), 206.95 (t, J(CP) = 20 Hz, Ru−C). 31P
NMR (CDCl3): δ 81.0 (s, dppe). ES-MS (MeCN, m/z): 635,
[Ru(dppe)Cp*]+; 676, [Ru(NCMe)(dppe)Cp*]+; 736, M+; 759, [M
+ Na]+; 1371, [M + Ru(dppe)(C5Me5)]+; 1495, [2 M + Na]+.
(ii) Addition of Li[BHEt3] (72 μL of 1.00 M solution in thf, 0.072
mmol) to 1 (50 mg, 0.066 mmol) in thf (10 mL) at −78 °C and
warming to room temperature gave an orange-red solution. Removal
of solvent and chromatography (silica column, acetone/hexane, 3/7)
gave 14 (22 mg, 45%), identical with the complex obtained above.
Structure Determinations. Full spheres of diffraction data were
measured using CCD area-detector instrumentation. Ntot reflections
were merged to Nunique (Rint cited) after “empirical”/multiscan
absorption correction (proprietary software), No with F > 4σ(F)
being considered “observed”; all data were used in the full matrix least-
squares refinements on F2. Data were measured using monochromatic
Mo Kα radiation; λ = 0.710 73 Å. Anisotropic displacement parameter
forms were refined for the non-hydrogen atoms, with hydrogen atom
ACKNOWLEDGMENTS
■
This work was supported by the Australian Research Council.
We are grateful to Johnson Matthey plc, Reading, England, for
a generous loan of RuCl3·nH2O.
REFERENCES
(1) Bruce, M. I. Aust. J. Chem. 2011, 64, 77.
■
(2) (a) Bruce, M. I.; Burgun, A.; Kramarczuk, K. A.; Nicholson, B. K.;
Parker, C. R.; Skelton, B. W.; White, A. H.; Zaitseva, N. N. Dalton
Trans. 2009, 33. (b) Bruce, M. I.; Fox, M. A.; Low, P. J.; Nicholson, B.
K.; Parker, C. R.; Patalinghug, W. C.; Skelton, B. W.; White, A. H.
Organometallics 2012, 31, 2639.
(3) (a) Barlow, S.; Marder, S. R. In Functional Organic Materials;
Muller, T. J. J., Bunz, U. H. F., Eds.; Wiley-VCH: Weinheim, Germany,
2005; pp 393−437. (b) Forrest, S. R.. Thompson, M. E., Eds. Chem.
Rev. 2007, 107, 923−1386 (special issue on organic electronics and
optoelectronics).
(4) (a) Cairns, T. L.; Carboni, R. A.; Coffman, D. D.; Engelhardt, V.
A.; Heckert, R. E.; Little, E. L.; McGeer, E. G.; McKusick, B. C.;
Middleton, W. J.; Scribner, R. M.; Scribner, C. W.; Theobald, C. W.;
Winberg, H. E. J. Am. Chem. Soc. 1958, 80, 2775 and the following 11
papers. (b) Ciganek, E.; Linn, W. J.; Webster, O. W. In Chemistry of the
Cyano Group; Rappoport, Z., Ed.; Interscience: London, 1970;
Chapter 9, p 423.
(5) (a) Fatiadi, A. Synthesis 1986, 249. (b) Fatiadi, A. Synthesis 1987,
749. (c) Fatiadi, A. Synthesis 1987, 959.
(6) Trippett, S. J. Chem. Soc. 1962, 4733.
(7) Zbiral, E. Monatsh. Chem. 1965, 96, 1967.
(8) Gamasa, M. P.; Gimeno, J.; Godefroy, I.; Lastra, E.; Martin-Vaca,
B. M.; García-Granda, S.; Guttierez-Rodriguez, A. J. Chem. Soc., Dalton
Trans. 1995, 1901.
(9) (a) Cleary, B. P.; Eisenberg, R. Organometallics 1992, 11, 2335.
(b) Cleary, B. P.; Eisenberg, R. J. Am. Chem. Soc. 1995, 117, 3510.
(10) Gobbi, A.; Landini, D.; Maia, A.; Secci, D. J. Org. Chem. 1995,
60, 5954.
(11) Faust, R.; Weber, C.; Fiandanese, V.; Marchese, G.; Punzi, A.
Tetrahedron 1997, 53, 14655.
(12) Lepore, S. D.; Bhunia, A. K.; Cohn, P. J. Org. Chem. 2005, 70,
8117.
2
treatment following a “riding” model. Reflection weights were (σ2(Fo )
2
+ (aP)2 + bP)−1 (P = (Fo + 2Fc2)/3). Neutral atom complex
scattering factors were used; computation used the SHELXL 97
program.24 Pertinent results are given in the figures (which show non-
hydrogen atoms with 50% probability amplitude displacement
ellipsoids) and in Tables 2 and 3 and Table S1 (Supporting
Information).
(13) King, R. B.; Saran, M. S. J. Am. Chem. Soc. 1973, 95, 1811.
(14) Bruce, M. I. J. Organomet. Chem. 1968, 14, 461.
(15) Bruce, M. I.; Burgun, A.; Parker, C. R.; Skelton, B. W. J.
Organomet. Chem. 2010, 695, 619.
(16) H. Meier, H. Angew. Chem., Int. Ed. 2005, 44, 2482.
(17) He, G. S.; Tan, L.-S.; Zheng, Q.; Prasad, P. N. Chem. Rev. 2008,
108, 1245.
(18) Kivala, M.; Diederich, F. Acc. Chem. Res. 2009, 42, 235.
(19) The Cambridge Structure Data Base (Version 15.3, November
2011) contains over 130 structures containing −C−Ru(PP)Cp*
fragments.
(20) (a) Moonen, N. N. P.; Pomerantz, W. C.; Gist, R.; Boudon, C.;
Gisselbrecht, J.-P.; Kawai, T.; Kishioka, A.; Gross, M.; Irie, M.;
ASSOCIATED CONTENT
■
S
* Supporting Information
Table S1, containing selected bond parameters for 2−4, 6, 7,
13, and 14, figures giving additional crystal structures, and CIF
files containing crystallographic details. This material is
available free of charge via the Internet at http://pubs.acs.org.
Full details of the structure determinations have also been
deposited with the Cambridge Crystallographic Data Centre as
CCDC 705838−705844 (2, 14, 4, 6, 3, 7, and 13, respectively).
Copies of this information may be obtained free of charge from
The Director, CCDC, 12 Union Street, Cambridge CB2 1EZ,
U.K. (fax, +44 1223 336 033; e-mail, deposit@ccdc.cam.ac.uk;
web, http://www.ccdc.cam.ac.uk).
Diederich, F. Chem. Eur. J. 2005, 11, 3325. (b) Bures,
Kivala, M.; Diederich, F. J. Phys. Org. Chem. 2011, 24, 274.
(21) (a) May, J. C.; Baggio, I.; Bures, F.; Diederich, F. Appl. Phys.
̌
F.; Pytela, O.;
̌
Lett. 2007, 90, 251106. (b) Kato, S.-i.; Diederich, F. Chem. Commun.
2010, 46, 235. (c) Gisselbrecht, J.-P.; Moonen, N. N. P.; Boudon, C.;
Nielsen, M. B.; Diederich, F.; Gross, M. Eur. J. Org. Chem. 2004, 2959.
(22) Kuzyk, M. G. J. Mater. Chem. 2009, 19, 7444.
(23) Henderson, W.; McIndoe, J. S.; Nicholson, B. K.; Dyson, P. J. J.
Chem. Soc., Dalton Trans. 1998, 519.
AUTHOR INFORMATION
■
Corresponding Author
*Fax: + 61 8 8303 4358. E-mail: michael.bruce@adelaide.edu.
au.
(24) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
Present Address
∥Centre for Microscopy, Characterisation and Analysis,
University of Western Australia, Crawley, Western Australia
6009, Australia.
Notes
The authors declare no competing financial interest.
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