A synthetic and X-ray crystallographic study of zinc and platinum complexes of 4,5-Diazafluoren-9-one (dafone) and dicobalt hexacarbonyl derivatives of 9-phenylethynyl-4,5-diazafluoren-9-ol: Chelation versus monocoordination

Article abstract of DOI:10.1002/ejic.200900161

Reaction of 4,5-diazafluoren-9-one (dafone, 6) and zinc dichloride yields [(dafone)ZnCl₂(H₂O)] (11) in which the ZnCl₂ moiety is coordinated to a single nitrogen atom, and also to a molecule of water. Hydrogen, bonding, not only to the uncomplexed nitrogen atom, of dafone but also to the ketonic oxygen atom of a neighbouring molecule, leads to a zigzag chain structure. In contrast, reaction with anhydrous zinc iodide forms cis-(dafone)₂ZnI₂ (12) in which the metal-nitrogen distances - 2.170(5) and 2.456(5) A - are significantly different. Dafone, in the presence of dimethyl sulfoxide, reacts with K₂PtCl ₄ to produce square-planar (dafone)PtCl₂(dmso) (13), whereas with K₂PtBr₆ the octahedral complex (dafone)PtBr₄ (14) is formed in. which, the ligand chelates in a symmetrical fashion. Treatment of dafone with phenylethynyllithium furnishes 9-phenylethynyl-4,5-diazafluoren-9-ol (7), which forms a square-planar nitrogen-bonded PtCl₂ complex, 15. Reaction of 7 with Co ₂(CO)₈ yields the (μ-alkyne)hexacarbonyldicobalt cluster 17, which undergoes protonation at the nitrogen atom to form 20 rather than at the alcohol to form a cobalt-complexed propargyl cation. Alkynol 7 also reacts with HBr by addition across the triple bond to form Z-9-[(2-bromo-2- phenyl)ethenyl]-4,5-dlazafluoren-9-ol (10). X-ray crystal structures are reported for 6, 7, 10-15, 17 and 20, and their differing hydrogen-bonding motifs are discussed.

Full text of DOI:10.1002/ejic.200900161

FULL PAPER
DOI: 10.1002/ejic.200900161
A Synthetic and X-ray Crystallographic Study of Zinc and Platinum
Complexes of 4,5-Diazafluoren-9-one (Dafone) and Dicobalt Hexacarbonyl
Derivatives of 9-Phenylethynyl-4,5-Diazafluoren-9-ol: Chelation versus
Monocoordination
Linda Maguire,[a] Corey M. Seward,[a] Sladjana Baljak,[b] Thea Reumann,[b]
Yannick Ortin,[a] Emilie Banide,[a] Kirill Nikitin,[a] Helge Müller-Bunz,[a] and
Michael J. McGlinchey*[a]
Keywords: Metal-nitrogen linkages / Asymmetric bonds / Hydrogen bonds / Coordination modes / Zinc / Platinum / Cobalt
Reaction of 4,5-diazafluoren-9-one (dafone, 6) and zinc di-
chloride yields [(dafone)ZnCl2(H2O)] (11) in which the ZnCl2
moiety is coordinated to a single nitrogen atom and also to a
molecule of water. Hydrogen bonding, not only to the un-
complexed nitrogen atom of dafone but also to the ketonic
oxygen atom of a neighbouring molecule, leads to a zigzag
chain structure. In contrast, reaction with anhydrous zinc io-
dide forms cis-(dafone)2ZnI2 (12) in which the metal–nitrogen
distances – 2.170(5) and 2.456(5) Å – are significantly dif-
ferent. Dafone, in the presence of dimethyl sulfoxide, reacts
with K2PtCl4 to produce square-planar (dafone)PtCl2(dmso)
(13), whereas with K2PtBr6 the octahedral complex (dafone)-
PtBr4 (14) is formed in which the ligand chelates in a symmet-
rical fashion. Treatment of dafone with phenylethynyllithium
furnishes 9-phenylethynyl-4,5-diazafluoren-9-ol (7), which
forms a square-planar nitrogen-bonded PtCl2 complex, 15.
Reaction of 7 with Co2(CO)8 yields the (µ-alkyne)hexacar-
bonyldicobalt cluster 17, which undergoes protonation at the
nitrogen atom to form 20 rather than at the alcohol to form a
cobalt-complexed propargyl cation. Alkynol 7 also reacts
with HBr by addition across the triple bond to form Z-9-[(2-
bromo-2-phenyl)ethenyl]-4,5-diazafluoren-9-ol (10). X-ray
crystal structures are reported for 6, 7, 10–15, 17 and 20, and
their differing hydrogen-bonding motifs are discussed.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
Introduction
We have recently reported a route to electroluminescent
tetracenes through dimerisation of fluorenylideneall-
enes.[1–3] As depicted in Scheme 1, treatment of fluorenone
with an alkynyllithium yields the corresponding 9-alk-
ynylfluoren-9-ol, 1. Conversion to the required 3,3-(bi-
phenyl-2,2Ј-diyl)-1-arylallene 3 can be accomplished either
by reaction with BF3/Et3SiH (to form an alkyne 2, which
readily rearranges under basic conditions)[4–6] or by forma-
tion of the bromoallene 4,[7] followed by lithiation and hy-
drolysis.[8] Subsequent thermolysis of the allenes yields tet-
racenes 5. This general procedure has since been extended
to include allene dimers containing halogens, and also si-
lyl,[8,9] phosphane[10] and ferrocenyl[11] substituents.
Scheme 1. Synthetic routes to diindenotetracenes 5.
We here describe the preparation of 9-phenylethynyl-4,5-
diazafluoren-9-ol (7), an attempt to convert it into the cor-
responding allene 8 and the synthesis and characterisation
of a series of metal complexes of 7 and 8.
[a] School of Chemistry and Chemical Biology,
University College Dublin,
Results and Discussion
Belfield, Dublin 4, Ireland
With the goal of preparing an allene 8 en route to a tetra-
azatetracene 9, with potentially interesting photophysical
properties, 4,5-diazafluoren-9-one (dafone, 6) was treated
with phenylethynyllithium to yield the alkynol 7, as shown
Fax: +353-1-716-2880
E-mail: michael.mcglinchey@ucd.ie
[b] Institut für Anorganisch und Angewandte Chemie,
Universität Hamburg,
Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
3250
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 3250–3258

Chelation vs. Monocoordination in Diazafluorene Complexes of Zn, Pt and Co
in Scheme 2. The structure of dafone (6) determined at
293 K has already been reported;[12] however, as X-ray qual-
ity crystals were at hand, a data set was collected at 100 K.
The changes in bond lengths and angles are minor. Alkynol
7 is almost insoluble in many common solvents but can be
recrystallised from 95:5 dichloromethane/methanol, and its
molecular structure is shown in Figure 1. More interest-
ingly, it can be obtained in two crystalline forms: as an an- Figure 2. The OH···N hydrogen bonding in 9-phenylethynyl-4,5-di-
azafluoren-9-ol (7).
hydrous dimeric version with hydrogen bonds (N···HO
2.059 Å) linking a nitrogen atom of one molecule with a
hydroxyl group of its neighbour, as shown in Figure 2, and
closely resemble those found in dafone, except, of course,
also as a hydrated molecule that exists as a dimer with water
for those around the tetrahedral carbon atom C9, which
molecules bridging both nitrogen atoms of one diazafluor-
bears the newly introduced alkynol functionality. The dis-
enyl unit to the hydroxyl group of a neighbouring alkynol
tances between the facing biaryl planes in the dimers 7 and
(N···H2O 1.975 Å; H2O···HO 1.754 Å), as depicted in Fig-
7·H2O are 3.359 Å and 3.279 Å, respectively.
ure 3.
As noted above, the conventional route to allenes from
alkynols requires treatment with boron trifluoride and tri-
ethylsilane to furnish the corresponding alkyne, with subse-
quent base-promoted isomerisation to the allene;[4–6] in the
present case, one might suspect that the Lewis acidic BF3
would preferentially bind to a ring nitrogen atom and so
preclude this approach. An alternative approach (Scheme 1)
involves the reaction of the alkynol with cold dilute HBr to
yield a bromoallene that can be lithiated and then quenched
with water or dilute acid.[7,8] However, as shown in
Scheme 2, when 7 was treated with HBr, the resulting prod-
uct was shown to arise instead from addition across the
Scheme 2. Potential route to tetraazatetracenes 9.
triple bond to give Z-9-[(2-bromo-2-phenyl)ethenyl]-4,5-di-
azafluoren-9-ol (10), which was unequivocally characterised
by X-ray crystallography (Figure 4). As with the alkynol
precursor 7, the system crystallises as a dimer, in which the
hydroxyl moiety is hydrogen-bonded (OH···N 2.082 Å) to a
nitrogen atom in the other molecule (Figure 5); the distance
between the facing biaryl planes in the dimer of 10 is
3.295 Å.
It was therefore decided to consider the possibility of
protecting 6 or 7 by complexation of the nitrogen atoms to
a range of transition-metal centres, and here we discuss the
syntheses and characterisation of several such complexes.
The structures of a number of dafone derivatives of Mn,[13]
Figure 1. Molecular structure of 9-phenylethynyl-4,5-diazafluoren-
9-ol (7).
Co,[14] Ni,[15] Cu,[16] Zn,[17] Cd,[18] Pd,[19] Ru,[20] Eu,[21] and
Sn[22] have been previously reported. Comparisons of the
The N···N distances in 7 and in 7·H2O are 3.061 and N···N distances with those (≈2.62–2.65 Å) in the widely-
3.076 Å, respectively, whereas in dafone itself the N···N dis- studied bipyridyl or 1,10-phenanthrolene systems, which
tance is 3.053 Å. The metric parameters of 7, and of 7·H2O, have a noticeably smaller bite, must be made. Evidently, the
Figure 3. The hydrogen-bonding motif in 9-phenylethynyl-4,5-diazafluoren-9-ol (7·H2O).
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Figure 6. Bird’s eye view of the hydrogen-bonding pattern in
[(dafone)ZnCl2(H2O)] (11).
Figure 4. Molecular structure of Z-9-[(2-bromo-2-phenyl)ethenyl]-
4,5-diazafluoren-9-ol (10).
Figure 7. Side view of the hydrogen bonding in 11, which illustrates
the zigzag pattern.
dafone molecule is considerably shorter [2.170(5) Å]. The
N···N distance within the dafone ligands in 12 (2.912 Å) is
slightly contracted as a result of chelation to Zn2+; the in-
ternal N–Zn–N angle is 77.8° and the I–Zn–I angle is
Figure 5. The intermolecular OH···N hydrogen bonding in 10.
102.1°. Likewise, in the analogous complexes cis-(dafone)2-
MnCl2
presence of the five-membered ring in dafone pulls the ni-
trogen atoms further apart, increases the rigidity of the sys-
tem, and makes chelate formation somewhat more challeng-
ing for small metals.[16d]
[13]
and cis-(dafone)2Co(NCS)2,[14b] the metal–N
bonds involving the nitrogen atoms trans to the halide or
pseudohalide group are longer: Mn–N 2.445(2) and
2.323(2) Å, N–Mn–N 75.8° and Cl–Mn–Cl 103.3°; Co–N
2.266(3) and 2.224(3) Å, N–Co–N 79.8° and SCN–Co–
NCS 96.8°. As noted above, the structure of [trans-(dafone)2-
Zn(H2O)2]2+ has been reported,[17] and, once again, the Zn–
N bonds are not equivalent [2.276(4) and 2.151(4) Å, N–
Zn–N 80.8° (perchlorate salt); 2.290(3) and 2.201(3) Å, N–
Zn–N 81.3° (nitrate salt)], which demonstrates the difficulty
in forming symmetrical chelate complexes of dafone with
first row transition metals. The analogous copper com-
plexes [trans-(dafone)2CuX2] exhibit even more dramatic
differences for the metal–nitrogen bond lengths [2.785(6)
Metal Complexes of 4,5-Diazafluoren-9-one (dafone)
The reaction of a thf solution of ZnCl2 with dafone in
dichloromethane yielded X-ray quality crystals, which were
analysed to be [(dafone)ZnCl2(H2O)] (11). As shown in Fig-
ure 6, the zinc is tetrahedrally coordinated to a single nitro-
gen atom [Zn–N 2.0932(12) Å] and to two chlorine atoms,
as well as to a water molecule [Zn–O 1.9886(11) Å]; the
N···N distance in 11 (3.148 Å) is slightly longer than that in
the free ligand. The coordinated water molecule is hydrogen
bonded not only to the uncomplexed nitrogen atom in
dafone (N···H 1.890 Å), but also to the carbonyl oxygen
atom of a neighbouring molecule (C=O···H 2.085 Å). This
results in a series of one-dimensional hydrogen-bonded zig-
zag chains, which stack in an antiparallel fashion; moreover,
as illustrated in Figure 7, the chain is not planar but rather
adopts a structure such that all the zinc atoms lie on one
side of the plane defined by the dafone molecules and the
bridging water molecules are situated above this plane. This
is in contrast to the situation in [(dafone)2Zn(H2O)2]2+ (as
either the nitrate or perchlorate salt), which adopts a trans
octahedral geometry and forms a one-dimensional hydro-
gen-bonded chain structure.[17]
As depicted in Scheme 3, treatment of dafone with ZnI2
under rigorously anhydrous conditions yielded crystals of
cis-(dafone)2ZnI2 (12, Figure 8). The metal adopts a dis-
torted octahedral environment in which the nitrogen atoms
within each dafone molecule are asymmetrically bonded to
the metal. The Zn–N bond trans to the iodine atom is long
[2.456(5) Å], whereas the Zn–N linkage trans to the other Scheme 3. Reactions of dafone (6) with metal salts.
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Chelation vs. Monocoordination in Diazafluorene Complexes of Zn, Pt and Co
and 1.966(5) Å in the dibromido complex],[16d] but such
phenomena may be amplified by Jahn–Teller effects that, of
course, do not operate in d10 ZnII systems.
Figure 8. Molecular structure of cis-(dafone)2ZnI2 (12).
In the case of platinum, a metal with a larger ionic radius
than zinc, chelation may be expected to be favoured. Treat-
ment of a dichloromethane solution of dafone with an
aqueous solution of K2PtCl4 containing some dmso, to help
solubilise both reactants, furnished crystals of [(dafone)-
PtCl2(dmso)] (13). The X-ray crystal structure (Figure 9) re- Figure 9. Molecular structures of [(dafone)PtCl2(dmso)] (13) and
(dafone)PtBr4 (14).
veals that the dichloridoplatinum moiety is coordinated to
only one of the dafone nitrogen atoms – the square plane
is completed by a sulfur-bonded dimethyl sulfoxide mole-
Pt–N angles only range from 88° to 92°; the N–Pt–N angle
cule. The N···N distance of 3.086 Å is scarcely changed
is 82.7(2)°. The bulky bromido ligands limit the approach
from that in the free ligand, and the Pt–N bond length of
of the dafone nitrogen atoms to 2.099(5) and 2.103(4) Å,
2.024(4) Å in 13 is significantly shorter than the Zn–N dis-
but the N···N distance of 2.778 Å is by far the shortest of
tance of 2.0932(12) Å in [(dafone)ZnCl2(H2O)] (11). A pos-
all the molecules reported herein; the Pt–N bonds are not
sible explanation lies in the extended structure seen in 11,
significantly different.
in which the hydrogen-bonding motif places the zinc out of
the plane defined by the dafone ligands, which results in a
somewhat stretched Zn–N distance.
Metal Complexes of 9-Phenylethynyl-4,5-diazafluoren-9-ol
Finally, to avoid interference from a potentially coordi-
nating solvent such as dimethyl sulfoxide, an aqueous solu-
In addition, we prepared some metal complexes of the
tion of K2PtBr6 was treated with dafone in methanol; crys- alkynol 7, not only by coordination to the nitrogen atoms,
tals of (dafone)PtBr4 (14) were obtained. As shown also in but also by addition to the alkyne unit, as shown in
Figure 9, the platinum atom is in a very slightly perturbed Scheme 4. It was found that the reaction with K2PtCl4 gave
octahedral environment, and the cis-Br–Pt–Br and cis-Br– a square-planar complex, 15; although the connectivity is
Scheme 4. Reactions of 9-phenylethynyl-4,5-diazafluoren-9-ol (7).
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M. J. McGlinchey et al.
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evident (Figure 10), the crystal quality[23] did not permit a nitrogen atoms of one diazafluorenyl unit to the hydroxyl
detailed discussion of the bond lengths. Moreover, reaction group of the neighbouring alkynol [N4···H2O 2.048 Å;
of 7 with anhydrous ZnI2 led to the formation of bis(9- N5···H2O 2.153 Å; H2O···HO 1.880 Å], as depicted in Fig-
phenylethynyl-4,5-diazafluoren-9-ol)ZnI2 (16), which pre- ure 11.
sumably is analogous to (dafone)2ZnI2 (12); however, it was
not possible to obtain X-ray quality crystals of 16.
It is well established that propargyl cations are greatly
stabilised when complexed to a Co2(CO)6 moiety.[24] More-
over, it has been reported that protonation of the closely
analogous (9-ferrocenylethynyl-fluoren-9-ol)Co2(CO)6 clus-
ter (18), and subsequent reduction of the resulting cation,
yields the corresponding alkyne 19, which was proposed to
be in equilibrium with its isomeric allene 19Ј, as shown in
Scheme 5.[25]
Figure 10. Structure of dichlorido(9-phenylethynyl-4,5-diazaflu-
oren-9-ol)platinum(II) (15).
Scheme 5. Proposed conversion of a ferrocenylalkynol to an allene.
However, when (9-phenylethynyl-4,5-diazafluoren-9-ol)-
Alkynol 7 also reacted readily with dicobalt octacarbonyl
to yield the anticipated (µ-alkyne)hexacarbonyldicobalt
cluster 17. As with the free ligand, 7·H2O, the system crys- hexacarbonyldicobalt (17) was treated with HBF4, product
tallises as a dimer in which water molecules bridge both 20 was obtained. It was isolated and characterised by X-ray
Figure 11. Structure of the cobalt cluster 17 illustrating the hydrogen bonding in the dimer, which is mediated by bridging water molecules.
Figure 12. Structure of the alkynylpyridinium–dicobalt hexacarbonyl cluster 20, illustrating the hydrogen bonding through the tetra-
fluoroborate groups and water molecules in the tetrameric assembly.
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Chelation vs. Monocoordination in Diazafluorene Complexes of Zn, Pt and Co
tion was stirred for 72 h. The solution was quenched with water
crystallography, which reveals that protonation occurs at a
ring nitrogen atom rather than at the propargyl alcohol.
Apparently, as shown in Scheme 4, formation of the cobalt-
stabilised cationic cluster 21 is less favoured than generation
of the pyridinium salt. Moreover, in the solid state, complex
20 exhibits a strikingly picturesque hydrogen-bonding motif
in which a cationic N–H unit in one molecule is linked
through a tetrafluoroborate and a water molecule to both
the neutral nitrogen and the protonated nitrogen atoms of
(10 mL), and the precipitate was filtered and washed with thf.
Chromatography on alumina (eluent dichloromethane/methanol,
95:5) and removal of solvent yielded 7 as a colourless powder
(5.37 g, 18.9 mmol, 86%). M.p. 219 °C. A sample suitable for an
X-ray diffraction structural determination was obtained by
recrystallisation from CH2Cl2/MeOH, 95:5. 1H NMR (500 MHz,
CD3OD): δ = 8.69 (dd, J = 5.0, J = 1.5 Hz, 2 H, H3,6), 8.22 (dd, J
= 7.5, J = 1.5 Hz, 2 H, H1,8), 7.51 (dd, J = 7.5, J = 5.0 Hz, 2 H,
H2,7), 7.41 (dd, J = 7.5, J = 1.5 Hz, 2 H, H13,17), 7.34 (m, 1 H,
a proximate molecule. This “dimeric” fragment of two pyr- H15), 7.31 (m, 2 H, H14,16), 5.49 (s, 1 H, OH) ppm. 13C NMR
(125 MHz, CD3OD): δ = 157.5 (C4a,4b), 152.0 (C3,6), 144.8 (C8a,9a),
idinium cationic clusters sharing a single tetrafluoroborate
anion is, in turn, hydrogen-bonded to its two hydroxyl units,
through another pair of tetrafluoroborate anions, thus gen-
erating the tetrameric assembly shown in Figure 12.
134.0 (C1,8), 132.8 (C13,17), 130.0 (C15), 129.5 (C14,16), 126.0 (C2,7),
123.2 (C12), 88.6 (C10), 84.2 (C11), 72.1 (C9) ppm. MS (ES): m/z =
285 [M + H]. IR (KBr): ν = 3456 (OH), 2222 (CϵC) cm–1.
˜
C19H12N2O (284.32): calcd. C 80.27, H 4.25, N 9.85; found C
79.90, H 4.35, N 9.69.
Synthesis of Z-9-[(2-Bromo-2-phenyl)ethenyl]-4,5-diazafluoren-9-ol
(10): Alkynol 7 (43.2 mg, 0.152 mmol) in acetic acid (1.5 mL) was
treated with a fourfold excess of HBr in acetic acid, and the solu-
Conclusions
As noted by a number of previous workers,[13–22] the
rather long N···N distance in 4,5-diazafluoren-9-one
(dafone) (6) frequently renders symmetrical chelate forma- acid, dissolution of the residue in dichloromethane, and washing
tion stirred at room temperature for 2 h. After removal of acetic
with aqueous sodium carbonate, the solution was dried with so-
dium sulfate. Removal of the solvent furnished 10 (26.8 mg,
0.073 mmol; 48%). X-ray quality crystals were obtained from
tion to be non-competitive, with monocoordination and in-
corporation of an additional ligand. The asymmetry of the
M–N bond lengths is clearly apparent in both cis- and
trans-(dafone)2MX2 complexes, and is particularly evident
in d9 CuII systems in which geometric distortions are ampli-
fied by Jahn–Teller effects.[16] However, with larger metal
ions in high oxidation states, such as PtIV, dafone can func-
tion as a symmetrically bonded chelating ligand. The
closely related molecule 9-phenylethynyl-4,5-diazafluoren-
9-ol (7) likewise forms complexes with zinc and platinum
and also reacts with Co2(CO)8 to yield the dicobalt hexa-
carbonyl cluster 17, which undergoes preferential proton-
ation at the nitrogen atom rather than the formation a co-
balt-stabilised diazafluorenyl cation. Derivatives of 7 in
which both the alkyne substituent and the ring nitrogen
atoms are complexed by metals will be the topic of a future
report.
1
dichloromethane/diethyl ether. H NMR (300 MHz, CD3OD): δ =
8.34 (d, J = 5.0 Hz, 2 H, H3,6), 7.82 (d, J = 7.3 Hz, 2 H, H1,8), 7.47
(m,
2 5 H, phenyl H) ppm.
H, H2,7), 7.30–7.01 (m,
C19H13BrN2O·C4H10O (439.35): calcd. C 62.88, H 5.28, Br 18.19,
N 6.38; found C 63.04, H 4.95, Br 18.05, N 6.32.
Synthesis of Dichloridoaqua(4,5-diazafluoren-9-one)zinc(II) (11):
Dafone (100 mg, 0.55 mmol) was dissolved in dry CH2Cl2 (4 mL)
and layered with benzene (4 mL). ZnCl2 (75 mg, 0.55 mmol) was
dissolved in thf (4 mL) and carefully layered onto the benzene. The
mixture was left for 4 d to allow formation of yellow crystals at
the interface. Filtration yielded ZnCl2(dafone)(H2O) (11) (101 mg,
0.30 mmol; 54%). C11H6Cl2N2OZn·H2O (336.49): calcd. C 39.26,
H 2.40, N 8.33; found C 39.51, H 2.35, N 8.63.
Synthesis of cis-Diiodido-bis(4,5-diazafluoren-9-one)zinc(II) (12):
Dafone (200 mg, 1.10 mmol) dissolved in dry CH2Cl2 (4 mL) was
layered onto a solution of anhydrous ZnI2 (530 mg, 1.66 mmol)
dissolved in dry thf (4 mL), and the sample was sealed for 20 h,
after which time crystal formation had occurred at the interface.
Filtration yielded (dafone)2ZnI2 (12) (320 mg, 0.47 mmol; 85%).
1H NMR (300 MHz, CDCl3/CD3OD): δ = 8.75 (br., 4 H, H3,6),
7.98 (d, J = 7.3 Hz, 4 H, H1,8), 7.36 (br., 4 H, H2,7) ppm.
C22H12I2N4O2Zn·CH2Cl2 (768.49): calcd. C 35.95, H 1.84, N 7.29;
found C 35.63, H 1.84, N 6.85. A sample suitable for an X-ray
diffraction structural determination was obtained by recrystalli-
sation from CH2Cl2.
Experimental Section
General: All experiments were carried out under an atmosphere of
dry nitrogen. 1H and 13C NMR spectra were recorded on Varian
VNMRS 300 MHz, 400 MHz or Inova 500 MHz spectrometers;
the sparing solubility of some complexes resulted in very weak
spectra. Infrared spectra were recorded on a Perkin–Elmer Paragon
1000 FTIR spectrometer and were calibrated with polystyrene.
Melting points were determined on an Electrothermal ENG instru-
ment and are uncorrected. Elemental analyses were carried out by
the Microanalytical Laboratory at University College Dublin. 4,5-
Diazafluoren-9-one (dafone) was prepared from 1,10-phenan-
throline, potassium hydroxide and potassium permanganate by a
literature method.[26]
Synthesis of Dichlorido(4,5-diazafluoren-9-one)(dimethylsulfoxide)-
platinum(II) (13): Dafone (200 mg, 1.10 mmol) was dissolved in dry
CH2Cl2 (4 mL) and layered onto benzene (4 mL). K2PtCl4 (457 mg,
1.10 mmol) was dissolved in water (3 mL) and dmso (5 mL) and
carefully layered onto the benzene. The mixture was left for 4 d to
allow formation of yellow crystals at the interface. Filtration
yielded (dafone)PtCl2(dmso) (13) (390 mg, 0.74 mmol; 67%).
Synthesis of 9-Phenylethynyl-4,5-diazafluoren-9-ol (7): n-Butyl-
lithium (27.5 mL of a 1.6  solution, 44 mmol) was added dropwise
to phenylacetylene (4.8 mL, 44 mmol) in dry thf (120 mL) at 0 °C, C13H12Cl2N2O2PtS (526.3): calcd. C 29.67, H 2.30, N 5.32; found
and the solution was then held in a warm water bath (approxi- C 29.50, H 2.35, N 5.53. A sample suitable for an X-ray diffraction
mately 45 °C) for about 20 min. 4,5-Diazafluoren-9-one (4.01 g, structural determination was obtained by recrystallisation from
22.0 mmol) was added slowly at room temperature, and the solu- CH2Cl2.
Eur. J. Inorg. Chem. 2009, 3250–3258
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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3255

M. J. McGlinchey et al.
FULL PAPER
Synthesis of Tetrabromido(4,5-diazafluoren-9-one)platinum(IV) (14):
Dafone (200 mg, 1.10 mmol) was dissolved in methanol (4 mL) and
carefully layered onto a solution of K2PtBr6 (828 mg, 1.10 mmol)
in water (4 mL). The reaction occurred immediately with formation
of a bright orange precipitate. Filtration yielded (dafone)PtBr4 (14)
Synthesis of Diiodido-bis(9-phenylethynyl-4,5-diazafluoren-9-ol)-
zinc(II) (16): 9-Phenylethynyl-4,5-diazafluoren-9-ol (151 mg, 0.533
mmol) and ZnI2 (88 mg, 0.275 mmol) were stirred in thf (20 mL)
for 20 h at room temperature. Removal of the solvent and
recrystallisation from dichloromethane yielded 16 (145 mg,
(620 mg, 0.89 mmol; 81%). C11H6Br4N2OPt (696.9): calcd. C 0.163 mmol; 61%) as a beige powder. 1H NMR (300 MHz, [D6]-
18.96, H 0.87, Br 45.86, N 4.02; found C 19.30, H 1.01, Br 46.02,
N 4.23. A sample suitable for an X-ray diffraction structural deter-
mination was obtained by recrystallisation from CH2Cl2.
acetone): δ = 8.55 (d, J = 5.1 Hz, 4 H, H3,6), 8.05 (d, J = 7.6 Hz,
4 H, H1,8), 7.41–7.26 (m, 14 H, H2,7, phenyl H), 5.87 (s, 1 H, OH)
ppm. C38H24I2N4O2Zn·0.5CH2Cl2 (930.3): calcd. C 49.71, H 2.71,
N 6.02; found C 49.77, H 2.68, N 5.61.
Synthesis of Dichlorido(9-phenylethynyl-4,5-diazafluoren-9-ol)-
platinum(II) (15): 9-Phenylethynyl-4,5-diazafluoren-9-ol (57 mg, Synthesis of (9-Phenylethynyl-4,5-diazafluoren-9-ol)hexacarbonyl-
0.200 mmol) in methanol (2 mL) was added dropwise to a hot dicobalt (17): 9-Phenylethynyl-4,5-diazafluoren-9-ol (7) (77 mg,
(70 °C) solution of K2PtCl4 (83 mg, 0.200 mmol) in 0.1  HCl
0.272 mmol) and dicobalt octacarbonyl (94 mg, 0.274 mmol) were
(6 mL), and the mixture was heated at reflux for 2 h. The resulting stirred in dry thf (20 mL) for 24 h at room temperature. The sample
precipitate was filtered and washed thoroughly with water, meth- was reduced to a volume of 1 mL; addition of diethyl ether and
anol and diethyl ether to yield 15 as a yellow powder (100 mg,
0.182 mmol; 91%); 1H NMR (400 MHz, CDCl3): δ = 8.76 (d, J M.p. 62 °C. 1H NMR (300 MHz, [D6]acetone): δ = 8.52 (d, J =
= 5.7 Hz, 2 H, H3,6), 8.34 (d, J = 7.7 Hz, 2 H, H1,8), 7.65 (m, 2 4.3 Hz, 2 H, H3,6), 7.89 (d, J = 7.6 Hz, 2 H, H1,8), 7.81 (m, 7 H,
H, H2,7), 7.42 (d, J = 8 Hz, 2 H, o-phenyl), 7.35 (m, 3 H, m-, p- H2,7), 7.40–7.16 (m, 5 H, phenyl H), 5.96 (s, 1 H, OH) ppm.
phenyl) ppm. IR (KBr): ν = 3316 (OH), 2232 (CϵC) cm–1
C25H12Co2N2O7·(C2H5)2O (644.4): calcd. C 54.06, H 3.44, N 4.35;
19H12Cl2N2OPt (550.3): calcd. C 41.47, H 2.20, Cl 12.88, N 5.09; found C 53.91, H 3.73, N 4.36. Upon addition of HBF4·OEt2 to
cooling yielded 17 (153 mg, 0.269 mmol; 99%) as dark red crystals.
.
˜
C
found C 41.23, H 2.00, Cl 12.61, N 5.40. A sample suitable for an ethereal solution of the alkyne–dicobalt complex 17 at 0 °C, a
an X-ray diffraction structural determination was obtained by red precipitate was eventually formed, which was recrystallised
recrystallisation from CH2Cl2.
from acetone to yield X-ray quality crystals of 20.
Table 1. Crystallographic data for 6, 7, 7·H2O, 10 and 11.
6
7
7·H2O
10
11
Formula
Formula mass
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C11H6N2O
182.18
100(2)
0.71073
monoclinic
P21/c (#14)
9.8958(9)
12.3746(12)
6.6687(6)
90
99.509(2)
90
805.41(13)
4
1.502
0.100
C19H12N2O
284.31
293(2)
C19H14N2O2
302.32
100(2)
C19H13BrN2O
365.22
100(2)
C11H8Cl2N2O2Zn
336.46
100(2)
0.71073
triclinic
0.71073
triclinic
0.71073
0.71073
triclinic
triclinic
¯
¯
¯
¯
P1 (#2)
P1 (#2)
P1 (#2)
P1 (#2)
8.1451(14)
9.5973(16)
9.8067(16)
86.894(3)
66.943(2)
89.281(3)
704.3(2)
2
7.9361(10)
10.2148(13)
10.4803(13)
85.197(2)
67.872(2)
69.493(2)
736.00(16)
2
8.2371(12)
9.3676(14)
10.2678(15)
85.532(3)
81.873(2)
84.309(3)
778.8(2)
5.8614(6)
9.4507(9)
11.4436(11)
94.299(1)
94.028(1)
107.718(1)
599.25(10)
2
γ [°]
V [Å3]
Z
2
ρcalcd. [gcm–3]
µ [mm–1]
F(000)
1.341
0.085
296
1.364
0.090
316
1.557
2.645
368
1.865
2.487
336
376
Crystal size [mm]
θ range [°]
Index ranges
0.70ϫ0.70ϫ0.50
2.09 to 28.28
–13 Յ h Յ 13
–16 Յ k Յ 16
–8 Յ l Յ 8
6553
0.40ϫ0.40ϫ0.40
2.13 to 28.30
–10 Յ h Յ 10
–12 Յ k Յ 12
–12 Յ l Յ 12
11896
0.30ϫ0.20ϫ0.20
2.10 to 27.00
–10 Յ h Յ 10
–13 Յ k Յ 12
–13 Յ l Յ 13
6933
0.80ϫ0.50ϫ0.02
2.01 to 28.00
–10 Յ h Յ 10
–12 Յ k Յ 12
–13 Յ l Յ 13
7532
0.50ϫ0.10ϫ0.05
1.79 to 28.51
–7 Յ h Յ 7
–12 Յ k Յ 12
–14 Յ l Յ 15
10085
Reflections collected
Independent reflections
Rint
1883
0.0236
3284
0.0211
3204
0.0219
3721
0.0373
2796
0.0157
Completeness to θmax [%]
Absorption correction
equivalents
Max. and min. transmission 0.9516 and 0.6695
94.2
93.9
99.6
98.9
92.1
semi-empirical from semi-empirical from
semi-empirical from
equivalents
0.9822 and 0.7742
3204/0/264
1.037
semi-empirical from
equivalents
0.9490 and 0.4566
3721/0/209
1.094
semi-empirical from
equivalents
0.8857 and 0.6093
2796/0/195
1.064
equivalents
0.9670 and 0.8973
3284/0/247
1.019
Data/restraints/parameters
1883/0/151
1.043
Goodness-of-fit on F2
Final R values [IϾ2σ (I)]
R1
wR2
0.0438
0.1146
0.0424
0.1064
0.0412
0.1014
0.0463
0.1383
0.0196
0.0520
R values (all data)
R1
wR2
0.0460
0.1171
0.0533
0.1132
0.279 and –0.145
0.0464
0.1051
0.353 and –0.237
0.0518
0.1437
0.944 and –0.741
0.0202
0.0523
0.493 and –0.213
Largest diff. peak/hole [eÅ–3] 0.359 and –0.502
3256
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© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 3250–3258

Chelation vs. Monocoordination in Diazafluorene Complexes of Zn, Pt and Co
Table 2. Crystallographic data for 12, 13, 14, 17 and 20.
12
13
14
17
20
Formula
C22H12N4O2ZnI2·
CH2Cl2
768.45
100(2)
0.71073
monoclinic
C2 (#5)
8.412(2)
13.620(3)
10.905(3)
90
99.380(4)
90
(C13H12N2O2SCl2Pt)2· (C11H6N2OBr4Pt)2·
(C25H12N2O7Co2H2O)8· {[C25H13N2O7Co2][BF4]}2·
[a]
CH2Cl2·H2O
1135.50
100(2)
CH2Cl2
1478.74
100(2)
(C5H12)3·C4H8O2
5010.48
100(2)
H2O
Formula mass
Temperature [K]
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
1334.10
100(2)
0.71073
triclinic
0.71073
triclinic
P1 (#2)
8.3870(12)
9.8490(14)
11.3912(16)
66.705(2)
86.617(2)
78.209(2)
845.8(2)
0.71073
0.71073
monoclinic
P21/c (#14)
14.4297(14)
18.2910(17)
12.4507(12)
90
92.513(2)
90
3283.0(5)
4
monoclinic
C2/c (#15)
24.928(3)
24.901(3)
34.744(4)
90
98.148(2)
90
21349(4)
¯
¯
P1 (#2)
8.8436(6)
16.2401(11)
18.5611(13)
84.299(1)
84.169(1)
80.154(1)
2603.8(3)
2
γ [°]
V [Å3]
1232.6(5)
2
2.071
3.747
732
Z
1
4
ρcalcd. [gcm–3]
µ [mm–1]
F(000)
2.265
2.992
1.559
1.702
8.903
18.443
1.297
1.354
546
2664
10168
1332
Crystal size [mm]
θ range [°]
Index ranges
0.20ϫ0.20ϫ0.01
1.89 to 26.00
–9 Յ h Յ 10
–16 Յ k Յ 16
–13 Յ l Յ 13
4769
0.60ϫ0.50ϫ0.40
1.95 to 28.46
–11 Յ h Յ 11
–13 Յ k Յ 13
–14 Յ l Յ 14
14331
0.15ϫ0.10ϫ0.02
1.80 to 26.00
–17 Յ h Յ 17
–22 Յ k Յ 22
–15 Յ l Յ 15
50321
0.60ϫ0.40ϫ0.02
1.16 to 26.00
–30 Յ h Յ 30
–30 Յ k Յ 21
–42 Յ l Յ 42
57148
0.45ϫ0.30ϫ0.20
1.11 to 27.00
–11 Յ h Յ 11
–20 Յ k Յ 20
–23 Յ l Յ 23
47610
Reflections collected
Independent reflections
Rint
2407
0.0356
3949
0.0453
6451
0.0557
20794
0.0437
11365
0.0321
Completeness to θmax [%]
Absorption correction
99.8
92.3
100.0
99.0
100.0
semi-empirical from
equivalents
0.9635 and 0.6521
2407/1/155
1.015
semi-empirical from
equivalents
0.1249 and 0.0214
3949/0/192
1.088
semi-empirical from
equivalents
0.7093 and 0.3889
6451/0/370
1.098
semi-empirical from
equivalents
0.9822 and 0.7742
20794/18/1451[a]
1.031
semi-empirical from
equivalents
0.7735 and 0.6961
11365/0/860
1.052
Max. and min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R values [IϾ2σ (I)]
R1
wR2
0.0334
0.0702
0.0253
0.0589
0.0276
0.0528
0.0624
0.1567
0.0316
0.0792
R values (all data)
R1
0.0376
0.0269
0.0352
0.0853
0.0396
wR2
0.0720
1.679 and –0.738
0.0594
2.496 and –1.974
0.0549
1.228 and –0.761
0.1677
1.182 and –0.690
0.0843
0.783 and –0.263
Largest diff. peak/hole [eÅ–3]
[a] A SAME restraint was used to make both halves of the disordered pentane molecule [C90 to C94] equivalent. Also DELU restraints
were applied to these atoms.
X-ray Measurements for 6, 7, 7·H2O, 10–14, 17, 20: Crystal data
were collected using a Bruker SMART APEX CCD area detector
diffractometer and are listed in Tables 1 and 2. A full sphere of the
reciprocal space was scanned by phi-omega scans. Pseudoempirical
absorption correction based on redundant reflections was per-
formed by the program SADABS.[27] The structures were solved by
direct methods by using SHELXS-97,[28] and refined by full-matrix
least-squares on F2 for all data by using SHELXL-97.[29] Hydro-
gen-atom treatment varied from compound to compound, de-
pending on the crystal quality. In 6, 7, 7·H2O and 20, all hydrogen
atoms were located in the difference Fourier map and allowed to
refine freely with isotropic thermal displacement factors. The same
applies to the water protons in 17. All other hydrogen atoms were
added at calculated positions and refined by using a riding model.
Their isotropic temperature factors were fixed to 1.2 times (1.5
times for methyl groups) the equivalent isotropic displacement pa-
rameters of the carbon atom to which the H atom is attached.
Anisotropic temperature factors were used for all non-hydrogen
atoms. In 13 and 17, the PLATON “squeeze” procedure[30] was
used to treat regions of diffuse solvent(s) that could not be mod-
elled in terms of atomic sites. Their contribution to the diffraction
pattern was removed, and modified Fo2 written to a new HKL file.
The number of electrons thus located was assigned to appropriate
solvent molecules (one molecule of dichloromethane and one mole-
cule of water in 13, and one molecule of ethyl acetate in 17). These
solvents are included in the formula, formula weight, calculated
density, µ and F(000). CCDC-716985 (6), -716990 (7), -716992
(7·H2O), -716994 (10), -716987 (11), -716988 (12), -716986 (13),
-716989 (14), -716991 (17) and -716993 (20) contain the supplemen-
tary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgments
We thank the Science Foundation Ireland and University College
Dublin for generous financial support. S. B. and T. R. thank the
University of Hamburg for Exchange Scholarships.
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Eur. J. Inorg. Chem. 2009, 3250–3258
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3257

M. J. McGlinchey et al.
FULL PAPER
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Received: February 17, 2009
Published Online: June 17, 2009
3258
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