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Synthesis, structural characterization and growth features of some (Ph)Se–Cd cluster compounds (Ph = phenyl)
Polyhedron 29 (2010) 1760–1763
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Synthesis, structural characterization and growth features of some (Ph)Se–Cd cluster compounds (Ph = phenyl) Ernesto Schulz Lang *, Rafael Stieler, Gelson Manzoni de Oliveira * LMI – Laboratório de Materiais Inorgânicos, Departamento de Química, Universidade Federal de Santa Maria (UFSM), 97105-900 Santa Maria, RS, Brazil
a r t i c l e
i n f o
Article history: Received 1 October 2009 Accepted 15 February 2010 Available online 18 February 2010 Keywords: Cd(II)-clusters Cd(II)-selenolate clusters Clusters growth
a b s t r a c t Cd(SePh)2, CdBr24H2O/CdI2 and PCh3 (Ph = phenyl; PCh3 = tricyclohexylphosphine) react to give [(SePh)2Cd2Br2(PCh3)2] (1), [(SePh)2Cd2I2(PCh3)2] (2) and [(SePh)7Cd4Br(PCh3)]n (3). The new compounds are examples of Cd(II) clusters obtained starting from the cluster-forming reagents Cd(SePh)2 and CdX2 (X = Br, I) in the presence of variable amounts of PCh3. While 1 and 2 are single, tetranuclear clusters, compound 3 attains polymeric adamantanoid cages linked through selenium bridges. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Clusters of the IIbVI groups have become progressively important due to their semiconductor potentialities, among other materials and biological applications [1–4]. Since the chemistry of adamantane-like mercury/cadmium–chalcogen cages has been also extensively studied [5–11], in recent reports we have discussed the use of mercury bis-phenylselenolate/tellurolate, Hg(EPh)2 (E = Se, Te), as efficient start for the synthesis of ternary clusters and polymers [12–16]. It is well known that metal chalcogenide clusters and derivatives can show variable sizes and shapes, whether concerning to single clusters like [(PhTe)16Ag4Hg6Py4] (Ph = phenyl; Py = pyridine) [17] or regarding to bulkier, polymeric clusters like [Hg5Cl3(SePh)7]n and [Hg7Br3(SePh)11]n [18]. In the study of the architecture of nanocrystals building blocks, Cheon et al. [19] elected ‘‘time”, ‘‘temperature” ‘‘capping molecules” and ‘‘kinetic energy barrier, (DG#), as the parameters whose interaction should influence the growth pattern of nanocrystals. Although nanocrystals and nanoclusters are different species, and this report does not address nanoclusters, we have observed that some parameters discussed by Cheon et al. [19] for nanocrystals seem to be also valid in the managing of the growth of (l-Se)Cd(II) clusters. We report now the use of cadmium bis-phenylselenolate, Cd(SePh)2, plus CdX2 (X = Br, I), in the synthesis of the new tetranuclear and adamantanoid shaped clusters [Cd2(SePh)2Br2(PCh3)2] (1),
* Corresponding authors. Tel.: +55 3220 8980; fax: +55 3220 8031 (G.M. de Oliveria). E-mail addresses: [email protected] (E.S. Lang), [email protected] (G.M. de Oliveira). 0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2010.02.023
[Cd2(SePh)2I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3) (PCh3 = tricyclohexylphosphine). The structural characterization of the new compounds will be also presented, together with a brief comparative discussion on their formation and growth. 2. Experimental 2.1. General All reactions were carried out under dry Ar. Solvents were purified and dried by standard procedures and freshly distilled before use. Cadmium bromide tetrahydrate, cadmium iodide and tricyclohexylphosphine were purchased from Sigma AldrichÒ. Cd(SePh)2 [20] was prepared according to literature procedures [21]. Elemental analyses were made using a FlashEA 1112 device. The synthetic procedures can be summarized in the form of the chemical Eqs. (a) and (b) below, CdðSePhÞ2 þ CdX2 þ 2PCy3 ! ½Cd2 ðSePhÞ2 X2 ðPCy3 Þ2 ðX ¼ Brð1Þ; Ið2Þ 4CdðSePhÞ2 þ CdBr2 þ PCy3 ! ½Cd4 ðSePhÞ7 BrðPCy3 Þn ð3Þ þ ðCdSePhBrÞn
ðaÞ ðbÞ
In the case of 3, the equation does not correspond to the actually used stoichiometry (2:1:2), since the excess of Cd(SePh)2 leads to the polymerization of the main product in the solvothermal reaction. 2.2. Preparation of [Cd2(SePh)2Br2(PCh3)2] (1) A mixture of CdBr24H2O (0.034 g, 0.1 mmol), Cd(SePh)2 (0.042 g, 0.1 mmol), PCh3 (0.056 g, 0.2 mmol) in 8 mL of methanol was heated at 130 °C for 1 h in a 12 mL stainless steel sealed reactor. Thereafter the reactor was cooled down slowly to room
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E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763 Table 1 Crystal data and structure refinement for 1, 2 and 3.
Empirical formula Formula weight T (K) Radiation, k (Å) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z DCalc (g cm1) Absorption coefficient (mm1) F (0 0 0) Crystal size (mm) h (°) Index range Reflections collected Reflections unique (Rint) Completeness to theta maximum (%) Absorption correction Maximum and minimum transmission Refinement method Data/restraints/parameters Goodness-of-fit (GOF) on F2 Final R indices [I > 2r (I)] R indices (all data) Largest diff. peak and hole (e Å3)
1
2
3
C48H76Br2Cd2P2Se2 1257.57 293(2) Mo Ka, 0.71073 triclinic P1
C48H76Cd2I2P2Se2 1351.55 296(2) Mo Ka, 0.71073 triclinic P1
C60H68BrCd4PSe7 1902.34 293(2) Mo Ka, 0.71073 monoclinic P21/n
10.2012(4) 10.8207(4) 12.2261(5) 72.776(2) 88.663(2) 83.995(3) 1281.93(9) 1 1.629 3.900 628 0.355 0.265 0.08 2.22–27.22 10 6 h 6 13, 13 6 k 6 13, 15 6 l 6 15 14 708 5685 (0.0403) 99.3 gaussian 0.7455 and 0.5566
10.3511(10) 10.7551(12) 12.1186(13) 101.577(8) 87.752(6) 84.188(6) 1280.2(2) 1 1.753 3.551 664 0.11 0.1 0.09 1.99–27.56 13 6 h 6 13, 13 6 k 6 13, 15 6 l 6 15 23 064 5846 (0.0687) 98.7 multi-scan 0.7456 and 0.6557
20.8440(3) 14.1347(2) 22.2968(3) 90 98.3040(10) 90 6500.29(16) 4 1.944 5.885 3632 0.22 0.082 0.055 1.71–30.06 29 6 h 6 26, 19 6 k 6 17, 31 6 l 6 30 65 510 18 992 (0.0428) 99.6 multi-scan 0.746 and 0.5784
full-matrix least-squares on F2 5685/0/254 1.037 R1 = 0.0443, wR2 = 0.0974 R1 = 0.0838, wR2 = 0.1129 1.926 and 0.898
full-matrix least-squares on F2 5846/0/241 1.061 R1 = 0.0502, wR2 = 0.1182 R1 = 0.0847, wR2 = 0.1352 3.828 and 1.918
full-matrix least-squares on F2 18 992/0/658 1.031 R1 = 0.0419, wR2 = 0.0991 R1 = 0.1108, wR2 = 0.1364 1.256 and 1.126
temperature (4 h) and white crystals suitable for X-ray analysis were obtained. Yield: 82% based on Cd(SePh)2. Melting point: 178180 °C. Anal. Calc. for C48H76Br2Cd2P2Se2 (1257.62): C, 45.84; H, 6.09. Found: C, 45.90; H, 5.82%. IR (KBr): 3064 [ms(CH)]; 2932 [mas(CH2)]; 2849 [ms(CH2)]; 1573, 1472, 1446 [ms(C@C)]; 1069, 1020 [dip(C=CH)]; 737, 690 [dop(C=CH)]; 462 cm1 [dop(C@C– C)]. 2.3. Preparation of [Cd2(SePh)2I2(PCh3)2] (2) According to the preparation of 1, with CdI2 (0.037 g, 0.1 mmol) in the place of CdBr24H2O. White crystals were obtained. Yield: 85% based on Cd(SePh)2. Melting point: 216218 °C. Anal. Calc. for C48H76I2Cd2P2Se2 (1351.62): C, 42.65; H, 5.67. Found: C, 42.93; H, 5.37%. IR (KBr): 3063 [ms(CH)]; 2932 [mas(CH2)]; 2848 [ms(CH2)]; 1572, 1472, 1446 [ms(C@C)]; 1069, 1020 [dip(C=CH)]; 736, 689 [dop(C=CH)]; 461 cm1 [dop(C@C–C)]. 2.4. Preparation of [Cd4(SePh)7Br(PCh3)] (3) According to the preparation of 1, with 0.084 g (0.2 mmol) of Cd(SePh)2. White crystals were also obtained. Yield: 53% based on Cd(SePh)2. Melting point: 185187 °C. Anal. Calc. for C60H68BrCd4PSe7 (1902.44): C, 37.88; H, 3.60. Found: C, 38.15; H, 3.41%. IR (KBr): 3045 [ms(CH)]; 2930 [mas(CH2)]; 2849 [ms(CH2)]; 1573, 1472, 1434 [ms(C@C)]; 1068, 1019 [dip(C@C–H)]; 735, 688 [dop(C@C–H)]; 462 cm1 [dop(C@CC)]. 2.5. X-ray structural determination Data were collected with a Bruker APEX II CCD area-detector diffractometer and graphite-monochromatized Mo Ka radiation.
The crystal structures were solved by direct methods using SHELXS [22]. Subsequent Fourier-difference map analyses yielded the positions of the non-hydrogen atoms. Refinements were carried out with SHELXL package [22]. All refinements were made by fullmatrix least-squares on F2 with anisotropic displacement parameters for all non-hydrogen atoms. Hydrogen atoms were included in the refinement in calculated positions. Crystal data and more details of the data collections and refinements are contained in Table 1. 3. Results and discussion The X-ray crystal data and the experimental conditions for the analyses of the complexes [Cd2(SePh)2Br2(PCh3)2] (1), [Cd2(SePh)2I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3), are given in Table 1. Table 2 presents selected bond distances and angles for the title compounds. Figs. 1 and 2 represent the dimeric assembly of the unit cells [CdSePhXPCh3] (X = Br, I) and the resulting configurations of compounds 1 and 2. Fig. 3 shows the adamantanoid structure of the unit cell of 3, and Fig. 4 displays the polymeric arrangement of 3, achieved through (Ph)Se-l(CdxCdy) bridging bonds between the adamantane-like moieties. The association in pairs of the monomeric units [CdSePhXPCh3] {X = Br (1), I (2)} leads to a distorted tetrahedral configuration of the Cd(II) centers, with the bond distances ranging within 2.5380(7) (CdBr)2.7449(7) Å (CdSe0 ) in 1, and 2.5666(15) (CdP)2.7484(9) Å (CdSe) in 2. In both dimeric compounds the SeCdSe0 Cd0 bonds achieve a quadratic ring with an inversion center. In the adamantanoid structure of 3 all the selenium atoms attain l2-bridges linking the four cadmium centers, with a medium distance of 2.65 Å; one bromide ligand and one P(Ch3) group accomplish the distorted tetrahedral
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E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763
Table 2 Selected bond lengths (Å) and angles (°) for 1, 2, and 3. Complex 1 Bond lengths CdBr CdP CdSe CdSe0 Bond angles BrCdP BrCdSe PCdSe BrCdSe0 PCdSe0 SeCdSe0 CdSeCd0 Complex 2 Bond lengths PCd SeCd CdSe0 CdI Bond angles Cd0 SeCd PCdSe0 PCdI Se0 CdI PCdSe Se0 CdSe ICdSe Complex 3 Bond lengths Cd3Se4 Cd3Se6 Cd3Se5 Cd3Se3 Cd2P Cd2Se2 Cd2Se3 Cd2Se1
2.5380(7) 2.5737(12) 2.6786(7) 2.7449(7) 116.64(4) 107.69(2) 118.26(3) 120.43(3) 99.57(3) 92.24(2) 87.76(2)
2.5666(15) 2.7484(9) 2.6851(8) 2.7182(7) 86.55(3) 118.10(4) 116.78(4) 107.08(2) 98.91(4) 93.45(3) 120.78(2)
2.6179(7) 2.6235(7) 2.65507) 2.6641(7) 2.5810(15) 2.6458(7) 2.6480(7) 2.6742(7)
Cd1Br Cd1Se4 Cd1Se7 Cd1Se2 Se1Cd4 Cd4Se50 Cd4Se7 Cd4Se6 Bond angles Se4Cd3Se6 Se4Cd3Se5 Se6Cd3Se5 Se4Cd3Se3 Se6Cd3Se3 Se5Cd3Se3 PCd2Se2 PCd2Se3 Se2Cd2Se3 PCd2Se1 Se2Cd2Se1 Se3Cd2Se1 BrCd1Se4 BrCd1Se7 Se4Cd1Se7 BrCd1Se2 Se4Cd1Se2 Se7Cd1Se2 Cd4Se1Cd2 Cd2Se2Cd1 Cd3Se4Cd1 Cd400 Se5Cd3 Cd2Se3Cd3 Se50 Cd4Se7 Se50 Cd4Se6 Se7Cd4Se6 Se50 Cd4Se1 Se7Cd4Se1 Se6Cd4Se1
2.5580(7) 2.6476(7) 2.6621(8) 2.6652(7) 2.6616(7) 2.6309(7) 2.6431(7) 2.6439(7) 122.65(2) 118.50(2) 105.31(2) 100.10(2) 109.01(2) 97.83(2) 114.05(4) 110.15(4) 107.24(2) 108.11(4) 108.58(2) 108.59(2) 108.10(3) 108.11(3) 124.99(2) 109.71(2) 113.69(2) 90.83(2) 105.73(2) 109.93(2) 104.33(2) 121.06(2) 111.29(2) 105.46(2) 97.65(2) 122.85(2) 122.67(2) 107.05(2) 102.46(2)
Fig. 2. Dimeric assembly of [Cd2(SePh)2I2(PCh3)2] (2). Symmetry transformations used to generate equivalent atoms: (0 ) x + 1, y + 1, z.
Symmetry transformations used to generate equivalent atoms: 1: (0 ) x + 1, y + 2, z + 1; 2: (0 ) x + 1, y + 1, z; 3: (0 ) x + 1.5, y + 0.5, z + 1.5; (00 ) x + 1.5, y 0.5, z + 1.5.
Fig. 3. Molecular structure of [Cd4(SePh)7Br(PCh3)] (3).
Fig. 1. Structure of [Cd2(SePh)2Br2(PCh3)2] (1). Symmetry transformations used to generate equivalent atoms: (0 ) x + 1, y + 2, z + 1.
configuration of Cd1 and Cd2, respectively, with distances of 2.5580(7) (Cd1Br) and 2.5810(15) Å (Cd2P). The adamantanes
are linked as well through Se bonds (bridges) which measure 2.6309(7) Å. The main difference in the synthesis of compound 3, if compared with the syntheses of 1 and 2, is the use of 0.2 mmol of Cd(SePh)2 instead of 0.1 mmol. Thus, the amount of the effective cluster-forming reagent was duplicated, hence the amount of the co-ligand PCh3 was relatively reduced to the half. In consequence, compound 3 results from the polymerization of 13-membered adamantanoid moieties, in contrast with the tetranuclear clusters 1 and 2. Finally, the title compounds 1, 2 and 3 are not examples of ‘‘giant” chalcogenide tetrahedral nanoclusters like [Cd32S14(SPh)38]2 [23] or [Cd32Se14(SePh)36(L)4] (L = OPPh3, OC4H8) [24], among others. In our case, two main factors seem to have prevented the growth of the cluster products, and, specially, in the case of 3, the fusion of the adamantanoid cages, instead of their polymerization: the use of two sources of Cd2+ ions and the
E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763
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Acknowledgment This work was supported with funds from PRONEX-CNPq/FAPERGS (Brazil). References
Fig. 4. Polymerization of 3 along the b axis. Symmetry transformations used to generate equivalent atoms: (0 ) x + 1.5, y + 0.5, z + 1.5; (00 ) x + 1.5, y 0.5, z + 1.5.
presence of a capping phosphine ligand, PCh3. Solvothermal syntheses of bulky nanoclusters are in general carried out starting from one single metal ion source {like Cd(SePh)2} and in the absence of phosphine (or halogen) ligands, with reaction times of the order of a few days.
4. Supplementary data CCDC 730892, 730893 and 745060 contains the supplementary crystallographic data for 1, 2 and 3. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected].
[1] D.L. Klein, R. Roth, A.K.L. Lim, A.P. Alivisatos, P.L. McEuen, Nature 389 (1997) 699. [2] C. Radloff, C.E. Moran, J.B. Jackson, N.J. Halas, in: M.A. Reed, T. Lee (Eds.), Molecular Nanoelectronics, ISBN: 1-58883-006-3, 2003, p. 229. [3] X. Michalet, A.N. Kapanidis, T. Laurence, F. Pinaud, S. Doose, M. Pflughoefft, S. Weiss, Annu. Rev. Biophys. Biomol. Struct. 32 (2003) 161. [4] M. Bruchez, M. Moronne, P. Gin, S. Weiss, A. Alivisatos, Science 281 (1998) 2013. [5] I.G. Dance, R.G. Garbutt, D.C. Craig, M.L. Scudder, Inorg. Chem. 26 (1987) 4057. [6] J.J. Vittal, P.A.W. Dean, N.C. Payne, Can. J. Chem. 71 (1993) 2043. [7] P.A.W. Dean, J.J. Vittal, M.H. Trattner, Inorg. Chem. 26 (1987) 4245. [8] J.J. Vittal, P.A.W. Dean, N.C. Payne, Can. J. Chem. 70 (1992) 792. [9] P.A.W. Dean, N.C. Payne, J.J. Vittal, Y. Wu, Inorg. Chem. 32 (1993) 4632. [10] P.A.W. Dean, V. Manivannan, J.J. Vittal, Inorg. Chem. 28 (1989) 2360. [11] P.A.W. Dean, N.C. Payne, J. Wranich, J.J. Vittal, Polyhedron 17 (1998) 2411. [12] E. Schulz Lang, R.A. Zan, C.C. Gatto, R.A. Burrow, E.M. Vázquez-López, Eur. J. Inorg. Chem. 2 (2002) 331. [13] G.A. Casagrande, E. Schulz Lang, G. Manzoni de Oliveira, M. Hörner, F. Broch, Inorg. Chim. Acta 360 (2007) 1776. [14] E. Schulz Lang, C. Peppe, R.A. Zan, U. Abram, E.M. Vázquez-López, B. Krumm, O.P. Ruscitti, Z. Anorg. Allg. Chem. 628 (2002) 2815. [15] E. Schulz Lang, G. Manzoni de Oliveira, D.F. Back, S.S. Santos, Z. Anorg. Allg. Chem. 630 (2004) 730. [16] D.F. Back, G. Manzoni de Oliveira, R.A. Burrow, E.E. Castellano, U. Abram, E. Schulz Lang, Inorg. Chem. 46 (2007) 2356. [17] E. Schulz Lang, D.F. Back, G. Manzoni de Oliveira, Polyhedron 27 (2008) 3255. [18] E. Schulz Lang, G. Manzoni de Oliveira, B. Tirloni, A.B. Lago, E.M. VázquezLópez, J. Clust. Sci. 20 (2009) 467. [19] J. Cheon, Y.-W. Jun, S.M. Lee, Architecture of nanocrystal building blocks, in: V. Rotello (Ed.), Nanoparticles – Building Blocks for Nanotechnology, Springer Science & Business Media, Inc., New York, 2004, p. 53. [20] K.S. Anjali, J.J. Vittal, Inorg. Chem. Commun. 3 (2000) 708. [21] D.D. Perrin, W.L.F. Armarego, Purifications of Laboratory Chemicals, third ed., Pergamon Press, New York, 1988. [22] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112. [23] N. Zheng, H. Lu, X. Bu, P. Feng, J. Am. Chem. Soc. 128 (2006) 4528. [24] A. Eichhöfer, Eur. J. Inorg. Chem. (2005) 1245.
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Polyhedron journal homepage: www.elsevier.com/locate/poly
Synthesis, structural characterization and growth features of some (Ph)Se–Cd cluster compounds (Ph = phenyl) Ernesto Schulz Lang *, Rafael Stieler, Gelson Manzoni de Oliveira * LMI – Laboratório de Materiais Inorgânicos, Departamento de Química, Universidade Federal de Santa Maria (UFSM), 97105-900 Santa Maria, RS, Brazil
a r t i c l e
i n f o
Article history: Received 1 October 2009 Accepted 15 February 2010 Available online 18 February 2010 Keywords: Cd(II)-clusters Cd(II)-selenolate clusters Clusters growth
a b s t r a c t Cd(SePh)2, CdBr24H2O/CdI2 and PCh3 (Ph = phenyl; PCh3 = tricyclohexylphosphine) react to give [(SePh)2Cd2Br2(PCh3)2] (1), [(SePh)2Cd2I2(PCh3)2] (2) and [(SePh)7Cd4Br(PCh3)]n (3). The new compounds are examples of Cd(II) clusters obtained starting from the cluster-forming reagents Cd(SePh)2 and CdX2 (X = Br, I) in the presence of variable amounts of PCh3. While 1 and 2 are single, tetranuclear clusters, compound 3 attains polymeric adamantanoid cages linked through selenium bridges. Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction Clusters of the IIbVI groups have become progressively important due to their semiconductor potentialities, among other materials and biological applications [1–4]. Since the chemistry of adamantane-like mercury/cadmium–chalcogen cages has been also extensively studied [5–11], in recent reports we have discussed the use of mercury bis-phenylselenolate/tellurolate, Hg(EPh)2 (E = Se, Te), as efficient start for the synthesis of ternary clusters and polymers [12–16]. It is well known that metal chalcogenide clusters and derivatives can show variable sizes and shapes, whether concerning to single clusters like [(PhTe)16Ag4Hg6Py4] (Ph = phenyl; Py = pyridine) [17] or regarding to bulkier, polymeric clusters like [Hg5Cl3(SePh)7]n and [Hg7Br3(SePh)11]n [18]. In the study of the architecture of nanocrystals building blocks, Cheon et al. [19] elected ‘‘time”, ‘‘temperature” ‘‘capping molecules” and ‘‘kinetic energy barrier, (DG#), as the parameters whose interaction should influence the growth pattern of nanocrystals. Although nanocrystals and nanoclusters are different species, and this report does not address nanoclusters, we have observed that some parameters discussed by Cheon et al. [19] for nanocrystals seem to be also valid in the managing of the growth of (l-Se)Cd(II) clusters. We report now the use of cadmium bis-phenylselenolate, Cd(SePh)2, plus CdX2 (X = Br, I), in the synthesis of the new tetranuclear and adamantanoid shaped clusters [Cd2(SePh)2Br2(PCh3)2] (1),
* Corresponding authors. Tel.: +55 3220 8980; fax: +55 3220 8031 (G.M. de Oliveria). E-mail addresses: [email protected] (E.S. Lang), [email protected] (G.M. de Oliveira). 0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.poly.2010.02.023
[Cd2(SePh)2I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3) (PCh3 = tricyclohexylphosphine). The structural characterization of the new compounds will be also presented, together with a brief comparative discussion on their formation and growth. 2. Experimental 2.1. General All reactions were carried out under dry Ar. Solvents were purified and dried by standard procedures and freshly distilled before use. Cadmium bromide tetrahydrate, cadmium iodide and tricyclohexylphosphine were purchased from Sigma AldrichÒ. Cd(SePh)2 [20] was prepared according to literature procedures [21]. Elemental analyses were made using a FlashEA 1112 device. The synthetic procedures can be summarized in the form of the chemical Eqs. (a) and (b) below, CdðSePhÞ2 þ CdX2 þ 2PCy3 ! ½Cd2 ðSePhÞ2 X2 ðPCy3 Þ2 ðX ¼ Brð1Þ; Ið2Þ 4CdðSePhÞ2 þ CdBr2 þ PCy3 ! ½Cd4 ðSePhÞ7 BrðPCy3 Þn ð3Þ þ ðCdSePhBrÞn
ðaÞ ðbÞ
In the case of 3, the equation does not correspond to the actually used stoichiometry (2:1:2), since the excess of Cd(SePh)2 leads to the polymerization of the main product in the solvothermal reaction. 2.2. Preparation of [Cd2(SePh)2Br2(PCh3)2] (1) A mixture of CdBr24H2O (0.034 g, 0.1 mmol), Cd(SePh)2 (0.042 g, 0.1 mmol), PCh3 (0.056 g, 0.2 mmol) in 8 mL of methanol was heated at 130 °C for 1 h in a 12 mL stainless steel sealed reactor. Thereafter the reactor was cooled down slowly to room
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E.S. Lang et al. / Polyhedron 29 (2010) 1760–1763 Table 1 Crystal data and structure refinement for 1, 2 and 3.
Empirical formula Formula weight T (K) Radiation, k (Å) Crystal system Space group Unit cell dimensions a (Å) b (Å) c (Å) a (°) b (°) c (°) V (Å3) Z DCalc (g cm1) Absorption coefficient (mm1) F (0 0 0) Crystal size (mm) h (°) Index range Reflections collected Reflections unique (Rint) Completeness to theta maximum (%) Absorption correction Maximum and minimum transmission Refinement method Data/restraints/parameters Goodness-of-fit (GOF) on F2 Final R indices [I > 2r (I)] R indices (all data) Largest diff. peak and hole (e Å3)
1
2
3
C48H76Br2Cd2P2Se2 1257.57 293(2) Mo Ka, 0.71073 triclinic P1
C48H76Cd2I2P2Se2 1351.55 296(2) Mo Ka, 0.71073 triclinic P1
C60H68BrCd4PSe7 1902.34 293(2) Mo Ka, 0.71073 monoclinic P21/n
10.2012(4) 10.8207(4) 12.2261(5) 72.776(2) 88.663(2) 83.995(3) 1281.93(9) 1 1.629 3.900 628 0.355 0.265 0.08 2.22–27.22 10 6 h 6 13, 13 6 k 6 13, 15 6 l 6 15 14 708 5685 (0.0403) 99.3 gaussian 0.7455 and 0.5566
10.3511(10) 10.7551(12) 12.1186(13) 101.577(8) 87.752(6) 84.188(6) 1280.2(2) 1 1.753 3.551 664 0.11 0.1 0.09 1.99–27.56 13 6 h 6 13, 13 6 k 6 13, 15 6 l 6 15 23 064 5846 (0.0687) 98.7 multi-scan 0.7456 and 0.6557
20.8440(3) 14.1347(2) 22.2968(3) 90 98.3040(10) 90 6500.29(16) 4 1.944 5.885 3632 0.22 0.082 0.055 1.71–30.06 29 6 h 6 26, 19 6 k 6 17, 31 6 l 6 30 65 510 18 992 (0.0428) 99.6 multi-scan 0.746 and 0.5784
full-matrix least-squares on F2 5685/0/254 1.037 R1 = 0.0443, wR2 = 0.0974 R1 = 0.0838, wR2 = 0.1129 1.926 and 0.898
full-matrix least-squares on F2 5846/0/241 1.061 R1 = 0.0502, wR2 = 0.1182 R1 = 0.0847, wR2 = 0.1352 3.828 and 1.918
full-matrix least-squares on F2 18 992/0/658 1.031 R1 = 0.0419, wR2 = 0.0991 R1 = 0.1108, wR2 = 0.1364 1.256 and 1.126
temperature (4 h) and white crystals suitable for X-ray analysis were obtained. Yield: 82% based on Cd(SePh)2. Melting point: 178180 °C. Anal. Calc. for C48H76Br2Cd2P2Se2 (1257.62): C, 45.84; H, 6.09. Found: C, 45.90; H, 5.82%. IR (KBr): 3064 [ms(CH)]; 2932 [mas(CH2)]; 2849 [ms(CH2)]; 1573, 1472, 1446 [ms(C@C)]; 1069, 1020 [dip(C=CH)]; 737, 690 [dop(C=CH)]; 462 cm1 [dop(C@C– C)]. 2.3. Preparation of [Cd2(SePh)2I2(PCh3)2] (2) According to the preparation of 1, with CdI2 (0.037 g, 0.1 mmol) in the place of CdBr24H2O. White crystals were obtained. Yield: 85% based on Cd(SePh)2. Melting point: 216218 °C. Anal. Calc. for C48H76I2Cd2P2Se2 (1351.62): C, 42.65; H, 5.67. Found: C, 42.93; H, 5.37%. IR (KBr): 3063 [ms(CH)]; 2932 [mas(CH2)]; 2848 [ms(CH2)]; 1572, 1472, 1446 [ms(C@C)]; 1069, 1020 [dip(C=CH)]; 736, 689 [dop(C=CH)]; 461 cm1 [dop(C@C–C)]. 2.4. Preparation of [Cd4(SePh)7Br(PCh3)] (3) According to the preparation of 1, with 0.084 g (0.2 mmol) of Cd(SePh)2. White crystals were also obtained. Yield: 53% based on Cd(SePh)2. Melting point: 185187 °C. Anal. Calc. for C60H68BrCd4PSe7 (1902.44): C, 37.88; H, 3.60. Found: C, 38.15; H, 3.41%. IR (KBr): 3045 [ms(CH)]; 2930 [mas(CH2)]; 2849 [ms(CH2)]; 1573, 1472, 1434 [ms(C@C)]; 1068, 1019 [dip(C@C–H)]; 735, 688 [dop(C@C–H)]; 462 cm1 [dop(C@CC)]. 2.5. X-ray structural determination Data were collected with a Bruker APEX II CCD area-detector diffractometer and graphite-monochromatized Mo Ka radiation.
The crystal structures were solved by direct methods using SHELXS [22]. Subsequent Fourier-difference map analyses yielded the positions of the non-hydrogen atoms. Refinements were carried out with SHELXL package [22]. All refinements were made by fullmatrix least-squares on F2 with anisotropic displacement parameters for all non-hydrogen atoms. Hydrogen atoms were included in the refinement in calculated positions. Crystal data and more details of the data collections and refinements are contained in Table 1. 3. Results and discussion The X-ray crystal data and the experimental conditions for the analyses of the complexes [Cd2(SePh)2Br2(PCh3)2] (1), [Cd2(SePh)2I2(PCh3)2] (2) and [Cd4(SePh)7Br(PCh3)]n (3), are given in Table 1. Table 2 presents selected bond distances and angles for the title compounds. Figs. 1 and 2 represent the dimeric assembly of the unit cells [CdSePhXPCh3] (X = Br, I) and the resulting configurations of compounds 1 and 2. Fig. 3 shows the adamantanoid structure of the unit cell of 3, and Fig. 4 displays the polymeric arrangement of 3, achieved through (Ph)Se-l(CdxCdy) bridging bonds between the adamantane-like moieties. The association in pairs of the monomeric units [CdSePhXPCh3] {X = Br (1), I (2)} leads to a distorted tetrahedral configuration of the Cd(II) centers, with the bond distances ranging within 2.5380(7) (CdBr)2.7449(7) Å (CdSe0 ) in 1, and 2.5666(15) (CdP)2.7484(9) Å (CdSe) in 2. In both dimeric compounds the SeCdSe0 Cd0 bonds achieve a quadratic ring with an inversion center. In the adamantanoid structure of 3 all the selenium atoms attain l2-bridges linking the four cadmium centers, with a medium distance of 2.65 Å; one bromide ligand and one P(Ch3) group accomplish the distorted tetrahedral
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Table 2 Selected bond lengths (Å) and angles (°) for 1, 2, and 3. Complex 1 Bond lengths CdBr CdP CdSe CdSe0 Bond angles BrCdP BrCdSe PCdSe BrCdSe0 PCdSe0 SeCdSe0 CdSeCd0 Complex 2 Bond lengths PCd SeCd CdSe0 CdI Bond angles Cd0 SeCd PCdSe0 PCdI Se0 CdI PCdSe Se0 CdSe ICdSe Complex 3 Bond lengths Cd3Se4 Cd3Se6 Cd3Se5 Cd3Se3 Cd2P Cd2Se2 Cd2Se3 Cd2Se1
2.5380(7) 2.5737(12) 2.6786(7) 2.7449(7) 116.64(4) 107.69(2) 118.26(3) 120.43(3) 99.57(3) 92.24(2) 87.76(2)
2.5666(15) 2.7484(9) 2.6851(8) 2.7182(7) 86.55(3) 118.10(4) 116.78(4) 107.08(2) 98.91(4) 93.45(3) 120.78(2)
2.6179(7) 2.6235(7) 2.65507) 2.6641(7) 2.5810(15) 2.6458(7) 2.6480(7) 2.6742(7)
Cd1Br Cd1Se4 Cd1Se7 Cd1Se2 Se1Cd4 Cd4Se50 Cd4Se7 Cd4Se6 Bond angles Se4Cd3Se6 Se4Cd3Se5 Se6Cd3Se5 Se4Cd3Se3 Se6Cd3Se3 Se5Cd3Se3 PCd2Se2 PCd2Se3 Se2Cd2Se3 PCd2Se1 Se2Cd2Se1 Se3Cd2Se1 BrCd1Se4 BrCd1Se7 Se4Cd1Se7 BrCd1Se2 Se4Cd1Se2 Se7Cd1Se2 Cd4Se1Cd2 Cd2Se2Cd1 Cd3Se4Cd1 Cd400 Se5Cd3 Cd2Se3Cd3 Se50 Cd4Se7 Se50 Cd4Se6 Se7Cd4Se6 Se50 Cd4Se1 Se7Cd4Se1 Se6Cd4Se1
2.5580(7) 2.6476(7) 2.6621(8) 2.6652(7) 2.6616(7) 2.6309(7) 2.6431(7) 2.6439(7) 122.65(2) 118.50(2) 105.31(2) 100.10(2) 109.01(2) 97.83(2) 114.05(4) 110.15(4) 107.24(2) 108.11(4) 108.58(2) 108.59(2) 108.10(3) 108.11(3) 124.99(2) 109.71(2) 113.69(2) 90.83(2) 105.73(2) 109.93(2) 104.33(2) 121.06(2) 111.29(2) 105.46(2) 97.65(2) 122.85(2) 122.67(2) 107.05(2) 102.46(2)
Fig. 2. Dimeric assembly of [Cd2(SePh)2I2(PCh3)2] (2). Symmetry transformations used to generate equivalent atoms: (0 ) x + 1, y + 1, z.
Symmetry transformations used to generate equivalent atoms: 1: (0 ) x + 1, y + 2, z + 1; 2: (0 ) x + 1, y + 1, z; 3: (0 ) x + 1.5, y + 0.5, z + 1.5; (00 ) x + 1.5, y 0.5, z + 1.5.
Fig. 3. Molecular structure of [Cd4(SePh)7Br(PCh3)] (3).
Fig. 1. Structure of [Cd2(SePh)2Br2(PCh3)2] (1). Symmetry transformations used to generate equivalent atoms: (0 ) x + 1, y + 2, z + 1.
configuration of Cd1 and Cd2, respectively, with distances of 2.5580(7) (Cd1Br) and 2.5810(15) Å (Cd2P). The adamantanes
are linked as well through Se bonds (bridges) which measure 2.6309(7) Å. The main difference in the synthesis of compound 3, if compared with the syntheses of 1 and 2, is the use of 0.2 mmol of Cd(SePh)2 instead of 0.1 mmol. Thus, the amount of the effective cluster-forming reagent was duplicated, hence the amount of the co-ligand PCh3 was relatively reduced to the half. In consequence, compound 3 results from the polymerization of 13-membered adamantanoid moieties, in contrast with the tetranuclear clusters 1 and 2. Finally, the title compounds 1, 2 and 3 are not examples of ‘‘giant” chalcogenide tetrahedral nanoclusters like [Cd32S14(SPh)38]2 [23] or [Cd32Se14(SePh)36(L)4] (L = OPPh3, OC4H8) [24], among others. In our case, two main factors seem to have prevented the growth of the cluster products, and, specially, in the case of 3, the fusion of the adamantanoid cages, instead of their polymerization: the use of two sources of Cd2+ ions and the
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Acknowledgment This work was supported with funds from PRONEX-CNPq/FAPERGS (Brazil). References
Fig. 4. Polymerization of 3 along the b axis. Symmetry transformations used to generate equivalent atoms: (0 ) x + 1.5, y + 0.5, z + 1.5; (00 ) x + 1.5, y 0.5, z + 1.5.
presence of a capping phosphine ligand, PCh3. Solvothermal syntheses of bulky nanoclusters are in general carried out starting from one single metal ion source {like Cd(SePh)2} and in the absence of phosphine (or halogen) ligands, with reaction times of the order of a few days.
4. Supplementary data CCDC 730892, 730893 and 745060 contains the supplementary crystallographic data for 1, 2 and 3. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: [email protected].
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