Ferrocenyl-naphthalimide donor-acceptor dyads with aromatic spacer groups

Article abstract of DOI:10.1021/om1000452

The preparation and characterization of a series of dyads containing ferrocene donor and naphthalimide acceptor units, separated by aromatic spacer groups, are reported. The compounds contain a ferrocene-ethenyl spacer component linked to the 4-position of a naphthalimide by an ethynyl bridge, Fc-CH=CH-spacer-C≡C-naphthalimide (Fc = ferrocenyl), where the spacers are 1,4-phenyl, 4,4′-biphenyl, and 9,10-anthryl. Precursors to the dyad systems, halo-spacer-C≡C-naphthalimide, are also characterized where the halo-spacers are 1-bromophenyl, 4-bromobiphenyl, and 9-iodoanthryl. Various synthetic strategies are examined, with attachment of the spacer to 4-ethynylnaphthalimide followed by reaction with ethenylferrocene proving the most effective route. Crystal structures of the donor-spacer-acceptor (D-S-A) compound (E)-1-ethenylferrocenyl-4-(4-ethynyl-N-methyl-1,8-naphthalimide)benzene (7) and the precursor compounds (E)-4-bromo-4′-(ethenylferrocenyl) biphenyl (2) and 4-ethynyl-4′-(4-ethynyl-N-methyl-1,8-naphthalimide) biphenyl (4) are reported, with packing in the two naphthalimide derivatives dominated by offset π-stacking interactions. Compounds containing the ferrocenyl groups show the anticipated one-electron oxidation processes at potentials that vary little with the spacer groups. Both the ferrocenyl derivatives and their naphthalimide precursors show reversible reduction waves. The single wave for the phenyl and biphenyl compounds and their precursors is assigned to reversible one-electron reduction of the naphthalimide unit. The corresponding anthracene derivatives display two reversible reductions associated with the naphthalimide and the anthryl moieties, respectively.

Full text of DOI:10.1021/om1000452

2474 Organometallics 2010, 29, 2474–2483
DOI: 10.1021/om1000452
Ferrocenyl-Naphthalimide Donor-Acceptor Dyads with
Aromatic Spacer Groups
C. John McAdam, Brian H. Robinson, Jim Simpson,* and Tei Tagg
Department of Chemistry, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
Received January 20, 2010
The preparation and characterization of a series of dyads containing ferrocene donor and naph-
thalimide acceptor units, separated by aromatic spacer groups, are reported. The compounds contain
a ferrocene-ethenyl spacer component linked to the 4-position of a naphthalimide by an ethynyl
bridge, Fc-CHdCH-spacer-CtC-naphthalimide (Fc = ferrocenyl), where the spacers are
1,4-phenyl, 4,40-biphenyl, and 9,10-anthryl. Precursors to the dyad systems, halo-spacer-CtC-
naphthalimide, are also characterized where the halo-spacers are 1-bromophenyl, 4-bromobiphenyl,
and 9-iodoanthryl. Various synthetic strategies are examined, with attachment of the spacer to
4-ethynylnaphthalimide followed by reaction with ethenylferrocene proving the most effective route.
Crystal structures of the donor-spacer-acceptor (D-S-A) compound (E)-1-ethenylferrocenyl-
4-(4-ethynyl-N-methyl-1,8-naphthalimide)benzene (7) and the precursor compounds (E)-4-bromo-
40-(ethenylferrocenyl)biphenyl (2) and 4-ethynyl-40-(4-ethynyl-N-methyl-1,8-naphthalimide)biphenyl (4)
are reported, with packing in the two naphthalimide derivatives dominated by offset π-stacking
interactions. Compounds containing the ferrocenyl groups show the anticipated one-electron oxida-
tion processes at potentials that vary little with the spacer groups. Both the ferrocenyl derivatives and
their naphthalimide precursors show reversible reduction waves. The single wave for the phenyl and
biphenyl compounds and their precursors is assigned to reversible one-electron reduction of the
naphthalimide unit. The corresponding anthracene derivatives display two reversible reductions
associated with the naphthalimide and the anthryl moieties, respectively.
Introduction
from biological to material science applications, and with
outputs that range from esoteric to practical and commercial
in nature.2 One area of particular activity is the study of
nonlinear optical (NLO) behavior3 of donor-acceptor (D-A)
dyads. The ferrocenyl moiety has proven to be readily in-
corporated (in a donor role) into push-pull assemblies,
generally in conjunction with connective links comprising
single or multiple π-systems.4
We have recently investigated the preparation and spec-
troscopic and electrochemical properties of simple ferrocene
dyads with alkene or alkyne links. Acceptors include poly-
aromatics,5 acridone and anthraquinone,6 and importantly
in the context of this work, model 1,8-naphthalimide systems
(Figure 1)7 and related naphthalic anhydrides.7,8 In all cases,
there was strong evidence not only for charge separation in
the excited states of the molecules but also for a reversal of
the donor-acceptor roles upon the one-electron oxidation of
the ferrocene. This is signaled by the appearance of strongly
solvatochromic LMCT transitions9 in the near-IR. Absorption
Ferrocene compounds continue to attract attention due to
their combination of electronic and robust physical proper-
ties.1 Research contributions cover a wealth of disciplines,
*Corresponding author. E-mail: jsimpson@alkali.otago.ac.nz.
(1) Togni, A.; Hayashi, T. Ferrocenes; VCH: Weinheim, Germany,
1995.
(2) (a) Wang, J. Chem. Rev. 2008, 108, 814. (b) Szacilowski, K. Chem.
Rev. 2008, 108, 3481. (c) Whittell, G. R.; Manners, I. Adv. Mater. 2007, 19,
3439.
(3) (a) Marder, S. R. Inorganic Materials, 2nd ed.; Bruce, D. W.;
O'Hare, D., Eds.; Wiley: Chichester, 1996. (b) Long, N. J. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 21.
(4) (a) Barlow, S.; Bunting, H. E.; Ringham, C.; Green, J. C.; Bublitz,
G. U.; Boxer, S. G.; Perry, J. W.; Marder, S. R. J. Am. Chem. Soc. 1999,
121, 3715. (b) Jayaprakash, K. N.; Ray, P. C.; Matsuoka, I.; Bhadbhade,
M. M.; Puranik, V. G.; Das, P. K.; Nishihara, H.; Sarkar, A. Organometallics
1999, 18, 3851. (c) Hudson, R. D. A.; Asselberghs, I.; Clays, K.; Cuffe, L. P.;
Gallagher, J. F.; Manning, A. R.; Persoons, A.; Wostyn, K. J. Organomet.
Chem. 2001, 637-639, 435. (d) Mata, J. A.; Peris, E.; Llusar, R.; Uriel, S.;
Cifuentes, M. P.; Humphrey, M. G.; Samoc, M.; Luther-Davies, B. Eur. J.
Inorg. Chem. 2001, 2113. (e) Malaun, M.; Kowallick, R.; McDonagh, A. M.;
Marcaccio, M.; Paul, R. L.; Asselberghs, I.; Clays, K.; Persoons, A.;
Bildstein, B.; Fiorini, C.; Nunzi, J.-M.; Ward, M. D.; McCleverty, J. A.
J. Chem. Soc., Dalton Trans. 2001, 3025. (f) Mueller-Westerhoff, U. T.;
Sanders, R. W. Organometallics 2003, 22, 4778. (g) Zhang, F.; Vill, V.; Heck,
J. Organometallics 2004, 23, 3853. (h) Colbran, S. B.; Lee, S. T.; Donnon,
D. G.; Maharaj, F. J. D.; McDonagh, A. M.; Walker, K. A.; Young, R. D.
Organometallics 2006, 25, 2216. (i) Winters, M. U.; Dahlstedt, E.; Blades,
H. E.; Wilson, C. J.; Frampton, M. J.; Anderson, H. L.; Albinsson, B. J. Am.
Chem. Soc. 2007, 129, 4291. (j) Kinnibrugh, T. L.; Salman, S.; Getmanenko,
Y. A.; Coropceanu, V.; Porter, W. W., III; Timofeeva, T. V.; Matzger, A. J.;
(5) Cuffe, L.; Hudson, R. D. A.; Gallagher, J. F.; Jennings, S.;
McAdam, C. J.; Connelly, R. B. T.; Manning, A. R.; Robinson, B. H.;
Simpson, J. Organometallics 2005, 24, 2051.
(6) McGale, E. M.; Robinson, B. H.; Simpson, J. Organometallics
2003, 22, 931.
(7) McAdam, C. J.; Morgan, J. L.; Robinson, B. H.; Simpson, J.;
Rieger, P. H.; Rieger, A. L. Organometallics 2003, 22, 5126.
(8) Munro, N. H.; Hanton, L. R.; McAdam, C. J.; McMorran, D. A.
Acta Crystallogr. 2008, E64, m572.
(9) Flood, A. H.; McAdam, C. J.; Gordon, K. C.; Kjaergaard, H. G.;
ꢀ
Bredas, J.-L.; Marder, S. R.; Barlow, S. Organometallics 2009, 28, 1350.
Manning, A. R.; Robinson, B. H.; Simpson, J. Polyhedron 2007, 26, 448.
r
pubs.acs.org/Organometallics Published on Web 05/14/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 11, 2010 2475
Scheme 1
Figure 1. Ferrocenyl naphthalimide dyad 1 and representation
of the charge transfer excited state.
through-space interactions between the excited state of the
naphthalimide and the ferrocenyl headgroup.7,15
It is on these premises that we examine here synthetic
routes to interpolate an additional aromatic spacer between
the donor and acceptor units of 1 and the resulting effect
on the spectroscopic and electrochemical behavior of the
materials formed.
Figure 2. Generic (upper) and target (lower) D-S-A assemblies.
of NIR radiation has attracted considerable recent attention
due to the potential applications in both telecommunications
and for in vivo luminescent imaging.10 Similar behavior is
also observed for ferrocenyl-cobalt metallocene dyads,11
and naphthalimide,12 or polyaromatic acceptor systems13
where the ferrocenyl moiety is replaced by metal acetylides
from groups 8 and 10. This charge separation is critically
dependent on the link between the donor and acceptor sys-
tems with CdC-CdC > CdC> CtC for a given donor-
acceptor combination.
Our selection of the 4-naphthalimido moiety for the accep-
tor role in D-A dyads is attractive for several reasons; first,
is its strength as an acceptor, on a par with p-nitrophenyl.12
Additionally, synthesis of 4-substituted naphthalimides is
facilitated by the ready availability of 4-bromonaphthalic
anhydride starting material and a well-characterized14 and
high-yielding derivative chemistry. Ultimately, these naph-
thalimides offer the tantalizing possibility of multiresponsive
electro- and photoactive species. In sharply contrasting
behavior, spectral properties are much less affected in situa-
tions where the redox-active ferrocene unit is located in the
N-headgroup of the naphthalimide due to the existence of
a node at the imide nitrogen. In such cases, photophysical
characteristics of the molecules appear to be dependent on
Results and Discussion
The interpolation of an aromatic spacer into a ferrocenyl-
naphthalimide D-A compound like 1 to prepare donor-
spacer-acceptor (D-S-A) assemblies [Figure 2 (upper)]
can potentially be approached from either terminus or con-
structed outward from the central spacer. Upon considering
connective links (direct attachment, alkyne link, alkene link,
polyene link, etc.), a bewildering number of permutations
and synthetic strategies arises. To limit these, we determined
to focus on 4-ethynylnaphthalimides, Figure 2 (lower).
Our first strategy was to prepare monoferrocenyl-substituted
derivatives (D-S-X) of the desired dihalogenated aro-
matic spacer (X-S-X) via Heck or Sonogashira coupling.
This would then be reacted with 4-ethynylnaphthalimide to
generate the D-S-A assembly.
This approach, Scheme 1, was used to prepare 4-bromo-
40-(ethenylferrocenyl)biphenyl, 2. Ethenylferrocene was reac-
ted with an equimolar quantity of 4,40-dibromobiphenyl
under Heck coupling conditions.16 The yield however was
poor, the major product being the disubstituted 4,40-bis-
(ethenylferrocenyl)biphenyl (3).17 Sufficient quantities of 2
for an X-ray crystallographic study and characterization
purposes were obtained, but the practical difficulties of sepa-
ration of minor from major reaction components led us to
explore alternative synthetic strategies.
(10) (a) Wang, Z. Y.; Zhang, J.; Wu, X.; Birau, M.; Yu, G.; Yu, H.;
Qi, Y.; Desjardins, P.; Meng, X.; Gao, J. P.; Todd, E.; Song, N.; Bai, Y.;
Beaudin, A. M. R.; LeClair, G. Pure Appl. Chem. 2004, 76, 1435.
(b) Ward, M. D. Coord. Chem. Rev. 2007, 251, 1663.
(11) Kjaergaard, H. G.; McAdam, C. J.; Manning, A. R.; Mueller-
Bunz, H.; O’Donohue, P.; Ortin, Y.; Robinson, B. H.; Simpson, J. Inorg.
Chim. Acta 2008, 361, 1616.
Our next approach was to couple the ferrocenyl donor with
a preprepared spacer-naphthalimide component as depic-
ted, again with the biphenyl group, in Scheme 2. Desilylation
of 4,40-bis(trimethylsilylethynyl)biphenyl followed by reac-
tion with an equimolar quantity of 4-bromo-N-methyl-1,
8-naphthalimide under Sonogashira conditions18 gave the
(12) McAdam, C. J.; Manning, A. R.; Robinson, B. H.; Simpson, J.
Inorg. Chim. Acta 2005, 358, 1673.
(13) Butler, P.; Gallagher, J. F.; Manning, A. R.; Mueller-Bunz, H.;
McAdam, C. J.; Robinson, B. H.; Simpson, J. J. Organomet. Chem.
2005, 690, 4545.
(14) (a) de Silva, A. P.; Gunaratne, H. Q. N.; Gunnlaugsson, T.;
Huxley, A. J. M.; McCoy, C. P.; Rademacher, J. T.; Rice, T. E. Chem.
Rev. 1997, 97, 1515. (b) Wintgens, V.; Valat, P.; Kossanyi, J.; Biczok, L.;
Demeter, A.; Berces, T. J. Chem. Soc., Faraday Trans. 1 1994, 90, 411.
(c) Gan, J.; Tian, H.; Wang, Z.; Chen, K.; Hill, J.; Lane, P. A.; Rahn, M. D.;
Fox, A. M.; Bradley, D. D. C. J. Organomet. Chem. 2002, 645, 168.
(15) McAdam, C. J.; Robinson, B. H.; Simpson, J. Organometallics
2000, 19, 3644.
(16) Heck, R. F.; Nolley, J. P., Jr. J. Org. Chem. 1972, 37, 2320.
(17) Rodrıguez, J.-G.; Gayo, M.; Fonseca, I. J. Organomet. Chem.
´
1997, 534, 35.
(18) Sonogashira, K.; Tohda, Y.; Hagihara, N. Tetrahedron Lett.
1975, 16, 4467.

2476 Organometallics, Vol. 29, No. 11, 2010
McAdam et al.
Scheme 2a
a (i) Pd(Ph3)2Cl2, CuI, iPr2NH.
Scheme 3a
D-S-A’s and their attendant computational study will be
reported on separately.19
a (i) Fc-CHdCH2, Pd(OAc)2, (o-tolyl)3P, Et3N, DMF.
required product, 4, in good yield, Scheme 2. However,
attempts to cross couple 4 with iodoferrocene were enti-
rely unsuccessful due to oxidative coupling that produced
the sparingly soluble and generally intractable bis[(naph-
thalimidoethynyl)biphenyl]buta-1,3-diyne as the major
product.
A corresponding reaction scheme starting from 9,10-bis-
(trimethylsilylethynyl)anthracene gave no anthryl equivalent
of 4, presumably due to the instability of the deprotected
9,10-diethynylanthracene.
In the third and ultimately successful route, Sonogashira
coupling of 4-ethynyl-N-methyl-1,8-naphthalimide with stoi-
chiometric 4,40-dibromobiphenyl gave the monocoupled
bromobiphenyl derivative, 8. Heck coupling of this halo-
spacer-acceptor (X-S-A) 6 to ethenylferrocene gave the
desired D-S-A system, 9 (Scheme 3).
The same two-step strategy was used to produce the halo-
aromatic X-S-A intermediates 6 and 11 and subsequen-
tly D-S-A molecules with 1,4-phenyl, 7, and 9,10-anthryl,
12, groups as spacers. The yields of the monoethynyla-
ted X-S-A were not high (15-25%), and undoubtedly,
although not characterized, significant quantities of disub-
stituted A-S-A products were formed. Nevertheless isola-
tion proved more successful, and ultimately fruitful, than the
monoferrocenylated D-S-X methodology (Scheme 1). To
provide a clearer understanding of electrochemical and
spectroscopic results, reference compounds 5 and 10 were
similarly synthesized from iodobenzene and 9-bromoan-
thracene, respectively. Following on from, and complemen-
tary to, the ferrocenylethenyl D-S-A derivatives presented
here, the preparation of a series of ferrocenylethynyl
All compounds were characterized by elemental analysis,
MS, NMR, and electronic spectra. The 4-aryl-substituted
naphthalimide derivatives are yellow and strongly fluore-
scent, the exceptions being 10 and 11, which are red. The
ferrocenyl D-S-A compounds are characteristically orange-
red with no apparent fluorescence. The thermodynamically
favored E-configuration for the alkene system of these deri-
vatives (2, 3, 7, 9, and 12) is obtained without the need for
additional cis-trans conversion5 and was established un-
1
ambiguously by H and 2-D NMR techniques, with addi-
tional confirmation in the case of 2 and 7 by X-ray crys-
tallography. Compounds 2-12 are moderately to readily
soluble in chlorinated solvents but poorly soluble in aro-
matic solvents and alcohols. This provided us with some
challenges in obtaining crystals of sufficient quality for X-ray
determinations, presumably due to ready aggregation in the
solid state associated with π-π stacking interactions.15 Only
intermediate molecules 2 and 4 and one complete D-S-A
molecule, 7, gave crystals suitable for X-ray crystallography.
Their structures are reported here.
Crystal Structure of 2. The structure of 2 consists of a
ferrocenyl group linked by a disordered alkene bridge to a
4,40-biphenyl unit with a bromo-substituent in the 40-posi-
tion and one cyclopentadienyl ring of a ferrocene molecule in
the 4-position, Figure 3.
The phenyl rings of the biphenyl are almost coplanar with
a dihedral angle of 4.32(18)° between them. The C7 C12
3 3 3
(19) Tagg, T.; Kjaergaard, H. G.; Lane, J. R.; McAdam, C. J.;
Robinson, B. H.; Simpson, J. Organometallics, manuscript in preparation.

Article
Organometallics, Vol. 29, No. 11, 2010 2477
Figure 4. Structure of 4 showing the atom-numbering scheme
with ellipsoids drawn at the 50% probability level. For clarity
only the first two C atoms of consecutively numbered phenyl
rings are numbered. Selected bond distances [A] and angles
[deg]: C4-C14 1.4307(19); C14-C15 1.201(2); C15-C16
1.423(19); C19-C22 1.4822(19); C25-C28 1.469(2); C28-C29
1.146(2); C4-C14-C15 179.94(19); C14-C15-C16 175.06(15);
C25-C28-C29 175.10(18).
Figure 3. Structure of 2 showing the atom-numbering scheme
with ellipsoids drawn at the 50% probability level. For clarity,
only atoms of the major disorder component of the disordered
alkene group are shown and only the first two C atoms of conse-
cutively numbered phenyl and cyclopentadienyl rings are num-
bered. Selected bond distances [A] and angles [deg]: C10-C13
1.506(7);C13-C14 1.309(10); C14-C15 1.509(7); C4-C7 1.490(4);
C1-Br1 1.905(3); (C15 C19) ring av C-C 1.415(9); (C20
Bond lengths and angles in the naphthalenedicarboxi-
mide fragment compare well with those found in similar
systems,7,12,15,24 with the bond lengths in the dicarboximide
ring suggesting a degree of delocalization over the entire
naphthalimide unit, but this does not extend to the methyl
substituent on the N1 atom.25 The naphthalimide unit is
reasonably planar with an rms deviation of 0.0156 A from
the best fit mean plane and, importantly, makes an angle of
3 3 3
3 3 3
C24) ring av C-C 1.420(3); Fe1 (C15-C19) av 2.045(6);
3 3 3
Fe1
(C20-C24) av 2.047(3); C10-C13-C14 122.0(6);
3 3 3
C13-C14-C15 116.5(6).
phenyl ring makes an angle of 17.52(19)° to the substituted
cyclopentadienyl ring of the ferrocene moiety. The CdC bond
distances in the two disordered components of the linking
just 6.80(6)° to the C16 C21 ring of the biphenyl moiety,
3 3 3
again consistent with a highly desirable degree of delocaliza-
tion between the spacer and acceptor components of this
D-S-A intermediate. The two biphenyl rings are inclined to
one another at an angle of 9.41(8)°.
alkene unit, 1.320(6) and 1.324(6) A, are unremarkable.20
A
search of the Cambridge database (V 5.31 to November
2009)21 reveals 46 other p-substituted phenyl rings bound to
alkene ferrocenyl groups; analysis of the CdC bonds in these
molecules using Vista22 shows a mean CdC distance of
1.32(3) A. The cyclopentadienyl rings of the ferrocene are
staggered, with a mean Cm-Cg1-Cg2-Cn torsion angle of
25.7(4)° (Cg1 and Cg2 are the centroids of the cyclopenta-
dienyl rings, m=15-19 when n=20-24), and the dihedral
angle between the two Cp ring planes is 1.3(3)°.
In the crystal, C-H O and C-H π interactions form
3 3 3
3 3 3
zigzag chains along the c axis. Further C-H O hydrogen
3 3 3
bonds and, inevitably for a naphthalimide system, extensive
π-π stacking interactions form stacks of parallel chains
down a (Supporting Information, Figure S2).
Crystal Structure of 7. As detailed in the Experimental
Section, there was positional disorder involving the alkyne
group and the naphthalimide unit in this structure. In the
discussion that follows, data will be discussed only for the
major disorder component of the structure. The compound
comprises a ferrocenyl linked from the cyclopentadiene ring by
an E-configured alkene to a benzene ring. In the para-position
of the benzene ring, an alkyne bridge connects to the 4-position
of an N-methyl-1,8-naphthalimide, Figure 5. The molecule thus
comprises a complete D-S-A system. One benzene solvate
molecule completes the asymmetric unit of the compound.
The C14tC15 bond (1.207(14) A) of the alkyne is not
unusual and compares with a distance of 1.201(2) A in 4.
Similarly, the C22dC23 alkene bond at 1.318(12) A com-
pares well with the values found in 2 and in the other
p-substituted phenyl rings bound to alkene ferrocenyl groups
mentioned previously. The naphthalimide unit is again
reasonably planar, with an rms deviation of 0.0183 A from
the best fit mean plane, and makes an angle of 3.1(4)° to the
The absence of a naphthalimide group in 2 lessens the
opportunities for π-stacking interactions in this system. Not
surprisingly therefore, crystal packing in the solid state struc-
ture of this molecule relies on nonclassical C-H Br hydrogen
3 3 3
bonds23 and C-H π interactions that link the molecules
into zigzag chains down the b axis (Supporting Information,
Figure S1).
3 3 3
Crystal Structure of 4. The compound comprises an N-methyl-
1,8-naphthalimide unit linked at the 4-position to a biphenyl
group through an alkyne bridge, Figure 4. The biphenyl carries a
terminal alkyne substituent in the 40-position. The C28tC29
bond of the terminal alkyne is significantly shorter, 1.146(2) A,
than that of C14tC15, 1.201(2) A, which links the naphthali-
mide and biphenyl systems. This and the relatively short C4-
C14 and C15-C16 bonds, 1.4307(19) and 1.4323(19) A, suggest
some delocalization between the naphthalimide and the biphenyl
systems.
C16 C21 benzene ring. This in turn is inclined at an angle
3 3 3
of 6.1(5)° to the substituted cyclopentadiene ring of the
ferrocenyl moiety. The cyclopentadienyl rings of the ferro-
cene are approximately eclipsed, and the dihedral angle
between the two Cp ring planes is 2.2(6)°.
(20) McAdam, C. J.; Robinson, B. H.; Simpson, J. Inorg. Chim. Acta
2008, 361, 2172.
(21) Allen, F. H. Acta Crystallogr. 2002, B58, 380.
(22) Cambridge Crystallographic Data Centre. Vista-A Program for
the Analysis and Display of Data Retrieved from the CSD; Cambridge
Crystallographic Data Centre: Cambridge, England, 1994.
(23) (a) McAdam, C. J.; Robinson, B. H.; Simpson, J. Acta Crystal-
logr. 2007, E63, m1362. (b) Tagg, T.; McAdam, C. J.; Robinson, B. H.;
Simpson, J. Acta Crystallogr. 2008, C64, o388. (c) McAdam, C. J.; Hanton,
L. R.; Moratti, S. C.; Simpson, J. Acta Crystallogr. 2009, E65, o1573.
(24) (a) McAdam, C. J.; Morgan, J. L.; Murray, R. E.; Robinson,
B. H.; Simpson, J. Aust. J. Chem. 2004, 57, 525. (b) McAdam, C. J.;
Robinson, B. H.; Simpson, J. Acta Crystallogr. 2005, E61, m110.
(25) Easton, C. J.; Gulbis, J. M.; Hoskins, B. F.; Scharfbillig, I. M.;
Tiekink, E. R. T. Z. Crystallogr. 1992, 199, 249.

2478 Organometallics, Vol. 29, No. 11, 2010
McAdam et al.
Figure 5. Asymmetric unit of 7 showing the atom-numbering scheme with ellipsoids drawn at the 30% probability level. Only the first
two C atoms of consecutively numbered phenyl and cyclopentadienyl rings are numbered. Selected bond distances [A] and angles [deg]:
C4-C14 1.482(9); C14;C15 1.207(14); C15;C16 1.479(16); C19;C22 1.506(11); C22-C23 1.318(12); C23-C24 1.456(11);
(C24 C28) ring av C-C 1.42(1); (C29 C33) ring av C-C 1.423(8); Fe1 (C24-C28) av 2.045(7); Fe1 (C29-C33) av
3 3 3 3 3 3 3 3 3 3 3 3
2.044(7); C4-C14-C15 176.1(14); C14-C15-C16 179.6(16); C19-C22-C23 125.6(9); C22-C23-C24 123.7(9).
Figure 6. (a) Offset π π stacking in 7 with close centroid centroid interactions shown as dashed lines. (b) Crystal packing in 7.
3 3 3 3 3 3
In the crystal structure, π π stacking interactions be-
stacks of molecules with the ferrocenyl substituents packing
in a head-to-tail fashion at either end of each stack, Figure 6a.
3 3 3
tween the substituted Cp ring of the ferrocene and the amide
ring of an adjacent naphthalimide (Cg1 Cg3=3.508(5) A,
Weak C22-H22 O12 hydrogen bonds and C-H π inter-
3 3 3 3 3 3
3 3 3
symmetry operation -x, 1-y, -z) and between the amide
actions involving the benzene solvate molecules link indivi-
dual molecules in each stack to four adjacent molecules. These
in turn stack to generate a series of approximately orthogonal
ring and the benzene ring of the spacer group (Cg3 Cg4=
3.705(5) A, symmetry operation -x, -y, -z) form offset
3 3 3

Article
Organometallics, Vol. 29, No. 11, 2010 2479
Table 1. Electrochemical, UV-Vis, and Fluorescence Data for 1-12
E/Va(ipr/ipf)
[Naph]0/-
λ
Abs (ε)c
compound
[Fc]þ/0
[Ar]0/-
A (π-π*)
B (π-π*)
391 (13)
C
λ
Flu (Φf)d
17
2
3
4
0.60 (1.0)
0.55 (1.0)
0.55 (1.0)
-1.20 (0.5)
526 (5)
460 (2.2)
460 (3.3)
326 (39)
348 (30)
304 (28)
-1.06 (0.9)
-1.09 (0.9)
-1.07 (0.8)
-1.08 (0.9)
-1.07 (0.9)
-1.08 (1.0)
-1.03 (1.0)
-1.0 (0.3)
384 (34)
396 (33)
375 (28)
390 (25)
376 (31)
393 (28)
390 (31)
465 (0.55)
432 (0.52)
435 (0.51)
444 (0.002)
463 (0.53)
471 (0.01)
579 (0.03)
581 (0.02)
588 (0.002)
5
280 (11)
291 (11)
282 (13)
295 (14)
338 (23)
352 (23)
293 (24)
6
7
0.57 (1.0)
0.55 (1.0)
500 (7.5)
∼500 (3)e
8
383 (33)
399 (32)
390 (35)
9
342 (29)
350 (30)
353 (12)
365 (13)
353 (12)
370 (12)
353 (13)
370 (11)
10
11
12
-1.38 (0.8)
-1.4b
444 (20)
461 (20)
447 (21)
470 (21)
477 (25)
e
0.60 (1.0)
-1.03 (1.0)
-1.33 (0.9)
a 1 ꢀ 10-3 M in CH2Cl2, Pt, 0.1 M TBAPF6, 20 °C; referenced against decamethylferrocene [Fc*]þ/0, for which [FcH]þ/0 = 0.55 V;26 ipr/ipf at 100 mV s-1
.
b Irreversible. c In CH2Cl2; λ nm (ε/mol-1 cm-1 L ꢀ 103), 20 °C. d In CH2Cl2; λ nm, (Φf), 20 °C. e Under the naphthalimide envelope.
Figure 7. Cyclic voltammograms of 7 (- - -) and 9 (;) (∼1 ꢀ
10-3 M in CH2Cl2, Pt, 0.1 M TBAPF6, 100 mV s-1, 20 °C,
Figure 8. Cyclic voltammogram of 12 (1 ꢀ 10-3 M in CH2Cl2,
[Fc*]þ/0, for which [FcH]þ/0 = 0.55 V26).
referenced against [Fc*]þ/0, for which [FcH]þ/0 = 0.55 V26).
Pt, 0.1 M TBAPF6, 100 mV s-1, 20 °C, referenced against
columns in the bc plane as a result of similar π π stack-
3 3 3
reversibility and number of electrons involved in the transfer
ing interactions, Figure 6b.
Electrochemistry. The results of cyclic voltammetry for
process.7,14c,15,27 In this work compounds containing the
naphthalimide unit (4-12) show cleanly reversible or quasi
reversible one-electron reduction processes in the range
methane solution are shown in Table 1. The ferrocenyl
compounds 2-12 and the model D-A dyad 17 in dichloro-
-1.03 to -1.09 V (Table 1). With the exception of 11, these
processes remain chemically reversible at scan rates in the
range 50-500 mV s-1 and can be assigned to a one-electron
reduction of the naphthalimide moiety. Predictably, replace-
ment of a phenyl spacer with biphenyl has no effect on the
naphthalimide reduction potential. Peak-to-peak separa-
tions for both the ferrocenyl oxidation and the naphthali-
mide reduction resemble that of the internal decamethyl-
ferrocene chemical reference, so we can consider the waves
Nernstian. Peak current values proportional to v1/2 indicate a
diffusion-controlled process. For S-A and D-S-A com-
pounds incorporating an anthryl group a subtle (∼50 mV)
anodic shift of the naphthalimide reduction peak occurs,
but more importantly, an additional one-electron process at
derivatives (2, 3, 7, 9, and 12) display the anticipated
chemically reversible [Fc]þ/0 couple with ipc/ipa=1.0. Both
2 and 3 show a single reversible wave with E° = 0.55 V.
However for 3, with no interaction between the two equi-
valent ferrocenyl redox centers, this is a two-electron pro-
cess. The oxidation potentials for the extended D-S-A
systems 7, 9, and 12 with different spacer groups fall in a
relatively narrow range, E°=0.55-0.60 V, Figures 7 and 8.
Within experimental error, the potentials of the D-S-A
systems are the same as those for the analogous D-S
system.5 This suggests that augmentation of the simple
ferrocenyl-phenyl, -biphenyl, and -anthryl dyads at
the 4-, 40-, and 10-positions, respectively, with an alkyne-
linked naphthalimide moiety, has only a minor influence
on the [Fc]þ/0 couple. The simple D-A dyad 1 has an oxidation
potential of 0.60 V.7
(27) (a) Altieri, A.; Gatti, F. G.; Kay, E. R.; Leigh, D. A.; Martel, D.;
Paolucci, F.; Slawin, A. M. Z.; Wong, J. K. Y. J. Am. Chem. Soc. 2003,
125, 8644. (b) Nelsen, S. F. J. Am. Chem. Soc. 1967, 89, 5925. (c) Sioda,
R. E.; Koski, W. S. J. Am. Chem. Soc. 1967, 89, 475. (d) Ryabinin, V. A.;
Starichenko, V. F.; Vorozhtsov, G. N.; Shein, S. M. Zhur. Struct. Khim.
1978, 19, 804.
Reduction processes for several previously reported naph-
thalimide systems occur with varying degrees of chemical
ꢁ
(26) Barriere, F.; Geiger, W. E. J. Am. Chem. Soc. 2006, 128, 3980.

2480 Organometallics, Vol. 29, No. 11, 2010
McAdam et al.
-1.33 V is also observed, Figure 8, associated with the
anthryl moiety.28 This also appears reversible over a wide range
of scan rates. The exception again is 11, where the electro-
chemistry is uniformly irreversible. Clearly cleavage follow-
ing reduction of the reactive 9-iodo substituent is respon-
sible; confirmation of this is provided by comparison with
the reversible electrochemical sweeps of D-S-A 12 and the
model compound 10, where the iodine substituent is replaced
by hydrogen.
Electronic Spectra. UV-visible data for 2-12 and the
model D-A dyad 17 are given in Table 1. For 4-12, the
broad absorption bands of λabs A (280-370 nm) and λabs B
(375-477 nm) are assigned to π-π* transitions of the p-band
of the aryl group29 and the 1,8-naphthalimide, respectively.
Ferrocenyl derivatives 2 and 3 show the aryl spacer absorp-
tion A at ca. 330 nm, but in the absence of the masking by the
strongly absorbing naphthalimide chromophore, we can
now observe the weaker ferrocenyl transition C at 460 nm.
Predictably, these spectral results fit comfortably with find-
ings from previous work on ferrocenyl ethenyl simple poly-
aromatic dyad systems. Specifically, an ethenyl-connected
ferrocenyl results in some perturbation of arene π orbitals, as
evidenced by a less-structured and significantly red-shifted A
(compared with the parent arene) UV p-band. Second, the
wavelength of the visible spectrum ferrocenyl-based absorp-
tion C is independent of the simple polyaromatic, but the
intensity increases with annulation.5 Band C for compound 3
with two ferrocenyl chromophores has approximately twice
the molar absorptivity of the mono(ethenylferrocenylated) 2.
This finding supports our interpretation of the electrochemis-
try for 3 that the two metallocene substituents act additively
and not cooperatively.
Electronic spectra of 6-9 are shown in Figure 9. Attach-
ment of an ethenyl ferrocene to precursor (X-S-A) com-
pounds 6 and 8 to generate D-S-A dyads 7 and 9 has similar
consequences on absorption A; the aryl π-π* transition
undergoes a red-shift in comparison to that of the equivalent
D-S. The naphthalimide band loses vibrational fine struc-
ture and shows only a slight red-shift from X-S-A.
Manifestly different from D-S 2 and 3, the ferrocenyl
absorption of D-S-A 7 is stronger and red-shifted from ca.
460 nm, behavior typical of a strongly conjugated D-A
system30 and assignable to metal-to-ligand charge transfer
(MLCT)4-7,9 with extensive charge separation in the singlet
excited state. It occurs at similar intensity but not as low energy
as the model ferrocenylethenyl naphthalimide, 1.7 Evidence for
the inverse distance dependence of the conjugation is pro-
vided by the much weaker (masked by the naphthalimide
spectral envelope) C band of the longer biphenyl, 9, cf.
phenyl spacer, 7, dyad. Clearly the donor-acceptor interac-
tion propagates through the phenyl spacer (and connective
links) and to a lesser extent through the biphenyl system. The
C absorption for 7 displays the classic solvent effect31 char-
acteristic of a charge transfer (CT) band with λabs shifting to
lower energy with increased solvent polarity32 (Supporting
Figure 9. Electronic spectra of 6 (;), 7 (- -), 8 (
(- - -) in CH2Cl2.
), and 9
3
3 3 3 3
Information, Figure S3). Determining whether the charge
transfer is optical (full charge separation upon excitation) or
photoinduced (stepwise, formation of a localized excited
state followed by charge separation) will be addressed by
time-resolved studies.19
The electronic spectra for the anthryl systems proved
similar (Table 1 and Supporting Information, Figure S4).
The model 10 and halo X-S-A precursor 11 again show A
and B structured features attributable to the anthryl and
naphthalimide π-π* transitions. The anthryl band however
does not appear to red-shift upon attachment of the ethe-
nylferrocene to produce 12. Anomalous behavior has been
previously noted for ferrocenylethenyl anthracene deriva-
tives,5 ascribed to their inability to avoid “fjord”-type inter-
actions33 and maintain coplanarity (and hence conjugation)
between the ethenyl and the two anthryl peri hydrogens. We
would predict an equivalent MLCT band to that observed
for 7, but this feature is either not resolved from or is masked
by the naphthalimide’s broad spectral envelope.
Oxidation of the ferrocene groups in 7, 9, and 12 causes
significant changes to the UV spectra and the growth of
additional absorption bands in the near-infrared region.
These are the result of a reversal of the ferrocenyl donor role
from that of the ferrocenium acceptor. The resultant low-
energy ligand-to-metal charge transfer (LMCT) has been
presented for ferrocenyl naphthalimide dyads previously,7,8
but closer examination has revealed a second lower
energy transition again. Details of this, together with TD-
DFT calculations and the results of time-resolved studies
on these and related molecules, will be reported in another
publication.19
Emission Spectra. Fluorescence data for 4-12 are given in
Table 1. The emission spectra are approximate mirror images
of their long-wavelength absorption spectra, a result com-
monly encountered for rigid polyaromatic systems and indi-
cative of the geometry of the molecule in its relaxed Franck-
Condon excited state being not very different from that of
the ground state molecule. The absorption and emission
spectra of 8 and 9 in CH2Cl2 are shown in the Supporting
Information, Figure S5. As with the absorption bands, the
biphenyl derivatives 4, 8, and 9 display emission bands at
lower energy than their phenyl equivalents 5-7; the anthryl
compounds 10-12 are at lower energy again. This behavior
is predicted from that of the simple aromatics themselves.29
As expected, in all cases, attachment of a ferrocenyl sub-
stituent to an S-A fragment to generate the D-S-A systems
~
ꢀ
(28) (a) Rosa-Montanez, M. E.; Jesus-Cardona, H. D.; Cabrera,
C. R. Electrochim. Acta 1997, 42, 1839. (b) Cao, W.; Zhang, X.; Bard.,
A. J. J. Electroanal. Chem. 2004, 566, 409.
(29) (a) Jones, R. N. Chem. Rev. 1947, 41, 353–371. (b) Clar, E.
Polycyclic Hydrocarbons, Vol. 1; Academic Press: London, 1964.
(30) Barlow, S.; Marder, S. R. Chem Commun. 2000, 1555.
(31) Alexiou, M. S.; Tychopoulos, V.; Ghorbanian, S.; Tyman, J. H.
P.; Brown, R. G.; Brittain, P. I. J. Chem. Soc., Perkin Trans. 2 1990, 837.
(32) Reichardt, C. Angew. Chem., Int. Ed. Engl. 1979, 18, 98.
(33) Bartle, K. D.; Jones, D. W. Adv. Org. Chem. 1972, 8, 317.

Article
Organometallics, Vol. 29, No. 11, 2010 2481
results in significant intramolecular quenching of the fluo-
rescence.7,34 The higher fluorescence quantum yield obta-
ined for the D-S-A with the longer biphenyl spacer 9 (cf.
phenyl and anthryl 7 and 12) supports this mechanism.
Ethenylferrocene,37 4-ethynyl-N-methyl-1,8-naphthalimide,24a
and 9,10-diiodoanthracene38 were prepared by published or modi-
fied literature methods. Other compounds were purchased from
Aldrich and used as received.
(E)-4-Bromo-40-(ethenylferrocenyl)biphenyl (2). Ethenylferro-
cene (0.64 g, 3.00 mmol), 4,40-dibromobiphenyl (0.94 g, 3.00 mmol),
tri-o-tolylphosphine (0.27 g, 0.90 mmol), PdII acetate (0.20 g,
0.90 mmol), and 6 mL of NEt3 were heated at 80 °C in 60 mL of
DMF for 24 h. Solvent was removed in vacuo and the residue
purified by column chromatography (SiO2, CH2Cl2/hexane,
1:5) to give the second band, from which orange crystals of
1 were obtained on removal of solvent, 0.15 g (11%). Anal.
Calcd for C24H19FeBr: C 64.05, H 4.32. Found: C 64.07, H 4.22.
APCI-APCI-MS: 445 (MH)þ. 1H NMR (δ): 4.15 (s, 5H, C5H5),
4.30 (t, 2H, Fc-Hβ), 4.48 (t, 2H, Fc-HR), 6.73 {d (J=16 Hz), Fc-
CHd}, 6.93 {d (J=16 Hz), dCH-biph}, 7.52 (m, 8H, biph. H).
Conclusions
Donor-spacer-acceptor compounds consisting of ferro-
cene as the donor and naphthalimide as the acceptor can be
prepared in reasonable yield with the appropriate synthetic
strategy. Investigation of the compounds by X-ray crystal-
lography was rather challenging, due to extensive π-π stack-
ing associated with the inherently planar spacer and acceptor
naphthalimide moieties, leading to ready aggregation in the
solid state and affecting the quality of the crystals. None-
theless, three crystal structures (2, 4, and 7) of D-S, S-A,
and D-S-A configuration were obtained, which provided
insight into the intramolecular and intermolecular spatial
arrangements.
The spacers in the D-S-A compounds had minimal effect
on the ferrocenyl oxidation potentials and the naphthalimide
reduction potentials. While it is common that upon oxidation
of the ferrocenyl unit, a chemically reversible one-electron
oxidation process would be obtained, it is less usual that a
chemically reversible one-electron reduction process was
obtained for the naphthalimide unit.
IR (KBr): 960 (E-CHdCH wag) cm-1
.
(E,E)-4,40-Bis(ethenylferrocenyl)biphenyl (3). Following elu-
tion of 2, the fourth band from the above column gave an orange
solid of 3 upon removal of solvent, 0.38 g (22%). Anal. Calcd for
C36H30Fe2: C 75.29, H 5.26. Found: C 75.38, H 5.54. APCI-MS:
575 (MH)þ. 1H NMR (δ): 4.16 (s, 10H, C5H5), 4.31 (s, 4H, Fc-
Hβ), 4.50 (s, 4H, Fc-HR), 6.73 {d (J=16 Hz), Fc-CHd}, 6.92 {d
(J=16 Hz), dCH-biph), 7.50 {d (J=8 Hz), 4H, biph. H}, 7.59
{d (J=8 Hz), 4H, biph. H}. IR (KBr): 959 (E-CHdCH wag) cm-1
.
4-Ethynyl-40-(4-ethynyl-N-methyl-1,8-naphthalimide)biphenyl
(4). 4,40-Diethynylbiphenyl (0.61 g, 3.00 mmol) and 4-bromo-N-
methyl-1,8-naphthalimide (0.59 g, 2.00 mmol) were added to
50 mL of degassed iPr2NH containing 2% CuI and 2% PdCl2-
(PPh3)2. The resulting cloudy yellow suspension was heated to
reflux for 2 h and stirred overnight at room temperature. Solvent
was removed in vacuo and the residue purified by column
chromatography (SiO2, CH2Cl2). The second band eluted
yielded a sulfur yellow solid, 3, 0.35 g (43%). Anal. Calcd for
C29H17NO2: C 84.65, H 4.16, N 3.40. Found: C 84.47, H 4.14, N
3.34. ESI-MS: 434.11 [calcd (M þ Na)þ 434.12]. 1H NMR (δ):
3.17 (s, 1H, CtCH), 3.58 (s, 3H, N-CH3), 7.61 (s, 4H, biph. H),
7.67 {d (J=8 Hz), 2H, biph. H}, 7.76 {d (J=8 Hz), 2H, biph.
H}, 7.87 {dd (J = 8, 7 Hz), naphth. H6}, 7.99 {d (J = 8 Hz),
naphth. H3}, 8.59 {d (J=8 Hz), naphth. H2}, 8.68 {dd (J=7,
1 Hz), naphth. H7}, 8.77 {dd (J=8, 1 Hz), naphth. H5}. IR (KBr):
All D-S-A compounds showed evidence of charge trans-
fer. Oxidation of the ferrocenyl moiety, which resulted in
bleaching of the MLCT band and the growth of two new
LMCT bands in the near-infrared region, is to be reported on
in more detail. As predicted, the fluorescence of all D-S-A
compounds was significantly quenched due to the presence
of the ferrocene donor.
Experimental Section
Solvents were dried and distilled by standard procedures, and
unless otherwise stated all reactions were performed under
nitrogen. Microanalyses were carried out by the Campbell Micro-
analytical Laboratory, University of Otago. Mass spectra were
recorded on a Shimadzu LCMS-QP8000 and a Bruker micrO-
TOF. IR spectra were recorded on a Perkin-Elmer Spectrum BX
ν
CtC 2194, νCdO 1691, 1651 cm-1
(4-Ethynyl-N-methyl-1,8-naphthalimide)benzene (5). 4-Ethynyl-
.
N-methyl-1,8-naphthalimide (0.20 g, 0.85 mmol) and 1-iodobenzene
(0.19 mL, 1.70 mmol) were added to 25 mL of degassed iPr2NH
containing 2% CuI and 2% PdCl2(PPh3)2. The resulting brown
mixture was heated to reflux for 7 h. Solvent was removed in vacuo
and the residue purified by column chromatography (SiO2,
CH2Cl2), from which the second band yielded a yellow solid,
0.19 g (72%). Anal. Calcd for C21H13NO2: C 81.01, H 4.21, N
4.50. Found: C 81.08, H 4.27, N 4.53. APCI-MS: 312 (MH)þ. 1H
NMR (δ): 3.56 (s, 3H, N-CH3), 7.44 {t (J=3 Hz), ph. H18, H19,
and H20}, 7.67 (m, 2H, ph. H17 and H21), 7.82 {t (J = 8 Hz),
naphth. H6}, 7.93 {d (J=8 Hz), naphth. H3}, 8.54 {d (J=8 Hz),
naphth. H2}, 8.63 {d (J=7 Hz), naphth. H7}, 8.71 {d (J=8 Hz),
1
FT-IR spectrometer. H and 13C NMR spectra were recorded
on Varian Unity Inova 300 and 500 MHz spectrometers in
CDCl3 (7.26 ppm) at 25 °C. Electronic spectra were recorded on
a Varian Cary 500 UV-vis spectrophotometer. Fluorescence
measurements were conducted on optically dilute samples
(absorbance <0.05) in spectroscopic grade solvents, and the
quantum yield was calculated by comparing the integrated
fluorescence spectra with a comparable compound, fluorescein
(Φf = 0.94).35 The estimated error in the determination of Φf
was 20%. Cyclic and square-wave voltammetry in CH2Cl2 were
performed using a three-electrode cell with a polished Pt 1 mm
disk working electrode; solutions were ∼10-3 M in electroactive
material and 0.10 M in supporting electrolyte (recrystallized
TBAPF6). Data were recorded on a Powerlab/4sp computer-
controlled potentiostat. Scan rates of 50-500 mV s-1 were
typically employed for cyclic voltammetry. All potentials are
referenced to decamethylferrocene; E1/2 for sublimed ferrocene
was 0.55 V.36
naphth. H5}. IR (KBr): νCtC 2204, νCdO 1700, 1666 cm-1
.
1-Bromo-4-(4-ethynyl-N-methyl-1,8-naphthalimide)benzene (6).
4-Ethynyl-N-methyl-1,8-naphthalimide (0.66 g, 2.81 mmol) and
1,4-dibromobenzene (0.66 g, 2.81 mmol) were added to 50 mL of
degassed iPr2NH containing 2% CuI and 2% PdCl2(PPh3)2. The
resulting black mixture was heated to reflux for 16 h. Solvent
was removed in vacuo and the residue purified by column chro-
matography (SiO2, CH2Cl2), giving a second band, which yiel-
ded a yellow solid, 6, 0.26 g (24%). Anal. Calcd for C21H12-
BrNO2: C 64.64, H 3.10, N 3.59, Br 20.48. Found: C 64.91,
(34) Fery-Forgues, S.; Delavaux-Nicot, B. J. Photochem. Photobiol.
A 2000, 132, 137.
(35) Magde, D.; Wong, R.; Seybold, P. G. Photochem. Photobiol.
(37) Liu, W.-Y.; Xu, Q.-H.; Ma, Y.-X.; Liang, Y.-M.; Dong, N.-L.;
Guan, D.-P. J. Organomet. Chem. 2001, 625, 128.
(38) Duerr, B. F.; Chung, Y. S.; Czarnik, A. W. J. Org. Chem. 1988,
53, 2120.
2002, 75, 327.
(36) Noviandri, I.; Brown, K. N.; Fleming, D. S.; Gulyas, P. T.; Lay,
P. A.; Masters, A. F.; Phillips, L. J. Phys. Chem. B 1999, 103, 6713.

2482 Organometallics, Vol. 29, No. 11, 2010
McAdam et al.
H 3.14, N 3.42, Br 20.57. EI-MS: 389.01 [calcd Mþ (C21H12
-
Table 2. Crystal and Structure Refinement Data for 2, 4, and 7
79
BrNO2) 389.01], 391.00 [calcd Mþ (C21H1281BrNO2) 391.00]. 1H
NMR (δ): 3.57 (s, 3H, N-CH3), 7.53 {d (J=9 Hz), ph. H17 and
H21}, 7.58 {d (J = 9 Hz), ph. H18 and H20}, 7.84 {dd (J = 9,
7 Hz), naphth. H6}, 7.95 {d (J=8 Hz), naphth. H3}, 8.57 {d (J=
8 Hz), naphth. H2}, 8.66 {dd (J=7, 1 Hz), naphth. H7}, 8.70 {dd
(J = 9, 1 Hz), naphth. H5}. IR (KBr): νCtC 2207, νCdO 1699,
2
4
7
emp formula
fw
temp/K
cryst syst
space group
a/A
C
443.15
85(2)
24H19FeBr
C29H17NO2
411.44
85(2)
orthorhombic
Pbca
9.5527(2)
18.1790(4)
23.3617(4)
90
4056.96(14)
8
0.085
C33H23FeNO2
599.48
85(2)
monoclinic
P21/n
16.275(5)
9.665(5)
18.385(5)
99.922(5)
2848.7(19)
4
monoclinic
P21
1661 cm-1
.
6.0896(2)
7.8142(2)
18.7986(6)
95.268(2)
890.76(5)
2
(E)-1-Ethenylferrocenyl-4-(4-ethynyl-N-methyl-1,8-naphthali-
mide)benzene (7). 6 (0.21 g, 0.54 mmol), ethenylferrocene (0.23 g,
1.08 mmol), tri-o-tolylphosphine (0.04 g, 0.16 mmol), PdII
acetate (0.04 g, 0.16 mmol), and 2 mL of NEt3 were heated at
80 °C in 25 mL of DMF for 18 h. Solvent was removed in vacuo,
and the residue was purified by column chromatography (SiO2,
CH2Cl2). The second band eluted yielded a red solid, 7, 0.13 g
(46%). Anal. Calcd for C33H23FeNO2: C 76.02, H 4.45, N 2.69.
Found: C 76.32, H 4.67, N 2.74. EI-MS: 521.11 [calcd Mþ
b/A
c/A
β/deg
V/A3
Z
μ/mm-1
reflns measd
unique reflns
Rint
3.094
16 393
3517
0.0277
0.567
20 104
4120
0.0741
66 069
3990
0.0301
0.857 and 0.599 0.980 and 0.887 1.000 and 0.699
max. and min.
transmn
1
(C33H2356FeNO2) 521.11]. H NMR (δ): 3.58 (s, 3H, N-CH3),
4.17 (s, 5H, C5H5), 4.34 (s, 2H, Fc-Hβ), 4.50 (s, 2H, Fc-HR), 6.72
{d (J=17 Hz), Fc-CHd}, 6.99 {d (J=17 Hz), dCH-ph), 7.49 {d
(J=9 Hz), ph. H18 and H20}, 7.63 {d (J=9 Hz), ph. H17 and
H21}, 7.85 {t (J = 8 Hz), naphth. H6}, 7.96 {d (J = 8 Hz),
naphth. H3}, 8.58 {d (J=8 Hz), naphth. H2}, 8.67 {d (J=7 Hz),
naphth. H7}, 8.76 {d (J= 8 Hz), naphth. H5}. IR (KBr): νCtC
data/restraints/ 3517/1/254
params
goodness of fit 1.081
3990/0/290
4120/52/386
1.093
0.0411
0.1179
1.184
0.0998
0.2514
R [I>2σ(I)]
wR (all data)
0.0266
0.0682
2202, νCdO 1695, 1655, (E-CHdCH wag) 960 cm-1
.
{d (J=8 Hz), naphth. H2}, 8.69 (m, 3H, anthr. H and naphth.
H7}, 8.98 {dd (J=8, 2 Hz), naphth. H5}. IR (KBr): νCtC 2183,
4-Bromo-40-(4-ethynyl-N-methyl-1,8-naphthalimide)biphenyl (8).
4-Ethynyl-N-methyl-1,8-naphthalimide (0.14 g, 0.60 mmol) and
4,40-dibromobiphenyl (0.19 g, 0.60 mmol) were added to 25 mL
of degassed iPr2NH containing 2% CuI and 2% PdCl2(PPh3)2.
The resulting black mixture was heated to reflux for 3 h. Solvent
was removed in vacuo and the residue purified by column
chromatography (SiO2, CH2Cl2), giving a second band, which
yielded a sulfur yellow solid, 8, 0.07 g (25%). Anal. Calcd for
C27H16BrNO2: C 69.54, H 3.46, N 3.00, Br 17.13. Found: C
69.76, H 3.41, N 3.05, Br 17.10. EI-MS: 465.04 [calcd Mþ
ν
CdO 1700, 1662 cm-1
.
9-Iodo-10-(4-ethynyl-N-methyl-1,8-naphthalimide)anthracene
(11). 4-Ethynyl-N-methyl-1,8-naphthalimide (0.18 g, 0.77 mmol)
and 9,10-diiodoanthracene (0.33 g, 0.77 mmol) were added to
25 mL of degassed iPr2NH containing 2% CuI and 2% PdCl2-
(PPh3)2. The resulting black mixture was heated to reflux for 3 h.
Solvent was removed in vacuo and the residue purified by
column chromatography (SiO2, CH2Cl2), giving a second band,
which yielded a red solid, 11, 0.06 g (15%). Anal. Calcd for
C29H16INO2: C 64.82, H 3.00, N 2.61, I 23.62. Found: C 64.70,
H 2.98, N 2.59, I 23.36. EI-MS: 537.02 [calcd Mþ (C29H16INO2)
537.02]. 1H NMR (δ): 3.61 (s, 1H, N-Me), 7.67 (m, 4H, anthr.
H), 7.88 {dd (J=8 Hz), naphth. H6}, 8.16 {d (J=7 Hz), naphth.
H3}, 8.63 {m, 6H, (anthr. H, naphth. H2 and H7)}, 8.90 {d (J=
(C27H1679BrNO2) 465.04]. H NMR (δ): 3.57 (s, 3H, N-CH3),
1
7.50 {d (J=9 Hz), biph. H23 and H27}, 7.60 {d (J=9 Hz), biph.
H24 and H26}, 7.63 {d (J=9 Hz), biph. H18 and H20}, 7.74 {d
(J=9 Hz), biph. H17 and H21}, 7.85 {dd (J=9, 8 Hz), naphth.
H6}, 7.97 {d (J=8 Hz), naphth. H3}, 8.58 {d (J=8 Hz), naphth.
H2}, 8.66 {dd (J=8, 1 Hz), naphth. H7}, 8.75 {dd (J=9, 1 Hz),
8 Hz), naphth. H5}. IR (KBr): νCtC 2183, νCdO 1701, 1663 cm-1
.
naphth. H5}. IR (KBr): νCꢁC 2207, νCdO 1697, 1667 cm-1
.
(E)-9-Ethenylferrocenyl-10-(4-ethynyl-N-methyl-1,8-naphtha-
limide)anthracene (12). 11 (0.06 g, 0.11 mmol), ethenylferrocene
(0.05 g, 0.22 mmol), tri-o-tolylphosphine (0.01 g, 0.03 mmol),
PdII acetate (0.01 g, 0.03 mmol), and 0.7 mL of NEt3 were heated
at 80 °C in 20 mL of DMF for 24 h. Solvent was removed
in vacuo and the residue purified by column chromatography
(SiO2, CH2Cl2), giving a second band, which yielded a dark red
solid, 12, 0.04 g (51%). Anal. Calcd for C41H27FeNO2: C 79.23,
H 4.38, N 2.25. Found: C 78.96, H 4.39, N 2.29. EI-MS: 621.14
[calcd Mþ (C41H2756FeNO2) 621.14]. 1H NMR (δ): 3.61 (s, 3H,
N-Me), 4.37 (s, 5H, C5H5), 4.50 (s, 2H, Fc-Hβ), 4.75 (s, 2H, Fc-
HR), 6.75 {d (J=17 Hz), Fc-CHd), 7.49 {d (J=17 Hz), dCH-
naphth.), 7.58 {dd (J = 8 Hz), 2H, anthr. H}, 7.70 {dd (J = 9,
7 Hz), 2H, anthr. H}, 7.91 {dd (J=8 Hz), naphth. H6}, 8.20 {d
(J=7 Hz), naphth. H3}, 8.46 {d (J=9 Hz), naphth. H2 and H7},
8.70 (m, 4H, anthr. H), 9.00 {d (J=8 Hz), naphth. H5}. IR (KBr):
(E)-4-Ethenylferrocenyl-40-(4-ethynyl-N-methyl-1,8-naphthali-
mide)biphenyl (9). 8 (0.07 g, 0.15 mmol), ethenylferrocene (0.06 g,
0.30 mmol), tri-o-tolylphosphine (0.01 g, 0.05 mmol), PdII acetate
(0.01 g, 0.05 mmol), and 0.7 mL of NEt3 were heated at 80 °C in
25 mL of DMF for 24 h. Solvent was removed in vacuo and the
residue purified by column chromatography (SiO2, CH2Cl2/pet
ether, 1:0.5). The second band eluted yielded an orange solid, 9,
0.01 g (11%). Anal. Calcd for C39H27FeNO2: C 78.40, H 4.56, N
2.34. Found: C 78.29, H 4.55, N 2.71. EI-MS: 597.14 [calcd Mþ
(C39H2756FeNO2) 597.14]. 1H NMR (δ): 3.58 (s, 3H, N-Me), 4.49
(s, 5H, C5H5), 4.77 (s, 2H, Fc-Hβ), 4.98 (s, 2H, Fc-HR), 6.38 (s, 1H,
Fc-CHd), 6.83 (s, 1H, dCH-naphth), 7.60 (m, 8H, biph-H), 7.86
{dd (J=8), naphth H6}, 7.98 {d (J=8 Hz), naphth H3}, 8.59 {d
(J=8 Hz), naphth H2}, 8.67 {d (J=7 Hz), naphth H7}, 8.77 {d
(J= 8 Hz), naphth H5}. IR (KBr): νCtC 2203, νCdO 1698, 1656,
(E-CHdCH wag) 957 cm-1
.
ν
CꢁC 2177, νCdO 1693, 1655 cm-1, (E-CHdCH wag) 966 cm-1
X-ray Data Collection and Structure Solution for 2, 4, and 7.
.
9-(4-Ethynyl-N-methyl-1,8-naphthalimide)anthracene (10).
4-Ethynyl-N-methyl-1,8-naphthalimide (0.35 g, 1.48 mmol) and
9-bromoanthracene (0.57 g, 2.22 mmol) were added to 25 mL of
degassed iPr2NH containing 2% CuI and 2% PdCl2(PPh3)2. The
mixture was heated to reflux for 10 h. Solvent was removed
in vacuo and the residue purified by column chromatography
(SiO2, CH2Cl2), from which the fourth band yielded an orange
solid (0.32 g, 53%). Anal. Calcd for C29H17NO2: C 84.65, H
4.16, N 3.40. Found: C 84.42, H 4.19, N 3.33. 1H NMR (δ): 3.60
(s, 3H, N-CH3), 7.58 (m, 2H, anthr. H), 7.68 (m, 2H, anthr. H),
7.90 {dd (J = 9, 7 Hz), naphth. H6}, 8.08 {d (J = 9 Hz), anthr.
H}, 8.18 {d (J=8 Hz), naphth. H3}, 8.54 (s, 1H, anthr. H), 8.63
Crystals of 2 (orange plates from CH2Cl2/pentane), 4 (yellow plates
from CH2Cl2/methanol), and 7 (orange plates from CH2Cl2/
benzene) were used for data collection. Data were collected on a
Bruker APEXII CCD diffractometer at 90 K using APEX239
and processed using SAINT;39 empirical absorption corrections
were applied using SADABS.39 Crystal data for the compounds
are summarized in Table 2.
(39) APEX2 V2.0-2, SAINT V7.23A, and SADABS 2004/1; Bruker
AXS Inc.: Madison, WI, 2006.

Article
The structures were solved using SHELXS40 and were refi-
Organometallics, Vol. 29, No. 11, 2010 2483
disorder with an alternative placement of the alkyne unit.
However, attempts to generate an appropriate disorder model
were not successful. Potential disorder problems also contribute
to the relatively high final residuals observed for this structure.
The structures of 2, 4, and 7 together with the atom labeling are
illustrated in Figures 3-5, respectively.
ned by full-matrix least-squares on F2 using SHELXL-9740 and
Titan2000.41 All non-hydrogen atoms were assigned anisotropic
displacement parameters, with hydrogen atoms included in cal-
culated positions. The alkene C atoms of 2 were disordered over
two positions. Refinement of the occupancy factor converged at
0.64(1) for the major disorder component. 2 crystallizes in the
non-centrosymmetric space group P21, and the Flack parameter42
-0.011(9) confirms the correct absolute configuration. For 7 a
number of high peaks were found in the difference electron
density map once all non-hydrogen atoms of the main molecule
had been found. These peaks were consistent with the presence
of a benzene solvate molecule in the asymmetric unit, and these
atoms were included in the final refinements. Additional high
peaks in the vicinity of C14 and C15 suggested further possible
Acknowledgment. We are grateful to the Universiti
Malaysia Terengganu for a Ph.D. scholarship to T.T.
and the New Zealand Foundation for Research Science
and Technology for a postdoctoral fellowship to C.J.M.
We also thank the University of Otago for purchase of the
diffractometer.
Supporting Information Available: CIF files giving crystal-
lographic data for 2, 4, and 7, crystal-packing diagrams of 2 and
4, solvent polarity studies for 7, selected absorption and emis-
sion spectra. This material is available free of charge via the Internet
at http://pubs.acs.org.
(40) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, A64, 112.
(41) Hunter, K. A.; Simpson, J. TITAN2000: A molecular graphics
program to aid structure solution and refinement with the SHELX suite of
programs; University of Otago: New Zealand, 1999.
(42) Flack, H. D. Acta Crystallogr. Sect. B 1983, B39, 876.