The synthesis of small azamacrocycles bearing pendant aromatic functionalities

Article abstract of DOI:10.1016/S0277-5387(01)00994-9

A simple synthetic procedure for the mono- or di-functionalization of tri- and tetra-azamacrocycles with electron rich arenes has been developed. Specifically, 1,4,7-triazacyclononane (tacn), 1,4,7,10-tetraazacyclododecane (cyclen) and 1,4,8,11-tetraazacyclotetradecane (cyclam) react with 2,4,6-trimethylstyrene in the presence of n-butyllithium to give, respectively N-(mesitylethyl)-1,4,7-triazacyclononane (L₁), N-(mesitylethyl)-1,4,7,10-tetraazacyclododecane (L₄), and N-(mesitylethyl)-1,4,8,11-tetraazacyclotetradecane (L₅). In contrast, when styrene itself or p-vinylanisole are used as the Michael acceptor with 1,4,7-triazacyclononane, the N′,N″ product is formed, respectively N′,N″-bis(phenylethyl)-1,4,7-triazacyclononane (L₂) and N′,N″-bis(p-methoxyphenylethyl)-1,4,7-triazacyclononane (L₃). Using conventional mono-functionalization techniques, the phenyl derivatives N-(4-hydroxymethylbenzyl)-1,4,7-triazacyclononane (L₆) and N-(4-benzylcarboxylic acid)-1,4,7-triazacyclononane (L₇) have also been synthesised. A series of transition metal complexes of L₁ to L₇ with Ni(II), Cu(II), Zn(II) and Co(II) have been prepared. The X-ray crystal structures of [Cu(L₁)₂](PF₆)₂, [(L₁)CuCl₂], [Cu(L₆)(NO₃)₂] and [Cu₂(L₇-H)₂(OH₂)₂] (PF₆)₂·3H₂O are described. In all of these complexes, coordination to the metal takes place through the macrocycle nitrogens. The crystal structure of [Cu₂(L₇-H)₂(OH₂)₂] (PF₆)₂·3H₂O reveals that it is a coordinate-polymeric material. Attempts to coordinate the pendent arenes to Rh(I) are discussed.

Full text of DOI:10.1016/S0277-5387(01)00994-9

Polyhedron 21 (2002) 333–342
www.elsevier.com/locate/poly
The synthesis of small azamacrocycles bearing pendant aromatic
functionalities.
The crystal structures of [Cu(L1)2](PF6)2, [(L1)CuCl2],
[Cu(L6)(NO3)2] and [Cu2(L7ꢀH)2(OH2)2](PF6)2·3H2O
(L1=N-(mesitylethyl)-1,4,7-triazacyclononane,
L6=N-(4-hydroxymethylbenzyl)-1,4,7-triazacylcononane,
L7=N-(4-benzylcarboxylic acid)-1,4,7-triazacylcononane)
Andrew C. Benniston a,b,*, David Ellis a, Louis J. Farrugia a, Roselyn Kennedy a,
Robert D. Peacock a,*, Sarah Walker a
a Department of Chemistry, Joseph Black Building, The Uni6ersity of Glasgow, Glasgow G12 8QQ, UK
b Department of Chemistry, Bedson Building, Uni6ersity of Newcastle, Newcastle-upon-Tyne NE1 7RU, UK
Received 24 September 2001; accepted 13 November 2001
Abstract
A simple synthetic procedure for the mono- or di-functionalization of tri- and tetra-azamacrocycles with electron rich arenes has
been developed. Specifically, 1,4,7-triazacyclononane (tacn), 1,4,7,10-tetraazacyclododecane (cyclen) and 1,4,8,11-tetraazacyclote-
tradecane (cyclam) react with 2,4,6-trimethylstyrene in the presence of n-butyllithium to give, respectively N-(mesitylethyl)-1,4,7-
triazacyclononane (L1), N-(mesitylethyl)-1,4,7,10-tetraazacyclododecane (L4), and N-(mesitylethyl)-1,4,8,11-tetraazacyclo-
tetradecane (L5). In contrast, when styrene itself or p-vinylanisole are used as the Michael acceptor with 1,4,7-triazacyclononane,
the N%,N¦ product is formed, respectively N%,N¦-bis(phenylethyl)-1,4,7-triazacyclononane (L2) and N%,N¦-bis(p-methoxyphenyl-
ethyl)-1,4,7-triazacyclononane (L3). Using conventional mono-functionalization techniques, the phenyl derivatives N-(4-hydrox-
ymethylbenzyl)-1,4,7-triazacyclononane (L6) and N-(4-benzylcarboxylic acid)-1,4,7-triazacyclononane (L7) have also been synthe-
sised. A series of transition metal complexes of L1 to L7 with Ni(II), Cu(II), Zn(II) and Co(II) have been prepared. The X-ray
crystal structures of [Cu(L1)2](PF6)2, [(L1)CuCl2], [Cu(L6)(NO3)2] and [Cu2(L7ꢀH)2(OH2)2](PF6)2·3H2O are described. In all of
these complexes, coordination to the metal takes place through the macrocycle nitrogens. The crystal structure of
[Cu2(L7ꢀH)2(OH2)2](PF6)2·3H2O reveals that it is a coordinate-polymeric material. Attempts to coordinate the pendent arenes to
Rh(I) are discussed. © 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Azamacrocycles; Aromatic pendant arms; Coordination compounds; Metallic polymer
1. Introduction
and pyridine [7] is now well established. More recently
the chemistry has been extended to include more classic
soft donors such as sulfides [8], alkenes [9], phosphines
[10] and alkynes [11]. As part of our own research effort
we have been exploring the possibility of introducing
aromatic groups onto the macrocycle (Scheme 1),
which are either electron rich so as to generate
organometallic clusters, or have oxygen binding sites
for further molecular recognition [12]. As a result we
The chemistry of triazamacrocycles, N-functionalized
with hard ligators, e.g. carboxylic acids [1], alcohols [2],
amines [3], sulfates [4], phosphates [5], imidazoles [6]
* Corresponding authors. Tel.: +44-141-222-5706; fax: +44-141-
222-6929.
E-mail address: a.c.benniston@ncl.ac.uk (A.C. Benniston).
0277-5387/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0277-5387(01)00994-9

334
A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
vated’ arene of the coordinated ligand would react with
soft metal centres, but no reaction was observed with
Rh(I) [13] or Mo(0) [14] despite the use of forcing
conditions. Complexes of L6 with the metals, Cu(II),
Ni(II), Co(II) and L7 with Cu(II) were also prepared. In
these two cases it was expected that the hydroxyl or
carboxyl unit would play host to intermolecular bond-
ing, and hence the construction of self-assembled
molecular aggregates (e.g. polymers, boxes) as illus-
trated in Scheme 2.
2. Experimental
All chemicals unless otherwise stated were purchased
from Aldrich and used as received. 1,4,7,10-Tetraazacy-
clododecane (cyclen) was purchased from Strem Chem-
icals. Solvents where necessary were dried by reported
methods [15]. 1,4,7-Triazacyclononane (tacn) [16],
1,4,8,11-tetraazacyclotetradecane (cyclam) [17], 1,4,7-
triazacyclo[5.2.1.04.10]decane [18] and [Rh(m-Cl)(COD)]2
[19] were synthesised according to literature procedures.
1H and 13C NMR spectra were recorded using a Bruker
AM360 360 MHz spectrometer. UV–Vis spectra were
recorded using a Shimadzu UV-3101 PC spectrophoto-
meter. Mass spectra were obtained using a JEOL JMS
700 (The MStation) mass spectrometer. Combustion
analysis was performed using in-house facilities.
Scheme 1. List and numbering scheme of the macrocycles discussed in
the text.
now present some of our work towards these goals. In
particular, a high yielding procedure is reported for the
monofunctionalization of tacn with the electron rich
arene derived from 2,4,6-trimethylstyrene.
Syntheses of single pendent arm macrocycles are
comparatively rare, and are often not straightforward,
requiring chromatographic separation of the products.
We have found that direct reaction of an excess of
2,4,6-trimethylstyrene with either of the macrocycles,
tacn, cyclen or cyclam in the presence of n-butyllithium
leads to good yields of the monosubstituted products
without further separation. Under the same experimen-
tal conditions, the vinylaromatics styrene or p-vinylan-
isole give the N%,N¦ disubstituted products, in a
similarly pure state.
2.1. Synthesis of N-(mesitylethyl)-1,4,7-
triazacyclononane (L1)
nBuLi (4 ml of a 2.5 M solution in hexanes, 10 mmol)
was added dropwise to a solution of tacn (1.0 g, 7.8
mmol) dissolved in THF (20 ml). The reaction mix was
stirred for 5 min, followed by the dropwise addition of
2,4,6-trimethylstyrene (3.4 g, 23.2 mmol) in THF (10
ml) and the solution stirred at 60 °C for 16 h. Water (1
ml) was added and the reaction mix stirred for 5 min.
All volatiles were removed in vacuo. The residue was
extracted into CH2Cl2 and the solution extracted with 2
M HCl (2×40 ml). The aq. phase was basified with
NaOH (1 M) solution and the free ligand extracted into
CHCl3 (3×40 ml). The combined organic phases were
dried over MgSO4, filtered and the solvents removed in
vacuo to leave a clear oil which slowly solidified. Yield:
Complexes of L1 with the metals, Cu(II), Ni(II),
Co(II) and Zn(II) were synthesised and the X-ray crys-
tal structures of [Cu(L1)2](PF6)2 and [(L1)CuCl2] are
described. It was anticipated that the pendent ‘acti-
1
1.1 g, 3.9 mmol, 50%. H NMR (CDCl3): l=6.80 (s,
2H, C6H2Me3), 2.98–2.60 (m, 18H, CH2NH), 2.27 (s,
6H, o-C6H2(CH3)2), 2.21 (s, 3H, p-C6H2CH3). 13C
NMR (CDCl3): l=136.0, 135.3, 133.3, 128.9
(phenylꢀC), 55.6 (NꢀCH2ꢀCH2ꢀC6H2Me3), 52.3, 46.7,
46.4 (NꢀCH2ꢀCH2ꢀN), 27.2 (NꢀCH2ꢀCH2ꢀC6H2Me3),
20.8 (p-C6H2CH3), 19.8 (o-C6H2(CH3)2). EI MS: m/
z=273 [M−2H]+, 154 [M−C6H2Me3]+.
Scheme 2. Pictorial representation of potential products from the
self-assembly of an ‘L’ type motif.

A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
335
2.2. Synthesis of N-(mesitylethyl)-1,4,7,10-
tetraazacyclododecane (L4)
MS: m/z=335 [M]+, 246 [M−CH2C6H5]+, 105
[C6H5(CH2)2]+.
nBuLi (1.6 ml of a 2.5 M solution in hexanes, 4.0
mmol) was added dropwise to a solution of cyclen (0.50
g, 3.0 mmol) in THF (20 ml). The reaction mixture was
stirred for 5 min, followed by the addition of 2,4,6-
trimethylstyrene (1.3 g, 9 mmol) in THF (10 ml) and
the reaction mixture was stirred at 60 °C for 16 h.
Water (5 ml) was added and the reaction mixture
stirred for 5 min. All volatiles were removed in vacuo.
The residue was dissolved in CH2Cl2 and the solution
extracted into 2 M HCl (2×40 ml). The aq. phase was
basified with NaOH (1 M) solution and the free ligand
extracted into CHCl3 (3×40 ml). The combined or-
ganic phases were dried over MgSO4, filtered and the
solvents removed in vacuo to leave a clear, yellow oil.
Yield: 0.58 g, 1.8 mmol, 60%. 1H NMR (CDCl3):
l=6.80 (s, 2H, C6H2Me3), 2.82–2.50 (m, 23H,
CH2,NH), 2.27 (s, 6H, o-C6H2(CH3)2), 2.21 (s, 3H,
p-C6H2CH3). 13C NMR (CDCl3): l=135.9, 135.0,
133.2, 129.7 (phenylꢀC), 53.0 (NꢀCH2ꢀCH2ꢀC6H2Me3),
51.0, 46.9, 45.7, 45.3 (NꢀCH2ꢀCH2ꢀN), 26.8 (NꢀCH2ꢀ
CH2ꢀC6H2Me3), 20.6 (p-C6H2CH3), 19.5 (o-C6H2-
(CH3)2). EI MS: m/z=185 [M−(CH2)2C6-H2Me3]+,
147 [(CH2)2C6H2Me3]+, 133 [CH2C6H2Me3]+.
2.5. Synthesis of N%,N¦-bis(p-methoxyphenylethyl)-
1,4,7-triazacyclononane (L3)
Prepared similarly to L1 from tacn (0.21 g, 1.58
n
mmol), BuLi (1.0 ml of a 2.5 M solution in hexanes,
2.1 mmol), and p-vinylanisole (0.64 g, 4.8 mmol). Yield:
0.28 g, 0.71 mmol, 45%. 1H NMR (CDCl3): l=7.09 (d,
4H, C6H4, J=8.64 Hz), 6.81 (d, 4H, C6H4, J=8.68
Hz), 3.74 (s, 6H, CH3), 2.71–2.58 (m, 21H, CH2, NH).
13C NMR (CDCl3): 157.8, 132.2, 129.6, 113.7
(phenylꢀC), 59.0 (NꢀCH2ꢀCH2ꢀC6H4OMe), 55.1
(CH3), 52.3, 50.1, 45.8 (NꢀCH2ꢀCH2ꢀN), 33.0
(NꢀCH2ꢀCH2ꢀC6H4OMe). EI MS: m/z=396 [M]+,
276 [M−CH2C6H4OMe]+, 135 [CH2CH2C6H4OMe]+.
2.5.1. Synthesis of A
To a one-necked flask flushed with dinitrogen and
charged with 1,4,7-triazacyclo[5.2.1.04.10]decane (0.69 g,
4.96 mmol) in dry THF (30 ml), was slowly added
4-bromomethylbenzyl alcohol (1 g, 4.98 mmol) in dry
THF (20 ml). The reaction mixture was stirred
overnight and the resultant white precipitate filtered
washed with THF and dried. Yield: 1.03 g, 3.02 mmol,
61%. 1H NMR (C3H6O-d6): l=7.73–7.72 (d, 2H,
C6H4, J=7.9 Hz), 7.54–7.52 (d, 2H, C6H4, J=7.9
Hz), 5.97 (s, 1H, NꢀCH), 4.75 (s, 2H, ArꢀCH2), 4.71 (s,
2H, ArCH2), 4.04–3.98 (m, 2H, NCH2), 3.81–3.70 (m,
4H, NCH2), 3.50–3.42 (m, 2H, NꢀCH2), 3.33–3.25 (m,
4H, NꢀCH2).
2.3. Synthesis of N-(mesitylethyl)-1,4,8,11-tetra-
azacyclotetradecane (L5)
Prepared similarly to L1 from cyclam (0.40 g, 2.0
n
mmol), BuLi (1.1 ml of a 2.5 M solution in hexanes,
2.8 mmol) and 2,4,6-trimethylstyrene (1.2 g, 8.0 mmol).
Yield: 0.30 g, 0.88 mmol, 44%. 1H NMR (CDCl3):
l=6.73 (s, 2H, C6H2Me3), 2.72–2.51 (m, 23H, NH,
NꢀCH2ꢀCH2ꢀN,NꢀCH2ꢀCH2ꢀCH2ꢀN), 2.23 (s, 6H, o-
C6H2(CH3)2), 2.15 (s, 3H, p-C6H2CH3), 1.67 (m, 4H,
NꢀCH2ꢀCH2ꢀC6H2Me3). 13C NMR (CDCl3): l=135.9,
134.8, 133.4, 128.7 (phenylꢀC), 54.0, 52.3, 50.9, 50.7,
50.5, 49.3, 49.1, 49.0, 48.9, 47.9, 28.9, 28.6, 26.3, 24.5
(CH2), 20.7 (p-C6H2CH3), 19.8 (o-C6H2(CH3)2). EI
MS: m/z=213 [M−CH2(C6H2Me3]+, 147 [(CH2)2C6-
H2Me3]+.
2.6. Synthesis of N-(4-hydroxymethylbenzyl)-1,4,7-
triazacyclononane (L6)
Compound A (1.31 g, 3.85 mmol) was refluxed in
water (40 ml) for 4 h followed by the addition of NaOH
(0.54 g, 10 mmol). The resulting basic solution was
refluxed for 24 h and the water removed with C6H5CH3
using
a Dean–Stark apparatus. Removal of the
C6H5CH3 afforded an oil which was sufficiently pure
enough for metal ion complexation. Yield: 0.65 g, 2.6
1
mmol, 68%. H NMR (CDCl3): l=7.26 (s, 4H, C6H4),
4.53 (s, 2H, NꢀCH2ꢀOH), 3.62 (s, 2H, CH2ꢀN), 2.65
(m, 4H, NꢀCH2), 2.54 (m, 8H, NꢀCH2). EI MS: m/z=
250 [MH]+.
2.4. Synthesis of N%,N¦-bis(phenylethyl)-1,4,7-
triazacyclononane (L2)
Prepared similarly to L1 from tacn (0.20 g, 1.58
n
mmol), BuLi (1.0 ml of a 2.5 M solution in hexanes,
2.6.1. Synthesis of B
2.1 mmol) and styrene (0.50 g, 4.8 mmol). Yield: 0.24 g,
This compound was prepared in a similar manner to
that reported for compound A, using methyl-4-(bro-
momethyl)benzoate (1 g, 4.37 mmol) and 1,4,7-triazacy-
clo[5.2.1.04.10]decane (0.69 g, 4.96 mmol). Yield: 1.1 g,
2.98 mmol, 68%. H NMR (C3H6O-d6): l=8.11–8.09
(d, 2H, C6H4, J=8.1 Hz), 7.91–7.88 (d, 2H, C6H4,
1
0.72 mmol, 45%. H NMR (CDCl3): l=7.29–7.18 (m,
10H, C6H5), 2.79–2.62 (21H, CH2 NH). 13C NMR
(CDCl3): l=140.6, 128.6, 128.3, 125.9 (phenylꢀC),
1
59.1
(NHꢀCH2ꢀCH2ꢀC6H5),
53.0,
53.5,
46.7
(NHꢀCH2ꢀCH2ꢀNH), 34.1 (NHꢀCH2ꢀCH2ꢀC6H5). EI

336
A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
J=8.2 Hz), 6.02 (s, 1H, NCH), 4.79 (s, 2H, ArꢀCH2),
3.98–3.93 (m, 2H, NCH2), 3.90 (s, 3H, OCH3),
3.82–3.75 (m, 4H, NꢀCH2), 3.45–3.32 (m, 2H, NCH2),
3.26–3.31 (q, 4H, NCH2, J=6.7 Hz).
(Calc.): C, 44.9 (45.06); H, 6.52 (6.45); N, 9.23 (9.27)%.
1H NMR (CD3CN): l=6.87 (s, 4H, phenylꢀH), 3.31
(s, 4H, NH), 2.96–2.64 (m, 32H, CH2), 2.25 (s, 12H,
o-C6H2(CH3)2), 2.23 (s, 6H, p-C6H2CH3). 13C NMR
(CD3CN): 136.8, 131.6, 129.5, 117.8 (phenylꢀC), 55.8,
49.1, 44.0, 43.2 (NꢀCH2), 22.5 (CH2-mesityl), 20.3 (p-
C6H2CH3), 19.5 (o-C6H2(CH3)2).
2.7. Synthesis of N-(4-benzylcarboxylic
acid)-1,4,7-triazacyclononane (L7)
Compound B (1 g, 2.8 mmol) was dissolved in water
(50 ml) and refluxed for 2 h followed by addition of
NaOH (0.2 g, 5 mmol) and further refluxing for 4 h.
The solution was cooled to room temperature and
extracted with CH2Cl2 to remove organic impurities.
The solution was made acidic with concd. HBr and the
solvent removed on a rotary evaporator. The remaining
solid was extracted with EtOH (3×50 cm3) and the
combined EtOH fractions removes on a rotary evapo-
rator to afford a yellow solid, which was recrystallized
from MeOH–Et2O (1:5). Yield: 0.44 g, 1.7 mmol, 60%.
1H NMR (DMSO-d6): l=7.91–7.88 (d, 2H, C6H4,
J=8.0 Hz), 7.57–7.54 (d, 2H, C6H4, J=8.1 Hz), 4.42
(s, 2H, ArꢀCH2), 3.88 (m, 4H, NꢀCH2), 3.13 (m, 4H,
NꢀCH2), 2.87 (m, 4H, NꢀCH2). EI MS: m/z=264
[MH]+, 247 [M−OH]+, 219 [M−CO2H]+.
2.8.4. [Ni(L1)2](PF6)2 (4)
The ligand L1 (150 mg, 0.55 mmol) in EtOH (5 ml)
was added to NiCl2·6H2O (60 mg, 0.25 mmol) in EtOH
(20 ml), containing NH4PF6 (200 mg). The mixture was
stirred for 4 h. A purple precipitate was filtered off and
air-dried. Yield: 100 mg (44%). IR (cm−1): 3270 w(NꢀH)
,
841 w(PꢀF). CHN Found (Calc.): C, 44.9 (45.4); H, 6.71
(6.50); N, 8.88 (9.34)%.
2.8.5. [Cu(L4)](ClO4)2·1/2EtOH (5)
The ligand L4 (140 mg, 0.44 mmol) in EtOH (5 ml)
was added to Cu(ClO4)2·6H2O (130 mg, 0.35 mmol) in
EtOH (20 ml). The solution was stirred for 24 h. A
purple precipitate was filtered off, washed with EtOH
and dried in vacuo. Yield: 114 mg (54%). IR (cm−1):
3280 w(NꢀH), 1100 w(ClꢀO). CHN Found (Calc.): C, 40.0
(39.77); H, 5.78 (6.17); N, 8.95 (9.28)%. UV–Vis
(CH3NO2): umax (nm) (mmax, mol−1 l cm−1): 579 (334).
2.8. Metal complexes
2.8.1. [Cu(L1)2](PF6)2·1/2CH3CN (1)
2.8.6. [Zn(L4)Cl](ClO4)2 (6)
The ligand L1 (150 mg, 0.55 mmol) in EtOH (2 ml)
was added to CuCl2·2H2O (48 mg, 0.28 mmol) in EtOH
(10 ml), containing NH4PF6 (230 mg). Stirring was
continued for approximately 16 h. A blue precipitate
was filtered off, washed with EtOH and ether, and
air-dried. The compound was recrystallized from
The ligand L4 (202 mg, 0.64 mmol) in EtOH (3 ml)
was added to ZnCl2 (69 mg, 0.51 mmol) in EtOH (20
ml) containing LiClO4 (300 mg). Stirring was continued
for approximately 24 h. The white precipitate was
filtered off, washed with EtOH and ether and dried in
1
vacuo. Yield: 120 mg (45%). H NMR (CD3CN): l=
MeCN. Yield: 138 mg (50%). IR (cm−1): 3142 w(NꢀH)
843 w(PꢀF). CHN Found (Calc.): C, 45.80 (45.45); H,
6.55 (6.48); N, 9.46 (9.84)%.
,
6.84 (s, 2H, phenylꢀH), 3.11–2.69 (m, 23H, CH2 NH),
2.27 (s, 6H, o-C6H2(CH3)2), 2.20 (s, 3H, p-C6H2CH3).
13C NMR (CD3CN): 137.2, 132.8, 130.0, 118.3
(phenylꢀC), 53.0 (NꢀCH2ꢀCH2ꢀmes), 50.2, 45.5, 44.6,
43.6 (NꢀCH2ꢀCH2ꢀN), 22.5 (CH2ꢀmes), 20.9 (p-
C6H2CH3), 19.9 (o-C6H2(CH3)2). IR (cm−1): 3280
w(NꢀH), 1090 w(ClꢀO). CHN Found (Calc.): C, 44.1 (44.6);
H, 6.74 (6.71); N, 10.2 (10.9)%.
2.8.2. [Co(L1)2](PF6)2 (2)
The ligand L1 (256 mg, 0.93 mmol) in EtOH (5 ml)
was added to CoCl2·6H2O (88 mg, 0.37 mmol) in
degassed EtOH (20 ml), containing NH4PF6 (300 mg).
The reaction mixture was stirred for approximately 16
h under nitrogen. A pink precipitate was filtered off,
washed repeatedly with EtOH and dried in vacuo.
2.8.7. [Ni(L4)](ClO4)2·1/2Et2O (7)
The ligand L4 (301 mg, 0.94 mmol) in butan-1-ol (10
ml) was added to Ni(ClO4)2·6H2O (278 mg, 0.76 mmol)
in hot butan-1-ol (30 ml). The reaction mixture was
stirred for 24 h. A green precipitate was filtered off,
washed with butan-1-ol and dried in vacuo. Yield: 142
mg. The blue liquor was concentrated in vacuo to
dryness to leave a yellow solid. This was washed repeat-
edly with ether and dried in vacuo. Yield: 280 mg
(64%). IR (cm−1): 3260 w(NꢀH), 1100 w(ClꢀO). CHN
Found (Calc.): C, 40.60 (41.14); H, 6.19 (6.41); N, 8.54
Yield: 200 mg (60%). IR (cm−1): 3200 w(NꢀH), 845 w(PꢀF)
CHN Found (Calc.): C, 45.30 (45.39); H, 6.57 (6.50);
N, 9.18 (9.34)%.
.
2.8.3. [Zn(L1)2](PF6)2 (3)
The ligand L1 (200 mg, 0.72 mmol) in EtOH (2 ml)
was added to ZnCl2 (48 mg, 0.36 mmol) in EtOH (20
ml) containing NH4PF6 (300 mg). The mixture was
stirred for 2 h. A white precipitate was then filtered off,
washed with EtOH and dried in vacuo. Yield: 183 mg
(56%). IR (cm−1): 3214 w(NꢀH), 843 w(PꢀF). CHN Found
(9.14)%. UV–Vis (CH3NO2): umax (nm) (mmax, mol−1
l
cm−1): 418 (40), 454 (26.1), 878 (27.9).

A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
337
2.8.8. [Cu(L5)](ClO4)2·H2O (8)
ganic layer was separated and removed to give oil,
which was recrystallized from CH3CN–Et2O (1:3).
Yield: 100 mg (30%). IR (cm−1): 3424 w(NꢀH), 2927
w(CꢀH), 843 w(PꢀF). FAB MS: m/z=701 [Ni(L6)2](PF6)+,
The ligand L5 (120 mg, 0.34 mmol) in EtOH (2 ml)
was added to Cu(ClO4)2·6H2O (100 mg, 0.27 mmol)
in EtOH (10 ml). The reaction mixture was stirred for
approximately 16 h. A purple precipitate was filtered
off, washed with EtOH and ether, and dried in vacuo.
Yield: 105 mg (63%). IR (cm−1): 3230 w(NꢀH), 1100
w(ClꢀO). CHN Found (Calc.): C, 40.7 (40.23); H, 6.38
(6.43); N, 9.33 (8.94)%. UV–Vis (MeOH): umax (nm)
(mmax, mol−1 l cm−1): 516 (135).
555 [Ni(L6)2]+. UV–Vis (CH3CN): umax (nm) (mmax
,
mol−1 l cm−1): 885 (18), 533 (10), 316 (63).
2.8.13. [Co(L6)(NO3)2(OH2)]·H2O (13)
The ligand L6 (100 mg, 0.4 mmol) in EtOH (5 ml)
was added to a solution of Co(NO3)2·6H2O (116 mg,
0.4 mmol) in H2O (5 ml) and stirred for 5 min. The
solution was left to slowly evaporate until a precipi-
tate formed, which was filtered off and purified by
2.8.9. [Ni(L5)](ClO4)2 (9)
The ligand L5 (150 mg, 0.43 mmol) in EtOH (5 ml)
was added to Ni(ClO4)2·6H2O (124 mg, 0.34 mmol) in
EtOH (20 ml). The reaction mixture was stirred for
approximately 16 h. A red precipitate was filtered off,
washed with EtOH and ether, and dried in vacuo.
Yield: 98 mg (50%). IR (cm−1): 3210 w(NꢀH), 1100
w(ClꢀO). CHN Found (Calc.): C, 41.3 (41.7); H, 6.24
(6.35); N, 9.28 (9.28)%. UV–Vis (MeOH): umax (nm)
(mmax, mol−1 l cm−1): 463.5 (79).
passing down
a Sephadex column eluting with
CH3CN. Yield: 69 mg (40%). IR (cm−1): 3527 wOH
,
3272 wNH, 1480, 1318 wNO . FAB MS: m/z=370
[Co(L6)NO3]+. CHN Found 2(Calc.): C, 37.10 (37.34);
H, 5.85 (5.60); N, 15.08 (15.55)%. UV–Vis (CH3CN):
umax (nm) (mmax, mol−1 l cm−1): 539 (119).
2.8.14. [Cu(L6)(NO3)2] (14)
The ligand L6 (97 mg, 0.39 mmol) in EtOH (5 ml)
was added to a solution of Cu(NO3)2·3H2O (94 mg,
0.39 mmol) in H2O (5 ml) and stirred for 5 min. The
solution was left to slowly evaporate until a precipi-
tate was formed, which was filtered off and purified
as described above. Yield: 85 mg (50%). IR (cm−1):
2.8.10. [Ni(L5)Cl2] (10)
(a) The ligand L5 (150 mg, 0.43 mmol) in EtOH (5
ml) was added to NiCl2·6H2O (93 mg, 0.39 mmol) in
warm EtOH (20 ml). The reaction mixture was stirred
for approximately 16 h. Diethyl ether was added and
a mauve precipitate was filtered off, washed with
ether and dried in vacuo. Yield: 23 mg (12%).
3527 wOH, 3272 wNH, 1480, 1318 wNO . FAB MS: m/
2
z=374 [Cu(L6)NO3]+. CHN Found (Calc.): C, 38.68
(38.48); H, 5.36 (5.31); N, 15.87 (16.03)%. UV–Vis
(CH3CN): umax (nm) (mmax, mol−1 l cm−1): 647 (59).
(b) LiCl (108 mg, 2.55 mmol) in C3H6O (10 ml)
was added to 9 (150 mg, 0.207 mmol) in C3H6O (10
ml) with stirring. A mauve precipitate was filtered off,
washed with C3H6O, and dried in vacuo. Yield: 23
mg (15%). IR (cm−1): 3190 w(NꢀH). CHN Found
(Calc.): C, 52.9 (53.0); H, 7.99 (8.06); N, 11.57
2.8.15. [Cu(L7)(Br2)]·2H2O (15)
The ligand L7·HBr (158 mg, 0.46 mmol) in H2O (5
ml) was added to a solution of Cu(NO3)2·3H2O (111
mg, 0.46 mmol) in H2O (5 ml) and stirred for 5 min.
The solution was left to slowly evaporate until a pre-
cipitate formed, which was filtered off and dried un-
der vacuum. Yield: 89 mg (37%). IR (cm−1): 3430
wOH, 3288 wNH, 2920 wCH, 1695 wCO. FAB MS: m/z=
485 [Cu(L7)Br2]+, 407 [Cu(L7)Br]+, 326 [Cu(L7)]+.
CHN Found (Calc.): C, 31.79 (32.16); H, 4.12 (4.82);
(11.77)%. UV–Vis (MeOH): umax (nm) (mmax, mol−1
l
cm−1): 463 (90).
2.8.11. Reaction of L1 with [Rh(COD)]+(PF6)−
AgPF6 (101 mg, 0.40 mmol) in MeCN (5 ml) was
added under nitrogen to [Rh(m-Cl)(COD)]2 (100 mg,
0.20 mmol) in MeCN (10 ml). The yellow solution
was separated from precipitated AgCl and added to 6
(362 mg, 0.40 mmol) in MeCN (10 ml). No reaction
N, 8.55 (8.04)%. UV–Vis (H2O): umax (nm) (mmax
,
mol−1 l cm−1): 650 (39).
1
was observed by H or 13C NMR spectroscopy after
prolonged heating and stirring. When 6 was substi-
tuted by free L1, no reaction of the pendent arene
group was observed.
2.8.16. [Cu2(L7ꢀH)2(OH2)2](PF6)2·6H2O (16)
A saturated aq. solution of KPF6 was added to a
solution of [Cu(L7)(Br2)]·2H2O (40 mg, 0.076 mmol)
in H2O (5 ml). The water was allowed to slowly evap-
orate until a blue crystalline solid precipitated, which
was filtered off and dried under vacuum. Yield: 37 mg
(95%). IR (cm−1): 3430 wOH, 2925 wCH, 1609 wCO, 838
wPF. CHN Found (Calc.): C, 30.36 (30.96); H, 4.03
(4.79); N, 7.33 (7.74)%. FAB MS: m/z=326
[Cu(L7)]+.
2.8.12. [Ni(L6)2](PF6)2 (12)
The ligand L6 (200 mg, 0.8 mmol) in EtOH (5 ml)
was added to a solution of Ni(NO3)2·6H2O (0.23 g,
0.79 mmol) in H2O (5 ml) and stirred for 5 min. A
saturated NH4PF6 solution was added and the
product extracted with CH3NO2 (2×5 ml). The or-

338
A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
2.9. Crystallography
Michael type reaction [23]. An excess of the ‘activated’
vinylaromatic was added to a THF solution of the free
macrocycle to which an excess of nBuLi had been
added. After removal of solvents, the residue was con-
verted to the hydrochloride salt, extracted into water
then basified to liberate the free amine. In the case of
those reactions involving 2,4,6-trimethylstyrene, the sin-
gle pendent arm product was the only one isolated.
When the Michael acceptor was styrene or p-vinylan-
isole, the N%,N¦ disubstituted product was the only one
isolated after work up. This variation is curious and no
explanation is apparent. The ligands L6–L7 were pre-
pared by the conventional mono-functionalization tech-
nique of reacting the appropriate arylalkyl halide with
1,4,7-triazacyclo[5.2.1.04.10]decane followed by base hy-
drolysis (Scheme 3).
Details of the data collection and analysis of 1, 14
and 16 are collected in Table 1. Single crystals were
attached to a glass fibre using acrylic resin, and
mounted on a goniometer head in a general position.
Data were collected using an Enraf–Nonius CAD4
diffractometer (compound 1) or a Bruker–Nonius
Kappa CCD diffractometer (compounds 14 and 16)
using graphite-monochromated X-radiation (u=
,
0.71073 A). The structures were solved by direct meth-
ods (SIR-92) [20]. All non-H atoms were allowed
anisotropic thermal motion. Aliphatic CH hydrogen
atoms were included at calculated positions with
,
CꢀH=0.96 A. Refinement (SHELXL-97) [21] was by
full-matrix least-squares on F2. All crystals of 16, which
were examined proved to be twins. The crystal chosen
was twinned according to a rotation of 180° about 010.
Many reflections from both lattices are overlapped.
Despite these problems, the overall identity of com-
pound 16 was satisfactorily determined by the X-ray
analysis. Neutral atom scattering factors, coefficients
and anomalous dispersion and absorption coefficients
were obtained from [22].
3.2. Synthesis of the complexes
The complexes were prepared by addition of the free
ligand to ethanolic or water solutions of the appropri-
ate metal salts. The solid complexes could be obtained
as precipitates by addition of a suitable counter ion
((PF6)− or (ClO4)−). In the case of the neutral complex
1, the product was precipitated from ethanolic solution
by the addition of diethyl ether. Crystals suitable for
X-ray crystallography were obtained for complexes 1,
14 and 16.
3. Results and discussion
3.1. Synthesis of the ligands
3.3. Description of the crystal structures
The ligands L1–L5 were synthesised according to a
The structure of the two different cations found in
the unit cell of complex 1 are illustrated in Fig. 1. In the
first case the Cu(II) metal ion is coordinated to the
three nitrogens of the macrocycle with the two other
sites occupied by chloride ions. The CuꢀN bond lengths
Table 1
Crystallographic data
Compound
1
14
16
Chemical
formula
Formula
weight
C68H116Cl4Cu3- C14H23CuN5-
C
28H50N6Cu2O9
F12N12P2
1724.09
O7
436.91
P2F12
1031.76
Temperature
(°C)
291
−123
−173
(
(
(
Space group
Crystal system triclinic
P1
P1
P1
triclinic
7.3210(2)
8.2780(2)
16.3904(6)
80.800(1)
89.262(1)
67.288(1)
903.20(5)
2
triclinic
10.2057(1)
12.8715(2)
16.6340(3)
72.597(1)
85.361(1)
81.907(1)
2062.56(5)
2
,
a (A)
11.834(2)
13.114(3)
13.581(3)
75.556(19)
84.126(17)
75.980(17)
1978.3(7)
1
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
v (mm−1
)
1.05
1.258
1.218
Data collected 8050
12 462
18 679
Unique data
Rint
6951
4145
0.0356
0.0553
0.142
8927
0.0503
0.1207
0.3328
0.0208
0.0545
0.161
Final R1
Final Rw2
Scheme 3. Reactions used in the preparation of N-funtionalized
triazamacrocycles.

A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
339
are consistent with a complex that is Jahn–Teller dis-
torted, affording the cation a square-based pyramidal
geometry. The pendant mesitylene is non-coordinated
which is compatible with the ‘soft’ nature of the ligand.
The second cation is a six coordinate centrosymmetric
copper complex containing two macrocycles. Again the
complex is Jahn–Teller distorted with two long bonds,
the CuꢀN (axial) bond length significantly greater than
that found in the five coordinate complex. The pendant
mesitylene group is well separated from the copper
centre suggesting that steric hindrance is not a major
factor in rationalising the lack of any reaction of the
group with organometallic reagents (see later).
For complexes containing the ligands L6 and L7, the
alcohol and carboxyl groups, respectively are, in con-
trast to most pendant arm macrocyclic ligands, not
available for binding to the same metal ion centre. For
complexes of the two ligands intermolecular bonding is
however feasible, and hence affords a way to create
well-defined supramolecular structures. Illustrated in
Fig. 2 is the structure of the complex [Cu(L6)(NO3)2],
and collected is a list of selected bond lengths and
angles. The complex is five-coordinate and, as observed
for the previously discussed copper systems, has a
Jahn–Teller distorted square-based pyramidal struc-
ture. The two nitrate ions act as monodentate ligands
and the pendant aromatic group is well separated from
the copper–tacn core. The oxygen of the benzylalcohol
segment is disordered over two sites consistent with a
lack of intermolecular bonding to an adjacent unit.
Indeed, no weak forces such as H-bonding to the
nitrate ions are evident in the crystal-packing diagram.
In contrast to the previous complex the structure of
the Cu(II) system containing the ligand L7 displays a
more interesting recognition phenomenon as depicted
in Fig. 3. As before the three nitrogens of the macrocy-
cle are all coordinated and the pendant aromatic is well
separated from the Jahn–Teller distorted Cu(II) centre.
Unlike the copper complex of L6 the carboxyl oxygen
from a neighbouring unit coordinates to the copper so
Fig. 1. ORTEP for Windows [30] plot of: (A) [Cu(L1)Cl2]; and (B)
[Cu(L1)2]2+ (thermal ellipsoids are shown at 50% probability and
hexafluorophosphate anions are omitted or clarity); selected bond
,
lengths (A) and angles (°): Cu2ꢀN21, 2.268(3); Cu2ꢀN24, 2.045(4);
Cu2ꢀN27, 2.040(4); Cu2ꢀCl1, 2.295(1); Cu2ꢀCl2, 2.253(1);
N27ꢀCu2ꢀN24, 81.71(15); N27ꢀCu2ꢀCl2, 154.03(11); N24ꢀCu2ꢀCl2,
89.12(11); N27ꢀCu2ꢀN21, 83.64(14); N24ꢀCu2ꢀN21, 82.08(14);
Cl2ꢀCu2ꢀN21, 119.25(10); N27ꢀCu2ꢀCl1, 91.22(12); N24ꢀCu2ꢀCl1,
172.61(11); Cl2ꢀCu2ꢀCl1, 98.21(5); N21ꢀCu2ꢀCl1, 95.05(10);
Cu1ꢀN11, 2.571(4); Cu1ꢀN14, 2.056(3); Cu1ꢀN17, 2.023(4);
N17ꢀCu1ꢀN17,
180.00(18);
N17ꢀCu1ꢀN14,
82.54(15);
N17ꢀCu1ꢀN14, 97.46(15); N17ꢀCu1ꢀN14, 97.46(15); N17ꢀCu1ꢀN14,
82.54(15); N14ꢀCu1ꢀN14, 180.0(2).
that the asymmetric unit contains
a
basic
[Cu2(L7ꢀH)2]2+ repeat unit. As a result, a one-dimen-
sional coordination polymer is produced as illustrated
in the packing diagram of Fig. 4. A water molecule
completes the fifth coordination sphere of each copper
and it is noted that these water molecules point in the
same direction but do not hydrogen bond to the layer
above. The ‘L’ motif of the complex has dimensions of
2
,
approximately 9.5×11 A , which leads to speculation
that further self-assembly using an appropriate tem-
plate could generate a tetracopper molecular box
(Scheme 2). Such control of molecular self-assembly is
currently of great interest but as of yet has not utilised
triazamacrocycles containing pendant arms. Further
coordination studies of ligands based on L7 are under-
way and will be reported at a later date.
Fig. 2. ORTEP for Windows [30] plot of [Cu(L6)(NO3)2] (thermal
,
ellipsoids are shown at 50% probability); selected bond lengths (A)
and angles (°): CuꢀN1, 2.243(3); CuꢀN4, 2.005(3); CuꢀN7, 2.016(3);
CuꢀO100, 1.952(3); CuꢀO200, 2.018(3); O100ꢀCu1ꢀN4, 177.77(13);
O100ꢀCu1ꢀN7, 97.27(13); N4ꢀCu1ꢀN7, 84.65(13); O100ꢀCu1ꢀO200,
85.63(13); N4ꢀCu1ꢀO200, 92.47(13); N7ꢀCu1ꢀO200, 176.90(12);
O100ꢀCu1ꢀN1, 94.16(12); N4ꢀCu1ꢀN1, 84.88(12); N7ꢀCu1ꢀN1,
84.46(11); O200ꢀCu1ꢀN1, 96.47(10).

340
A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
Fig. 5. Proposed folding of the cyclen macrocycle to generate a
cis-complex.
moiety to be essentially unshifted from those of the free
ligand.
3.4.2. L4 complexes
The copper complex 5 is, as isolated in the solid
state, a 1:1 species containing a four coordinate Cu(II)
centre [24], though it may well become five coordinate
in solution. When L2 in butan-1-ol is added to
Ni(ClO4)2·6H2O in hot butan-1-ol, a green solid precip-
itates from solution. This species shows three visible
bands in nitromethane solution at 882, 586 and 443 nm,
respectively. On this basis, we postulate a five- or
six-coordinate nickel species. The size of the macro-
cyclic cavity in the 12 membered cyclen ring is such that
square coplanar coordination of the metal is unlikely.
The ligand rather is wrapped around the metal forming
a cis complex [25], with the remaining coordination
sites occupied by water (Fig. 5).
The blue liquor from the reaction yields, on removal
of the solvent, a yellow solid. This dissolves in ni-
tromethane or acetonitrile to give blue solutions. The
yellow colour of the solid suggests a four-coordinate
square coplanar environment for the nickel atom. This
behaviour is well documented and Lincoln and cowork-
ers [24] have described such a high spin-low spin equi-
librium for the nickel complex of 1,4,7,10-tetra-
methyl-1,4,7,10-tetraazacyclododecane (tmc) (Eq. (1)).
Fig. 3. ORTEP for Windows [30] plot of [Cu2(L7ꢀH)2(H2O)2]2+ (ther-
mal ellipsoids are shown at 50% probability and hexafluorophosphate
anions and extraneous water molecules are omitted or clarity); se-
,
lected bond lengths (A) and angles (°): Cu1ꢀN11, 2.235(6); Cu1ꢀN14,
2.021(7); Cu1ꢀN17, 2.035(7); Cu1ꢀO1, 1.981(6); Cu1ꢀO21, 1.946(6);
Cu2ꢀN21, 2.246(7); Cu2ꢀN24, 2.024(8); Cu2ꢀN27, 2.035(9); Cu2ꢀO2,
1.978(7); Cu2ꢀO11, 1.932(6); O21ꢀCu1ꢀO1, 92.4(3); O21ꢀCu1ꢀN14,
175.3(3);
O1ꢀCu1ꢀN17, 168.1(3); N14ꢀCu1ꢀN17, 85.4(3); O21ꢀCu1ꢀN11,
97.6(2); O1ꢀCu1ꢀN11, 107.4(2); N14ꢀCu1ꢀN11, 83.4(3);
N17ꢀCu1ꢀN11, 83.7(3); O11ꢀCu2ꢀO2, 93.2(3); O11ꢀCu2ꢀN24,
175.0(4); O2ꢀCu2ꢀN24, 91.5(4); O11ꢀCu2ꢀN27, 89.0(4);
O2ꢀCu2ꢀN27, 166.6(3); N24ꢀCu2ꢀN27, 86.0(4); O11ꢀCu2ꢀN21,
96.0(3); O2ꢀCu2ꢀN21, 109.6(3); N24ꢀCu2ꢀN21, 83.9(3);
N27ꢀCu2ꢀN21, 83.2(3).
O1ꢀCu1ꢀN14,
91.6(3);
O21ꢀCu1ꢀN17,
90.2(3);
3.4. Description of the metal complexes
3.4.1. L1 complexes
The L1 complexes are all typical octahedral bis ligand
species as expected for the metal ions concerned. As is
described above, a second form of 1 is observed in the
crystal, namely a neutral 1:1 dichloro-complex. This
five coordinate species is analogous to the copper com-
plex of N-(5-pent-2-yne)-1,4,7-triazacyclononane de-
scribed elsewhere [11]. Solutions of the pale pink cobalt
complex rapidly darken in air suggesting oxidation to
Co(III), though no single species could be obtained
from the dark solutions.
(1)
The ‘hard’ Lewis acidic metal centres in these com-
plexes do not interact with the pendent arm arene
groups, and coordination takes place exclusively
through the ring nitrogens. For example, the 13C NMR
of the zinc complex 3 shows the signals due to the arene
In addition, Fabbrizzi [26] has noted that in aqueous
solutions of the nickel complex of cyclen, the normal
blue colour of the octahedral high spin species becomes
yellow on addition of 6 M LiClO4 when heated, and the
electronic spectrum, showing a new band at 23 000
Fig. 4. ORTEP for Windows [30] view down the a-axis of the coordination polymer generated by the repeating [Cu2(L7ꢀH)2(H2O)2]2+ moiety.

A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
341
cm−1 becomes more typical of a low spin square planar
species. Unfortunately, electronic spectra of the yellow
form of 7 were not available in solution, as any solvent
which led to dissolution, regenerated the octahedral
form.
wards ‘softer’ transition metals. Such metal species as
[Rh(COD)]+, generated in situ from [Rh(m-Cl)(COD)]2
(COD=1,5-cyclooctadiene) and AgPF6 react smoothly
with arenes at room temperature to give h6 arene
complexes [28,29]. However, in our hands, reaction of
either L1 or the zinc complex 3 with [Rh(COD)](PF6) in
refluxing THF showed no reaction of the arene ring
3.4.3. L5 complexes
1
The macrocyclic cavity of the larger 14-membered
ring is large enough to accommodate the metal ions
Cu(II) and Ni(II) in square coplanar coordination. The
UV–Vis spectrum of [Ni(L5)](ClO4)2 (9) in methanol
(u=463 nm, mmax=79 mol−1 l cm−1) is consistent with
a four coordinate complex. On addition of an excess of
LiCl, a mauve solid separates from an acetone solution,
which may be identified as [Ni(L5)Cl2] (10). This com-
plex may also be prepared by addition of free ligand to
NiCl2·6H2O in ethanol [27]. The UV–Vis spectrum of
10 in methanol is identical to that of 9 indicating the
ionisation of the two chlorides in methanolic solution.
after 24 h. In the former case, H NMR spectroscopy
indicated reaction of the rhodium centre with the
macrocycle ring nitrogens, but addition of further
[Rh(COD)](PF6) did not lead to the formation of an h6
complex. Clearly, the presence of the ring nitrogens
must have a considerable deactivating effect on the
arene moiety.
4. Conclusions
A number of aromatic functionalized azamacrocycles
have been prepared along with their metal complexes.
Electron rich aromatics can be selectively incorporated
into tri- and tetra-azamacrocycles in good yields using
Michael-type chemistry. Complexation via the macro-
cycle nitrogens to hard metal ions is facile but unfortu-
nately the p-rich aromatics do not react with soft metal
ions to create mixed metal systems.
The Cu(II) complex of a single pendant arm benzyl-
carboxylic acid funtionalized 1,4,7-triazacyclononane
macrocycle displays interesting self-assembly properties.
This recognition phenomenon has the potential to be
exploited in the creation of large superstructures with
interesting magneto properties, and hence the genera-
tion of novel inorganic materials.
3.4.4. L6 complexes
The complexation of L6 with Ni(II) produced a pale
pink solid which exhibited three bands in the UV–Vis
region at 885, 533 nm and a shoulder at 316 nm,
respectively. The mass spectrum of the complex re-
vealed a prominent ion at m/z=701 which is assigned
to the [Ni(L6)2](PF6)+ ion. Interestingly a weaker peak
as also observed in the mass spectrum at m/z=1547
which can be attributed to a dimeric [Ni(L6)2]2(PF6)3+
ion. It is possible that weak intermolecular H-bonds
between the hydroxyl groups are responsible for the
self-aggregation (Fig. 6).
The cobalt complex of L6 is dark claret in colour and
displays one band at 539 nm in the UV–Vis region.
The mass spectrum of the complex reveals a prominent
ion at m/z=370 which is compatible with the
[Co(L6)NO3]+ ion. The IR and elemental analysis sup-
ports the existence of coordinated water so that as in
the nickel case the complex is six-coordinate. Unlike the
cobalt complex of L1 a solution of 13 exhibits no
observable change in air suggesting that oxidation to
Co(III) is slow.
5. Supplementary data
Crystallographic data (excluding structure factors)
for the structures in this paper have been deposited
with the Cambridge Crystallographic Data Centre as
supplementary publication nos. CCDC 166329 ,166330,
166331 for compounds 1, 14 and 16. Copies of the data
may be obtained free of charge on application to The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
3.5. Attempts to coordinate the pendent arene arm
Electron rich arenes such as mesitylene (1,3,5-
trimethylbenzene) are excellent p acceptor ligands to-
Acknowledgements
This work was supported by the University of Glas-
gow and the Engineering and Physical Sciences Re-
search Council (EPSRC).
Fig. 6. Proposed dimerization of [Ni(L6)2]2+ by H-bonding of the
alcohol groups.

342
A.C. Benniston et al. / Polyhedron 21 (2002) 333–342
[10] (a) D. Ellis, L.J. Farrugia, D.T. Hickman, P.A. Lovatt, R.D.
References
Peacock, J. Chem. Soc., Chem. Commun. (1996) 1817;
(b) D. Ellis, L.J. Farrugia, P.A. Lovatt, R.D. Peacock, Eur. J.
Chem. (2000) 1489.
[1] (a) M. Takahashi, S. Takamoto, Bull. Chem. Soc. Jpn. 50 (1977)
3413;
[11] (a) D. Ellis, L.J. Farrugia, R.D. Peacock, Polyhedron 18 (1999)
1229;
(b) M.J. van der Merwe, J.C.A. Boeyens, R.D. Hancock, Inorg.
Chem. 24 (1985) 1208.
(b) M.V. Baker, D.H. Brown, B.W. Skelton, A.H. White, J.
Chem. Soc., Dalton Trans. (2000) 4607.
[2] (a) B.A. Sayer, J.P. Michael, R.D. Hancock, Inorg. Chim. Acta
77 (1983) L63;
[12] S. Leininger, B. Olenyuk, P.J. Stang, Chem. Rev. 100 (2000)
853.
[13] G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.), Comprehensive
Organometallic Chemistry, vol. 5, Pergamon, Oxford, Ch. 35
and references therein.
(b) R.D. Peacock, J. Robb, Inorg. Chim. Acta 121 (1986) L15;
(c) A.A. Belal, L.J. Farrugia, J. Robb, R.D. Peacock, J. Chem.
Soc., Dalton Trans. (1989) 931;
(d) I.A. Fallis, L.J. Farrugia, N.M. Macdonald, R.D. Peacock, J.
Chem. Soc., Dalton Trans. (1993) 2759.
[14] G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.), Comprehen-
sive Organometallic Chemistry, vol. 3, Pergamon, Oxford, Ch.
27.
[3] A. Hammershøi, A.M. Sargeson, Inorg. Chem. (1983) 3554.
[4] K. Weighardt, U. Bossek, M. Guttmann, J. Weiss, Z. Natur-
forsch., Teil. B 38 (1983) 81.
[15] D.D. Perrin, W.L.F. Armarego, Purification of Laboratory
Chemicals, 3 ed., Pergamon Press, England, 1988.
[16] T.J. Atkins, J.E. Richman, J. Am. Chem. Soc. 96 (1974) 2268.
[17] E.K. Barefiled, F. Wagner, A.W. Herlinger, A.R. Dahl, Inorg.
Synth. 16 (1976) 220.
[5] M.I. Kabachnik, T.Ya. Medved, B.K. Shcherbakov, E.I.
Sinyavskaya, Yu M. Polikarpov, K.B. Yatsimirskii, Russ. J.
Inorg. Chem. 30 (1985) 1463.
[6] M. Di Vaira, F. Mani, P. Stoppioni, Inorg. Chim. Acta 303
(2000) 61.
[18] T.J. Atkins, J. Am. Chem. Soc. 102 (1980) 6364.
[19] J. Chatt, L.M. Venanzi, J. Chem. Soc. (1957) 4735.
[20] SIR-92—a program for automatic solution of crystal structures
by direct methods: A. Altomare, G. Cascarno, C. Giacovazzo,
A. Gualiardi, J. Appl. Crystallogr. 27 (1994) 435.
[21] G.M. Sheldrick, SHELXL-97, a program for crystal structure
refinement, University of Go¨ttingen, Germany, 1997.
[22] Table 4.24.2, 4.2.6.8 and 6.1.1.4 from International Tables for
Crystallography, Volume C Mathematical, Physical and Cemical
Tables, Kluwer, Dordrecht, 1995.
[23] B.F. Ross, J.G. Grasselli, W.M. Ritchey, H.D. Kaesz, Inorg.
Chem. 2 (1963) 1023.
[24] J.H. Coates, D.A. Hadi, S.F. Lincoln, Aust. J. Chem. 35 (1982)
903.
[25] Y. Iitaka, M. Shina, E. Kimura, Inorg. Chem. 13 (1974) 2886.
[26] L. Fabbrizzi, Inorg. Chem. 16 (1977) 2667.
[27] B. Bosnich, M.L. Tobe, G.A. Webb, Inorg. Chem. 4 (1965) 1109.
[28] M. Green, T.A. Kuc, J. Chem. Soc., Dalton Trans. (1972) 832.
[29] R.R. Schrock, J.A. Osborn, J. Am. Chem. Soc. 93 (1971) 3089.
[30] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[7] (a) G.A. McLachlan, G.D. Fallon, R.L. Martin, B. Moubaraki,
K.S. Murray, L. Spiccia, Inorg. Chem. 33 (1994) 4663;
(b) G.A. McLachlan, G.D. Fallon, R.L. Martin, L. Spiccia,
Inorg. Chem. 34 (1995) 254;
(c) G.A. McLachlan, S.J. Brudenell, G.D. Fallon, R.L. Martin,
L. Spiccia, E.R.T. Tiekink, J. Chem. Soc., Dalton Trans. (1995)
439;
(d) G.D. Fallon, G.A. McLachlan, B. Moubaraki, K.S. Murray,
L. O’Brien, L. Spiccia, J. Chem. Soc., Dalton Trans. (1997) 2765.
[8] (a) D.J. Evans, G. Garcia, G.J. Leigh, M.S. Newton, M.D.
Sontana, J. Chem. Soc., Dalton Trans. (1992) 3229;
(b) D.J. Evans, G. Garcia, D.L. Hughes, G.J. Leigh, M.D.
Santana, Acta Crystallogr., Sect. C C49 (1993) 905;
(c) K. Mockizyki, F. Kesting, T. Weyhermuller, K. Wieghardt,
C. Butzlaff, A.X. Trautwein, J. Chem. Soc., Chem. Commun.
(1994) 909;
(d) R.P. Houser, V.G. Young Jr., W.D. Tolman, J. Am. Chem.
Soc. 118 (1996) 2101.
[9] L.J. Farrugia, P.A. Lovatt, R.D. Peacock, Inorg. Chim. Acta
246 (1996) 343.