- Email: [email protected]
Synthesis, characterization and crystal structure of copper(I) thiolates: [(C6H5)4P+]2[Cu4(C2H5S−)6]·0.5C2H6O2 and [(C6H5)4P+][Cu7(C2H5S−)8]
Po/yhedron Vol. 9, No. 9, pp. 1155-I 164, 1990 Printed in Great Britain
0
0277-5387/90 s3.00+ .m 1990 Pergamon Press plc
SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF COPPER(I) THIOLATES : I(C,H,),P+I,[C~(C,H,S-),I MARKUS BAUMGARTNER,
l
0=5CJ-b02 AND HELMUT
I~~,~~~~~+lI~~,~~~~,~-~,l
SCHMALLE
and
ERICH DUBLER”
Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse CH-8057 Zurich, Switzerland
190,
(Received 20 October 1989 ; accepted 8 December 1989)
Abstract-The reaction of the monodentate ligand thioethane with (&H&,PBr and Cu,O in organic solvents results in the crystallization of two new homoleptic polynuclear copper(I) thiolates : [(C6HJ4P+]2[C~4(C2H5S-)6] * 0.5C2H,02 (1) and [(C6HS)~P+][C~7(C2H5S-)8] (2). Both compounds have been characterized by X-ray crystallography, thermal analysis, luminescence spectroscopy and IR spectroscopy. Compound 1 is triclinic, space group PI with a = 12.066(5), b = 13.824(5), c = 19.112(3) A, c( = 90.82(2), p = 101.85(2), y = 93.53(3)O and Z = 2. Compound 2 is monoclinic, space group P2 ,/c with a = 19.208(3), b = 16.975(4), c = 16.394(6) A, /I = 108.68(2)” and Z = 4. The structure of 1 is built up by [(Cu,(RS),)*-] adamantane-type cluster units, separated by [(&H&P+] cations. Compound 2 consists of copper(I) thiolate chains, also separated by [(&H&P+] cations. In 2, structural units of the stoichiometry Cu,(C ZH$), ,, are connected by common sharing of four sulphur atoms, leading to a chain of the stoichiometry CU~(C~H$-)~. The shortest Cu-Cu distance is 2.692(l) A in 1 and 2.736(2) A in 2. Excitation at 450 nm of 1 in the solid state results in a weak emission at 665 nm, compound 2 exhibits in the solid state an intense luminescence at 591 nm upon excitation at 365 nm.
The coordination chemistry of thiolates, a fundamental ligand type in transition metal chemistry, ‘3’is of much current interest in view of forming appropriate model compounds of active sites in metalloproteins. We are interested in crystallizing metal-rich copper(I) thiolates as model compounds of copper(I) thioneins. Metallothioneins (MT) are believed to play a role in the metabolism and in the detoxification of a number of essential and nonessential trace metals in animals and plants, mainly of the metals zinc, cadmium, mercury and copper.3 They are characterized by an unusually high cysteinate content of the peptide and a metal-tocysteinate ratio of 1: 3 for Zn- and Cd-MT. In copper(I) thioneins, the metal content found is even higher. In the case of only copper(I)-containing MTs, cluster core types of the stoichiometries CUSS9 and CusSi are often suggested.4*5 A copper-to-sulphur ratio of 2: 3 seems to be * Author to whom correspondence should he addressed.
a characteristic feature of Cu’-MTs as well as of synthetic polynuclear copper(I) complexes with mono- or bidentate thiolates.6.7 The MT with the highest metal content is a fungal MT found in Neurospora crassa with a copper(I)-to-cysteinate ratio of 6 : 7.* Syntheses of copper(I) thiolates with monodentate ligands RS revealed species that contain core units of the stoichiometries cu4s6 (R = C6H5, CH3), Cu& (R = (CH,),C) and Cu& (R = C,H,).’ The most favoured Cu4S6 “adamantane” type can also be obtained with bidentate ligands ((SRS) like 1,2-dithioethane, 1,3-dithiopropane or o-xylene+a’-dithiol. ‘O*’’ In addition, the formation Of core Units Of the type cu3&, Cu$ , z and Cu, $, 6 has been observed with bidentate dithiol ligands. ’ *-’ 4 Our syntheses using the monodentate ligand thioethane (TE) revealed two new homoleptic polynuclear copper(I) thiolates : One with the well-known adamantane-type cu4!& cluster, the other with a non-molecular one-dimensional Cu7Ss chain structure. In both structures, all the copper atoms are trigonally coordinated by
1155
1156
M. BAUMGARTNER
bridging thiolates. We report here on synthesis, structure, spectroscopical and thermoanalytical data of these new copper(I) thiolates.
EXPERIMENTAL
Syntheses and thermal analysis Thioethane (TE), (Ph),PBr and Cu20 were purchased from Fluka AG, Buchs/Switzerland and used without further purification. The 1 M solution of NaOMe was obtained by adding 23.0 g (1 mol) of sodium to 1000 cm3 of methanol, stirred on an ice bath. The syntheses were performed in a Schlenk-type apparatus in a nitrogen atmosphere. Thermogravimetric (TG) data in the temperature range 30-700°C were recorded in a flowing N2atmosphere, using heating rates of 10°C min- ’ and sample weights of 4-l 5 mg on a Perkin-Elmer TGS-2 thermobalance. X-ray powder diffraction diagrams of the final products were produced by a Guinier-type camera with a Johansson monochromator (Cu-K,, radiation).
To a solution of 3.34 g (7.8 mmol) of (Ph),PBr in ethylene glycol (20 cm3), MeOH (33 cm’) and 1 M NaOMe/MeOH (7 cm3), 1.05 g (16.9 mmol) of TE was added. After warming up to a reaction temperature of 55°C and addition of 400 mg (2.8 mmol) of CuZO, a clear yellow solution was obtained. Slow evaporation at room temperature first yielded dark red bulky crystals of 1. Later on, yellow crystals of compound 2 could also be isolated from the same solution. The red crystals of 1 were separated manually. Found: C, 54.2; H, 5.6; Cu, 20.1 (TG analysis) ; S, 15.1. Calc. for C61H73C~4 0P2S6 (1330.8): C, 55.1; H, 5.5; Cu, 19.1; S, 14.5%.
[(C,H,),P+I[Cu,(TE-),I (2) To a solution of 2.5 g (6.0 mmol) of (Ph),PBr in ethylene glycol(20 cm3), MeOH (33 cm’) and 1 M NaOMe/MeOH (8 cm3), 1.11 g (17.9 mmol) of TE was added. After addition of 400 mg (2.8 mmol) of CuZO, the solution was kept at 60°C for 30 min until it became clear yellow. Slow evaporation at room temperature yielded yellow crystals of 2. Found : C, 37.7 ; H, 4.9 ; Cu, 34.6 (TG analysis). Calc. for C40HSOC~,PSB(1273.8) : C, 37.7 ; H, 4.7 ; cu, 34.9%.
et al.
X-ray crystallography Symmetry, preliminary cell parameters and space groups of the complexes investigated were established by precession and Weissenberg photography. Final lattice parameters and crystal orientations were obtained from least-squares refinement of the 8 values of 25 reflections on an Enraf-Nonius CAD4 diffractometer. Intensity data were collected by using graphitemonochromated MO-K, radiation. Four standard reflections lying in different regions of the reciprocal space were monitored periodically. A total loss in intensity of -2.3% (1) and - 1.3% (2) was observed and corrected for in data reduction. The intensities were reduced to F, by applying corrections for Lorentz and polarization effects. A numerical absorption correction based on carefully indexed crystal faces was carried out for both compounds. The structure of 1 was solved by using the Patterson interpretation routine in SHELXS-86” and by conventional Fourier techniques, and refined with full-matrix least-squares methods including anisotropic temperature factors for copper, sulphur, phosphorus and the carbon atoms of the ligands. The phenyl rings were refined as rigid groups with free varying isotropic temperature factors. The atoms of the inserted solvent molecule were also treated with isotropic temperature factors. Due to a disordered arrangement of the terminal carbon atom C(22), the C(21)---C(22) distance was treated with a constrained length in the refinement. The positions of the hydrogen atoms of the phenyl rings and of the ligand molecules were calculated, and the hydrogen atoms were included as fixed contributions in the refinement. The structure of 2 could be solved with direct methods using 937 negative quartets in SHELXS86. For the structure refinement of 2 (full-matrix least-squares methods including anisotropic temperature factors for copper, sulphur, phosphorus and the carbon atoms of the ligands) it was not necessary to fix the phenyl ring atoms. These carbon atoms were used with free varying isotropic temperature factors. Due to a disordered arrangement, some of the terminal carbon atoms [C(52), C(62), C(72), C(82)] of the thiolate ligands were treated with a constrained bond length to the adjacent carbon atom in the refinement. The position of all the hydrogen atoms was calculated and the hydrogen atoms included as fixed contributions in the refinement. The structure of 1 was finally refined with unit weights. The weighting scheme for 2 was w = 1.0/a2(F). Interatomic distances and angles have
1157
Copper(I) thiolates been calculated with the 0RFFE3 program. I6 The calculations were performed with the programs SHELXS-86 and SHELX-76” on an IBM 3033 and a NAS AS/XL V60 computer at the University of Zurich. Crystal parameters, data collection details, and results of the refinements are summarized in Table 1. Atomic coordinates and thermal parameters for the two structures have been deposited with the Editor as supplementary material, from whom copies are available on request.
Luminescence spectroscopy Emission spectra were recorded on a PerkinElmer Model 204 fluorescence spectrophotometer using a Xenon lamp as exciting source. Powder samples were hxed on a quartz plate with a nonfluorescing glue.
IR spectroscopy Solid-state IR spectra in the range 40&l 80 cm- ’ were obtained on a Perkin-Elmer spectrophotometer type 983. Spectra were run on Nujol mulls between CsI or polyethylene plates. RESULTS AND DISCUSSION i%Z
SttY4CtWeS
oe5c2H602
Of and
[(C6H5)4P+]*[CU4(C~H5S-)6]. [(C~H~)~P+I[CU~(C~HSS-)BI
(2)
The structure of 1 is built up by [(Cu&)‘-] adamantane-type cluster units, separated by bulky [(C,H,),P+] cations, as shown in Fig. 1. The structure of the cluster anion can be considered as a tetrahedron of copper atoms inscribed in a distorted octahedron formed by six p,-sulphur atoms (Fig. 2). This cluster type is very common for copper(I) thiolates. ‘,*,’ The Cu-Cu distances range from 2.692(l) to 2.780(l) A, with a mean distance of
Table 1. Crystal data and structure determination 1
Formula Mol. wt Data crystal (nun) Colour a (A) b (A) c (A) x (“) B (“) Y(“) v (A’) Crystal system Z &, (8 em- 3, Space group Scan method 219range (“) hkl range Max time/rlln (s) p(Mo-K,) (cm- ‘) Transmission factors (max/min) Data measured (incl. stds.) R,,/ No. of refln av. Unique data Observed data [I 2 3a(Z)] Number of variables MaxImin Ap (e’/A’) R RW Weight
(1)
parameters for 1 and 2 2
G,H,~CU~~P&
GJ-L&u,PS~
1330.8 0.52 x 0.50 x 0.65 Orange-red 12.066(5) 13.824(5) 19.112(3) 90.82(2) 101.85(2) 93.53(3) 3112.9 Triclinic 2 1.42 PT *2e 2.Cb52.0 +14, f17, +23 30 15.66 0.514/0.363 11,934 0.0271614 11,499 6976 321 l.Ol/-0.71 0.065 0.068 w = 1 (unit weight)
1273.8 0.18 x 0.22 x 0.55 Yellow, transparent 19.208(3) 16.975(4) 16.394(6) 90.0 108.68(2) 90.0 5063.8 Monoclinic 4 1.68 P2,lc (u-2e 2.c50.0 +22, +20, +19 30 31.62 0.621/0.492 9645 0.02411274 8884 3538 385 0.71/-0.53 0.054 0.049 w = l/a2(Fo)
1158
M. BAUMGARTNER et al.
Fig. 1. Stereoview of the unit cell of 1.
Fig. 2. Stereoview of the adamantane-type
2.725 A. The 12 crystallographically-independent Cu-S distances range from 2.248(3) to 2.309(3) A, with a mean distance of 2.281 A (Table 2). Five of the six Cu-S-Cu angles range from 72.6(l) to 73.8(l)“, whereas an increased angle of 75.1(l)’ is observed at the sixth sulphur atom as a consequence of a hydrogen bond linking this sulphur atom to the solvate molecule. The two [(Cu,SJ2-] clusters within the unit cell are linked by two hydrogen bonds of the type S. . . H-O to the ethylene glycol solvate molecule at the inversion centre in the middle of the cell. The corresponding S(4) * . . 0 acceptor-donor distance is 3.170(7) A. The hydrogen atom of the hydroxy group of the inserted solvate molecule could be located in a difference Fourier map. The resulting
[(Cu,(TE-),)*-I
cluster anion in 1.
distances, O-H of I .05 A (with a C-O-H angle of 108.1”) and Se+- H of 2.27 8, are within the range found for solvate molecules linked to metal coordinating thiolates. ‘*,” The O-H . . . S angle of 142.4” is comparable with values found in a neutron diffraction study.20 The structure of 2 consists of copper(I) thiolate chains parallel to the c-axis (see Figs 3 and 4) separated by bulky [(C,H,),P+] cations. The shortest Cu-Cu distance within the chain is 2.736(2) A. Structural units of the stoichiometry Cu,(TE-), o are connected by common sharing of four sulphur atoms, leading to a chain of the overall stoichiometry Cu,(TE-)+ Adjacent units within the chain are generated by a glide-plane operation. This structure type is unique within copper(I) thiolates,
1159
Copper(I) thiolates Table 2. Cu-Cu distances (A) and Cu-S bond lengths (A) in 1 and 2 1
2
2
C4)_-s(l) wlF-w) Cu(I)_S(3) Cu(2)-S(I) cu(2~4) Cu(2WW) cu(3)-8(2) Cu(3)_8(4) ‘X3)-S(6) Cu(4)_S(3) Cu(4)-S(5) Cu(4)_-s(6)
2.253(3) 2.295(3) 2.306(3) 2.292(3) 2.274(2) 2.271(2) 2.283(3) 2.287(2) 2.248(3) 2.257(3) 2.295(3) 2.309(3)
Cu(l)--cu(2) Cu(I>--cu(3) Cu(I)--cu(4) cu(2)--cu(3) Cu(2>--cu(4) Cu(3)-Cu(4)
2.692( 1)
2.748(2) 2.701(2) 2.780(1) 2.712(l) 2.718(2)
Cu(I)_S(3) Cu(I)_-s(4) WI)-S(5) Cu(2)-S(I) cu(2)-8(4) (X2)-S(6) Cu(3)+2) Cu(3)_-s(3) (X3)--s(8) Cu(4KW) Cu(4)-S(3) Cu(4>-S(7) Cu(5)_S(I) cu(5)+2) (%5)-S(5) Cu(6>-S(5) Cu(6W(8) Cu(6>-S(7) cu(7)+2) Cu(7)_-s(6) Cu(7)_-s(7)
and it can obviously only be realized with the ligand molecule ethanethiolate. On the one hand, the terminal C2HS group of this ligand is able to separate and stabilize the well-known [(CU&)~-] cluster found in 1, on the other hand, this ligand seems to have an optimal size and flexibility to favour the building of the chain structure found in 2. Using the smaller CH$- molecule as a ligand, the adam-
2.280(4) 2.219(4) 2.304(4) 2.359(3) 2.236(4) 2.241(4) 2.273(4) 2.263(3) 2.247(4) 2.246(4) 2.267(4) 2.298(4) 2.286(4) 2.310(4) 2.270(4) 2.262(4) 2.228(4) 2.291(4) 2.310(4) 2.206(4) 2.284(4)
Cu(l l-(342) Cu(IVN3) Cu(I)-W4) Cu(I)--cu(5) Cu(IWW6) cu(2)--cu(4) Cu(2)-cu(5) Cu(2)--cu(7) Cu(3WW4) Cu(3PW5) Cu(3)-cu(6) Cu(3)-W7) Cu(4)--cu(5) Cu(4)--cu(6) Cu(4)---W7) Cu(5)--cu(6) Cu(5)--cu(7) Cu(6)-Cu(7)
2.802(2) 4.243(3) 2.758(2) 4.066(3) 3.657(2) 2.761(3) 4.347(3) 3.028(2) 3.266(3) 2.736(2) 2.759(3) 4.032(2) 3.043(2) 3.969(3) 3.529(3) 2.813(2) 2.834(2) 3.129(3)
antane-type [(CU&)~-] is the only structure realized.2’ Syntheses with the more space-filling ligands 2-propanthiolate [(CH,),CH-S-1 or ‘BUS- thiolate with copper(I) under the same reaction conditions always lead to the well-known [Cu,(RS-),I cluster,‘0,22 albeit several enlarged molecular clusters and one-dimensional chain structures are known with ‘BUS- or with even more
Fig. 3. Stereoview of the unit cell of 2.
1160
M. BAUMGARTNER et al.
Fig. 4. Stereoview of the [(Cu,(TE-),)I, chain in 2.
space-filling thiolates in the case of cadmium(II), silver(I) and other metals. ‘Jo The copper(I) thiolate chain in 2 exhibits two different types of thiolates, involving pLz-and p3bridging RS- (see Fig. 5). The latter P~-S(CU)~unit, exhibiting a RS bridging three copper atoms with an approximately tetrahedral C-S(CU)~ arrangement, is only rarely reported in pure copper(I) thiolates.‘3,24 The mean value of all Cu-(p3S)-Cu angles is 99.3”; the mean value of the corresponding angles around the pLz-Satoms is 79.9“. The ~+%-Cu bond distances range from 2.206(4)
to 2.247(4) A, with a mean distance of 2.230 Ai, whereas the ~3-S-Cu bond distances range from 2.246(4) to 2.359(3) A, with a mean distance of 2.287 A (Table 2). Using an alternative description of the structures of 1 and 2, the CuS3 group is regarded as a rigid triangle with the copper atoms located a little above or below the S3 plane. The geometry of these triangles in both structures is determined by a set of three S-Cu-S angles which range from 102.9(l) to 137.3(2)“, with a mean value of 119.9”, and by three Cu-S distances ranging from 2.206(4) to
Fig. 5. Stereoview of a cut out of the [(Cu,(TE-),)JW chain in 2, representing the coordination sphere around the copper atoms in the asymmetric unit.
1161
Copper(I) thiolates Table 3. S-Cu-S 1
coordination angles (“) and deviation (A) of the Cu atoms from the corresponding S3 planes in 1 and 2 Angles Deviation
2
Angles Deviation
S(3>--cu(l)-S(l) s(3)--cu(ltiS(2)
114.4(l) 128.3(l) 117.2(l)
0.045
S(3)-W 1)--s(4) S(3)--cu(l)-S(5) S(4)-Cu( 1)-S(5)
122.8(l) 116.4(1) 120.9(1)
0.031
S(4)--cu(2>--s( 1) S(5)--cu(2)-S(l) S(5)--cu(2)_S(4)
113.6(l) 124.8(1) 121.3(l)
0.067
S(l>--cu(2~(4) S(1-u(2)---S(6) S(4)--cu(2)_-s(6)
120.0(1) 107.8(l) 131.6(2)
0.092
110.5(l) 129.4(l) 119.6(l)
0.085
116.2(l) 118.3(2) 125.4(2)
0.048
127.6(l) 118.7(l) 113.6(l)
0.043
S(lWu(4)---S(3) S(l>-cu(4W(7) S(3Wu(4W%7)
126.2(l) 122.6(l) 108.6(l)
0.213
S(1)--cu(5)--s(2) S(l)--cu(5)_S(5) S(2>-cu(5tiS(5)
111.8(l) 123.0(l) 125.3(l)
0.008
102.9(l) 137.3(2) 119.5(2)
0.046
126.4(1) 105.3(l) 127.8(l)
0.051
w>--cwb--s(l)
2.359(3)A, with a mean value of 2.274A (Tables 2 and 3). Table 3 summarizes the deviation of the copper atoms from the corresponding S3 plane. Using this point of view, the structure of 1 is built
-.
Fig. 6. Schematic stereoview of the [(Cu,(TE-),)I, chain in 2. Each hatched triangle represents a CuS, unit with the sulphur atoms at the corner of the triangle and the copper(I) lying slightly above or below the S, plane. The structural units are senarated bv dotted lines.
up by four CuS3 groups, each triangle being linked by corner-sharing to the three other triangles. All copper atoms in 1 are systematically displaced from the plane through the three sulphur atoms in a direction away from the centroid of the cage. The connection in structure 2 is similar with the restriction that three triangles instead of two only may be linked by comer-sharing (Fig. 6). The Cu& structural entity of 1 can be found in an expanded form as a Cu& substructure in 2. The four-triangle polyhedron of the CL&, core is modified by breaking the linkage of two comer-shared S3 triangles and by insertion of an additional S3 triangle. A similar transformation is observed in the formation of the M& cage (M = Ag’, Cur) from a M& polyhedron by replacing a sulphur vertex by a linear S-Cu-S bridge.23,25 A summary of interatomic bond distances and angles involving the p2- and p3-sulphur atoms in 1 and in 2 is given in Table 4. In both structures, the geometry of the ph,P+] cations as well as of the terminal C2Hs groups of the ligands shows no unusual features. The P-C distances range from 1.779(13) to l-812( 13) A, and the C-P-C angles give no indication for a distinct distortion of the tetrahedral environment about the phosphorus atoms. The C-C bond lengths range
M. BAUMGARTNER
1162
et al.
Table 4. Stereochemistry of the p2- and the pL,-bridging thiolates [Ph,P+]JCu4(TE-),]*0.5CzH602 Ligand
Type
cu-s-cu
(“)
(1) cu-S-C
1
PLz C~(l)-_S(l)--c~(2)
72.6( 1)
2
k
Cw-S(2)--c~(3)
73.q 1)
3
.k
Cu(l)_S(3kw4)
72.6( 1)
4
~2
Cu(2k-S(4)-W3)
75.1(l)
5
~2
W2)_-s(C--W4)
72.9(1)
6
P2
Cu(3)-S(6)--Cu(4)
73.2( 1)
Ligand
Type
1
fi3
2
P3
3
P3
4
I42
5
ps
6
P2
7
ps
8
P2
(“)
112.4(4) 103.4(4) 103.8(3) 110.0(3) 105.7(4) 113.8(4) 104.4(3) 104.8(3) 107.1(3) 101.5(3) 107.0(4) 109.1(5)
S-c
(A)
1.817(10) 1.818(g) 1.901(13) 1.839(9) 1.847(g) 1.826(11)
l?U’+IKu,VE-),I (4 cu-S-03 Cu(2)-_S( l)--c~(4) C~(2)-_S(l>--c~(5) cu(4)--s( 1)-Cu(5) Cu(3)_S(2)--cu(5) Cu(3)_S(2k--W7) Cu(5k-S(2FW7) C~(l)_S(3F-w3) Cu(lk--S(3Fw4) Cu(3)_S(3)--cu(4) Cu( 1)-S(4pCu(2) Cu(ltS(5k--w5) Cu( l)-S(5)-Cu(6) Cu(5)_S(5>-cu(6) Cu(2k-S(6FW7)
cu-s--c
(“) 73.6(l) 138.7(2) 84.4( 1) 73.3(l) 123.3(2) 75.7(l) 138.1(l) 74.7( 1) 92.3( 1) 77.9( 1) 125.4(2) 106.4(2) 76.7( 1) 85.9(l) 119.8(2) 100.8(l) 86.3(2) 76.1(l)
106.6(4) 109.0(4) 113.6(4) 113.3(5) 100.6(5) 118.3(5) 110.2(4) 111.6(4) 107.9(5) 106.4(5) 108.1(5) 118.5(6) 103.9(6) 120.0(6) 109.2(6) 104.0(5) 129.1(5) 105.9(6) 108.2(7) 104.4(6) 106.6(8)
(“)
s-c (A) 1.848(11)
1.817(13)
1.800(12)
1.812(12) 1.804(15)
1.842(16) 1.810(15)
1.760(19)
(TE-),]*0.5C2H602 (1) can be described as a twostep reaction. Within the first step in the range lOO18O”C,the inserted solvate molecule is evolved. The second step, partly overlapping with the first one, involves the decomposition of the solvent free Thermal analytical results species [Ph,P+],[Cu,(TE-),I and leads to the final Thermogravimetric investigations allow a char- product CU,.~$. Because this degradation is not acterization referring to the stoichiometry of the dependent on the Cu’-S score type,g the thermal compounds investigated and to possible decompodecomposition of [Ph,P+][Cu(TE-),I (2) shows a sition mechanisms. For different copper(I) thiolate pattern very similar with the second decomposition clusters, the final product of the degradation is step of [Ph,P+],[Cu,(TE-),I. The thermal stability CU,.~,$, as identified by X-ray powder diffraction. of copper(I) ethanethiolates is much smaller than The patterns were in agreement with those reported those of copper(I) thiophenolates. The final dein ref. 26 for a synthetic form of Chalcocite, Cu 1,96S. composition temperatures of both compounds The thermal decomposition of [Ph,P+],[Cu, investigated are about 270°C compared to 34s
from 1.407( 16) to 1.482( 16) A, the S-C-C are between 108.0(10) and 115.9(14)“.
angles
Copper(I) thiolates
I
I
I
400
300
200
Wavenumberkm-’
Fig. 7. IR spectra of 1 and 2. 390°C for copper(I) thiophenolates under the same reaction conditions. Spectroscopic
decomposed
results
Copper-containing metallothioneins have been found to exhibit significant luminescence which is related to the copper(I) thiolate chromophore.27v28 Excitation of the Neurospora crassa Cu-MT at 305 nm leads to luminescence at 565 nm. * A similar luminescence in the visible region results in a maximum at 609 nm upon excitation of yeast Cu-MT with UV light.7 This luminescence from copper(I)-containing species at room temperature in solution is highly unusual and is a further remainder of the remarkable coordination properties of MT. Luminescence emission is well known for d” systems, with most reports concerning solids. Investigations of the luminescence properties of copper(I) species showed that luminescence in the Table 5. IR spectra (400-180 cm-‘) of 1 and 2 at room temperature Compound 1 2
Wavenumber
(cm- ‘)
395(w), 368(m), 288(s), 240(w), 223(w,sh), 201(m) 383(w,sh), 376(w), 363(m), 326(w), 305(m,sh), 283(s), 244(w), 221(m), 198(m)
1163
range 500-700 nm is related in solution as well as in the solid state, to the triplet-singlet emission observed for isolated Cu+ ions.2’32 The colour and intensity of the emission of the two homoleptic copper(I) complexes, 1 and 2, differ considerably. Excitation at 450 nm of 1 in the solid state at about - 50°C results in a weak emission at 665 nm. Compound 2 exhibits in the solid state an intense luminescence at 591 nm upon excitation at 365 nm. This emission can be seen at room temperature by the naked eye whilst the luminescence appearance of 1 is only weak even at liquid nitrogen temperature. The intensities increase while cooling the samples. The emission spectra of both compounds are broad and structureless. The IR spectra in the range 420-180 cm-’ of 1 and 2 are given in Fig. 7. The bands above 420 cm-’ can be assigned to internal vibrations of the thiolate ligand and of the [Ph,P+] ion. The bands in the range given in Fig. 7 are expected to arise mainly from metal-ligand vibrations, e.g. coppersulphur stretching, v(~~__~). 33 The two spectra differ considerably. The spectrum of 2 (symmetry group of the Cu-S core: C,) reveals at least two bands more than the spectrum of 1 (symmetry group of the Cu-S core: approximately Td) (see Table 5). This difference could be a consequence of the different symmetries as well as of the different bridging types of sulphur atoms within the two structures. Supplementary material including tables of observed and calculated structure factors and of anisotropic thermal parameters may be obtained on request from one of the authors (E.D.). Acknowledgements-We thank Professor H. R. Oswald for supporting this project and Professor H. U. Giidel for helpful discussions concerning the luminescence investigation. Research grants from the Swiss National Science Foundation (No. 2OOc5.422) are gratefully acknowledged. REFERENCES 1. I. G. Dance, Polyhedron 1986, 5, 1037. 2. P. J. Blower and J. R. Dilworth, Coord. Chem. Rev. 1987,76, 121. 3. J. H. R. Kagi and Y. Kojima, 2nd Znt. Meet. Metallothionein, Ziirich, Switzerland (1985) Abstr. Book, p. 25. K. B. Nielson, C. L. Atkin and D. R. Winge, J. Biol. Chem. 1985,260,5342. G. N. George, J. Byrd and D. R. Winge, J. Biol.
Chem. 1988,263,8199. F. J. Hollander
and D. Coucouvanis,
J. Am. Chem.
Sot. 1974, %, 5646. J. Byrd, R. M. Berger, D. R. McMillin, C. F. Wright, D. Hamer and D. R. Winge, J. Biol. Chem. 1988,
263,6688.
1164
M. BAUMGARTNER
8. M. Beltramini and K. Lerch, Environ. Health Perspect. 1986,65,21, and refs therein. 9. M. Baumgartner, W. Bensch, P. Hug and E. Dubler, Znorg. Chim. Acta 1987, 136,139, and refs therein. 10. M. Baumgartner, H. Schmalle and E. Dubler, to be published. 11. G. Henkel, B. Krebs, P. Betz, H. Fietz and K. Saatkamp, Angew. Chem. 1988,100, 1373. 12. Ch. P. Rao, J. R. Dorfman and R. H. Holm, Znorg. Chem. 1986,25,428. 13. R. K. Chadha, R. Kumar and D. G. Tuck, Polyhedron 1988,7, 1121. 14. D. Coucouvanis, D. Swenson, N. C. Baenziger, R. Pedelty, M. L. Caffery and S. Kanodia, Znorg. Chem. 1989,28,2829. 15. G. M. Sheldrick, SHELXS-86. Crystallographic Computing (Edited by G. M. Sheldrick, C. Kruger and R. Goddard), p. 175. Oxford University Press, Oxford, U.K. (1985). 16. W. R. Busing, K. 0. Martin, H. A. Levy, G. M. Brown, C. K. Johnson and W. A. Thiessen, ORFFE3-A Fortran Function and Error Program. Oak Ridge National Laboratory, Tennessee (1971). 17. G. M. Sheldrick, SHELX-76Program for Crystal Structure Determination. University of Cambridge, Cambridge, U.K. (1976). 18. J. K. Money, J. C. Huffman and G. Christou, Znorg. Chem. 1985,24,3297. 19. I. G. Dance, J. Am. Chem. Sot. 1980,102,3445. 20. V. M. Padmanabhan, V. S. Yadava, Q. Q. Navarro,
21. 22. 23. 24.
25. 26. 27.
28. 29.
30.
et al.
A. Garcia, K. Karsono, I-H. Suh and L. S. Chien, Acta Crust. 1971, 27B, 253. I. G. Dance, G. A. Bowmaker, G. R. Clark and J. K. Seadon, Polyhedron 1983,2, 1031. G. A. Bowmaker, G. R. Clark, J. K. Seadon and I. G. Dance, Polyhedron 1984, 3, 535. I. G. Dance, Znorg. Chem. 1981,20, 1487. G. Henkel, P. Betz and B. Krebs, XXIV Znt. Conf. Coord. Chem., Athens, Greece (1986), Abstr. Book, p. 737. I. G. Dance, Aust. J. Chem. 1978,31, 2195. JCPDS, Powder Diffraction File, Card No. 29-578, Swarthmore, Pa, U.S.A. Z. Gasyna, A. Zelazowski, A. R. Green, E. Ough and M. J. Stillman, Znorg. Chim. Actu 1988,153, 115, and refs therein. M. J. Stillman, A. J. Zelazowski, J. Szymanska and Z. Gasyna, Znorg. Chim. Acta 1989,161,275. P. A. Breddels, P. A. M. Berdowski, G. Blasse and D. R. McMillin, J. Chem. Sot., Faraday Trans. II 1982,78, 595. A. Vogler and H. Kunkely, J. Am. Chem. Sot. 1986, 108,721l.
3 1. G. Blasse, P. A: Breddels and D. R. McMillin, Chem. Phys. Lett. 1984, 109, 24. 32. S. A. Payne, L. L. Chase and L. A. Boatner, J. Luminescence 1986,35, 171. 33. A. J. Canty, R. Kishimoto, G. B. Deacon and G. J. Farquharson, Znorg. Chim. Acta 1976,20, 161.
0
0277-5387/90 s3.00+ .m 1990 Pergamon Press plc
SYNTHESIS, CHARACTERIZATION AND CRYSTAL STRUCTURE OF COPPER(I) THIOLATES : I(C,H,),P+I,[C~(C,H,S-),I MARKUS BAUMGARTNER,
l
0=5CJ-b02 AND HELMUT
I~~,~~~~~+lI~~,~~~~,~-~,l
SCHMALLE
and
ERICH DUBLER”
Institute of Inorganic Chemistry, University of Zurich, Winterthurerstrasse CH-8057 Zurich, Switzerland
190,
(Received 20 October 1989 ; accepted 8 December 1989)
Abstract-The reaction of the monodentate ligand thioethane with (&H&,PBr and Cu,O in organic solvents results in the crystallization of two new homoleptic polynuclear copper(I) thiolates : [(C6HJ4P+]2[C~4(C2H5S-)6] * 0.5C2H,02 (1) and [(C6HS)~P+][C~7(C2H5S-)8] (2). Both compounds have been characterized by X-ray crystallography, thermal analysis, luminescence spectroscopy and IR spectroscopy. Compound 1 is triclinic, space group PI with a = 12.066(5), b = 13.824(5), c = 19.112(3) A, c( = 90.82(2), p = 101.85(2), y = 93.53(3)O and Z = 2. Compound 2 is monoclinic, space group P2 ,/c with a = 19.208(3), b = 16.975(4), c = 16.394(6) A, /I = 108.68(2)” and Z = 4. The structure of 1 is built up by [(Cu,(RS),)*-] adamantane-type cluster units, separated by [(&H&P+] cations. Compound 2 consists of copper(I) thiolate chains, also separated by [(&H&P+] cations. In 2, structural units of the stoichiometry Cu,(C ZH$), ,, are connected by common sharing of four sulphur atoms, leading to a chain of the stoichiometry CU~(C~H$-)~. The shortest Cu-Cu distance is 2.692(l) A in 1 and 2.736(2) A in 2. Excitation at 450 nm of 1 in the solid state results in a weak emission at 665 nm, compound 2 exhibits in the solid state an intense luminescence at 591 nm upon excitation at 365 nm.
The coordination chemistry of thiolates, a fundamental ligand type in transition metal chemistry, ‘3’is of much current interest in view of forming appropriate model compounds of active sites in metalloproteins. We are interested in crystallizing metal-rich copper(I) thiolates as model compounds of copper(I) thioneins. Metallothioneins (MT) are believed to play a role in the metabolism and in the detoxification of a number of essential and nonessential trace metals in animals and plants, mainly of the metals zinc, cadmium, mercury and copper.3 They are characterized by an unusually high cysteinate content of the peptide and a metal-tocysteinate ratio of 1: 3 for Zn- and Cd-MT. In copper(I) thioneins, the metal content found is even higher. In the case of only copper(I)-containing MTs, cluster core types of the stoichiometries CUSS9 and CusSi are often suggested.4*5 A copper-to-sulphur ratio of 2: 3 seems to be * Author to whom correspondence should he addressed.
a characteristic feature of Cu’-MTs as well as of synthetic polynuclear copper(I) complexes with mono- or bidentate thiolates.6.7 The MT with the highest metal content is a fungal MT found in Neurospora crassa with a copper(I)-to-cysteinate ratio of 6 : 7.* Syntheses of copper(I) thiolates with monodentate ligands RS revealed species that contain core units of the stoichiometries cu4s6 (R = C6H5, CH3), Cu& (R = (CH,),C) and Cu& (R = C,H,).’ The most favoured Cu4S6 “adamantane” type can also be obtained with bidentate ligands ((SRS) like 1,2-dithioethane, 1,3-dithiopropane or o-xylene+a’-dithiol. ‘O*’’ In addition, the formation Of core Units Of the type cu3&, Cu$ , z and Cu, $, 6 has been observed with bidentate dithiol ligands. ’ *-’ 4 Our syntheses using the monodentate ligand thioethane (TE) revealed two new homoleptic polynuclear copper(I) thiolates : One with the well-known adamantane-type cu4!& cluster, the other with a non-molecular one-dimensional Cu7Ss chain structure. In both structures, all the copper atoms are trigonally coordinated by
1155
1156
M. BAUMGARTNER
bridging thiolates. We report here on synthesis, structure, spectroscopical and thermoanalytical data of these new copper(I) thiolates.
EXPERIMENTAL
Syntheses and thermal analysis Thioethane (TE), (Ph),PBr and Cu20 were purchased from Fluka AG, Buchs/Switzerland and used without further purification. The 1 M solution of NaOMe was obtained by adding 23.0 g (1 mol) of sodium to 1000 cm3 of methanol, stirred on an ice bath. The syntheses were performed in a Schlenk-type apparatus in a nitrogen atmosphere. Thermogravimetric (TG) data in the temperature range 30-700°C were recorded in a flowing N2atmosphere, using heating rates of 10°C min- ’ and sample weights of 4-l 5 mg on a Perkin-Elmer TGS-2 thermobalance. X-ray powder diffraction diagrams of the final products were produced by a Guinier-type camera with a Johansson monochromator (Cu-K,, radiation).
To a solution of 3.34 g (7.8 mmol) of (Ph),PBr in ethylene glycol (20 cm3), MeOH (33 cm’) and 1 M NaOMe/MeOH (7 cm3), 1.05 g (16.9 mmol) of TE was added. After warming up to a reaction temperature of 55°C and addition of 400 mg (2.8 mmol) of CuZO, a clear yellow solution was obtained. Slow evaporation at room temperature first yielded dark red bulky crystals of 1. Later on, yellow crystals of compound 2 could also be isolated from the same solution. The red crystals of 1 were separated manually. Found: C, 54.2; H, 5.6; Cu, 20.1 (TG analysis) ; S, 15.1. Calc. for C61H73C~4 0P2S6 (1330.8): C, 55.1; H, 5.5; Cu, 19.1; S, 14.5%.
[(C,H,),P+I[Cu,(TE-),I (2) To a solution of 2.5 g (6.0 mmol) of (Ph),PBr in ethylene glycol(20 cm3), MeOH (33 cm’) and 1 M NaOMe/MeOH (8 cm3), 1.11 g (17.9 mmol) of TE was added. After addition of 400 mg (2.8 mmol) of CuZO, the solution was kept at 60°C for 30 min until it became clear yellow. Slow evaporation at room temperature yielded yellow crystals of 2. Found : C, 37.7 ; H, 4.9 ; Cu, 34.6 (TG analysis). Calc. for C40HSOC~,PSB(1273.8) : C, 37.7 ; H, 4.7 ; cu, 34.9%.
et al.
X-ray crystallography Symmetry, preliminary cell parameters and space groups of the complexes investigated were established by precession and Weissenberg photography. Final lattice parameters and crystal orientations were obtained from least-squares refinement of the 8 values of 25 reflections on an Enraf-Nonius CAD4 diffractometer. Intensity data were collected by using graphitemonochromated MO-K, radiation. Four standard reflections lying in different regions of the reciprocal space were monitored periodically. A total loss in intensity of -2.3% (1) and - 1.3% (2) was observed and corrected for in data reduction. The intensities were reduced to F, by applying corrections for Lorentz and polarization effects. A numerical absorption correction based on carefully indexed crystal faces was carried out for both compounds. The structure of 1 was solved by using the Patterson interpretation routine in SHELXS-86” and by conventional Fourier techniques, and refined with full-matrix least-squares methods including anisotropic temperature factors for copper, sulphur, phosphorus and the carbon atoms of the ligands. The phenyl rings were refined as rigid groups with free varying isotropic temperature factors. The atoms of the inserted solvent molecule were also treated with isotropic temperature factors. Due to a disordered arrangement of the terminal carbon atom C(22), the C(21)---C(22) distance was treated with a constrained length in the refinement. The positions of the hydrogen atoms of the phenyl rings and of the ligand molecules were calculated, and the hydrogen atoms were included as fixed contributions in the refinement. The structure of 2 could be solved with direct methods using 937 negative quartets in SHELXS86. For the structure refinement of 2 (full-matrix least-squares methods including anisotropic temperature factors for copper, sulphur, phosphorus and the carbon atoms of the ligands) it was not necessary to fix the phenyl ring atoms. These carbon atoms were used with free varying isotropic temperature factors. Due to a disordered arrangement, some of the terminal carbon atoms [C(52), C(62), C(72), C(82)] of the thiolate ligands were treated with a constrained bond length to the adjacent carbon atom in the refinement. The position of all the hydrogen atoms was calculated and the hydrogen atoms included as fixed contributions in the refinement. The structure of 1 was finally refined with unit weights. The weighting scheme for 2 was w = 1.0/a2(F). Interatomic distances and angles have
1157
Copper(I) thiolates been calculated with the 0RFFE3 program. I6 The calculations were performed with the programs SHELXS-86 and SHELX-76” on an IBM 3033 and a NAS AS/XL V60 computer at the University of Zurich. Crystal parameters, data collection details, and results of the refinements are summarized in Table 1. Atomic coordinates and thermal parameters for the two structures have been deposited with the Editor as supplementary material, from whom copies are available on request.
Luminescence spectroscopy Emission spectra were recorded on a PerkinElmer Model 204 fluorescence spectrophotometer using a Xenon lamp as exciting source. Powder samples were hxed on a quartz plate with a nonfluorescing glue.
IR spectroscopy Solid-state IR spectra in the range 40&l 80 cm- ’ were obtained on a Perkin-Elmer spectrophotometer type 983. Spectra were run on Nujol mulls between CsI or polyethylene plates. RESULTS AND DISCUSSION i%Z
SttY4CtWeS
oe5c2H602
Of and
[(C6H5)4P+]*[CU4(C~H5S-)6]. [(C~H~)~P+I[CU~(C~HSS-)BI
(2)
The structure of 1 is built up by [(Cu&)‘-] adamantane-type cluster units, separated by bulky [(C,H,),P+] cations, as shown in Fig. 1. The structure of the cluster anion can be considered as a tetrahedron of copper atoms inscribed in a distorted octahedron formed by six p,-sulphur atoms (Fig. 2). This cluster type is very common for copper(I) thiolates. ‘,*,’ The Cu-Cu distances range from 2.692(l) to 2.780(l) A, with a mean distance of
Table 1. Crystal data and structure determination 1
Formula Mol. wt Data crystal (nun) Colour a (A) b (A) c (A) x (“) B (“) Y(“) v (A’) Crystal system Z &, (8 em- 3, Space group Scan method 219range (“) hkl range Max time/rlln (s) p(Mo-K,) (cm- ‘) Transmission factors (max/min) Data measured (incl. stds.) R,,/ No. of refln av. Unique data Observed data [I 2 3a(Z)] Number of variables MaxImin Ap (e’/A’) R RW Weight
(1)
parameters for 1 and 2 2
G,H,~CU~~P&
GJ-L&u,PS~
1330.8 0.52 x 0.50 x 0.65 Orange-red 12.066(5) 13.824(5) 19.112(3) 90.82(2) 101.85(2) 93.53(3) 3112.9 Triclinic 2 1.42 PT *2e 2.Cb52.0 +14, f17, +23 30 15.66 0.514/0.363 11,934 0.0271614 11,499 6976 321 l.Ol/-0.71 0.065 0.068 w = 1 (unit weight)
1273.8 0.18 x 0.22 x 0.55 Yellow, transparent 19.208(3) 16.975(4) 16.394(6) 90.0 108.68(2) 90.0 5063.8 Monoclinic 4 1.68 P2,lc (u-2e 2.c50.0 +22, +20, +19 30 31.62 0.621/0.492 9645 0.02411274 8884 3538 385 0.71/-0.53 0.054 0.049 w = l/a2(Fo)
1158
M. BAUMGARTNER et al.
Fig. 1. Stereoview of the unit cell of 1.
Fig. 2. Stereoview of the adamantane-type
2.725 A. The 12 crystallographically-independent Cu-S distances range from 2.248(3) to 2.309(3) A, with a mean distance of 2.281 A (Table 2). Five of the six Cu-S-Cu angles range from 72.6(l) to 73.8(l)“, whereas an increased angle of 75.1(l)’ is observed at the sixth sulphur atom as a consequence of a hydrogen bond linking this sulphur atom to the solvate molecule. The two [(Cu,SJ2-] clusters within the unit cell are linked by two hydrogen bonds of the type S. . . H-O to the ethylene glycol solvate molecule at the inversion centre in the middle of the cell. The corresponding S(4) * . . 0 acceptor-donor distance is 3.170(7) A. The hydrogen atom of the hydroxy group of the inserted solvate molecule could be located in a difference Fourier map. The resulting
[(Cu,(TE-),)*-I
cluster anion in 1.
distances, O-H of I .05 A (with a C-O-H angle of 108.1”) and Se+- H of 2.27 8, are within the range found for solvate molecules linked to metal coordinating thiolates. ‘*,” The O-H . . . S angle of 142.4” is comparable with values found in a neutron diffraction study.20 The structure of 2 consists of copper(I) thiolate chains parallel to the c-axis (see Figs 3 and 4) separated by bulky [(C,H,),P+] cations. The shortest Cu-Cu distance within the chain is 2.736(2) A. Structural units of the stoichiometry Cu,(TE-), o are connected by common sharing of four sulphur atoms, leading to a chain of the overall stoichiometry Cu,(TE-)+ Adjacent units within the chain are generated by a glide-plane operation. This structure type is unique within copper(I) thiolates,
1159
Copper(I) thiolates Table 2. Cu-Cu distances (A) and Cu-S bond lengths (A) in 1 and 2 1
2
2
C4)_-s(l) wlF-w) Cu(I)_S(3) Cu(2)-S(I) cu(2~4) Cu(2WW) cu(3)-8(2) Cu(3)_8(4) ‘X3)-S(6) Cu(4)_S(3) Cu(4)-S(5) Cu(4)_-s(6)
2.253(3) 2.295(3) 2.306(3) 2.292(3) 2.274(2) 2.271(2) 2.283(3) 2.287(2) 2.248(3) 2.257(3) 2.295(3) 2.309(3)
Cu(l)--cu(2) Cu(I>--cu(3) Cu(I)--cu(4) cu(2)--cu(3) Cu(2>--cu(4) Cu(3)-Cu(4)
2.692( 1)
2.748(2) 2.701(2) 2.780(1) 2.712(l) 2.718(2)
Cu(I)_S(3) Cu(I)_-s(4) WI)-S(5) Cu(2)-S(I) cu(2)-8(4) (X2)-S(6) Cu(3)+2) Cu(3)_-s(3) (X3)--s(8) Cu(4KW) Cu(4)-S(3) Cu(4>-S(7) Cu(5)_S(I) cu(5)+2) (%5)-S(5) Cu(6>-S(5) Cu(6W(8) Cu(6>-S(7) cu(7)+2) Cu(7)_-s(6) Cu(7)_-s(7)
and it can obviously only be realized with the ligand molecule ethanethiolate. On the one hand, the terminal C2HS group of this ligand is able to separate and stabilize the well-known [(CU&)~-] cluster found in 1, on the other hand, this ligand seems to have an optimal size and flexibility to favour the building of the chain structure found in 2. Using the smaller CH$- molecule as a ligand, the adam-
2.280(4) 2.219(4) 2.304(4) 2.359(3) 2.236(4) 2.241(4) 2.273(4) 2.263(3) 2.247(4) 2.246(4) 2.267(4) 2.298(4) 2.286(4) 2.310(4) 2.270(4) 2.262(4) 2.228(4) 2.291(4) 2.310(4) 2.206(4) 2.284(4)
Cu(l l-(342) Cu(IVN3) Cu(I)-W4) Cu(I)--cu(5) Cu(IWW6) cu(2)--cu(4) Cu(2)-cu(5) Cu(2)--cu(7) Cu(3WW4) Cu(3PW5) Cu(3)-cu(6) Cu(3)-W7) Cu(4)--cu(5) Cu(4)--cu(6) Cu(4)---W7) Cu(5)--cu(6) Cu(5)--cu(7) Cu(6)-Cu(7)
2.802(2) 4.243(3) 2.758(2) 4.066(3) 3.657(2) 2.761(3) 4.347(3) 3.028(2) 3.266(3) 2.736(2) 2.759(3) 4.032(2) 3.043(2) 3.969(3) 3.529(3) 2.813(2) 2.834(2) 3.129(3)
antane-type [(CU&)~-] is the only structure realized.2’ Syntheses with the more space-filling ligands 2-propanthiolate [(CH,),CH-S-1 or ‘BUS- thiolate with copper(I) under the same reaction conditions always lead to the well-known [Cu,(RS-),I cluster,‘0,22 albeit several enlarged molecular clusters and one-dimensional chain structures are known with ‘BUS- or with even more
Fig. 3. Stereoview of the unit cell of 2.
1160
M. BAUMGARTNER et al.
Fig. 4. Stereoview of the [(Cu,(TE-),)I, chain in 2.
space-filling thiolates in the case of cadmium(II), silver(I) and other metals. ‘Jo The copper(I) thiolate chain in 2 exhibits two different types of thiolates, involving pLz-and p3bridging RS- (see Fig. 5). The latter P~-S(CU)~unit, exhibiting a RS bridging three copper atoms with an approximately tetrahedral C-S(CU)~ arrangement, is only rarely reported in pure copper(I) thiolates.‘3,24 The mean value of all Cu-(p3S)-Cu angles is 99.3”; the mean value of the corresponding angles around the pLz-Satoms is 79.9“. The ~+%-Cu bond distances range from 2.206(4)
to 2.247(4) A, with a mean distance of 2.230 Ai, whereas the ~3-S-Cu bond distances range from 2.246(4) to 2.359(3) A, with a mean distance of 2.287 A (Table 2). Using an alternative description of the structures of 1 and 2, the CuS3 group is regarded as a rigid triangle with the copper atoms located a little above or below the S3 plane. The geometry of these triangles in both structures is determined by a set of three S-Cu-S angles which range from 102.9(l) to 137.3(2)“, with a mean value of 119.9”, and by three Cu-S distances ranging from 2.206(4) to
Fig. 5. Stereoview of a cut out of the [(Cu,(TE-),)JW chain in 2, representing the coordination sphere around the copper atoms in the asymmetric unit.
1161
Copper(I) thiolates Table 3. S-Cu-S 1
coordination angles (“) and deviation (A) of the Cu atoms from the corresponding S3 planes in 1 and 2 Angles Deviation
2
Angles Deviation
S(3>--cu(l)-S(l) s(3)--cu(ltiS(2)
114.4(l) 128.3(l) 117.2(l)
0.045
S(3)-W 1)--s(4) S(3)--cu(l)-S(5) S(4)-Cu( 1)-S(5)
122.8(l) 116.4(1) 120.9(1)
0.031
S(4)--cu(2>--s( 1) S(5)--cu(2)-S(l) S(5)--cu(2)_S(4)
113.6(l) 124.8(1) 121.3(l)
0.067
S(l>--cu(2~(4) S(1-u(2)---S(6) S(4)--cu(2)_-s(6)
120.0(1) 107.8(l) 131.6(2)
0.092
110.5(l) 129.4(l) 119.6(l)
0.085
116.2(l) 118.3(2) 125.4(2)
0.048
127.6(l) 118.7(l) 113.6(l)
0.043
S(lWu(4)---S(3) S(l>-cu(4W(7) S(3Wu(4W%7)
126.2(l) 122.6(l) 108.6(l)
0.213
S(1)--cu(5)--s(2) S(l)--cu(5)_S(5) S(2>-cu(5tiS(5)
111.8(l) 123.0(l) 125.3(l)
0.008
102.9(l) 137.3(2) 119.5(2)
0.046
126.4(1) 105.3(l) 127.8(l)
0.051
w>--cwb--s(l)
2.359(3)A, with a mean value of 2.274A (Tables 2 and 3). Table 3 summarizes the deviation of the copper atoms from the corresponding S3 plane. Using this point of view, the structure of 1 is built
-.
Fig. 6. Schematic stereoview of the [(Cu,(TE-),)I, chain in 2. Each hatched triangle represents a CuS, unit with the sulphur atoms at the corner of the triangle and the copper(I) lying slightly above or below the S, plane. The structural units are senarated bv dotted lines.
up by four CuS3 groups, each triangle being linked by corner-sharing to the three other triangles. All copper atoms in 1 are systematically displaced from the plane through the three sulphur atoms in a direction away from the centroid of the cage. The connection in structure 2 is similar with the restriction that three triangles instead of two only may be linked by comer-sharing (Fig. 6). The Cu& structural entity of 1 can be found in an expanded form as a Cu& substructure in 2. The four-triangle polyhedron of the CL&, core is modified by breaking the linkage of two comer-shared S3 triangles and by insertion of an additional S3 triangle. A similar transformation is observed in the formation of the M& cage (M = Ag’, Cur) from a M& polyhedron by replacing a sulphur vertex by a linear S-Cu-S bridge.23,25 A summary of interatomic bond distances and angles involving the p2- and p3-sulphur atoms in 1 and in 2 is given in Table 4. In both structures, the geometry of the ph,P+] cations as well as of the terminal C2Hs groups of the ligands shows no unusual features. The P-C distances range from 1.779(13) to l-812( 13) A, and the C-P-C angles give no indication for a distinct distortion of the tetrahedral environment about the phosphorus atoms. The C-C bond lengths range
M. BAUMGARTNER
1162
et al.
Table 4. Stereochemistry of the p2- and the pL,-bridging thiolates [Ph,P+]JCu4(TE-),]*0.5CzH602 Ligand
Type
cu-s-cu
(“)
(1) cu-S-C
1
PLz C~(l)-_S(l)--c~(2)
72.6( 1)
2
k
Cw-S(2)--c~(3)
73.q 1)
3
.k
Cu(l)_S(3kw4)
72.6( 1)
4
~2
Cu(2k-S(4)-W3)
75.1(l)
5
~2
W2)_-s(C--W4)
72.9(1)
6
P2
Cu(3)-S(6)--Cu(4)
73.2( 1)
Ligand
Type
1
fi3
2
P3
3
P3
4
I42
5
ps
6
P2
7
ps
8
P2
(“)
112.4(4) 103.4(4) 103.8(3) 110.0(3) 105.7(4) 113.8(4) 104.4(3) 104.8(3) 107.1(3) 101.5(3) 107.0(4) 109.1(5)
S-c
(A)
1.817(10) 1.818(g) 1.901(13) 1.839(9) 1.847(g) 1.826(11)
l?U’+IKu,VE-),I (4 cu-S-03 Cu(2)-_S( l)--c~(4) C~(2)-_S(l>--c~(5) cu(4)--s( 1)-Cu(5) Cu(3)_S(2)--cu(5) Cu(3)_S(2k--W7) Cu(5k-S(2FW7) C~(l)_S(3F-w3) Cu(lk--S(3Fw4) Cu(3)_S(3)--cu(4) Cu( 1)-S(4pCu(2) Cu(ltS(5k--w5) Cu( l)-S(5)-Cu(6) Cu(5)_S(5>-cu(6) Cu(2k-S(6FW7)
cu-s--c
(“) 73.6(l) 138.7(2) 84.4( 1) 73.3(l) 123.3(2) 75.7(l) 138.1(l) 74.7( 1) 92.3( 1) 77.9( 1) 125.4(2) 106.4(2) 76.7( 1) 85.9(l) 119.8(2) 100.8(l) 86.3(2) 76.1(l)
106.6(4) 109.0(4) 113.6(4) 113.3(5) 100.6(5) 118.3(5) 110.2(4) 111.6(4) 107.9(5) 106.4(5) 108.1(5) 118.5(6) 103.9(6) 120.0(6) 109.2(6) 104.0(5) 129.1(5) 105.9(6) 108.2(7) 104.4(6) 106.6(8)
(“)
s-c (A) 1.848(11)
1.817(13)
1.800(12)
1.812(12) 1.804(15)
1.842(16) 1.810(15)
1.760(19)
(TE-),]*0.5C2H602 (1) can be described as a twostep reaction. Within the first step in the range lOO18O”C,the inserted solvate molecule is evolved. The second step, partly overlapping with the first one, involves the decomposition of the solvent free Thermal analytical results species [Ph,P+],[Cu,(TE-),I and leads to the final Thermogravimetric investigations allow a char- product CU,.~$. Because this degradation is not acterization referring to the stoichiometry of the dependent on the Cu’-S score type,g the thermal compounds investigated and to possible decompodecomposition of [Ph,P+][Cu(TE-),I (2) shows a sition mechanisms. For different copper(I) thiolate pattern very similar with the second decomposition clusters, the final product of the degradation is step of [Ph,P+],[Cu,(TE-),I. The thermal stability CU,.~,$, as identified by X-ray powder diffraction. of copper(I) ethanethiolates is much smaller than The patterns were in agreement with those reported those of copper(I) thiophenolates. The final dein ref. 26 for a synthetic form of Chalcocite, Cu 1,96S. composition temperatures of both compounds The thermal decomposition of [Ph,P+],[Cu, investigated are about 270°C compared to 34s
from 1.407( 16) to 1.482( 16) A, the S-C-C are between 108.0(10) and 115.9(14)“.
angles
Copper(I) thiolates
I
I
I
400
300
200
Wavenumberkm-’
Fig. 7. IR spectra of 1 and 2. 390°C for copper(I) thiophenolates under the same reaction conditions. Spectroscopic
decomposed
results
Copper-containing metallothioneins have been found to exhibit significant luminescence which is related to the copper(I) thiolate chromophore.27v28 Excitation of the Neurospora crassa Cu-MT at 305 nm leads to luminescence at 565 nm. * A similar luminescence in the visible region results in a maximum at 609 nm upon excitation of yeast Cu-MT with UV light.7 This luminescence from copper(I)-containing species at room temperature in solution is highly unusual and is a further remainder of the remarkable coordination properties of MT. Luminescence emission is well known for d” systems, with most reports concerning solids. Investigations of the luminescence properties of copper(I) species showed that luminescence in the Table 5. IR spectra (400-180 cm-‘) of 1 and 2 at room temperature Compound 1 2
Wavenumber
(cm- ‘)
395(w), 368(m), 288(s), 240(w), 223(w,sh), 201(m) 383(w,sh), 376(w), 363(m), 326(w), 305(m,sh), 283(s), 244(w), 221(m), 198(m)
1163
range 500-700 nm is related in solution as well as in the solid state, to the triplet-singlet emission observed for isolated Cu+ ions.2’32 The colour and intensity of the emission of the two homoleptic copper(I) complexes, 1 and 2, differ considerably. Excitation at 450 nm of 1 in the solid state at about - 50°C results in a weak emission at 665 nm. Compound 2 exhibits in the solid state an intense luminescence at 591 nm upon excitation at 365 nm. This emission can be seen at room temperature by the naked eye whilst the luminescence appearance of 1 is only weak even at liquid nitrogen temperature. The intensities increase while cooling the samples. The emission spectra of both compounds are broad and structureless. The IR spectra in the range 420-180 cm-’ of 1 and 2 are given in Fig. 7. The bands above 420 cm-’ can be assigned to internal vibrations of the thiolate ligand and of the [Ph,P+] ion. The bands in the range given in Fig. 7 are expected to arise mainly from metal-ligand vibrations, e.g. coppersulphur stretching, v(~~__~). 33 The two spectra differ considerably. The spectrum of 2 (symmetry group of the Cu-S core: C,) reveals at least two bands more than the spectrum of 1 (symmetry group of the Cu-S core: approximately Td) (see Table 5). This difference could be a consequence of the different symmetries as well as of the different bridging types of sulphur atoms within the two structures. Supplementary material including tables of observed and calculated structure factors and of anisotropic thermal parameters may be obtained on request from one of the authors (E.D.). Acknowledgements-We thank Professor H. R. Oswald for supporting this project and Professor H. U. Giidel for helpful discussions concerning the luminescence investigation. Research grants from the Swiss National Science Foundation (No. 2OOc5.422) are gratefully acknowledged. REFERENCES 1. I. G. Dance, Polyhedron 1986, 5, 1037. 2. P. J. Blower and J. R. Dilworth, Coord. Chem. Rev. 1987,76, 121. 3. J. H. R. Kagi and Y. Kojima, 2nd Znt. Meet. Metallothionein, Ziirich, Switzerland (1985) Abstr. Book, p. 25. K. B. Nielson, C. L. Atkin and D. R. Winge, J. Biol. Chem. 1985,260,5342. G. N. George, J. Byrd and D. R. Winge, J. Biol.
Chem. 1988,263,8199. F. J. Hollander
and D. Coucouvanis,
J. Am. Chem.
Sot. 1974, %, 5646. J. Byrd, R. M. Berger, D. R. McMillin, C. F. Wright, D. Hamer and D. R. Winge, J. Biol. Chem. 1988,
263,6688.
1164
M. BAUMGARTNER
8. M. Beltramini and K. Lerch, Environ. Health Perspect. 1986,65,21, and refs therein. 9. M. Baumgartner, W. Bensch, P. Hug and E. Dubler, Znorg. Chim. Acta 1987, 136,139, and refs therein. 10. M. Baumgartner, H. Schmalle and E. Dubler, to be published. 11. G. Henkel, B. Krebs, P. Betz, H. Fietz and K. Saatkamp, Angew. Chem. 1988,100, 1373. 12. Ch. P. Rao, J. R. Dorfman and R. H. Holm, Znorg. Chem. 1986,25,428. 13. R. K. Chadha, R. Kumar and D. G. Tuck, Polyhedron 1988,7, 1121. 14. D. Coucouvanis, D. Swenson, N. C. Baenziger, R. Pedelty, M. L. Caffery and S. Kanodia, Znorg. Chem. 1989,28,2829. 15. G. M. Sheldrick, SHELXS-86. Crystallographic Computing (Edited by G. M. Sheldrick, C. Kruger and R. Goddard), p. 175. Oxford University Press, Oxford, U.K. (1985). 16. W. R. Busing, K. 0. Martin, H. A. Levy, G. M. Brown, C. K. Johnson and W. A. Thiessen, ORFFE3-A Fortran Function and Error Program. Oak Ridge National Laboratory, Tennessee (1971). 17. G. M. Sheldrick, SHELX-76Program for Crystal Structure Determination. University of Cambridge, Cambridge, U.K. (1976). 18. J. K. Money, J. C. Huffman and G. Christou, Znorg. Chem. 1985,24,3297. 19. I. G. Dance, J. Am. Chem. Sot. 1980,102,3445. 20. V. M. Padmanabhan, V. S. Yadava, Q. Q. Navarro,
21. 22. 23. 24.
25. 26. 27.
28. 29.
30.
et al.
A. Garcia, K. Karsono, I-H. Suh and L. S. Chien, Acta Crust. 1971, 27B, 253. I. G. Dance, G. A. Bowmaker, G. R. Clark and J. K. Seadon, Polyhedron 1983,2, 1031. G. A. Bowmaker, G. R. Clark, J. K. Seadon and I. G. Dance, Polyhedron 1984, 3, 535. I. G. Dance, Znorg. Chem. 1981,20, 1487. G. Henkel, P. Betz and B. Krebs, XXIV Znt. Conf. Coord. Chem., Athens, Greece (1986), Abstr. Book, p. 737. I. G. Dance, Aust. J. Chem. 1978,31, 2195. JCPDS, Powder Diffraction File, Card No. 29-578, Swarthmore, Pa, U.S.A. Z. Gasyna, A. Zelazowski, A. R. Green, E. Ough and M. J. Stillman, Znorg. Chim. Actu 1988,153, 115, and refs therein. M. J. Stillman, A. J. Zelazowski, J. Szymanska and Z. Gasyna, Znorg. Chim. Acta 1989,161,275. P. A. Breddels, P. A. M. Berdowski, G. Blasse and D. R. McMillin, J. Chem. Sot., Faraday Trans. II 1982,78, 595. A. Vogler and H. Kunkely, J. Am. Chem. Sot. 1986, 108,721l.
3 1. G. Blasse, P. A: Breddels and D. R. McMillin, Chem. Phys. Lett. 1984, 109, 24. 32. S. A. Payne, L. L. Chase and L. A. Boatner, J. Luminescence 1986,35, 171. 33. A. J. Canty, R. Kishimoto, G. B. Deacon and G. J. Farquharson, Znorg. Chim. Acta 1976,20, 161.