Copper(I) halide complexes with 2,2′-bis(diphenylphosphano)-1,1′-binaphthyl (rac-binap) and heterocyclic thiones. Racemic compounds in chiral and achiral crystal space groups

Article abstract of DOI:10.1016/j.poly.2008.06.017

Reactions of copper(I) halides with racemic 2,2′-bis(diphenylphosphano)-1,1′-binaphthyl (rac-binap) in 1:1 molar ratio afforded mononuclear complexes of the type [CuX(rac-binap)] (X = Cl, Br, I) which, on further treatment with 1 equiv. of pyridine-2-thione (py2SH), pyrimidine-2-thione (pymtH) or 4,6-dimethyl-pyrimidine-2-thione (dmpymtH) gave rise to the formation of mixed-ligand complexes of the formula [CuX(rac-binap)(thione)]. The molecular structures of [CuBr(rac-binap)(py2SH)] · 2CH₂Cl₂, [CuBr(rac-binap)(py2SH)] · CH₂Cl₂ and [CuBr(rac-binap)(dmpymtH)] · CH₂Cl₂ have been established by single-crystal X-ray diffraction. Each of the complexes features a distorted tetrahedral copper(I) center with the phosphane acting in a chelating fashion. The complexes are strongly luminescent in the solid state at ambient temperature. Unusually, the [CuBr(rac-binap)(py2SH)] · 2CH₂Cl₂ molecules crystallise in a chiral space group with independent S- and R-enantiomers in the asymmetric unit.

Full text of DOI:10.1016/j.poly.2008.06.017

Polyhedron 27 (2008) 3029–3035
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Copper(I) halide complexes with 2,20-bis(diphenylphosphano)-1,10-binaphthyl
(rac-binap) and heterocyclic thiones. Racemic compounds in chiral and achiral
crystal space groups
b
a
P. Aslanidis a, , P.J. Cox , P. Tsaliki
*
a Aristotle University of Thessaloniki, Faculty of Chemistry, Inorganic Chemistry Laboratory, P.O. Box 135, GR-541 24 Thessaloniki, Greece
b School of Pharmacy, The Robert Gordon University, Schoolhill, Aberdeen AB10 1FR, Scotland, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Reactions of copper(I) halides with racemic 2,20-bis(diphenylphosphano)-1,10-binaphthyl (rac-binap) in
1:1 molar ratio afforded mononuclear complexes of the type [CuX(rac-binap)] (X = Cl, Br, I) which, on fur-
ther treatment with 1 equiv. of pyridine-2-thione (py2SH), pyrimidine-2-thione (pymtH) or 4,6-
dimethyl-pyrimidine-2-thione (dmpymtH) gave rise to the formation of mixed-ligand complexes of
the formula [CuX(rac-binap)(thione)]. The molecular structures of [CuBr(rac-binap)(py2SH)] ꢀ 2CH2Cl2,
[CuBr(rac-binap)(py2SH)] ꢀ CH2Cl2 and [CuBr(rac-binap)(dmpymtH)] ꢀ CH2Cl2 have been established by
single-crystal X-ray diffraction. Each of the complexes features a distorted tetrahedral copper(I) center
with the phosphane acting in a chelating fashion. The complexes are strongly luminescent in the solid
state at ambient temperature. Unusually, the [CuBr(rac-binap)(py2SH)] ꢀ 2CH2Cl2 molecules crystallise
in a chiral space group with independent S- and R-enantiomers in the asymmetric unit.
Ó 2008 Elsevier Ltd. All rights reserved.
Article history:
Received 16 May 2008
Accepted 15 June 2008
Available online 23 July 2008
Keywords:
Copper(I) complexes
2,20-Bis(diphenylphosphano)-1,10-
binaphthyl
Heterocyclic thiones
Luminescence
Racemic mixtures
1. Introduction
gard to its natural bite angle. Thus, the present report is concerned
with the syntheses, characterization and luminescent properties of
Transition metal derivatives containing polyphosphanes have
been the object of intensive investigations over the past three dec-
ades for their potential applications as catalysts in several homoge-
neous reactions [1]. Adducts of the monovalent coinage metal salts
with bidentate phosphanes also have been comprehensively stud-
ied and a vast number of structurally characterized examples exist,
revealing the chelating or bridging coordination behavior of these
ligands [2]. Within this later field, we have long been engaged
in the investigation of molecular architectures realized by thi-
one-ligated copper(I) and silver(I) complexes containing tertiary
aryl-diphosphanes as bulky auxiliary ligands, aiming to provide in-
sight into the interplay between steric and electronic properties of
the ligands employed, on the coordination number and the nucle-
arity of the complexes obtained [3]. In the course of our preceding
studies we have found that the steric profile and the geometrical
characteristics of the bidentate phosphanes used as ligands were
the keys for the intriguing geometries observed. As an extension
of this work, we have included a further diphosphane in our inves-
tigations, namely 2,20-bis(diphenylphosphano)-1,10-binaphthyl)
(hereafter abbreviated as ‘‘binap”) as a further example of a bulky
rigid diphosphane possessing a certain degree of flexibility with re-
some mixed-ligand copper(I) halide complexes of the general for-
mula [CuX(binap)(thione)] [thione = pyridine-2-thione (py2SH),
pyrimidine-2-thione (pymtH) or 4,6-dimethyl-pyrimidine-2-thi-
one (dmpymtH)]. It should be noted that, although binap has been
extensively evaluated as ligand for metal-mediated asymmetric
catalysis [4], relatively few structurally characterized coordination
complexes bearing this ligand have been reported so far. Moreover,
because of the enormous commercial concern, the coordination
chemistry of binap and its derivatives [5] has been mainly concen-
trated for now over two decades on metals with catalytic activity
such as Rh, Ru, Ir, Pd and Pt. Other metals have been less inten-
sively investigated and some of them, for example, silver or copper,
have been almost ignored. As far as we know, few papers quoting
the use of cationic silver(I) [6] and copper(I) [7] complexes of binap
as catalysts appeared in the last decade, and there are only two
publications contain structurally characterized copper(I) com-
plexes bearing binap [7b,8].
2. Experimental
2.1. Materials and instrumentation
* Corresponding author.
E-mail addresses: aslanidi@chem.auth.gr (P. Aslanidis), p.j.cox@rgu.ac.uk (P.J.
Cox).
Commercially available copper(I) halides (Merck) and racemic
2,20-bis(diphenylphosphano)-1,10-binaphthyl (rac-binap) (Aldrich)
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.06.017

3030
P. Aslanidis et al. / Polyhedron 27 (2008) 3029–3035
were used as received while pyridine-2-thione, pyrimidine-2-thi-
one and 3,5-dimethyl-pyrimidine-2-thione (Merck or Aldrich)
were re-crystallized from hot ethanol prior to their use. All the sol-
vents were purified by respective suitable methods and allowed to
stand over molecular sieves. Infra-red spectra in the region of
4000–250 cmꢁ1 were obtained in KBr discs with Perkin–Elmer
FT-IR Spectrum 1 spectrophotometer. Electronic absorption spec-
tra were measured with a Perkin–Elmer-Hitachi 200 spectropho-
tometer while a Hitachi F-700 fluorescence spectrophotometer
was used to obtain the emission spectra. Melting points were mea-
sured in open tubes with a STUART scientific instrument and are
uncorrected Scheme 1.
2.2. Crystal structure determination
Single crystals suitable for crystal structure analysis were ob-
tained by slow evaporation of dichloromethane solutions of the
complexes at room temperature. X-ray diffraction data were col-
lected on an Enraf-Nonius Kappa CCD area-detector diffractometer.
The programs DENZO [9] and COLLECT [10] were used in data collection
and cell refinement. Details of crystal and structure refinement are
shown in Table 1. The structures were solved using program SIR97
[11] and refined with program SHELX-97 [12]. Molecular plots were
obtained with program ORTEP-3 [13].
2.3. Synthesis of complexes 1–6
Rac-binap (311 mg, 0.5 mmol) was added to a suspension of
CuX (0.5 mmol) in 30 cm3 of dry acetonitrile and the mixture
was stirred for 2 h at 50 °C, during which time a white precipitate
was formed. A solution of the heterocyclic thione (0.5 mmol) in
20 ml of ethanol was the added slowly, and the reaction mixture
was stirred for additional 2 h at 50 °C, whereupon the white pre-
cipitate gradually disappeared and the color of the solution turned
yellow. The resulting solution was filtered off and left to slowly
evaporate at ambient temperature. The microcrystalline solid,
which was deposited upon standing for several days, was filtered
off and dried in vacuo. In some cases major amounts of the product
precipitated from the mother-liquid before evaporation. Some of
the powder solids were recrystallized from dichloromethane.
H3C
CH3
N
NH
NH
N
NH
PPh2
PPh2
S
S
S
pymtH
py2SH
dmpymtH
rac-binap
Scheme 1. The diphosphane and the heterocyclic thiones used as ligands with their
abbreviations.
Table 1
Crystal data and structure refinement for 2a, 2 and 8
2a
2
8
Chemical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
C
49H37BrCuNP2S ꢀ 2CH2Cl2
C49H37BrCuNP2S ꢀ CH2Cl2
962.17
120(2)
0.71073
monoclinic
P21/n
C50H40BrCuN2P2S ꢀ CH2Cl2
1047.10
120(2)
0.71073
monoclinic
P21
991.22
120(2)
0.71073
monoclinic
P21/n
11.2854(4)
11.2554(5) Å
36.5426(14)
90
11.99580(10)
20.2422(2)
18.2167(2)
90
11.9960(3)
20.5581(5)
18.2022(5)
90
b (Å)
c (Å)
a
(°)
b (°)
97.6030(10)
90
4600.9(3)
105.46
90
4263.29(7)
4
1.499
104.074(2)
90
4354.19(19)
4
1.512
1.703
c
(°)
Volume (Å3)
Z
4
Dcalc (Mg/m3)
1.512
1.728
2128
0.07 ꢂ 0.06 ꢂ 0.04
2.94–25.03
ꢁ13 6 h 6 13,
ꢁ43 6 k 6 43,
ꢁ27 6 l 6 27
26327
Absorption coefficient (mmꢁ1
F(000)
)
1.736
1960
2024
Crystal size (mm3)
0.44 ꢂ 0.40 ꢂ 0.14
3.07–27.48
ꢁ15 6 h 6 15,
ꢁ26 6 k 6 25,
ꢁ23 6 l 6 23
58477
0.60 ꢂ 0.46 ꢂ 0.20
3.04–27.51
ꢁ15 6 h 6 15,
ꢁ26 6 k 6 26,
ꢁ23 6 l 6 23
39471
Theta range for data collection (°)
Index ranges
Reflections collected
Independent reflections
Completeness to theta
Max. and min. transmission
Refinement method
12651 [R(int) = 0.0535]
91.9% (theta = 25.03o)
0.9341 and 0.8886
full-matrix 1.s. on F2
12651/1/980
1.152
9753 [R(int) = 0.0349]
99.7% (theta = 27.48°)
0.7931 and 0.5154
full-matrix l. s. on F2
9753/0/523
1.050
9727 [R(int) = 0.0608]
97.1% (theta = 27.51°)
0.7269 and 0.4281
full-matrix l. s. on F2
9727/0/543
1.040
Data/restraints/parameters
Goodness-of-fit on F2 (S)
Final R indices [(I > 2
r
(I)]
R1 = 0.0665,
wR2 = 0.1454
R1 = 0.0744,
wR2 = 0.1510
calc w = (a)
0.118(12)
R1 = 0.0254,
wR2 = 0.0597
R1 = 0.0275,
wR2 = 0.0607
calc w = (b)
R1 = 0.0413,
wR2 = 0.0955
R1 = 0.0571,
wR2 = 0.1033
calc w = (c)
R indices (all data)
Final weighting scheme
Absolute structure parameter
Largest difference in peak and hole (e Åꢁ3
)
1.429 and ꢁ0.677
0.502 and ꢁ0.649
0.660 and ꢁ0.665
a
1/[r
1/[r
1/[r
2(F2o) + 46.7660P] where P = (Fo2 + 2F2c)/3.
b
c
2(Fo2) + (0.0209P)2 + 4.0694P] where P = (Fo2 + 2F2c)/3.
2(Fo2) + (0.0427P)2+6.3919P] where P = (Fo2 + 2F2c)/3.

P. Aslanidis et al. / Polyhedron 27 (2008) 3029–3035
3031
2.3.1. [CuCl(binap)(py2SH)] (1)
2.3.9. [CuI(binap)(dmpymtH)] ꢀ CH2Cl2 (9)
Yellow powder (242 mg, 58%), m.p. 253–255 °C (decomp.); Anal.
Calc. for C49H37NClCuP2S: C, 70.67; H, 4.48; N, 1.68. Found: C,
71.13; H, 4.45; N, 1.64%. IR (cmꢁ1): 3165m, 3050w, 2959w,
1585m, 1501s, 1434vs, 1372s, 1131vs, 1096s, 993s, 909, 745vs,
Orange crystals (311 mg, 60%), m.p. 280–282 °C (decomp.);
Anal. Calc. for C51H42N2Cl2CuIP2S: C, 59.00; H, 4.07; N, 2.70. Found:
C, 59.06; H, 4.17; N, 2.67%. IR (cmꢁ1): 3036w, 2914w, 1615vs,
1560vs, 1435vs, 1225vs, 1385m, 1187s, 1093m, 1027m, 981s,
892m, 816m, 742s, 695vs, 523m, 507s, 496s, 462s. UV–Vis (CH2Cl2,
694vs, 508s, 494s. UV–Vis (CH2Cl2, kmax, loge): 238 (4.92), 291
(4.46). 393 (3.97).
kmax, loge): 230 (5.02), 288 (4.65), 380 (3.86).
2.3.2. [CuBr(binap)(py2SH)] (2)
3. Results and discussion
Orange crystals (333 mg, 76%), m.p. 250–252 °C (decomp.);
Anal. Calc. for C49H37NBrCuP2S: C, 67.09; H, 4.25; N, 1.60. Found:
C, 67.19; H, 4.50; N, 1.51%. IR (cmꢁ1): 3048w, 2960w, 1576vs,
1502s, 1477s, 1435vs, 1368s, 1269m, 1131vs, 1097s, 994s, 868m,
3.1. Preparative aspects
Previously when we prepared thione/phosphane mixed-ligand
mononuclear copper(I) complexes bearing chelating diphosphanes,
we used either flexible oligomethylene backboned symmetric
diphosphanes of appropriate chain length, or rigid diphosphanes
with bite angles suitable to span tetrahedral positions. In this re-
spect, on the basis of its conformational flexibility, binap was antic-
ipated to adopt the same chelating mode upon coordination to CuI.
Considering the vast majority of the binap complexes used in cat-
alytic processes, the ability of this atropisomeric diphosphane to
preferably act as a chelating ligand towards many metals, generat-
ing mononuclear complexes is already well established. Thus, in
order to obtain tetrahedral mixed-ligand complexes of binap, we
used once more our approved straightforward synthetic procedure,
involving mixing of copper(I) halides with 1 equivalent of rac-bin-
ap at 50 °C, followed by addition of 1 equiv. of the thione ligand,
and stirring the resulting mixture for 2 h.
All the compounds prepared by this means were air-stable dia-
magnetic powdery solids, featuring the stoichiometry employed,
and were moderately soluble in chloroform and dichloromethane
and only sparingly soluble in acetonitrile, ethanol and acetone.
Solutions of the new compounds in common organic solvents were
non-conducting, and as expected for compounds derived from a
racemic precursor, none of them exhibited any optical activity.
In order to obtain single crystals suitable for X-ray analysis, we
engaged intensively with re-crystallisation of the complexes from
various solvents, whereby we were at first only moderately suc-
cessful, being able to crystallise a very small amount of compound
2 from dichloromethane, the molecular structure of which was
found to correspond to the racemic compound [CuBr(rac-bin-
ap)(py2SH)]. However, during our further attempts, crystals sepa-
rated from one of the samples of compound 2 were of a clearly
different morphology and habit (small yellow blocks) than the
well-formed orange prisms of [CuBr(rac-binap)(py2SH)], thus we
decided also to perform X-ray crystal structure determination on
them. In doing so, we surprisingly noticed that these crystals were
composed of a mixture of the two possible enantiomers which,
however, were not related to each other by a center of symmetry
(compound 2a).
818s, 742vs, 696vs, 523s, 507vs, 446m. UV–Vis (CH2Cl2, kmax, loge):
238 (4.79), 286 (4.47), 387 (3.96).
2.3.3. [CuI(binap)(py2SH)] (3)
Orange powder (277 mg, 60%), m.p. 280–282 °C (decomp.);
Anal. Calc. for C49H37NCuIP2S: C, 63.67; H, 4.03; N, 1.51. Found:
C, 63.94; H, 4.07; N, 1.45%. IR (cmꢁ1): 3046m, 1584m, 1571m,
1499m, 1490m, 1435vs, 1305m, 1097s, 999m, 817vs, 751vs,
742vs, 694vs, 522s, 509vs, 493vs. UV–Vis (CH2Cl2, kmax, loge):
246 (4.91), 287 (4.48), 387 (3.69).
2.3.4. [CuCl(binap)(pymtH)] (4)
Yellow powder (371 mg, 89%), m.p. 265–267 °C (decomp.); Anal.
Calc. for C48H36N2ClCuP2S: C, 69.14; H, 4.35; N, 3.36. Found: C,
69.23; H, 4.40; N, 3.28%. IR (cmꢁ1): 3048m, 1568vs, 1529s,
1481s, 1434vs, 1373vs, 1241m, 1172s, 1089m, 1027m, 998m,
888m, 818vs, 749vs, 695vs, 517s, 507vs, 486vs, 458m. UV–Vis
(CH2Cl2, kmax, loge): 235 (4.68), 289 (4.21), 388 (3.27).
2.3.5. [CuBr(binap)(pymtH)] ꢀ CH2Cl2 (5)
Orange crystals (334 mg, 76%), m.p. 260–262 °C (decomp.);
Anal. Calc. for C49H38N2BrCl2CuP2S: C, 61.10; H, 3.98; N, 2.91.
Found: C, 61.41; H, 4.01; N, 2.94%. IR (cmꢁ1): IR (cmꢁ1): 3050m,
2818w, 1607s, 1566vs, 1471s, 1436s, 1376s, 1217m, 1179vs,
1093s, 977m, 872m, 751s, 740s, 698vs, 508vs, 495m. UV–Vis
(CH2Cl2, kmax, loge): 245 (4.87), 281 (4.53), 389 (3.27).
2.3.6. [CuI(binap)(pymtH)] (6)
Orange powder (390 mg, 83%), m.p. 265–267 °C (decomp.);
Anal. Calc. for C48H36N2CuIP2S: C, 62.31; H, 3.92%; N, 3.02. Found:
C, 62.60; H, 4.11; N, 2.96%. IR (cmꢁ1): 3047m, 1566vs, 1543s,
1481s, 1433vs, 1377vs, 1171s, 1089s, 980m, 877m, 818s, 750vs,
740vs, 695vs, 516s, 508vs, 486s. UV–Vis (CH2Cl2, kmax, loge): 242
(4.74), 286 (4.41), 382 (3.83).
2.3.7. [CuCl(binap)(dmpymtH)] ꢀ 2CH2Cl2 (7)
Orange crystals (218 mg, 46%), m.p. 260–262 °C (decomp.);
Anal. Calc. for C52H44N2Cl5CuP2S: C, 60.53; H, 4.30; N, 2.71. Found:
C, 60.55; H, 4.27; N, 2.88%. IR (cmꢁ1): 3050m, 2964w, 1617s,
1566vs,1479m, 1435s, 1393m, 1229vs, 1192s, 1096m, 1027m,
980m, 889m, 818s, 745vs, 696vs, 522m, 507s, 495s, 465s. UV–Vis
Generally, for a racemic material in solution, there are two pos-
sibilities for crystallization. Both enantiomers may crystallise in a
nonchiral space group with, e.g., S- and R- forms related by a center
of symmetry in the single crystal, or, spontaneous resolution may
provide equal amounts of S- and R- enantiopure crystals with iden-
tical chiral space groups [14]. Unsurprisingly, molecules of 2 crys-
tallized as a racemic mixture in a nonchiral space group but
molecules of 2a crystallized as a racemic mixture in a chiral space
group. The latter was possible because the asymmetric unit of the
crystal contained both S- and R- enantiomers (Z0 = 2) arranged as
independent molecules, i.e., not related by a center of symmetry.
Apart from the two different molecular arrangements for racemic
mixtures in single crystals of 2 and 2a other possible arrangements
for racemic mixtures in a single crystal include enantiomers that
may be related by a non-crystallographic center of symmetry
(CH2Cl2, kmax, loge): 231 (5.04), 291 (4.66).
2.3.8. [CuBr(binap)(dmpymtH)] ꢀ CH2Cl2 (8)
Orange crystals (327 mg, 66%), m.p. 269–270 °C (decomp.);
Anal. Calc. for C51H42N2BrCl2CuP2S: C, 61.80; H, 4.27; N, 2.82.
Found: C, 61.54; H, 4.34; N, 2.91%. IR (cmꢁ1): 3051m, 2853m,
1614s, 1560vs,1479s, 1436s, 1393m, 1229vs, 1188s, 1093m,
1028m, 978s, 891m, 816s, 749vs, 729s, 696vs, 522s, 506s,496s,
464s. UV–Vis (CH2Cl2, kmax, loge): 236 (4.99), 288 (4.50), 379
(3.74).

3032
P. Aslanidis et al. / Polyhedron 27 (2008) 3029–3035
(Z’ = 2) [15] and enantiomers that share identical sites throughout
the crystal (solid solution) [16].
Unfortunately thermal analysis of crystals was not informative
as the crystals decomposed at temperatures below their melting
points.
3.2. Spectroscopy
The infrared spectra of compounds 1–9, recorded in the range
4000–250 cmꢁ1 display strong vibrational phosphane bands,
which remain practically unshifted upon coordination. In addition,
the spectra contain the expected four characteristic ‘‘thioamide
bands” in the ꢃ1570, ꢃ1360, ꢃ980 and ꢃ740 cmꢁ1 regions [17],
with shifts due to coordination indicative of an exclusive S-coordi-
nation mode.
The electronic absorption spectra of the mixed-ligand com-
plexes recorded in dichloromethane at room temperature are dom-
inated by two intense main bands with maxima in the 230–246 nm
and 281–291 nm regions, as well as a third weak broad band in the
379–393 nm region. With reference to the absorption spectrum of
the uncoordinated binap, which exhibits three bands at
Fig. 1. Room temperature solid state excitation (___) and emission (---) spectrum of
[CuBr(binap)(py2SH)] (2) (kex = 350 nm, kem = 545 nm).
plex problem has been made by the group of A. Vogler in a series of
systematic investigations on the photophysical properties of Au+,
Ag+, Re+ and Cu+ complexes of binap and related phosphanes
[22]. In conclusion, the origin of the luminescence can be tenta-
kmax = 216 nm, 244 nm and 290 nm, the first two intense bands
*
are attributable to intraligand
p
p transitions on the phenyl
groups of the phosphane ligand, from which the lower energy sec-
tively assigned as having mixed character between metal–ligand
ond one can be considered as to possess some phosphane-originat-
*
charge transfer (MLCT) of the type Cu(I) ?
p
(PPh2) and ligand–li-
*
*
ing MLCT transition character involving
p
orbitals of the
gand charge transfer (LLCT) of the type thione ?
p (PPh2) or/and
phosphane ligand [18–19]. Finally, the weak band in the 379–
393 nm region can be ascribed to transitions within the thione
orbitals.
*
halide ?
p
(PPh2), with an unambiguous prevalence of the MLCT
emission.
As many other copper(I) complexes with certain aryl-phos-
phanes, compounds 1–9 are strongly emissive in the solid state,
with kmax values of the broad bands in the 526–555 nm range,
when excited at k = 342–375 nm at room temperature. The excita-
tion and emission data of the complexes under investigation are
summarized in Table 2 and a representative excitation and emis-
sion spectrum of compound 2 is shown in Fig. 1.
Various copper(I) phosphane complexes are luminescent in the
solid state at room temperature, and in many cases the lumines-
cence is found to be a phosphorescence, however the nature of
the emissive excited states of these compounds has not been yet
definitively clarified [20]. In the complexes presented here, a plau-
sible evidence for the presence of phosphorescence is being pro-
vided by the fact that the emission spectra do not overlap with
the parent excitation spectra (large Stokes shifts). Moreover, recent
TD-DFT calculations [21] showed the luminescence in CuI aryl-
3.3. X-ray structural investigations
The X-ray crystal structures of [CuBr(rac-binap)(py2SH)] ꢀ
2CH2Cl2 (2a), [CuBr(rac-binap)(py2SH)] ꢀ CH2Cl2 (2) and [CuBr(S-
binap)(dmpmtH)] ꢀ CH2Cl2 (8) (details of crystal and structure
refinement are shown in Table 1) corroborate the spectroscopic re-
sults discussed above. Tables 3–5 list selected distances and angles
of these complexes.
Yellow single crystals of 2a were grown from a dichlorometh-
ane solution upon slow evaporation during several days. The com-
pound crystallizes in the monoclinic space group P21 with four
discrete formula units in the unit cell. Single-crystal analysis of
Table 3
Selected bond lengths (Å) and angles (°) for 2a
phosphane complexes to partially originate from MLCT triplets of
*
p (PPh2), and this applies apparently also to the com-
pounds under investigation. This assignment is reinforced by the
fact that the maxima of the emission bands all undergo significant
red shifts relative to the solid state r.t. emission spectrum of the
free binap, the phosphorescence band of which appears at
490 nm. A further approach to this controversially discussed com-
Molecule F
Molecule D
type Cu(I) ?
Br(1)–Cu(1)
Cu(1)–P(2)
Cu(1)–P(1)
Cu(1)–S(1)
S(1)–C(1)
2.5192(17)
2.284(3)
2.310(3)
Br(2)–Cu(2)
Cu(2)–P(3)
Cu(2)–P(4)
Cu(2)–S(2)
S(2)–C(50)
P(3)–C(67)
P(3)–C(55)
P(3)–C(61)
P(4)–C(93)
P(4)–C(87)
P(4)–C(77)
2.5205(16)
2.264(3)
2.312(3)
2.339(3)
2.312(3)
1.720(11)
1.832(11)
1.844(11)
1.861(10)
1.830(10)
1.833(10)
1.851(10)
1.728(10)
1.817(10)
1.826(10)
1.830(11)
1.831(10)
1.846(11)
1.853(10)
P(1)–C(6)
P(1)–C(12)
P(1)–C(18)
P(2)–C(37)
P(2)–C(44)
P(2)–C(38)
Table 2
Absorption and emission maxima of [CuX(binap)(thione)] complexes at room
temperature
P(1)–Cu(1)–P(2)
P(1)–Cu(1)–S(1)
P(1)–Cu(1)–Br(1)
P(2)–Cu(1)–S(1)
P(2)–Cu(1)–Br(1)
S(1)–Cu(1)–Br(1)
C(1)–S(1)–Cu(1)
C(6)–P(1)–Cu(1)
C(12)–P(1)–Cu(1)
C(18)–P(1)–Cu(1)
C(37)–P(2)–Cu(1)
98.86(10)
117.38(10)
114.51(8)
105.84(10)
111.63(9)
107.98(8)
110.4(4)
120.0(3)
118.3(4)
106.4(3)
103.8(3)
P(3)–Cu(2)–P(4)
P(4)–Cu(2)–S(2)
P(3)–Cu(2)–Br(2)
P(3)–Cu(2)–S(2)
P(4)–Cu(2)–Br(2)
S(2)–Cu(2)–Br(2)
C(50)–S(2)–Cu(2)
C(61)–P(3)–Cu(2)
C(55)–P(3)–Cu(2)
C(67)–P(3)–Cu(2)
C(93)–P(4)–Cu(2)
99.80(10)
115.44(10)
110.55(9)
109.95(10)
111.89(8)
108.91(8)
109.9(3)
121.1(3)
119.2(4)
103.2(3)
112.5(3)
Compound
kexc [nm] (solid)
kem [nm] (solid)
1 [CuCl(binap)(py2SH)]
2 [CuBr(binap)(py2SH)]
3 [CuI(binap)(py2SH)]
4 [CuCl(binap)pymtH)]
5 [CuBr(binap)pymtH)]
6 [CuI(binap)pymtH)]
7 [CuCl(binap)(dmpymtH)]
8 [CuBr(binap)(dmpymtH)]
9 [CuI(binap)(dmpymtH)]
346
350
342
346
355
356
375
375
368
553
545
526
553
555
547
543
548
540

P. Aslanidis et al. / Polyhedron 27 (2008) 3029–3035
3033
Table 4
Selected bond lengths (Å) and angles (°) for [CuBr(S-binap)(py2SH)] ꢀ CH2Cl2 (2)
C4
C3
C2
C5
C1
C15
Angles (o)
C14
Bond lengths (Å)
Br(1)–Cu(1)
Cu(1)–P(1)
Cu(1)–P(2)
Cu(1)–S(1)
S(1)–C(1)
2.4808(2)
2.2944(4)
2.3194(4)
2.3365(4)
1.7034(16)
1.8359(15)
1.8396(15)
1.8331(15)
1.8272(15)
1.8417(15)
1.8507(15)
P(1)–Cu(1)–P(2)
P(1)–Cu(1)–S(1)
P(1)–Cu(1)–Br(1)
P(2)–Cu(1)–S(1)
P(2)–Cu(1)–Br(1)
S(1)–Cu(1)–Br(1)
C(1)–S(1)–Cu(1)
C(6)–P(1)–Cu(1)
C(12)–P(1)–Cu(1)
C(18)–P(1)–Cu(1)
C(37)–P(2)–Cu(1)
98.693(15)
106.225(15)
111.718(12)
118.045(15)
112.415(12)
109.125(12)
115.77(6)
116.59(5)
119.17(5)
105.31(5)
108.16(5)
C16
C13
S1
N1
C8
Cl2
C17
C9
C12
P1
C7
P(1)–C(6)
C10
Cu1
C49
P(1)–C(12)
P(1)–C(18)
P(2)–C(38)
P(2)–C(44)
P(2)–C(37)
C6
Br1
C11
C50
C48
Cl1
C18
C36
C35
C19
C33
C30
C34
P2
C47
C32
C44
C37
C29 C28
C27
C20
C31
C46
C39
Table 5
C38
Selected bond lengths (Å) and angles (°) for [CuBr(S-binap)(dmpmtH). CH2Cl2] (8)
C26
C21
Bond distances (Å)
Angles (°)
C40
C43
C25
C24
Br(1)–Cu(1)
Cu(1)–P(1)
Cu(1)–P(2)
Cu(1)–S(1)
S(1)–C(1)
P(1)–C(19)
P(1)–C(13)
P(1)–C(7)
2.4690(4)
2.2901(7)
2.3189(8)
2.3283(8)
1.699(3)
1.831(3)
1.836(3)
1.840(3)
1.846(3)
1.821(3)
1.847(3)
P(1)–Cu(1)–P(2)
P(1)–Cu(1)–S(1)
P(1)–Cu(1)–Br(1)
P(2)–Cu(1)–S(1)
P(2)–Cu(1)–Br(1)
S(1)–Cu(1)–Br(1)
C(1)–S(1)–Cu(1)
C(7)–P(1)–Cu(1)
C(19)–P(1)–Cu(1)
C(13)–P(1)–Cu(1)
C(38)–P(2)–Cu(1)
98.91(3)
106.31(3)
111.94(2)
117.21(3)
112.21(2)
109.66(2)
116.99(2)
120.40(9)
104.69(9)
116.42(9)
109.18(8)
C22
C41
C42
C23
Fig. 3. A view of [CuBr(S-binap)(py2SH)] with displacement ellipsoids shown in the
50% probability level.
P(2)–C(38)
P(2)–C(39)
P(2)–C(45)
torted tetrahedral coordination. This distortion is best displayed
by the P–Cu–P angles of 98.86o and 99.80o for molecules F and D,
respectively, which are markedly deviating from the ideal tetrahe-
dral geometry.
compound 2a indicates the presence of two solvent (dichlorometh-
ane) molecules per formula unit, trapped in the crystal lattice; the
latter solvate molecules do not interact specifically with the com-
plex molecules and will not be further discussed Fig. 2
As shown in the ORTEP drawing (Fig. 3) there are two individual
molecules in the asymmetric unit, molecule A and molecule B, con-
taining S-binap and R-binap, respectively, thus having different
absolute configurations. These two molecules are not related to
each other by a center of symmetry and this is a rare example of
a racemic mixture in a chiral space group. In each molecule, the
copper(I) center is surrounded by the P atoms of the chelating bin-
ap, the S atom of the thione and the halide atom, in a highly dis-
With reference to a large number of known tetrahedral mixed-
ligand copper(I) complexes with a CuXSP2 core, this P–Cu–P angle,
including the two bulkiest ligands, is expected to be the largest one
within the tetrahedron, but this is not the case here. However, con-
sidering the structural characteristics of the free diphosphane, the
steric constrains resulting from this narrow angle seem unavoid-
able. In fact, the dihedral angle of 88.3o between the two naphthyl
groups in free binap, which should provide the ideal situation for
the PPh2 groups to reduce the repulsions between them to a min-
imum, is narrowed to
a
value of 73.8(2)o in [CuBr(S-bin-
ap)(py2SH)]. On the other hand, the PꢀꢀꢀP separation of 4.218 Å in
P3
S2
P4
Cu2
P2
P1
S1
Cu1
Br2
Br1
Fig. 2. A view of compound 2a showing the two enantiomeric molecules with displacement ellipsoids in the 50% probability level.

3034
P. Aslanidis et al. / Polyhedron 27 (2008) 3029–3035
free binap is shortened to 3.490(3) Å in [CuBr(S-binap)(py2SH)].
This shortening of the PꢀꢀꢀP distance upon chelation is obviously
needed for the formation of Cu–P bonds of appropriate length.
There are only three structurally characterized copper(I) com-
pounds with chelating binap reported so far, namely the cationic
complexes [Cu(S-binap)(bpy)]PF6, and [Cu(S-binap)(dmp)]PF6
(bpy = 2,20-bipyridyl and dmp = 2,9-dimethyl-1,10-phenanthro-
line) [8], as well as [Cu(S-binap)(CH3CN)2]ClO4 [7b]. The Cu–H dis-
tances in these complexes are clearly shorter than those found in
the complexes under investigation. Finally, a comparison of the
structural characteristics of [CuBr(rac-binap)(py2SH)] with those
of a series of reported monomeric compounds of type [CuX(phos-
phane)2(S)] or [CuX(diphosphane)(S)], having the same CuP2SX
central core, revealed nearly similar values for the Cu–H, Cu–S
and Cu–Br distances [23].
Orange crystals of compounds 2 and 8 were grown upon re-
crystallization from dichloromethane solutions. Both compounds
crystallize in the monoclinic space group P21/n with four discrete
formula units in the unit cell, as well as one solvent (dichlorometh-
ane) molecule per formula unit, trapped in the crystal lattice. Bond
lengths and angles around the Cu(I) for 2 and 8 are listed in Tables
3–5, and respective drawings of the molecules with the labeling of
the atoms are given in Fig. 3 and 4.
similar CuXSP2 core. As in the structure of the aforementioned
compound 2a, some conformational adaptation on the part of the
diphosphane is required for the benefit of chelation, as it is forced
to lose its ‘‘relaxed” conformation, suppressing the dihedral angle
between the two naphthyl groups by ca. 16 in 2 and ca. 10 in 8,
but such a modification of the bite size of the diphosphane may
be considered as quite normal. Regarding the geometrical charac-
teristics of the heterocyclic rings in the thione units, coordination
to Cu(I) does not causes any significant alterations except for a
small lengthening of the C@S bond as a result of charge transfer
from the S-atom to the metal.
In summary, we demonstrated the coordination behavior of
binap towards copper(I) halides in the presence of heterocyclic thi-
ones. In all the complexes, CuI was found to be in a distorted tetra-
hedral coordination environment with the thione adopting the
monodentate-S coordination mode and the diphosphane acting
as a chelate. Thus, chelation has been reconfirmed to be the pre-
ferred coordination mode for binap, a fact that can be ascribed to
its conformational flexibility which allows modifications of the bite
angle within a wide range. The new complexes showed interesting
luminescent characteristics which will be the object of further pro-
spectively investigations.
In both cases the content of the asymmetric unit corresponds to
a single molecule and the unit cell is comprised of two S- and two
R- enantiomers. As it can be seen from the data in Tables 3–5, there
are only minor differences in the bond lengths and angles between
the three structures under investigation. As in the case of 2, there is
no indication of any specific interaction involving the solvent
molecule, but as in many other copper halide complexes contain-
ing heterocyclic thione ligands, strong intramolecular hydrogen
Acknowledgment
We thank the EPSRC X-ray crystallography service at the Uni-
versity of Southampton for collecting the X-ray data.
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