Synthesis, structure and metal compounds of a novel chromophoric cyanamide ligand

Article abstract of DOI:10.1039/a901959f

The novel compound 2-cyanaminofluoren-9-one (HL) has been synthesized, and is readily deprotonated to form the corresponding cyanamide anion L^-. This has been isolated as the Tl⁺L^- and AsPh₄⁺L^- salts. The UV/visible spectra of HL and AsPh₄⁺L^- show the same amine to carbonyl charge transfer transition seen in other aminofluorenones, although at longer wavelengths. The compound AsPh₄⁺L^- undergoes the reversible one electron reduction typical of fluorenones, whilst HL undergoes an irreversible reduction. The crystal structure of AsPh₄⁺L^- was determined and related to the solvatochromic behaviour of the L^- anion. Some simple EHMO calculations have been carried out on the L^- anion of AsPh₄⁺L^-, which show the cyanamide based HOMO and carbonyl based LUMO involved in the aforementioned CT transition. The thallium salt Tl⁺L^- has also been used as a transmetallating agent in reaction with trimethyltin chloride to produce the corresponding tin cyanamide complex [SnMe₃L], and in reaction with (triphenylphosphine)gold chloride to produce the first reported gold cyanamide compound [AuL(PPh₃)], whose crystal structure has been determined.

Full text of DOI:10.1039/a901959f

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Synthesis, structure and metal compounds of a novel chromophoric
cyanamide ligand
Christopher J. Adams
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge,
UK CB2 1EW. E-mail: cja1000@hermes.cam.ac.uk
Received 12th March 1999, Accepted 7th May 1999
The novel compound 2-cyanaminofluoren-9-one (HL) has been synthesized, and is readily deprotonated to form the
Ϫ
ϩ
Ϫ
ϩ
4
Ϫ
corresponding cyanamide anion L . This has been isolated as the Tl L and AsPh L salts. The UV/visible spectra
ϩ
Ϫ
of HL and AsPh L show the same amine to carbonyl charge transfer transition seen in other aminofluorenones,
although at longer wavelengths. The compound AsPh L undergoes the reversible one electron reduction typical
of fluorenones, whilst HL undergoes an irreversible reduction. The crystal structure of AsPh L was determined and
related to the solvatochromic behaviour of the L anion. Some simple EHMO calculations have been carried out
on the L anion of AsPh L , which show the cyanamide based HOMO and carbonyl based LUMO involved in the
aforementioned CT transition. The thallium salt Tl L has also been used as a transmetallating agent in reaction
4
ϩ
Ϫ
4
ϩ
Ϫ
4
Ϫ
Ϫ
ϩ
Ϫ
4
ϩ
Ϫ
with trimethyltin chloride to produce the corresponding tin cyanamide complex [SnMe L], and in reaction with
3
(
triphenylphosphine)gold chloride to produce the first reported gold cyanamide compound [AuL(PPh )], whose
3
crystal structure has been determined.
There has been a great deal of interest in the last decade in the
chemistry of compounds containing highly conjugated carbon
chains, both in organic and organometallic systems, because of
1
their potential utility in the synthesis of molecular wires and
2
other nanoelectronic devices, and as likely monomers for the
3
preparation of novel polymers related to polyacetylene. Work
here in Cambridge has focused on the chemistry of transition
4
metal–acetylide systems, and recently has concentrated in
particular on compounds containing highly conjugated organic
5
groups as spacers. This is designed to lower the HOMO–
LUMO gap of the compounds by having a ligand with a low
lying LUMO between the metal centres, since research has
shown that the LUMO in such compounds is confined to this
6
ligand.
Wishing to explore other conjugated systems, and bearing in
mind the promising results obtained with conjugated spacer
groups, recently I have investigated the chemistry of metal–
cyanamide compounds. Cyanamides are pseudo-halide nitro-
gen ligands that are readily co-ordinated to metals; their
chemistry has not been extensively investigated, although there
7
has been some work by Crutchley and co-workers in Canada
over the past ten years. I report here the synthesis and charac-
terisation of a new fluorenone–cyanamide compound and show
that it forms stable (triphenylphosphine)gold() and trimethyl-
tin derivatives.
Ϫ
Fig. 1 The UV/visible spectra of HL (——) and the L anion (---) in
acetonitrile.
Results and discussion
The novel compound 2-cyanaminofluoren-9-one (HL) is
readily synthesized from 2-aminofluoren-9-one by an adapt-
8
ation of the literature procedure. As is normally the case for
aryl cyanamides, the amine proton of this ligand is acidic and a
stable cyanamide anion is formed through deprotonation with
triethylamine. This has been isolated as the thallium() and
tetraphenylarsonium salts. The former of these is soluble only
in highly polar solvents such as DMF, but the latter is soluble in
common organic solvents such as dichloromethane, acetonitrile
and ethanol.
M+
N
C
N
N –
N
C
O
H
O
HL
M = Tl
M = Ph4As
propylamine to that used to record the spectrum of HL, so
the concentration is the same in both cases. Both spectra consist
of four bands, three of which have intensities that vary con-
siderably more than their wavelengths (Table 1). The fourth
band does, however, move considerably to longer wavelengths
Ϫ
The neutral compound HL is orange, whereas the anion L is
an intense purple. The UV/visible spectra of these compounds
are presented in Fig. 1; the solution used to record the spectrum
Ϫ
of the anion L was prepared by adding two drops of diiso-
J. Chem. Soc., Dalton Trans., 1999, 2059–2064
2059

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3
Ϫ1
Ϫ1
Ϫ
Table 1 Wavelengths (in nm) and absorption coefficients (in parentheses, /10 M cm ) in the UV/visible spectrum of HL and its anionic form L ,
and of its compounds
Compound
HL
Solvent
Observed absorptions
CH CN
433 (0.27)
365 (0.28)
311 (4.12)
99 (5.59)
296 (21.28)
300 (18.3)
283 (18.0)
265 (4.16)
3
2
Ϫ
L
CH CN
568 (0.73)
578 (0.58)
452 (0.25)
361 (13.21)
364 (12.6)
333 (2.59)
274 (11.25)
272 (12.1)
269 (20.8)
3
ϩ
L
Ϫ
AsPh4
CH Cl
2
2
[
SnMe L]
CH Cl
3
2
2
3
21 (4.10)
339 (0.80)
27 (0.89)
[
AuL(PPh )]
CH Cl
483 (0.49)
287 (2.03)
276 (1.94)
270 (1.94)
3
2
2
3
ϩ
Ϫ
Table 2 Selected bond lengths (Å) and angles (Њ) for AsPh4 L ؒ2H O
2
N(2)–C(14)
N(1)–C(2)
C(2)–C(3)
C(4)–C(11)
C(5)–C(6)
C(7)–C(8)
1.172(4)
1.394(3)
1.402(4)
1.380(4)
1.399(4)
1.397(4)
1.215(3)
1.500(3)
1.381(3)
1.404(4)
0.91(4)
C(14)–N(1)
C(1)–C(2)
C(3)–C(4)
C(5)–C(12)
C(6)–C(7)
C(8)–C(13)
C(9)–C(10)
C(10)–C(11)
C(11)–C(12)
1.295(3)
1.406(4)
1.392(4)
1.382(3)
1.375(4)
1.373(4)
1.485(3)
1.400(3)
1.484(4)
C(9)–O(1)
C(9)–C(13)
C(1)–C(10)
C(12)–C(13)
O(10)–H(10a)
O(11)–H(11a)
O(10)–H(10b)
O(11)–H(11b)
0.79(4)
0.73(3)
0.93(4)
C(10)–C(1)–C(2)
N(1)–C(2)–C(1)
C(4)–C(3)–C(2)
119.2(2)
123.7(2)
122.4(2)
117.8(3)
118.3(3)
126.9(2)
122.2(2)
109.3(2)
132.4(2)
120.0(3)
108.5(2)
129.5(2)
117.2(2)
120.0(3)
101(3)
N(1)–C(2)–C(3)
C(3)–C(2)–C(1)
C(11)–C(4)–C(3)
C(7)–C(6)–C(5)
O(1)–C(9)–C(10)
C(10)–C(9)–C(13)
C(1)–C(10)–C(9)
C(4)–C(11)–C(10)
C(10)–C(11)–C(12)
C(5)–C(12)–C(11)
C(8)–C(13)–C(12)
C(12)–C(13)–C(9)
N(2)–C(14)–N(1)
118.3(2)
118.0(2)
119.0(2)
122.1(3)
127.9(2)
105.1(2)
128.5(2)
119.2(2)
108.4(2)
131.5(3)
121.8(2)
108.7(2)
176.3(3)
C(12)–C(5)–C(6)
C(13)–C(8)–C(7)
O(1)–C(9)–C(13)
C(1)–C(10)–C(11)
C(11)–C(10)–C(9)
C(4)–C(11)–C(12)
C(5)–C(12)–C(13)
C(13)–C(12)–C(11)
C(8)–C(13)–C(9)
C(14)–N(1)–C(2)
C(6)–C(7)–C(8)
ϩ
Ϫ
Fig. 2 The asymmetric unit of the crystal structure of AsPh4 L ,
showing the atom numbering scheme. One of the phenyl rings of the
ϩ
[
AsPh4] cation, composed of C(20) to C(25), is obscured.
H(10a)–O(10)–H(10b)
H(11a)–O(11)–H(11b)
on deprotonation; it is also highly solvatochromic, shifting to
101(3)
3
Ϫ1
Ϫ1
5
18 nm (ε = 502 dm mol cm ) in ethanol, resulting in a
solution that is pink rather than purple. In common with
similar bands seen in the spectra of other aminofluorenones,
this is assigned to an intramolecular charge transfer from the
9
cyanamide moiety to the fluorenone π skeleton.
ϩ
Ϫ
The electrochemistry of AsPh L is straightforward; the
4
cyclic voltammogram shows a single reversible one electron
reduction at Ϫ1.42 V vs. Ag–AgCl. This is in common with the
10
electrochemistry of other 2-substituted fluorenone derivatives.
In contrast, the cyclic voltammogram of HL is more com-
plicated, showing an irreversible oxidation at ϩ0.52 V and an
irreversible reduction at Ϫ1.15 V. The oxidation is linked to the
reduction, in that if the reduction is not performed the oxid-
ation is not seen in the spectrum.
ϩ
Ϫ
Slow evaporation of a water–ethanol solution of AsPh L
4
resulted in purple crystals that were found to be suitable for
ϩ
Ϫ
X-ray diffraction, and the resulting crystal structure is shown in
Fig. 3 A view down the c axis of the crystal structure of AsPh4 L ,
showing the hydrogen bonding (dotted lines) and graphitic packing
present.
¯
Fig. 2. The salt crystallises in the triclinic space group P1, with
two molecules of water of crystallisation in the asymmetric
Ϫ
unit. The L ion is essentially planar, as expected given the
11
nature of the fluorenone unit and the tendency of cyanamide
kind of ligand. Selected bond lengths and angles are presented
in Table 2.
The crystal packing diagram of AsPh L (Fig. 3) reveals
4
ϩ
graphitic packing between adjacent [AsPh ] cations and
between adjacent L anions, both showing the expected offset
of rings. The former have neighbouring phenyl rings (related
11
moieties to lie parallel to aromatic rings, with the largest
ϩ
Ϫ
deviation from the plane of the fluorenone moiety being 0.15 Å
for the atom O(1). The cyanamide N᎐C᎐N group is pointing
᎐
᎐
4
Ϫ
slightly below the plane of the rest of the ion so that the
terminal nitrogen atom N(2) is 0.25 Å from the plane. The angle
at C(14) in the N᎐C᎐N group is 176.3(3)Њ, while the angle to the
by the symmetry operation Ϫx, 1 Ϫ y, 1 Ϫ z) at a distance of
᎐
᎐
aromatic ring C(2)–N(1)–C(14) is 117.2(2)Њ. The fluorenone
carbon–cyanamide nitrogen distance C(2)–N(1) of 1.394(3) Å
is within the range of previously observed distances for this
3.74 Å, and the latter have the phenyl rings of neighbouring
Ϫ
L
L
moieties (related by Ϫx Ϫ 1, 1 Ϫ y, Ϫz) at 3.60 Å. These
species are reversed with respect to each other, so the
Ϫ
2
060
J. Chem. Soc., Dalton Trans., 1999, 2059–2064

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hydrogen bond acceptor unit to the hydrogen atoms H(52)
at 2.514 Å) and H(41) (at 2.364 Å) of two of the phenyl rings
(
ϩ
of two adjacent [AsPh4] cations (related by Ϫx Ϫ 1, 1 Ϫ y,
Ϫ z and x Ϫ 1, y, z respectively). The other water oxygen
1
atom O(11) is also interacting with one of the phenyl rings of
ϩ
a [AsPh4] cation (H(34), related by Ϫx Ϫ 1, 2 Ϫ y, 1 Ϫ z, at
2
.572 Å). The result of all this hydrogen bonding is to produce a
geometry around both O(10) and O(11) that is approximately
tetrahedral. Finally, the carbonyl oxygen O(1) acts as a hydro-
ϩ
gen bond acceptor with atom H(35) of a [AsPh4] cation
(
related by x, y Ϫ 1, z Ϫ 1), 2.420 Å away.
Simple EHMO calculations have been performed upon the
Ϫ
L anion shown in Fig. 2, using the crystallographic data as an
12
input for the CACAO program. The resulting MOs support
the idea of a cyanamide to carbonyl charge transfer being
responsible for the longest wavelength band seen in the UV/
ϩ
Ϫ
visible spectrum of AsPh L . The HOMO is of π symmetry,
4
and is shown in Fig. 4(a); it contains a contribution from the πnb
orbital of the cyanamide group that is perpendicular to the
13
plane, but none from the carbonyl. The LUMO (Fig. 4(b)) is
also of π symmetry. In contrast to the HOMO, it contains no
contribution from the cyanamide part of the anion, but has a
large component from the carbonyl group. This provides strong
support for assigning the longest wavelength UV/visible band
to a cyanamide to carbonyl π–π* charge transfer.
ϩ
Ϫ
The crystal structure of AsPh L and the MO calculations
4
provide a good explanation for the observed solvatochromism
of the low energy charge transfer band. The structure deter-
mination shows that it is the cyanamide group rather than the
carbonyl that interacts most strongly with the polar solvent,
and the MO calculations show that this group forms part of the
HOMO. Thus, the lower of the two states involved in the trans-
ition is more stabilised by polar solvents, and so the transition
moves to higher energies (and thus shorter wavelengths) as the
14
solvent polarity increases.
Metal complexes
ϩ
Ϫ
The thallium complex Tl L behaves as a transmetallating
agent on reaction with trimethyltin chloride and (triphenyl-
phosphine)gold chloride, eliminating thallium chloride and
Ϫ
allowing attachment of the L ion to the metal as a ligand
(
Scheme 1). The red-orange trimethyltin–cyanamide [SnMe L]
3
has been characterised by standard spectroscopic and analytical
methods. The IR spectrum shows a broad ν(N᎐C᎐N) stretch
᎐
᎐
Ϫ1
ϩ
4
Ϫ
with a maximum at 2108 cm , very similar to that of AsPh L
Ϫ1
Ϫ1
at 2104 cm , and a shoulder at 2150 cm . This is surprising
since there is normally a large change of this frequency upon
co-ordination of a cyanamide ligand to a metal, as has been
observed for the gold–cyanamide compound [AuL(PPh )];
3
Ϫ1
here, ν(N᎐C᎐N) appears at 2159 cm , with a shoulder at 2123
᎐
᎐
Ϫ1
cm .
Slow evaporation of a saturated acetone solution of [AuL-
(PPh )] resulted in orange crystals that were suitable for X-ray
Ϫ
Fig. 4ϩ TϪhe HOMO (a) and LUMO (b) of the L anionic part of
3
AsPh4 L .
diffraction; the resulting crystal structure is shown in Fig. 5,
and selected bond lengths and angles are given in Table 3. The
gold–nitrogen bond length Au(1)–N(2) is 2.017 Å, and the only
bond distance in the co-ordinated L moiety that is significantly
different from that of the “free” ligand in the crystal structure
C(1)C(2)C(3)C(4)C(11)C(10) ring of one lies over the
C(5)C(6)C(7)C(8)C(13)C(12) ring of the other. There is also
extensive hydrogen bonding present within the lattice. The
water molecule H(11a)O(11)H(11b) acts as a hydrogen bond
donor, having hydrogen atom H(11b) interacting with the
terminal nitrogen atom N(2) of the nearest cyanamide groups
ϩ
Ϫ
of AsPh L is C(14)–N(1), which is slightly shorter at 1.257(9)
4
Å. Similarly, the bond angles within the co-ordinated and unco-
ϩ
Ϫ
(
at 2.08 Å), and hydrogen atom H(11a) interacting with the
ordinated L ligands are very similar. As for AsPh L , there are
4
same atom in a neighbouring unit cell (related by the symmetry
operation Ϫx Ϫ 1, 2 Ϫ y, Ϫz) in a bridging fashion. For the
water molecule H(10a)O(10)H(10b) only H(10a) is hydrogen
bonding to the nearest cyanamide group, to the amine nitrogen
N(1) at 1.974 Å. The atom H(10b) acts as a hydrogen bond
donor interacting with the oxygen atom O(11) of the water of
crystallisation in a neighbouring asymmetric unit (related by
Ϫx Ϫ 1, 2 Ϫ y, 1 Ϫ z). The oxygen atom O(10) also acts as a
intermolecular interactions within the crystal lattice; O(1) is at
2.49 Å from H(41a) of a neighbouring triphenylphosphine
group (related by Ϫx, Ϫy, Ϫz ϩ 2), and N(2) is at 2.577 Å from
H(23a) of another triphenylphosphine ligand (related by x,
y Ϫ 1, z). There are also two hydrogen atoms H(6a) (related by
x, y, z Ϫ 1) and H(3a) (related by Ϫx Ϫ 1, Ϫy Ϫ 1, Ϫz ϩ 2) that
are at 3.058 Å from Au(1), but which do not appear to have any
directional interactions with it. The geometry of the bonding
J. Chem. Soc., Dalton Trans., 1999, 2059–2064
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Tl+L–
Cl SnMe3
CH2Cl2, r.t., overnight
N
C
N
SnMe3
O
Tl+L–
Cl Au PPh3
CH2Cl2, r.t., overnight
N
C
N
Au PPh3
O
Scheme 1 Synthesis and structure of metal complexes.
and used as received, except for [AuCl(PPh )], which was pre-
3
17
1
pared according to the literature procedure. The H NMR
spectra were recorded on a Bruker DRX 400 spectrometer and
31
1
referenced to solvent resonances, and the P-{ H} spectrum on
a Bruker AC 250 and referenced to external trimethyl phos-
phite. Solution IR spectra were recorded in a NaCl cell, and
Nujol spectra between NaCl plates, on a Perkin-Elmer 1710
Fourier-transform spectrometer. The EI and ϩFAB mass
spectra were recorded on a Kratos MS890 mass spectrometer,
and ES mass spectra on a Micromass Quattro LC machine.
Electrochemistry was performed under an argon atmosphere
using an Autolab PGSTAT20, with platinum working and
auxiliary electrodes and a Ag–AgCl reference electrode, in a 0.5
n
Ϫ1
M solution of [ Bu N][BF ] in CH Cl at 250 mV s . The UV/
4
4
2
2
visible absorption spectra were obtained on a Perkin-Elmer
λ9 spectrometer. Microanalyses were carried out in this
Department.
Fig. 5 The crystal structure of [AuL(PPh )].
3
Table 3 Selected bond lengths (Å) and angles (Њ) for [AuL(PPh )]
3
Synthetic procedures
N(2)–C(14)
N(1)–C(2)
C(2)–C(3)
C(4)–C(11)
C(5)–C(6)
C(7)–C(8)
C(9)–O(1)
C(9)–C(13)
C(1)–C(10)
C(12)–C(13)
Au(1)–P(1)
1.195(9)
1.401(8)
1.395(9)
1.386(9)
1.411(12)
1.387(12)
1.211(8)
1.482(10)
1.372(9)
1.379(10)
2.2295(17)
C(14)–N(1)
C(1)–C(2)
C(3)–C(4)
C(5)–C(12)
C(6)–C(7)
C(8)–C(13)
C(9)–C(10)
C(10)–C(11)
C(11)–C(12)
Au(1)–N(2)
1.257(9)
1.399(9)
1.402(10)
1.390(10)
1.366(13)
1.371(10)
1.506(9)
1.403(9)
1.508(9)
2.017(6)
18
2
-Aminofluoren-9-one. This was synthesized by a modifi-
19
cation of a literature procedure. 2-Aminofluorene (1.52 g,
3
0.838 mmol) was dissolved in 20 cm of pyridine, and 4 drops of
Triton B (benzyltrimethylammonium hydroxide, 40% w/w solu-
tion in methanol) were added. The solution was heated to 80 ЊC
and oxygen bubbled through it for 4 h. It was then cooled,
acidified with a few drops of glacial acetic acid, and poured into
a mixture of 100 cm of water and 5 cm of glacial acetic acid.
The resulting precipitate was filtered out and recrystallised from
hot absolute ethanol to give the desired product as red-brown
3
3
C(10)–C(1)–C(2)
N(1)–C(2)–C(1)
C(4)–C(3)–C(2)
C(12)–C(5)–C(6)
C(13)–C(8)–C(7)
O(1)–C(9)–C(13)
C(1)–C(10)–C(11)
C(11)–C(10)–C(9)
C(4)–C(11)–C(12)
C(5)–C(12)–C(13)
C(13)–C(12)–C(11)
C(8)–C(13)–C(9)
C(14)–N(1)–C(2)
C(6)–C(7)–C(8)
N(2)–Au(1)–P(1)
118.7(6)
122.7(6)
122.7(6)
117.0(8)
118.4(8)
128.4(7)
121.9(6)
108.7(6)
132.2(6)
120.8(7)
109.3(6)
129.3(7)
119.4(6)
120.8(7)
178.47(19)
N(1)–C(2)–C(3)
C(3)–C(2)–C(1)
C(11)–C(4)–C(3)
C(7)–C(6)–C(5)
O(1)–C(9)–C(10)
C(10)–C(9)–C(13)
C(1)–C(10)–C(9)
C(4)–C(11)–C(10)
C(10)–C(11)–C(12)
C(5)–C(12)–C(11)
C(8)–C(13)–C(12)
C(12)–C(13)–C(9)
N(2)–C(14)–N(1)
C(14)–N(2)–Au(1)
118.2(6)
119.1(6)
117.0(6)
121.4(8)
126.0(7)
105.6(6)
129.3(6)
120.5(6)
107.2(6)
129.9(7)
121.6(7)
109.2(6)
173.3(7)
144.0(6)
18a
crystals (1.1 g, 5.63 mmol, 67%), mp 160–161 ЊC (lit., 159.5–
1
61 ЊC) (C H NO requires C, 79.98; H, 4.65; N, 7.16. Found:
13 9
C, 79.23; H, 4.80; N, 7.11%). IR (CH Cl ): 1717s (ν(C᎐O)) and
2
2
Ϫ1
1
3
396s cm (br) (ν(N–H)). H NMR (CDCl ): δ 3.87 [br s, 2 H,
3
3
NH], 6.72 [dd, 1 H, J(HH) = 8.01, arene CH], 6.96 [d, 1 H,
J(HH) = 2.09, arene CH], 7.14 [t, 1 H, J(HH) = 7.66, arene
4
3
3
CH], 7.27 [d, 1 H, J(HH) = 7.84, arene CH], 7.32 [d, 1 H,
3
3
J(HH) = 7.32, arene CH], 7.39 [t, 1 H, J(HH) = 7.38, arene
3
CH] and 7.56 [d, 1 H, J(HH) = 7.35 Hz, arene CH].
2-Cyanaminofluoren-9-one (HL). Ammonium thiocyanate
(0.565 g, 0.74 mmol) was refluxed under nitrogen in 30 cm of
acetone, and to this was added dropwise 0.86 cm (1 equivalent)
of benzoyl chloride, also in 30 cm of acetone. This mixture was
3
3
3
refluxed for 10 min, after which 1.45 g (0.74 mmol) of 2-
aminofluoren-9-one in another 30 cm of acetone were added
between metal and cyanamide is similar to that seen in the
3
11,15
structure of other neutral metal–cyanamide compounds.
The UV/visible spectra of the complexes are similar to that
slowly. After 1 h at reflux the solution was allowed to cool and
3
ϩ
Ϫ
poured into 200 cm of distilled water. The resulting orange
of AsPh L , with the same number of bands but with a shift
4
solid was filtered off, washed with copious amounts of water,
of these to shorter wavelengths (Table 1).
3
and then redissolved in 200 cm of 2 M sodium hydroxide solu-
tion. This solution was boiled for 5 min, then cooled to about
55 ЊC. Lead() acetate (2.81 g, 0.74 mmol) was added and
stirred for 6 min. The resulting precipitate of lead sulfide was
filtered off, and the filtrate cooled on ice. To the stirred
solution was then added 10 cm of glacial acetic acid, pre-
cipitating the desired product as an orange solid. This was
Experimental
General
3
Solvents were pre-dried and distilled from appropriate drying
16
agents. All chemicals were obtained from commercial sources
2
062 J. Chem. Soc., Dalton Trans., 1999, 2059–2064

View Article Online
ϩ
Ϫ
recrystallised from a hot solution of 1:1 acetone–water to give
-cyanaminofluoren-9-one as an orange solid (1.04 g, 0.47
mmol, 63%), mp 227 ЊC (C H N O requires C, 76.35; H, 3.66;
Table 4 Summary of crystal structure data for AsPh
AuL(PPh )]
4
L ؒ2H
2
O and
[
2
3
14
8
2
ϩ
Ϫ
AsPh4 L ؒ2H O
[AuL(PPh )]
N, 12.72. Found: C, 76.35; H, 3.79; N, 12.69%). IR (Nujol
mull): 3179m (ν(N–H)), 2235m, 2232 (sh) (ν(C᎐N)) and 1715s
2
3
᎐
Ϫ1
1
Empirical formula
M
C H AsN O
638.57
C H AuN OP
cm (ν(C᎐O)). H NMR (CD CN): δ 7.17 [m, 2 H, arene CH],
.30 [t, 1 H, J(HH) = 7.49 Hz, arene CH] and 7.54–7.62 [m, 5 H,
38 31
2
3
32 22
2
3
3
678.45
7
Crystal system
Space group
Triclinic
P1
Triclinic
ϩ
arene CH]. EI mass spectrum: m/z 220 (M ).
¯
¯
P1
a/Å
b/Å
c/Å
α/Њ
β/Њ
γ/Њ
12.9059(3)
13.584(3)
9.2290(18)
96.84(3)
97.86(3)
107.43(3)
1507.0(5)
2
1.170
180
9368
6912
10.527(3)
11.852(3)
12.330(3)
99.59(2)
107.35(2)
114.10(3)
1264.8(6)
2
5.908
180
6086
5800
؉
؊
Tl L . To a boiling solution of 0.91 g (4.13 mmol) of 2-
3
cyanaminofluoren-9-one in 25 cm of 1:1 acetone–water were
added 1.49 g (5.6 mmol) of thallium() acetate in 25 cm of the
same solvent and 0.96 cm of triethylamine. This was boiled for
min. Adding a little acetone to the hot solution dissolved all
the solid material, and letting the resulting solution stand and
cool overnight produced purple crystals of the desired product
1.24 g, 2.92 mmol, 70%), which were filtered off, washed with
:1 acetone–water and dried under vacuum (C H N OTl
3
3
1
3
U/Å
Z
µ(Mo-Kα)/mm
T/K
No. reflections collected
No. independent reflections
Obs. reflections [I > 2σ(I )]
Rint
R1, wR2 [I > 2σ(I )]
all data
Ϫ1
(
1
1
4
7
2
requires C, 39.70; H, 1.67; N, 4.64. Found: C, 39.69; H, 1.65; N,
.55%). H NMR (d -DMF): δ 6.80–7.42 [br m, 7 H, arene CH].
6
ϩ
ϩFAB mass spectrum: m/z 205 (M ).
5464
0.0353
0.0414, 0.0848
0.0633, 0.0930
4900
0.0290
0.0420, 0.0981
0.0566, 0.1044
1
4
؉
4
؊
AsPh L . To a solution of 0.074 g (0.336 mmol) of 2-
cyanaminofluoren-9-one in 10 cm of 2 M sodium hydroxide
was added 0.15 g (0.35 mmol) of tetraphenylarsonium chloride.
Dichloromethane (25 cm ) was added to extract the product,
and this organic layer was separated, dried over magnesium
sulfate, filtered, and reduced to the minimum volume. The
resulting solution was vigorously stirred and diethyl ether (100
ml) added to precipitate the product. This was filtered off,
washed with diethyl ether and dried in air and in vacuo, to yield
3
crystals of [AuL(PPh )] by slow evaporation of a saturated
3
acetone solution. Suitable crystals were mounted using per-
fluoroether oil, and cooled to 180 K with an Oxford Cryo-
stream apparatus. Geometric and intensity data were collected
on a Rigaku AFC7R diffractometer, using the ω–2θ scan
technique. Semiempirical absorption corrections based upon
3
20
ψ scans were applied (TEXSAN). The structure was solved
by Patterson methods (SHELXS 97), and subsequent Fourier-
21
0
(
7
1
.184 g (0.314 mmol, 93%) of the product as a violet powder
C H AsN O requires C, 75.74; H, 4.51; N, 4.64. Found: C,
difference syntheses, and refined by full-matrix least squares on
2
22
38
27
2
F (SHELXL 97). Details of crystal data, data collection and
structure solution and refinement are summarised in Table 4.
All non-hydrogen atoms were refined with anisotropic dis-
placement parameters, and all aromatic hydrogen atoms placed
in idealised positions and allowed to ride on the relevant carbon
4.57; H, 4.45; N, 4.55%). IR (CH Cl ): 2104s (ν(N᎐C᎐N)) and
2 2
Ϫ1 1
711s cm (ν(C᎐O)). H NMR (CDCl ): δ 6.91–6.97 [m, 3 H,
3
3
arene CH], 7.02 [d, 1 H, J(HH) = 7.4, arene CH], 7.15 [d, 1 H,
J(HH) = 7.4, arene CH], 7.26 [t, 1 H, J(HH) = 5.5, arene CH],
.35 [d, 1 H, J(HH) = 7.26 Hz, arene CH] and 7.57–7.81 [m,
0 H, Ph As ]. ϪES mass spectrum: m/z 219 (L ).
3
3
3
7
2
ϩ
4
Ϫ
atoms. The water hydrogen atoms of AsPh L ؒ2H O were
2
ϩ
Ϫ
4
located in the difference map and refined freely. A final elec-
tron density difference map showed no regions of significant
electron density.
CCDC reference number 186/1456.
See http://www.rsc.org/suppdata/dt/1999/2059/ for crystallo-
graphic files in .cif format.
[
SnMe L]. Trimethyltin chloride (0.07 g, 0.35 mmol) and
3
ϩ Ϫ 3
0
.16 g (0.37 mmol) of Tl L were stirred for 12 h in 10 cm
of dichloromethane. The resulting solution was filtered through
Celite and refrigerated to give the desired product as orange
crystals (0.06 g, 0.16 mmol, 41%) (C H N OSn requires C,
17
16
2
5
3.31; H, 4.21; N, 7.31. Found: C, 53.06; H, 4.22; N, 6.98%). IR
Ϫ1
Acknowledgements
I wish to thank the EPSRC for financial support, and Drs P. R.
Raithby and J. E. Davies for crystallographic data collection
and helpful discussions.
(
(
CH Cl ): 2150 (sh), 2108s (ν(N᎐C᎐N)) and 1718s cm
2 2
1 2
ν(C᎐O)). H NMR (CDCl ): δ 0.63 [s, 9 H, J(HSn) = 58.85,
᎐
3
3
Me Sn], 7.00 [d, 1 H, J(HH) = 7.9, arene CH], 7.19 [t, 1 H,
3
3
J(HH) = 7.2, arene CH], 7.33–7.42 [m, 3 H, arene CH] and
3
7
.59 [d, 1 H, J(HH) = 7.33 Hz, arene CH]. ϩFAB mass
ϩ
spectrum: m/z 384 (M ).
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AuL(PPh )]. (Triphenylphosphine)gold chloride (0.18 g,
3
ϩ
Ϫ
0
1
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ϩ
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ϩ
Ϫ
Deep purple crystals of AsPh L ؒ2H O were obtained by slow
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4
2
J. Chem. Soc., Dalton Trans., 1999, 2059–2064
2063

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J. Chem. Soc., Dalton Trans., 1999, 2059–2064