Copper(I) halide complexes with triphenylphosphane and heterocyclic thione ligands: The crystal structures of [Bis(triphenylphosphane)(benzimidazole-2-Thione)copper(I) iodide], [Bis(triphenylphosphane)(benzothiazole-2-Thione)copper(I) iodide], and Bis[μ-S-(benzimidazole-2-Thione)(triphenylphosphane)copper(I) chloride]

Article abstract of DOI:10.1002/1099-0682(200208)2002:8<2216::AID-EJIC2216>3.0.CO;2-R

While the reaction of benz-1,3-imidazole-2-thione (bzimtH₂) or benz-1,3-thiazole-2-thione (bztztH) with copper(I) iodide in the presence of two equivalents of triphenylphosphane led to mononuclear complexes of the type [CuI(PPh₃)₂(L)], the reaction of benz-1,3-imidazole-2-thione with copper(I) chloride gave a dimeric complex [CuCl(PPh₃)(bzimtH₂)]₂. These three compounds were characterized by IR, UV/Vis, and ¹H NMR spectroscopy, and the crystal structures determined by single-crystal X-ray diffraction methods. Vibrational, electronic, and ¹H NMR spectroscopic data of the complexes are discussed in relation to the structures. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200208)2002:8<2216::AID-EJIC2216>3.0.CO;2-R

FULL PAPER
Copper(I) Halide Complexes with Triphenylphosphane and Heterocyclic Thione
Ligands: The Crystal Structures of [Bis(Triphenylphosphane)(Benzimidazole-2-
Thione)Copper(I) Iodide], [Bis(Triphenylphosphane)(Benzothiazole-2-
Thione)Copper(I) Iodide], and Bis[µ-S-(Benzimidazole-2-
Thione)(Triphenylphosphane)Copper(I) Chloride]
Paraskevas Aslanidis,*[a] Phil J. Cox,[b] Petros Karagiannidis,[a] Sotiris K. Hadjikakou,[c] and
Constantinos D. Antoniadis[c]
Dedicated to Prof. Joseph Grobe on the occasion of his 70th birthday
Keywords: Copper / Sulfur heterocycles / Phosphane ligands
While the reaction of benz-1,3-imidazole-2-thione (bzimtH2)
or benz-1,3-thiazole-2-thione (bztztH) with copper(I) iodide
in the presence of two equivalents of triphenylphosphane led
to mononuclear complexes of the type [CuI(PPh3)2(L)], the
reaction of benz-1,3-imidazole-2-thione with copper(I) chlor-
NMR spectroscopy, and the crystal structures determined by
single-crystal X-ray diffraction methods. Vibrational, elec-
tronic, and H NMR spectroscopic data of the complexes are
1
discussed in relation to the structures.
ide gave a dimeric complex [CuCl(PPh3)(bzimtH2)]2. These ( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
three compounds were characterized by IR, UV/Vis, and 1H
2002)
Introduction
monodentate coordination mode, binding the metal centres
exclusively through the exocyclic sulfur atom in a terminal
or bridging mode. Nonetheless, a remarkable variety of
structures ranging from mononuclear three or four-coordin-
ate species with trigonal planar and tetrahedral Cu(I), re-
spectively, to dimers with pseudo-tetrahedral geometry
formed by bridging halogen or thione ligands was obtained,
even within a closely related series of thione ligands.[6]
The great interest, currently in copper(I) coordination
chemistry is due to the participation of this cation in certain
biochemical redox reactions,[1] and also because of its abil-
ity to adopt various coordination modes.[2] With tertiary
phosphanes as ligands, copper(I) halides produce com-
plexes with ligand to copper halide ratios 2:1, 2:2, 3:1, 3:2,
4:2, and 4:4, with the geometry normally being determined
by steric rather than by electronic properties of the phos-
phane ligands.[3]
During our previous work on the interaction of univalent
group IB metal cations with biologically interesting molec-
ules, a number of mixed-ligand coordination compounds of
copper(I) halides with heterocyclic thiones and triarylphos-
phanes were prepared and structurally characterized.[4,5] In
these complexes, the neutral thione molecules with both ni-
trogen and sulfur as donating atoms always adopted the
As for the factors governing the stoichiometric and struc-
tural preferences of these complexes, the bulk of the ligands
seemed to be the main factor that determined the coordina-
tion number of the metal atom, since the steric demands of
the ortho-methyl groups clearly lead to three-coordination
in the copper(I) halide complexes of tri-o-tolylphosphane.[6]
On the other hand, the interplay of several other para-
meters like the geometrical flexibility of the coinage metals,
electronic properties on the part of the ligands, as well as
the preparation conditions might also be expected to be of
major importance, causing significant changes to the coor-
dination geometry of the metal atom. Thus, for example,
the cause of dimerization as well as the reasons for the
formation of two different types of binuclear copper(I) hal-
ide complexes of general formula [CuX(PR3)thione]2, in
which the two copper centers are linked either by a double
halide or by a double thione-sulfur bridge, are still not fully
understood. On the basis of our earlier observations on di-
meric species of the above-mentioned type, the coordination
[a]
Aristotle University of Thessaloniki, Faculty of Chemistry,
Inorganic Chemistry Laboratory
P. O. Box 135, 541 24, Thessaloniki, Greece
E-mail: aslanidi@chem.auth.gr
[b]
School of Pharmacy, The Robert Gordon University
Schoolhill, Aberdeen AB10 1FR, Scotland
E-mail: p.j.cox@rgu.ac.uk
[c]
Section of Inorganic and Analytical Chemistry, Department of
Chemistry, University of Ioannina
45110 Ioannina, Greece
E-mail: shadjika@cc.uoi.gr
2216
 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0808Ϫ2216 $ 20.00ϩ.50/0 Eur. J. Inorg. Chem. 2002, 2216Ϫ2222

Copper(I) Halide Complexes with Triphenylphosphane and Heterocyclic Thione Ligands
FULL PAPER
behavior (terminal or bridging mode) of each ligand seems for these bands due to coordination (upward shifts of
to depend on the nature of the halogen present. In particu- 15Ϫ35 cmϪ1 for thioamide I, downward shifts of
lar, formation of halogen-bridges has been found to be pre- 10Ϫ30 cmϪ1 for thioamide II and III) in combination with
ferred for the ‘‘soft’’ iodine but not for the ‘‘harder’’ chlor- the lack of ν(SH) bands at ca. 2500Ϫ2600 cmϪ1, signify the
ine base,[7,8,9] whereas both bridging and terminal bonding exclusive S-coordination mode of the thione ligands.
modes were observed for bromo ligands[10,11] since bromide
The prevalence of the thione tautomer in the complexes
1
lies on the borderline between soft and hard. However, the is further confirmed by the H NMR spectra of the com-
information obtained so far is insufficient to establish the pounds, which display, apart from the signals expected for
above supposition, so we now report on the synthesis and the phosphane and thione ligands, a single resonance at δ ഠ
X-ray crystal structure of three novel copper(I) halide com- 12Ϫ14, attributed to the NH proton.
plexes in an attempt to obtain further insight into this prob-
Description of the Structures
lem.
[CuI(PPh3)2(bzimtH2)] (1) and [CuI(PPh3)2(bztztH)] (2)
Results and Discussion
The main bond lengths and angles for compounds 1 and
2 are given in Tables 1 and 2. Molecular plots showing the
atom numbering schemes are shown in Figures 1 and 2, re-
General Considerations
The complexes were prepared by reacting equimolar
quantities of copper(I) halide and triphenylphosphane
(PPh3) followed by the addition of one equivalent of the
appropriate thione (L) in dry acetonitrile solution. This
procedure, frequently used for the preparation of copper(I)
halide complexes containing both heterocyclic thiones and
triphenyl- or tritolylphosphane ligands, gave, in the case of
copper(I) iodide, the monomeric complexes [Cu-
I(PPh3)2(bzimtH2)] (1) and [CuI(PPh3)2(bztztH)] (2). In
contrast, copper(I) chloride, used exactly in the same man-
˚
Table 1. Selected bond lengths [A] and angles [°] for 1
Cu(1)ϪP(1)
Cu(1)ϪP(2)
Cu(1)ϪS(1)
Cu(1)ϪI(1)
S(1)ϪC(1)
P(1)ϪC(8)
2.2839 (10) P(1)ϪC(14)
2.2796 (9) P(1)ϪC(20)
2.3692 (9) P(2)ϪC(26)
2.6901 (6) P(2)ϪC(32)
1.691 (3) P(2)ϪC(38)
1.834 (3)
1.831 (3)
1.818 (3)
1.827 (3)
1.826 (3)
1.828 (3)
P(2)ϪCu(1)ϪP(1) 122.45(4)
C(14)ϪP(1)ϪCu(1) 114.16(10)
C(8)ϪP(1)ϪCu(1) 113.46(11)
C(32)ϪP(2)ϪC(26) 101.23(13)
C(32)ϪP(2)ϪC(38) 103.76(13)
C(26)ϪP(2)ϪC(38) 103.76(13)
C(32)ϪP(2)ϪCu (1) 114.83(10)
C(26)ϪP(2)ϪCu(1) 117.99(9)
C(38)ϪP(2)ϪCu(1) 113.88(10)
C(1)ϪS(1)ϪCu(1) 111.34(10)
ner, gave the dimer [CuCl(PPh3)(bzimtH2)]2 (3) with the P(2)ϪCu(1)ϪS(1) 104.55(3)
two copper centres being double bridged by the thione-S
atom.
P(1)ϪCu(1)ϪS(1) 105.97(3)
P(2)ϪCu(1)ϪI(1) 105.70(3)
P(1)ϪCu(1)ϪI(1) 106.14(3)
S(1)ϪCu(1)ϪI(1) 112.10(3)
C(20)ϪP(1)ϪC(14) 104.63(14)
C(20)ϪP(1)ϪC(8) 104.03(14)
C(14)ϪP(1)ϪC(8) 103.42(14)
C(20)ϪP(1)ϪCu(1) 115.80(10)
Crystals of the complexes, prepared by slow evaporation
of the solution remaining after filtration of the initial prod-
uct deposited from the reactions, were coloured solids, sol-
uble in chloroform, methanol, ethanol, acetone, and ace-
tonitrile. They were stable to air and moisture, and could be
manipulated in air after their isolation without appreciable
decomposition. Their solutions were non-conducting in
acetone and chloroform. Room temperature magnetic
measurements confirmed the diamagnetic nature of the
compounds.
The electronic absorption spectra of the three complexes
in chloroform, which are very similar, are dominated by two
broad bands with maxima at 240 nm and in the
310Ϫ340 nm region. The first one can be attributed to in-
traligand transitions of the phosphane ligand, since the un-
coordinated triphenylphosphane reveals a strong absorp-
tion at 245 nm, which usually remains non-shifted upon co-
ordination to CuI.[12,13] The lower energy band lies in the
region where the free thiones absorb, expressing a small red
shift as a consequence of the coordination to CuI and
should therefore be considered as a thione-originating in-
traligand transition with some MLCT character.[12,13]
The infrared spectra of the compounds, recorded in the
range 4000Ϫ250 cmϪ1 show, apart from the existence of
strong phosphane bands, the usual four ‘‘thioamide bands’’
required by the presence of the heterocyclic thione ligands,
as well as the characteristic NH stretching vibrations ob-
Figure 1. A view of compound 1 with atom labels. Displacement
served in the 3050Ϫ3160 cmϪ1 region. The shifts observed ellipsoids are shown at the 50% probability level
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222
2217

P. Aslanidis, P. J. Cox, P. Karagiannidis, S. K. Hadjikakou, C. D. Antoniadis
FULL PAPER
˚
spectively, and details of the hydrogen bonding are shown
in Table 3. Both complexes are mononuclear with the cop-
per atom being surrounded by two P, one S, and one I atom
in a distorted tetrahedral coordination. It should be noted
that copper(I) iodide usually tends to form dimeric com-
plexes with two iodine atoms serving as bridges between the
Table 3. Selected bond lengths [A] and angles [°] for 3
Cu(1)ϪP(1)
2.236(3)
2.332(2)
2.347(2)
2.555(3)
2.919(2)
2.234(3)
2.352(3)
2.357(2)
2.448(3)
2.943(2)
1.708(8)
2.332(2)
1.745(10)
2.352(3)
P(1)ϪC(8)
P(1)ϪC(20)
P(1)ϪC(14)
P(2)ϪC(33)
P(2)ϪC(45)
P(2)ϪC(39)
N(1)ϪC(1)
N(1)ϪC(2)
N(2)ϪC(1)
N(2)ϪC(7)
N(3)ϪC(26)
N(3)ϪC(27)
N(4)ϪC(26)
N(4)ϪC(32)
1.813(9)
1.819(8)
1.855(8)
1.828(9)
1.840(8)
1.844(9)
1.366(10)
1.378(10)
1.342(10)
1.381(10)
1.326(12)
1.391(11)
1.363(12)
1.409(12)
Cu(1)ϪS(1)1 [a]
Cu(1)ϪC1(1)
Cu(1)ϪS(1)
Cu(1)ϪCu(1)1
two copper atoms, while only one single representative of Cu(2)ϪP(2)
Cu(2)ϪS(2)2
mononuclear species with a CuIP2S core exists among the
Cu(2)ϪCl(2)
structures characterized by us so far.[5] The largest deviation
Cu(2)ϪS(2)
from the ideal geometry is reflected by the PϪCuϪP angles
with values of 122.45(4)° (1) and 125.33(2)° (2). These
higher angles are counterbalanced by the bond angles
IϪCuϪP(1), IϪCuϪP(2), SϪCuϪP(1), and SϪCuϪP(2),
whose values are all lower than the tetrahedral value of
109.4°. This tetrahedral distortion may be attributed to
Cu(2)ϪCu(2)2
S(1)ϪC(1)
S(1)ϪCu(1)1
S(2)ϪC(26)
S(2)ϪCu(2)2
P(1)ϪCu(1)ϪS(1)1
116.05(10)
114.53(9)
112.81(9)
110.90(9)
106.79(7)
93.06(8)
131.53(8)
56.92(7)
110.88(9)
49.87(6)
116.23(9)
105.96(10)
112.93(10)
114.52(9)
104.38(8)
P(2)ϪCu(2)ϪCu(2)1
S(2)1ϪCu(2)ϪCu(2)2
Cl(2)ϪCu(2)ϪCu(2)2
S(2)ϪCu(2)ϪCu(2)2
C(1)ϪS(1)ϪCu(1)1
C(1)ϪS(1)ϪCu(1)
Cu(1)1ϪS(1)ϪCu(1)
C(26)ϪS(2)ϪCu(2)2
C(26)ϪS(2)ϪCu(2)
Cu(2)2ϪS(2)ϪCu(2)
C(8)ϪP(1)ϪCu(1)
C(20)ϪP(1)ϪCu(1)
C(14)ϪP(1)ϪCu(1)
C(33)ϪP(2)ϪCu(2)
C(45)ϪP(2)ϪCu(2)
134.28(8)
steric interactions between the bulky phosphane ligands, P(1)ϪCu(1)ϪCl(1)
53.67(7)
119.05(10)
50.71(7)
107.7(3)
110.4(3)
73.21(7)
105.7(3)
105.2(4)
75.62(8)
117.7(3)
111.5(3)
117.6(3)
114.7(3)
112.5(3)
S(1)1ϪCu(1)ϪCl(1)
which is common among a large series of monomeric cop-
P(1)ϪCu(1)ϪS(1)
per(I) halide complexes containing one heterocyclic thione
S(1)1ϪCu(1)ϪS(1)
Cl(1)ϪCu(1)ϪS(1)
P(1)ϪCu(1)ϪCu(1)1
˚
Table 2. Selected bond lengths [A] and angles [°] for 2
S(1)1ϪCu(1)ϪCu(1)1
Cl(1)ϪCu(1)ϪCu(1)1
Cu(1)ϪP(1)
Cu(1)ϪP(2)
Cu(1)ϪS(1)
Cu(1)ϪI(1)
S(1)ϪC(1)
P(1)ϪC(8)
2.2822 (6)
2.2796 (6)
2.3660 (6)
2.6807 (3)
1.668 (2)
1.824 (2)
P(1)ϪC(14)
P(1)ϪC(20)
P(2)ϪC(26)
P(2)ϪC(32)
P(2)ϪC(38)
1.818 (2)
1.827 (2)
1.822 (2)
1.832 (2)
1.830 (2)
S(1)ϪCu(1)ϪCu(1)1
P(2)ϪCu(2)ϪS(2)2
P(2)ϪCu(2)ϪCl(2)
S(2)2ϪCu(2)ϪCl(2)
P(2)ϪCu(2)ϪS(2)
S(2)2ϪCu(2)ϪS(2)
P(2)ϪCu(1)ϪP(1)
P(2)ϪCu(1)ϪS(1)
P(1)ϪCu(1)ϪS(1)
P(2)ϪCu(1)ϪI(1)
P(1)ϪCu(1)ϪI(1)
S(1)ϪCu(1)ϪI(1)
C(1)ϪS(1)ϪCu(1)
C(2)ϪS(2)ϪC(1)
C(14)ϪP(1)ϪC(8)
C(14)ϪP(1)ϪC(20)
125.33(2)
104.44(2)
98.82(2)
107.053(17)
108.907(18)
111.740(18)
115.65(8)
91.69(11)
104.79(10)
106.03(10)
C(8)ϪP(1)ϪC(20)
C(14)ϪP(1)ϪCu(1)
C(8)ϪP(1)ϪCu(1)
C(20)ϪP(1)ϪCu(1)
C(26)ϪP(2)ϪC(38)
C(26)ϪP(2)ϪC(32)
C(38)ϪP(2)ϪC(32)
C(26)ϪP(2)ϪCu(1)
C(38)ϪP(2)ϪCu(1)
C(32)ϪP(2)ϪCu(1)
101.74(10)
115.99(7)
113.97(7)
112.95(7)
103.53(10)
102.60(9)
102.86(10)
111.53(7)
116.77(7)
117.68(7)
[a]
Symmetry transformations used to generate equivalent atoms:
#1: Ϫx ϩ 1, Ϫy ϩ 1, Ϫz ϩ 1; #2: Ϫx, Ϫy, Ϫz.
Figure 3. A view of compound 3 with atom labels. Displacement
ellipsoids are shown at the 50% probability level
and two monodentate triphenylphosphane ligands, and ex-
hibiting the same CuSP2X core.[11,14,15]
The CuϪI and CuϪS bonds in 1 and 2 are both some-
what longer, while the two individual CuϪP distances are
Figure 2. A view of compound 2 with atom labels. Displacement
ellipsoids are shown at the 50% probability level
2218
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222

Copper(I) Halide Complexes with Triphenylphosphane and Heterocyclic Thione Ligands
FULL PAPER
Table 4. Hydrogen bonding in the three complexes
˚
˚
˚
Compd.
Donor (D)
H
Acceptor (A)
DH [A]
HA [A]
DA [A]
DHA [°]
1
1
2
2
2
3
3
3
3
3
3
N1
N2
N1
C31
C40
N1
N2
N3
H1
H2
H1
H31
H40
H1
H2
H3
I1
0.88
0.88
0.88
0.95
0.95
0.88
0.88
0.88
0.88
0.95
0.95
2.73
2.06
2.63
2.87
2.83
2.56
2.30
2.18
2.36
2.48
2.80
3.526(2)
2.860(3)
3.493(2)
3.719(2)
3.648(2)
3.227(7)
3.105(7)
3.036(8)
3.198(9)
3.25(1)
151
150
167
149
146
133
153
165
159
137
134
O1i [a]
I1
S1
S1ii
Cl2iii
Cl1iv
Cl2v
Cl1
N2
N4
C15
C49
H4
H15
H49
Cl1
3.53(1)
[a]
Atom coordinates transposed by: i: x, 0.5 Ϫ y, 0.5 ϩ z; ii: Ϫ1 ϩ x, y, z; iii: 1 Ϫ x, 1 Ϫ y, 1 Ϫ z; iv: Ϫx, 1 Ϫ y, Ϫz; v: 1 ϩ x, y, z.
˚
slightly shorter than those found in [CuI(PPh3)2(pymtH)]. 2.236(3) A, somewhat longer than the values observed in B
˚
This represents, according to the Cambridge Structural and C, but clearly shorter than the ‘‘long’’ one [2.251(1) A]
˚
Database, a unique known structure of a monomeric, tetra- in A. Likewise, the CuϪCl bond length of 2.347(2) A in 3a
˚
hedrally coordinated copper(I) iodide complex with ter- and 2.357(2) A in 3b, lies well above the corresponding
minal iodine and thione-sulfur donors.[5] These bond values 2.283(1) and 2.300(1) A found in C and B, but is
˚
˚
lengths all lie within the range of the corresponding values significantly shorter than that in A [2.391(2) A]. As previ-
previously reported for a number of related tetracoordin- ously demonstrated, this CuϪCl bond appears to be associ-
ated copper(I) complexes.
ated with the SϪCuϪS angle, namely an opening up of the
SϪCuϪS angle from 92.48(2)° in B to 93.24(2)° in C and
110.2(1)° in A results in an elongation of the CuϪCl
bond.[16] As for the complex under consideration, it fits well
into the above mentioned series, even when the mean values
for the CuϪCl bond length and the SϪCuϪS angle for 3a
and 3b are taken into consideration.
The SϪCuϪS and CuϪSϪCu angles [106.79(7) and
73.21(7)° for 3a and 104.38(8) and 75.62(8)° for 3b], which
are close to the ideal values (109.5 and 70.5°) for symmetric
dimers, deviate significantly from those found in B and C,
but are not far from those observed in A. The value of
the ClϪCuϪS angle of 102.10(10)° in 3b is similar to the
corresponding values observed in the previous complexes B
and C, whereas the same angle in 3a [93.06(8)°] is strongly
distorted and very close to that observed in complex A.
Finally, the value of the PϪCuϪCl angle of 114.53(9)° in
3a is similar to the corresponding values observed in the
previous complexes A, B, and C, but the same angle in 3b
is surprisingly much smaller [105.96(10)°].
[CuCl(PPh3)(bzimtH2)]2 (3)
The asymmetric unit of the crystal cell contains two half-
molecules. The atoms in molecule 3a are Cu1, S1, Cl1,
C1ϪC25, H1, H2, H3A, H4A, H5ϪH24, and their equiva-
lent primed atoms. The atoms in molecule 3b are Cu2, S2
Cl2, N3, N4, C26ϪC50, H3, H4, H26ϪH50, and their
equivalent primed atoms. The main bond lengths and
angles for both molecules are given in Table 4, and an OR-
TEP view of molecule 3a showing the atom numbering is
given in Figure 3. There are some significant differences in
bond lengths and angles between the two molecules which
will be mentioned in the subsequent discussion. The basic
structural unit of [CuCl(PPh3)(bzimtH2)]2 is a dimer in
which the two copper atoms are doubly bridged by two S
atoms of the thione ligands to form a strictly planar four-
membered Cu2S2 core. The slightly distorted tetrahedral co-
ordination around copper is completed by one P atom from
the phosphane ligand and one chlorine atom.
Three
structurally
determined
analogues,
Computational Study
[CuCl(tmtp)(bzimtH2)]2 (tmtp ϭ tri-m-tolylphosphane),
[CuCl(tptp)(tzdtH)]2 (tptp ϭ tri-p-tolylphosphane, tzdtH ϭ
It is generally accepted that the local metal environment
1,3-thiazolidine-2-thione),
and
[CuCl(tptp)(pmtH)]2 in monovalent copper coordination compounds is mainly
(pmtH ϭ pyrimidine-2-thione) will be used for the sub- determined by steric effects as well as by the Lewis basicity
sequent comparative discussion (hereafter referred to as of the ligands, but additional considerations may be useful
complexes A, B, and C, respectively).
in explaining the situation in some specific cases. The
Each of the two non-equivalent CuϪS bonds of 2.332(2) dimerization often realized in copper(I) halide complexes
˚
˚
and 2.555(3) A in 3a and 2.322(3) and 2.448(3) A in 3b, containing heterocyclic thione and triarylphosphane li-
respectively, are within the range expected for binuclear CuI gands as well as the bridging or terminal bonding mode of
complexes with double bridging sulfur atoms. The asym- each ligand in such dimers, for instance, are of unknown
metry in the two bridging distances in molecule 3a, how- origin. The contribution of electronic factors, however, is
ever, is remarkably larger than in the three already known suspected to be important. The computations performed in
analogues. As in the other dimers, the two bulky phosphane the present paper are an attempt to unravel any such elec-
ligands are trans disposed with a CuϪP bond length of tronic factor.
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222
2219

P. Aslanidis, P. J. Cox, P. Karagiannidis, S. K. Hadjikakou, C. D. Antoniadis
FULL PAPER
The lowest unoccupied molecular orbitals (LUMO) for
The calculated overlap populations for the Cu(1)ϪS(1)
3A and 3B are 3.346 eV and 3.349 eV higher, respectively, and Cu(1)ϪS(1)1 bonds in 3 are 0.384 e and 0.178 e, re-
than their highest occupied molecular orbitals (HOMO), spectively. The calculated overlap populations for the
while the LUMO energies in complexes 2 and 1 are higher Cu(1)ϪP(1) and Cu(1)ϪCl(1) bonds are 0.607 and 0.330
than their HOMO energies by 3.518 and 3.432 eV, respect5- e, respectively. The calculated overlap populations, for the
ively. This indicates that the monomers are more stable than Cu(1)ϪI(1) and Cu(1)ϪS(1) bonds are 0.244 and 0.348 e,
the dimers. An overlap population of 0.005 e in 3A and respectively, in complex 2 and 0.255 and 0.344 e in complex
0.001 e in 3B between the two metal centres, which are sep- 1, while the values for the overlap population calculated for
˚
˚
arated by 2.919(2) A and 2.943(2) A, respectively, has been the two Cu(1)ϪP(1) and Cu(1)ϪP(2) bonds are 0.566 and
calculated for the dimeric structures, whereby the corres- 0.565 e in complex 2 and 0.561 and 0.571 e, respectively, in
ponding value for CuI(pytH)(tmtp)]2,[9] with a Cu···Cu dis- complex 1.
˚
tance of 3.119(1) A, was found to be 0.006 e. The bonding
nature of these metalϪmetal interactions is, of course, too
Conclusion
small to be considered as the crucial factor for the domina-
tion of the dimeric structures. The stabilizing effect of a
metalϪmetal interaction could be important only for
The coordination chemistry of copper(I) with heterocyclic thiones
and tertiary phosphanes as ligands offers opportunities for the de-
tailed examination of the factors governing the stereochemical pref-
erences of copper(I) compounds. According to our previous investi-
gations, the stoichiometry may be one of these factors, especially
in association with the solvent used for the preparation. The three
new copper(I) complexes investigated in this work were prepared
in an acetonitrile/methanol mixture, whereby two different types of
structures were formed, tetrahedral monomeric and pseudo-tetra-
hedral dimeric with the halogen acting as bridging ligand. However,
˚
Cu···Cu separations below the value of 2.80 A proposed
to be the sum of two copper covalent van der Waals
radii. In the case of [CuCl(bztzdtH)(tmtp)]2 or
[CuBr(pytH)(tmtp)]2,[16] where the Cu···Cu distances are
˚
2.764 and 2.691 A (both shorter than the sum of the
copperϪcopper van der Waals radius by 0.046 and 0.109
˚
A, respectively), the corresponding overlap populations are
0.019 e and 0.026 e.
Table 5. Crystal data and structure refinement
1
2
3
Chemical formula
Molecular weight
C43H36CuIN2P2S·CH3OH·0.85CH3CN·0.27H2O
934.4
C43H35CuINP2S2
882.22
C50H42Cl2Cu2N4P2S2
1022.92
Temperature
Wavelength
Crystal system
Space group
a
b
c
150(2) K
150(2) K
0.71073 A
Monoclinic
P21/n
9.6250(10) A
22.9400 (10) A
17.9130 (10) A
150(2) K
0.71073 A
˚
˚
˚
0.71073 A
Monoclinic
P21/c
12.528(3) A
18.573 (4) A
Triclinic
¯
P1
12.4251(8) A
˚
˚
˚
˚
˚
˚
˚
˚
˚
13.6559 (10) A
13.9637 (13) A
18.639 (4) A
α
β
γ
90°
91.49 (3)°
90°
90°
95.025 (5)°
90°
95.533 (3)°
91.756 (3)°
104.047 (7)°
3
3
3
˚
˚
˚
Volume
4335.7 (15) A
3939.9 (5) A
2284.2 (3) A
Z
4
4
2
3
3
3
˚
˚
˚
Density (calculated)
Absorption coefficient
F(000)
1.424 Mg/m A
1.375 mmϪ1
1873
1.487 Mg/m A
1.556 mmϪ1
1776
1.487 Mg/m A
1.250 mmϪ1
1048
Crystal size
Theta range for data collection
Index ranges
0.24 ϫ 0.22 ϫ 0.06 mm
2.27 to 27.48°
Ϫ16 Յ h Յ 15
0.34 ϫ 0.22 ϫ 0.18 mm
2.28 to 27.48°
Ϫ12 Յ h Յ 12
0.07 ϫ 0.05 ϫ 0.01 mm
2.43 to 25.06°
Ϫ14 Յ h Յ 14
Ϫ21 Յ k Յ 24
Ϫ26 Յ k Յ 29
Ϫ16 Յ k Յ 16
Ϫ24 Յ l Յ 24
Ϫ22 Յ l Յ 23
Ϫ16 Յ l Յ 16
Reflections collected
37460
34765
25382
Independent reflections
Completeness to theta ϭ 27.48°
Data [I Ͼ 2σ(I)] / restrains / parameters
Max. and min. transmission
Refinement method
9838 [R(int) ϭ 0.0525]
99.0%
7872 / 6 / 481
0.9220 and 0.7337
Full-matrix l.s. on F2
1.024
8940 [R(int) ϭ 0.0484]
98.8%
7266 / 0 / 452
0.7670 and 0.6197
Full-matrix 1.s. on F2
1.039
7977 [R(int) ϭ 0.1828]
98.5%
3776 / 0 / 559
0.9876 and 0.9176
Full-matrix 1.s. on F2
0.945
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
Final weighting scheme
R1ϭ0.0390, wR2ϭ0.0999
R1ϭ0.0547, wR2ϭ0.1091
Calc w ϭ 1/[σ2(F02) ϩ
(0.0582P)2 ϩ 4.5196P),
where P ϭ (F20 ϩ 2Fc2)/3
R1ϭ0.0315, wR2ϭ0.0727
R1ϭ0.0452, wR2ϭ0.0775
Calc wϭ1/[σ2(F02) ϩ
(0.0420P)2 ϩ 0.0789P),
where P ϭ (F20 ϩ 2Fc2)/3
R1ϭ0.0784, wR2ϭ0.1710
R1ϭ0.1873, wR2ϭ0.2203
Calc w ϭ 1/[σ2(F02) ϩ
(0.0989P)2 ϩ 0.0000P),
where P ϭ (F20 ϩ 2Fc2)/3
3
3
3
˚
˚
˚
Largest diff peak and hole
2220
1.103 and Ϫ1.496 e/A
0.488 and Ϫ1.240 e/A
0.823 and Ϫ0.597 e/A
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222

Copper(I) Halide Complexes with Triphenylphosphane and Heterocyclic Thione Ligands
FULL PAPER
since the softness of the halogen decisively affects its donor proper-
ties, reaction stoichiometry and solution media cannot be consid-
ered as the only reason for the structural preferences of copper(I),
at least in the case of complexes investigated in this work. Con-
sequently, this phenomenon needs more extensive studies in consid-
eration of further structures of this series. Finally, extended Hückel
calculations could not provide any evidence for significant interac-
tion between the two copper(I) centres, despite the short
CuϪCu distance, in the case of the dimeric complex
[CuCl(PPh3)(bzimtH2)]2 (3).
146 m, 121 s. UV-Vis, λmax (logε), CHCl3: 240.5 (4.358), 310.5
(4.530).
X-ray Crystallographic Study: The unit cell and intensity data were
collected on a Delft Instruments FAST diffractometer using the
routines ENDEX, REFINE, and MADONL in the MADNES
software suite[18] and processed using ABSMAD;[19] detailed pro-
cedures are described by Darr, Drake, Hursthouse, and Malik.[20]
Absence of crystal decay in the X-ray beam was confirmed by
checking equivalent reflections at the beginning and end of data
collection, which lasted about 8 hours. The structures were solved
with SIR92[21] and refined with SHELX93.[22] Details are given in
Table 5. The copper, bromine, chlorine, iodine, sulfur, phosphorus,
nitrogen, and carbon atoms were refined with anisotropic temper-
ature factors. The hydrogen atoms were allowed to ride on their
attached atoms with common isotropic temperature factors for
methyl and non-methyl hydrogens. An absorption correction was
made with DIFABS.[23]
Experimental Section
Materials and Instruments: Copper(I) chloride, copper(I) iodide,
and all solvents are commercially available and were used as ob-
tained, while the thiones (Merck or Aldrich) were recrystallized
from hot ethanol prior to their use. Elemental analyses for C, H,
N, and S were carried out with a Carlo erba EA MODEL 1108.
Melting points were measured in open tubes with a STUART sci-
entific instrument and are uncorrected. Infra-red spectra in the re-
gion of 4000Ϫ370 cmϪ1 were obtained in KBr discs while far-infra-
red spectra in the region of 400Ϫ50 cmϪ1 were obtained in poly-
ethylene discs, with a PerkinϪElmer Spectrum GX FT-IR spectro-
meter. A Jasco UV/Vis/NIR V 570 series spectrophotometer was
used to obtain the electronic absorption spectra.
CCDC-174528 (1), -174529 (2), and -174526 (3) contain the supple-
mentary crystallographic data for this paper. These data can be
obtained free of charge at www.ccdc.cam.ac.uk/conts/retriev-
ing.html [or from the Cambridge Crystallographic Data Centre, 12,
Union Road, Cambridge CB2 1EZ, UK; Fax: (internat.)
ϩ44Ϫ1223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
Acknowledgments
We thank the EPSRC X-ray crystallographic service at the Univer-
sity of Wales, Cardiff, (now based in Southampton) for data collec-
tion.
Computational: Extended Hückel calculations were performed us-
ing the CACAO program.[17] The calculations were carried out us-
ing crystallographic data from the studied molecules. The EHT
parameters for Cu were those established in the literature.
Synthesis of the Complexes: The complexes were prepared accord-
ing to the following general procedure. A suspension of copper(I)
halide (0.5 mmol) and triphenylphosphane (132 mg, 0.5 mmol) in
10 cm3 of acetonitrile was stirred until a white precipitation of the
intermediate [CunXn(PPh3)m] (X ϭ Cl or I) complex was formed.
A solution of the appropriate thione (0.5 mmol beznimidazoline-2-
thione (bzimtH) or benzthiazoline-2-thione (bztzdtH) in methanol
was then added and the new suspension was stirred until clear
(15 min). The resulting solution was filtered off and the clear solu-
tion was kept in darkness at room temperature. After 24 hours,
crystals of the complexes suitable for single crystal analysis by X-
ray crystallography were obtained by filtration.
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[5]
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[CuI(PPh3)2(bzimtH)] (1): Pale yellow crystals. Yield 340 mg (72%),
m.p. 221Ϫ222 °C; C43H36CuIN2P2S·CH3OH·0.85CH3CN·
0.27H2O: C 59.36, H 4.77, N 4.42; found C 59.55, H 4.63, N 4.30%.
IR ν˜ (cmϪ1): 3050 w, 1619 m, 1493 s, 1434 vs, 1161 s, 1093 s, 742
vs, 694 vs, 603 s, 517 vs, 490 vs; far-IR ν˜ (cmϪ1): 218 m, 200 m,
174 s, 162 s, 151vs, 146 m, 121 s. UV-Vis, λmax (logε), CHCl3: 241
(4.373), 310 (4.412).
Skoulika, Inorg. Chim. Acta 1992, 193, 129Ϫ135.
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[CuI(PPh3)2(bztzdtH)] (2): Orange crystals. Yield 335 mg (76%),
m.p. 218Ϫ219 °C; C43H35CuINP2S2: C 58.54, H 3.99, N 1.59;
found C 58.84, H 3.88, N 1.70%. IR ν˜ (cmϪ1): 3052 w, 1488 s, 1424
vs, 1322 s, 1094 s, 1029 s, 743 vs, 695 vs, 515 vs, 503 vs; far-IR ν˜
(cmϪ1): 219 m, 205 m, 200 m, 174 s, 164 s, 151 vs, 146 m, 121 s.
UV-Vis, λmax (logε), CHCl3: 243 (4.471), 329.5 (4.304).
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[13]
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[CuCl(PPh3)(bzimtH)]2 (3): Pale yellow crystals. Yield 395 mg
(77%), m.p. 249Ϫ250 °C; C50H42Cl2CuN2P2S2: C 58.71, H 4.13, N
5.48; found C 58.79, H 4.01, N 5.52%. IR ν˜ (cmϪ1): 3193 m, 3053
s, 1502 vs, 1459 vs, 1446 s, 1179 vs, 1095 s, 743 vs, 694 vs, 598 s,
520 vs, 501 vs; far-IR ν˜ (cmϪ1): 217 w, 200 w, 174 s, 163 s, 151 vs,
[15]
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[17]
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222
2221

P. Aslanidis, P. J. Cox, P. Karagiannidis, S. K. Hadjikakou, C. D. Antoniadis
FULL PAPER
[21]
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[18]
[22]
[23]
[19]
[20]
Received January 25, 2002
[I02044]
2222
Eur. J. Inorg. Chem. 2002, 2216Ϫ2222