Linked macrocyclic systems. Interaction of copper(I) with tris-ring N2S2-donor macrocycles and their single-ring analogues

Article abstract of DOI:10.1016/j.inoche.2007.06.002

The interaction of two tri-linked N₂S₂-donor macrocyclic ligands, 1 (R = H) and 2 (R = H), and their related single ring derivatives, 3 (R = H) and 4 (R = CH₂C₆H₅), with copper(I) is reported. Solid 3:1 (metal:ligand) complexes of type [Cu₃L](PF₆)₃ (L = 1 and 2, R = H) and single ring derivatives of type [CuL]PF₆ (L = 3, R = H; L = 4, R = CH₂C₆H₅) were isolated; the X-ray structure of [CuL]PF₆ (L = 3, R = H) showed that the four macrocyclic donor atoms coordinate to the copper(I) in a quasi-tetrahedral manner (Cu-N 2.089, 2.096(4); Cu-S 2.239, 2.264(2) ?, X-Cu-Y 104.5(1)-115.4(1))°.

Full text of DOI:10.1016/j.inoche.2007.06.002

Inorganic Chemistry Communications 10 (2007) 1070–1073
www.elsevier.com/locate/inoche
Linked macrocyclic systems. Interaction of copper(I) with
tris-ring N2S2-donor macrocycles and their single-ring analogues
a
b,
a
Andrew M. Groth , Leonard F. Lindoy *, George V. Meehan ,
c
c
Brian W. Skelton , Allan H. White
a
School of Pharmacy and Molecular Sciences, James Cook University, Townsville, Queensland 4811, Australia
b
School of Chemistry F11, University of Sydney, Sydney, NSW 2006, Australia
School of Biomedical, Biomolecular and Chemical Sciences, Chemistry M313, University of Western Australia, Crawley 6009, Australia
c
Received 4 March 2007; accepted 4 June 2007
Available online 9 June 2007
Dedicated to Professor K. Gloe, Technical University, Dresden on the occasion of his 60th birthday.
Abstract
The interaction of two tri-linked N2S2-donor macrocyclic ligands, 1 (R = H) and 2 (R = H), and their related single ring derivatives, 3
(R = H) and 4 (R = CH2C6H5), with copper(I) is reported. Solid 3:1 (metal:ligand) complexes of type [Cu3L](PF6)3 (L = 1 and 2, R = H)
and single ring derivatives of type [CuL]PF6 (L = 3, R = H; L = 4, R = CH2C6H5) were isolated; the X-ray structure of [CuL]PF6
(L = 3, R = H) showed that the four macrocyclic donor atoms coordinate to the copper(I) in a quasi-tetrahedral manner (Cu–N
˚
2.089, 2.096(4); Cu–S 2.239, 2.264(2) A, X–Cu–Y 104.5(1)–115.4(1))ꢀ.
ꢁ 2007 Elsevier B.V. All rights reserved.
Keywords: Copper(I); S2N2-donor macrocycle; Trinucleating macrocycle; X-ray
The synthesis of saturated S2N2-donor macrocycles,
together with aspects of their metal coordination chemis-
try, have now been the focus of a considerable number of
studies [1]. For example, we have investigated the use of
mixed nitrogen–sulfur donor macrocyclic species as selec-
tive reagents for individual transition and post-transition
metal ions [2–6]. Our studies have included solution and
solid state aspects of the interaction of the three-ring mac-
rocyclic ligands 1 and 2 (R = H or CH2C6H5) with palla-
dium(II) [2] and platinum(II) [2] and silver(I) [3]. In each
case corresponding trinuclear complex cations of type
[M3L]n+ (L = 1 or 2, R = H or CH2C6H5); (M = Ag,
n = 3; Pd, Pt, n = 6) were shown to form. The N2S2-donor
set of each macrocyclic ring was expected on HSAB princi-
ples to show a strong affinity for these soft metal ions and
the available evidence confirms that this is so. However, in
no case has it been possible to obtain crystals suitable for
an X-ray structure determination and hence it was not pos-
sible to define the solid state coordination geometries of the
respective metal centres in these complexes directly. In view
of this, corresponding mononuclear complexes of type
[ML](PF6)n (M = Ag, n = 1; Pd, Pt, n = 2) incorporating
the single ring ligands 3 (R = H or CH2C6H5) and 4 (R
= H or CH2C6H5) were prepared in anticipation that the
smaller overall size of these latter species might aid the for-
mation of suitable crystals for X-ray diffraction. In the case
of palladium(II) and 3 (R = H), this strategy proved
successful and suitable crystals for an X-ray structure
determination of mononuclear [PdL](PF6)2 (L = 3
R = H) were obtained [2]. The structure shows that the pal-
ladium is coordinated to all four donor atoms of the mac-
rocycle in a square planar manner, with the ligand
geometry around the 4-coordinate metal ion being slightly
puckered; physical measurements suggest that a similar
*
Corresponding author. Tel.: +61 2 9351 4400; fax: +61 2 9351 3329.
E-mail address: lindoy@chem.usyd.edu.au (L.F. Lindoy).
1387-7003/$ - see front matter ꢁ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2007.06.002

A.M. Groth et al. / Inorganic Chemistry Communications 10 (2007) 1070–1073
1071
coordination geometry occurs for each of the correspond-
ing complexes [Pd3L](PF6)6 (L = 1 and 2, R = H),
[PdL](PF6)2 (L = 3, R = H) and [PdL](PF6)2 (L = 4,
R = H).
of [CoLX2] (X = Cl or Br), [CuLCl2] Æ 0.5C7H8 [11],
[AgL(OCCH3)] Æ 2H2O, [RhLCl2]PF6, [PdL](PF6)2 [13]
and [PdL]Cl2 Æ 2H2O [14] show in each case that square pla-
nar (or near square planar) arrangements of the macrocy-
clic donors occur around the respective central metal ions.
We now report the synthesis of the four new copper(I)
species: [Cu3L](PF6)3 (L = 1 and 2; R = H) and [CuL]PF6
(L = 3, R = H; L = 4, R = CH2C6H5); the synthesis and
characterisation of the respective ligands has been reported
previously [2,3]. Reaction of [Cu(CH3CN)6]PF6 with 1
(R = H) or 2 (R = H) in a 1:3 molar ratio or with 3
(R = H) or 4 (R = CH2C6H5) in a 1:1 molar ratio in an
acetonitrile/methylene chloride solvent mixture under
nitrogen led to isolation of the corresponding 3:1 com-
plexes, [Cu3L](PF6)3 (L = 1, R = H) and (L = 2, R = H)
[15], and 1:1 complexes, [CuL]PF6 (L = 3, R = H) and
(L = 4, R = CH2C6H5) [16]. All products yielded satisfac-
tory microanalyses.
As also occurred for the palladium complex of 3
(R = H), we were only successful in isolating suitable crys-
tals for X-ray investigation in the case of the mononuclear
copper(I) complex of 3 (R = H); crystals of [CuL]PF6
(L = 3, R = H) were obtained by dissolving the product
isolated from the synthetic procedure in methylene chloride
and then adding a small amount of carbon tetrachloride;
crystals formed at room temperature over several days [16].
In contrast to the square planar arrangement found in
[PdL](PF6)2 (L = 3, R = H), the X-ray structure [17] of
[CuL]PF6 (L = 3, R = H) shows that the copper(I) site is
R
N
R
S
S
N
N
S
S
R = H, CH2C6H5
N
O
O
N
S
S
N
S
S
N
N
R
S
O
S
N
N
S
R
N
S
N
R
R
1
3
2
O
N
S
S
N
S
N
S
R = H, CH2C6H5
N
R
R
4
In a previous investigation Kaden et al. [7] determined
stability constants for the copper(I) (logK = 0.17) and cop-
per(II) (logK = 10.27) complexes of the parent (trans
donor) 16-membered macrocycle, 1,9-dithia-5,13-diazacy-
clohexadecane, but no solid complexes of copper(I) were
reported; nevertheless, based on molecular modelling it
was predicted that this ligand is capable of adopting a rel-
atively strain-free configuration around a tetrahedral metal
ion such as copper(I). In another study, the 1:1 copper(I)
complex of the isomeric cis-donor ligand, 1,5-dithia-9,13-
diazacyclohexadecane, was isolated and its X-ray structure
shows a close to tetrahedral (N2S2) coordination geometry
[8]. The coordination of all macrocyclic donors is perhaps
unsurprising since it has been proposed that copper(I)
has similar affinities for saturated N and thioether S donor
atoms [9].
S
N
N
S
5
6
Fig. 1. Projection of the [CuL]+ (L = 3; R = H) cation, showing non-
hydrogen atoms with 20% probability amplitude displacement envelopes,
˚
hydrogen atoms having arbitrary radii of 0.1 A. Cu–N(1,9) are 2.089,
Complexes of an octamethyl derivative 5 of the above
‘parent’ 16-membered macrocycle [10] with cobalt(II),
nickel(II), copper(II), copper(I), zinc(II), palladium(II),
rhodium(III) [11], silver(I) [12], cadmium(II), lead(II) and
mercury(II) [11] have been reported. The crystal structures
0
0
˚
2.096(4); Cu–S–(5,5 ) 2.264(2), 2.239(2) A; N(1)–Cu–N(9), S(5,5 ), N(9)–
Cu–S(5,50), S(5)–Cu–S(50) are 114.6(2), 109.4(2), 107.2(1), 105.9(1),
104.5(1), 115.4(2)ꢀ; the bond distances are similar to those in the 1:1
copper(I) complex of the cis-donor ligand, 1,5-dithia-9,13-diazacyclohex-
˚
adecane [8]: Cu–N 2.050(6), 2.063(8); Cu–S 2.253(2), 2.255(2) A.

1072
A.M. Groth et al. / Inorganic Chemistry Communications 10 (2007) 1070–1073
(e) G. Wei, C.C. Allen, T.W. Hambley, G.A. Lawrance, M. Maeder,
Aust. J. Chem. 48 (1995) 825;
(f) P.C. Riesen, T.A. Kaden, Helv. Chim. Acta 78 (1995)
1325;
(g) L. Siegfried, T.A. Kaden, J. Chem. Soc., Dalton Trans. (2005)
1136.
quasi-tetrahedrally coordinated, being bound to all four
donors of the macrocycle (Fig. 1).
A single formula unit, devoid of crystallographic sym-
metry, comprises the asymmetric unit of the structure.
The cation, shorn of the benzyl pendant, has quasi-2 sym-
metry, but, although chiral and in a non-centrosymmetric
space group, the structure overall is racemic. All chelate
rings are six-membered ‘chairs’, ‘flatter’ at the copper
atom, those defined by C(6,7,8), C(20,30,40) more distorted
than the other pair. The amino-hydrogen H(9) is hydro-
gen-bonded to a face of the PF6 anion, being essentially
[2] (a) I.M. Atkinson, J.D. Chartres, A.M. Groth, L.F. Lindoy, M.P.
Lowe, G.V. Meehan, B.W. Skelton, A.H. White, J. Chem. Soc.,
Dalton Trans. (2001) 2801;
(b) A.M. Groth, L.F. Lindoy, G.V. Meehan, J. Chem. Soc., Perkin
Trans. 1 (1996) 1553.
[3] J.D. Chartres, A.M. Groth, L.F. Lindoy, G.V. Meehan, J. Chem.
Soc., Dalton Trans. (2002) 371.
[4] I.M. Atkinson, J.D. Chartres, A.M. Groth, L.F. Lindoy, M.P. Lowe,
G.V. Meehan, Chem. Commun. (2002) 2428.
[5] J.D. Chartres, M.S. Davies, L.F. Lindoy, G.V. Meehan, G. Wei,
Inorg. Chem. Commun. 9 (2006) 751.
˚
equidistant (2.55–2.70 A (est.)) from F(4–6); it lies to the
same side of the macrocycle as the benzyl pendant, as in
the palladium(II) complex.
The 1:1 copper(I) complex of the related ‘trans’ N2S2
donor, dibenzo-substituted, unsaturated macrocycle 6 has
also been investigated by X-ray diffraction [18]. This com-
plex adopts a distorted tetrahedral arrangement with the
N(1)–Cu–N(2) bond angle = 118.00ꢀ and the S(1)–Cu–
S(2) bond angle = 132.07ꢀ; Cu–N are 1.981, 1.989(2) and
[6] I.M. Vasilescu, D.J. Bray, J.K. Clegg, L.F. Lindoy, G.V. Meehan, G.
Wei, Dalton Trans. (2006) 5115, and references therein.
[7] K.P. Balakrishnan, T.A. Kaden, L. Siegfried, A.D. Zuberbuhler,
Helv. Chim. Acta 67 (1984) 1060.
[8] K.P. Balakrishnan, A. Riesen, A.D. Zuberbuhler, T.A. Kaden, Acta
¨
Crystallogr. C 46 (1990) 1236.
[9] M.M. Bernardo, M.J. Heeg, R.R. Schroeder, L.A. Ochrymowycz,
D.B. Rorabacher, Inorg. Chem. 31 (1992) 191.
[10] R. McCrindle, A.J. McAlees, D.K. Stephenson, J. Chem. Soc.,
Perkin. Trans. 1 (1981) 3070.
[11] R. McCrindle, G. Ferguson, A.J. McAlees, M. Parvez, B.L. Ruhl,
D.K. Stephenson, T. Wieckowski, J. Chem. Soc., Dalton. Trans.
(1986) 2351.
[12] G. Ferguson, R. McCrindle, M. Parvez, Acta Crystallogr. Sect. C 40
(1984) 354.
[13] R. McCrindle, G. Ferguson, A.J. McAlees, M. Parvez, D.K.
Stephenson, J. Chem. Soc., Dalton Trans. (1982) 1291.
[14] G. Ferguson, R. McCrindle, A.J. McAlees, M. Parvez, D.K.
Stephenson, J. Chem. Soc., Dalton Trans. (1983) 1865.
[15] Synthesis of [Cu3L](PF6)3 (L = 1, R = H or 2, R = H).
[Cu(CH3CN)4](PF6) (0.193 mmol) in acetonitrile (5 cm3) was added
1 (R = H) or 2 (R = H) (0.064 mmol) in methylene chloride (8 cm3).
The solution was stirred under nitrogen for 0.5 h, after which
acetonitrile was added dropwise until no more precipitate formed.
The greenish white solid was collected by filtration and washed twice
with acetonitrile and then twice with diethyl ether. The precipitate was
initially dried under an atmosphere of nitrogen and then in vacuo.
[Cu3L](PF6)3 (L = 1, R = H) (yield, 92%). [Found: C, 35.40; H, 5.66;
N, 5.56; S, 12.98%. C45H84Cu3N6S6 (PF6)3 requires C, 35.39; H, 5.54;
N, 5.50; S, 12.60%]. [Cu3(L)](PF6)3 (L = 2, R = H) (yield 81%).
[Found: C, 35.45; H, 5.70; N, 5.11%. C48H90Cu3N6O3S6( PF6)3
requires C, 35.65; H, 5.61; N, 5.20%].
[16] Synthesis of [CuL]PF6 (L = 3, R = H or 4, R = CH2C6H5):
[Cu(CH3CN)4]PF6 (70.8 mg, 0.19 mmol) in methylene chloride
(5 cm3) and added to 3 (R = H) or 4 (R = CH2C6H5) (0.19 mmol)
in acetonitrile (8 cm3). The solution was stirred under nitrogen for
0.5 h, after which a small volume of acetonitrile was added until no
more precipitate formed. The greenish white precipitate was collected
by filtration and washed with a small volume of acetonitrile and then
twice with diethyl ether. The product was initially dried under an
atmosphere of nitrogen and then in vacuo. [CuL]PF6 (L = 3, R = H)
(yield 86%). [Found: C, 40.98; H, 5.56; N, 5.23; S, 11.49%.
C19H32CuN2PF6S2 requires C, 40.67; H, 5.75; N, 4.99; S, 11.43%].
[CuL]PF6 (L = 4, R = CH2C6H5) (yield 77%). [Found: C, 47.49; H,
5.81; N, 4.22; S, 9.65%. C27H40CuN2OPF6S2 requires C, 47.60; H,
5.92; N, 4.11; S, 9.41%].
˚
Cu–S 2.246, 2.247(1) A. The counter ion in this case is tri-
flate. Related copper(I) complexes of double ring, N2(imine)
S2-macrocycles have also been reported [19].
-
In this report we have demonstrated that both the pres-
ent tritopic ligands readily give 3:1 (metal:ligand) com-
plexes with copper(I) hexafluorophosphate while the
related single rings 3 (R = H) and 4 (R = CH2C6H5) yield
analogous 1:1 products. These complexes expand the
known examples of the otherwise little studied [20] cate-
gory of N2S2-donor macrocyclic complexes incorporating
copper(I). The structure of [CuL]PF6 (L = 3, R = H) once
again confirms that the 16-membered ring is able to span
four tetrahedral positions around copper(I) in an
unstrained fashion; it seems likely that a similar geometry
occurs for each metal site in the remaining three complex
species prepared in the present study.
Acknowledgement
We thank the Australian Research Council for support.
Appendix A. Supplementary material
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.inoche.2007.
06.002.
References
[1] (a) See for example: L. Siegfried, T.A. Kaden, Helv. Chim. Acta 67
(1984) 29;
(b) M. Micheloni, P. Paoletti, L. Siegfried-Hertli, T.A. Kaden, J.
Chem. Soc., Dalton Trans. (1985) 1169;
[17] Crystal/refinement data: [CuL]PF6 (L = 3; R = H) = C19H32CuF6-
(c) T.A. Kaden, S. Kaderli, W. Sager, L.C. Siegfried-Hertli, A.D.
Zuberbuhler, Helv. Chim. Acta 69 (1986) 1216;
¨
(d) B.C. Westerby, K.L. Juntunen, G.H. Leggett, V.B. Pett, M.J.
Koenigbauer, M.D. Purgett, M.J. Taschner, L.A. Ochrymowycz,
D.B. Rorabacher, Inorg. Chem. 30 (1991) 2109;
N2PS2, M = 561.1 Orthorhombic, space group Pca21 ðC52v; No: 29Þ,
3
˚
˚
a = 16.173(8), b = 8.277(2), c = 17.885(4) A, V = 2394 A . Dc
(Z = 4) = 1.557 cmꢀ3
. l ; specimen: 0.58 · 0.22 ·
Mo = 1.21 mmꢀ1
0.18 mm3; Tmin,max = 0.76, 0.81 (gaussian correction). 2hmax = 60ꢀ;

A.M. Groth et al. / Inorganic Chemistry Communications 10 (2007) 1070–1073
1073
3595 unique single-counter diffractometer reflections (T ca. 295 K;
[18] J.W.L. Martin, G.J. Organ, K.P. Wainwright, K.D.V. Weerasuria,
A.C. Willis, S.B. Wild, Inorg. Chem. 26 (1987) 2963.
[19] P. Comba, A. Fath, T.W. Hambley, A. Kuhner, D.T. Richens, A.
¨
Vielfort, Inorg. Chem. 37 (1998) 4389, and references therein.
[20] A.J. Blake, M. Schro¨der, Adv. Inorg. Chem. (1990) 1.
˚
monochromatic Mo Ka radiation, k = 0.71073 A; 2h/h scans), 2657 with
2
I > 2r(I); R1 = 0.045, wR2 = 0.12 (weights ððr2ðF 2Þ þ ð0:049PÞ þ
0:3969PÞꢀ1ðP ¼ ðF o2 þ 2F c2Þ=3ÞÞ), xabs = ꢀ0.12(2). jDqmaxj = 0.46
e Aꢀ3. CCDC: 638640.
˚