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Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 72| Part 2| February 2016| Pages 144-146

Crystal structure of Sr2CdPt2 containing linear platinum chains

aDepartment of Chemical Education, Sriwijaya University, Inderalaya, Ogan Ilir 30662, South Sumatra, Indonesia, and bMax Planck Institut für Festkörperforschung, Heisenbergstr. 1, 70698 Stuttgart, Germany
*Correspondence e-mail: fgulo@unsri.ac.id

Edited by M. Weil, Vienna University of Technology, Austria (Received 10 December 2015; accepted 30 December 2015; online 9 January 2016)

The ternary inter­metallic title phase, distrontium cadmium diplatinum, was prepared from stoichiometric amounts of the elements at 1123 K for one day. The crystal structure adopts the ortho­rhom­bic Ca2GaCu2 structure type in space group Immm. Its main features are characterized by linear (Pt—Pt⋯Pt—Pt)n chains that are aligned along [010] and condensed through cadmium atoms forming Cd-centred Pt2Cd2/2 rectangles to build up sheets parallel to (001). These sheets are connected to each other via alternating (001) sheets of strontium atoms along [001]. The strontium sheets consists of corrugated Sr4 units that are condensed to each other through edge-sharing parallel to [100].

1. Chemical context

A large number of transition metal-based ternary inter­metallic phases have been studied in terms of metal–metal inter­actions and structure–property relationships (Corbett, 2010[Corbett, J. D. (2010). Inorg. Chem. 49, 13-28.]). Exploratory synthetic approaches in systems A/Cd/Pt (A = alkaline earth metal) have revealed a great compositional and structural diversity. The calcium phase Ca6Cd16Pt8 contains a three-dimensional array of isolated Cd8 tetra­hedral stars (TS) and a face-centred cube of Pt@Ca6 octa­hedra (Samal et al., 2013[Samal, S. L., Gulo, F. & Corbett, J. D. (2013). Inorg. Chem. 52, 2697-2704.]) whilst the structure of Ca6Cd11Pt crystallizes in its own structure type consisting of apically inter­bonded Cd7 penta­gonal bipyramids and five-membered rings of Ca atoms (Gulo et al., 2013[Gulo, F., Samal, S. L. & Corbett, J. D. (2013). Inorg. Chem. 52, 10112-10118.]). The strontium phase SrCd4Pt2 is made up of chains of edge-sharing Cd4 tetra­hedra bridged by four-bonded Sr atoms (Samal et al., 2013[Samal, S. L., Gulo, F. & Corbett, J. D. (2013). Inorg. Chem. 52, 2697-2704.]) and SrCdPt presents six-membered rings of Sr atoms in a chair conformation (Gulo & Köhler, 2014[Gulo, F. & Köhler, J. (2014). Acta Cryst. E70, 590-592.]). The barium phase BaCd2Pt exhibits zigzag chains of Ba atoms and Pt-centred boat and anti-boat conformations formed by six-membered rings of Cd atoms (Gulo & Köhler, 2015[Gulo, F. & Köhler, J. (2015). Z. Anorg. Allg. Chem. 641, 557-560.]). The Pt-based ternary inter­metallic compounds with general formula A2XPt2 (A = alkaline-earth or rare-earth metal; X = diel, triel, or tetrel element) adopt five different structure types. Sr2InPt2 (Muts et al., 2007[Muts, I. R., Nilges, T., Rodewald, U. C., Zaremba, V. I. & Pöttgen, R. (2007). Z. Naturforsch. B, 62, 1563-1566.]) crystallizes in the monoclinic Ca2Ir2S type (Schoolaert & Jung, 2002[Schoolaert, S. & Jung, W. (2002). Z. Anorg. Allg. Chem. 628, 1806-1810.]), Pu2SnPt2 (Pereira et al., 1997[Pereira, L. C. J., Wastin, F., Winand, J. M., Kanellakopoulos, B., Rebizant, J., Spirlet, J. C. & Almeida, M. (1997). J. Solid State Chem. 134, 138-147.]) in the tetra­gonal Mo2FeB2 type (Gladyshevskii et al., 1996[Gladyshevskii, E. I., Fedorov, T. F., Kuz'ma, Y. B. & Skolozdra, R. V. (1996). Sov. Powder Metall. Met. Ceram. 5, 305-309.]) while U2CdPt2 has its own structure type (Gravereau et al., 1994[Gravereau, P., Mirambet, F., Chevalier, B., Weill, F., Fournès, L., Laffargue, D., Bourée, F. & Etourneau, J. R. (1994). J. Mater. Chem. 4, 1893-1895.]). Ce2CdPt2 (Pöttgen et al., 2000[Pöttgen, R., Fugmann, A., Hoffmann, R. D., Rodewald, U. C. & Niepmann, D. (2000). Z. Naturforsch. B, 55, 155-161.]) adopts the tetra­gonal U3Si2 type (Zachariasen, 1948[Zachariasen, W. H. (1948). Acta Cryst. 1, 265-268.]), and Ca2CdPt2 (Samal & Corbett, 2012[Samal, S. L. & Corbett, J. D. (2012). Z. Anorg. Allg. Chem. 638, 1963-1969.]) the ortho­rhom­bic Ca2GaCu2 type (Fornasini & Merlo, 1988[Fornasini, M. L. & Merlo, F. (1988). J. Less-Common Met. 142, 289-294.]).

In this article we present the crystal structure of the novel inter­metallic phase Sr2CdPt2 containing linear (Pt—Pt⋯Pt—Pt)n chains as a principal structural motif.

2. Structural commentary

The ternary inter­metallic title phase adopts the ortho­rhom­bic Ca2GaCu2 structure type (Fornasini & Merlo, 1988[Fornasini, M. L. & Merlo, F. (1988). J. Less-Common Met. 142, 289-294.]) with the Ca, Ga, and Cu sites replaced by Sr, Cd, and Pt sites, respectively. The three atoms occupy three independent sites in the unit cell. The Sr atom resides on a special position with site symmetry mm2 (Wyckoff site 4 j), the Cd atom occupies a special positions with site symmetry mmm (2 a) and the Pt atom is on a special positions with site symmetry m2m (4 h). In the two structures, the transition metals (platinum and copper, respectively) occupy the same positions. In contrast, in the structure of SrCd4Pt2 (Samal et al., 2013[Samal, S. L., Gulo, F. & Corbett, J. D. (2013). Inorg. Chem. 52, 2697-2704.]) which is isotypic with ZrFe4Si2 (Yarmolyuk et al., 1975[Yarmolyuk, Y. P., Lysenko, L. A. & Gladyshevskii, E. I. (1975). Uopov. Akad. Nauk Ukr. RSR, Ser. A. 279.]), the transition metals (platinum and iron, respectively) occupy different positions and the Pt atoms reside on the respective Si sites because silicon and platinum atoms are the most electronegative atoms in the two systems. The new phase Sr2CdPt2 contains 26 valence electrons and, as already mentioned, is isotypic with Ca2GaCu2. However, in comparison the structure of Sr2CdPt2 is appreciably distorted along the platinum chains, presumably because Ca2GaCu2 contains much smaller Cu atoms and a larger valence electron count of 29. Coordination spheres of each atomic site in the title structure are illustrated in Fig. 1[link]. The Sr atom is coordinated by five other Sr, four Cd, and four Pt atoms. The Sr—Sr bond lengths vary from 3.674 (3) to 3.854 (1) Å, the Sr—Cd distances range from 3.490 (1) to 3.577 (1) Å, whereas the Sr—Pt values vary only slightly, from 3.188 (1) to 3.231 (1) Å. Six Sr atoms construct a square-planar pyramid, Sr@Sr5. The existence of Sr—Sr strong bonds is observable in SrCdPt (Gulo & Köhler, 2014[Gulo, F. & Köhler, J. (2014). Acta Cryst. E70, 590-592.]) but not in SrCd4Pt2 (Samal et al., 2013[Samal, S. L., Gulo, F. & Corbett, J. D. (2013). Inorg. Chem. 52, 2697-2704.]). The Cd atom exhibits a coordination number of twelve and has eight Sr and four Pt atoms in its environment with Cd—Pt distances of 2.785 (1) Å. The Pt atom is surrounded by six Sr, two Cd and one Pt atoms with a Pt—Pt distance of 2.734 (1) Å. This distance is slightly longer than those found in Ca2CdPt2 (2.659 Å; Samal & Corbett, 2012[Samal, S. L. & Corbett, J. D. (2012). Z. Anorg. Allg. Chem. 638, 1963-1969.]) or Sr2InPt2 (2.707 Å; Muts et al., 2007[Muts, I. R., Nilges, T., Rodewald, U. C., Zaremba, V. I. & Pöttgen, R. (2007). Z. Naturforsch. B, 62, 1563-1566.]) but shorter than those in Pu2SnPt2 (Pereira et al., 1997[Pereira, L. C. J., Wastin, F., Winand, J. M., Kanellakopoulos, B., Rebizant, J., Spirlet, J. C. & Almeida, M. (1997). J. Solid State Chem. 134, 138-147.]), U2CdPt2 (Gravereau et al., 1994[Gravereau, P., Mirambet, F., Chevalier, B., Weill, F., Fournès, L., Laffargue, D., Bourée, F. & Etourneau, J. R. (1994). J. Mater. Chem. 4, 1893-1895.]) or Ce2CdPt2 (Pöttgen et al., 2000[Pöttgen, R., Fugmann, A., Hoffmann, R. D., Rodewald, U. C. & Niepmann, D. (2000). Z. Naturforsch. B, 55, 155-161.]). All other inter­atomic distances (Sr—Cd, Sr—Pt, and Cd—Pt) are in agreement with those found in some ternary compounds in A/Cd/Pt systems (A = alkaline earth metal).

[Figure 1]
Figure 1
Coordination of strontium, cadmium, and platinum atoms in Sr2CdPt2. Displacement ellipsoids are displayed at the 90% probability level.

3. Packing features

Sr atoms are bound together into corrugated sheets consisting of edge-sharing Sr4-units. These sheets spread parallel to (001) and are linked by another Sr—Sr bond of 3.674 (3) Å along [001]. (Fig. 2[link]). The crystal structure is also characterized by the existence of linear (Pt—Pt⋯Pt—Pt)n chains along [010] with longer distances of 3.2010 (14) Å between pairs of tightly bound Pt—Pt dumbbells, a significant distortion in the direction of dimerization. The platinum chains are condensed into (001) sheets through Cd atoms, forming Cd-centred rectangles with composition Pt2Cd2/2 (Fig. 3[link]). The Pt2Cd2/2 layers are stacked along [001] and are linked through the corrugated sheets of Sr atoms.

[Figure 2]
Figure 2
Projection of the crystal structure of Sr2CdPt2 approximately along the b axis.
[Figure 3]
Figure 3
Projection of linear platinum chains that are aligned along the b axis and condensed via cadmium atoms forming Pt2Cd2/2-rectangles in the ab-plane

4. Database survey

A search of the Pearson's Crystal Data – Crystal Structure Database for Inorganic Compounds (Villars & Cenzual, 2015[Villars, P. & Cenzual, K. (2015). Pearson's Crystal Data - Crystal Structure Database for Inorganic Compounds. Release 2015/16. ASM International, Materials Park, Ohio, USA.]) for the Sr/Cd/Pt family of compounds returned two compounds only: SrCd4Pt2 (Samal et al., 2013[Samal, S. L., Gulo, F. & Corbett, J. D. (2013). Inorg. Chem. 52, 2697-2704.]) and SrCdPt (Gulo & Köhler, 2014[Gulo, F. & Köhler, J. (2014). Acta Cryst. E70, 590-592.]).

5. Synthesis and crystallization

The title compound was synthesized from starting materials of Sr granules (99.9+%, Alfa Aesar), Cd powder (99.9+%, Alfa Aesar) and Pt powder (99.95%, Chempur). A stoichiometric mixture of these elements was loaded into a Nb ampoule in an Ar-filled dry box. The Nb ampoule was then weld-sealed under an Ar atmosphere and subsequently enclosed in an evacuated silica jacket. The sample was then heated to 1123 K for 15 h, equilibrated at 923 K for 4 days, and followed by slow cooling to room temperature.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1[link]. The maximum and minimum remaining electron densities are located 1.66 and 0.81 Å, respectively, from the Pt site.

Table 1
Experimental details

Crystal data
Chemical formula CdPt2Sr2
Mr 677.82
Crystal system, space group Orthorhombic, Immm
Temperature (K) 293
a, b, c (Å) 4.5596 (9), 5.9351 (12), 9.1874 (18)
V3) 248.63 (9)
Z 2
Radiation type Mo Kα
μ (mm−1) 81.39
Crystal size (mm) 0.08 × 0.06 × 0.05
 
Data collection
Diffractometer Bruker P4
Absorption correction Multi-scan (SADABS; Bruker, 2001[Bruker (2001). XSCANS and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.])
Tmin, Tmax 0.004, 0.017
No. of measured, independent and observed [I > 2σ(I)] reflections 1069, 190, 172
Rint 0.025
(sin θ/λ)max−1) 0.666
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.022, 0.058, 1.16
No. of reflections 190
No. of parameters 13
Δρmax, Δρmin (e Å−3) 1.84, −2.51
Computer programs: XSCANS (Bruker, 2001[Bruker (2001). XSCANS and SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]), SHELXS97 and SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and DIAMOND (Brandenburg, 2010[Brandenburg, K. (2010). DIAMOND. Crystal Impact GbR, Bonn, Germany.]).

Supporting information


Chemical context top

A large number of transition metal-based ternary inter­metallic phases have been studied in terms of metal–metal inter­actions and structure–property relationships (Corbett, 2010). Exploratory synthetic approaches in systems Pt/Cd/A (A = alkaline earth metal) has revealed a great compositional and structural diversity. The calcium phase Ca6Cd16Pt8 contains a three-dimensional array of isolated Cd8 tetra­hedral stars (TS) and a face-centred cube of Pt@Ca6 o­cta­hedra (Samal et al., 2013) whilst the structure of Ca6Cd11Pt crystallizes in its own structure type consisting of apically inter­bonded Cd7 penta­gonal bipyramids and five-membered rings of Ca atoms (Gulo et al., 2013). The strontium phase SrCd4Pt2 is made up of chains of edge-sharing Cd4 tetra­hedra bridged by four-bonded Sr atoms (Samal et al., 2013) and SrCdPt presents six-membered rings of Sr atoms in a chair conformation (Gulo & Köhler, 2014). The barium phase BaCd2Pt exhibits zigzag chains of Ba atoms and Pt-centred boat and anti-boat conformations formed by six-membered rings of Cd atoms (Gulo & Köhler, 2015). The Pt-based ternary inter­metallic compounds with general formula A2XPt2 (A = alkaline-earth or rare-earth metal; X = diel, triel, or tetrel element) adopt five different structure types. Sr2InPt2 (Muts et al., 2007) crystallizes in the monoclinic Ca2Ir2S type (Schoolaert & Jung, 2002), Pu2SnPt2 (Pereira et al., 1997) in the tetra­gonal Mo2FeB2 type (Gladyshevskii et al., 1996) while U2CdPt2 has its own structure type (Gravereau et al., 1994). Ce2CdPt2 (Pöttgen et al., 2000) adopts the tetra­gonal U3Si2 type (Zachariasen, 1948), and Ca2CdPt2 (Samal & Corbett, 2012) the orthorhombic Ca2GaCu2 type (Fornasini & Merlo, 1988).

In this article we present the crystal structure of the novel inter­metallic phase Sr2CdPt2 containing linear (Pt—Pt···Pt—Pt)n chains as a principal structural motif.

Structural commentary top

The ternary inter­metallic title phase adopts the orthorhombic Ca2GaCu2 structure type (Fornasini & Merlo, 1988) with the Ca, Ga, and Cu sites replaced by Sr, Cd, and Pt sites, respectively. The three atoms occupy three independent sites in the unit cell. The Sr atom resides on a special position with site symmetry mm2 (Wyckoff site 4 j), the Cd atom occupies a special positions with site symmetry mmm (2 a) and the Pt atom is on a special positions with site symmetry m2m (4 h). In the two structures, the transition metals (platinum and copper, respectively) occupy the same positions. In contrast, in the structure of SrCd4Pt2 (Samal et al., 2013) which is isotypic with ZrFe4Si2 (Yarmolyuk et al., 1975), the transition metals (platinum and iron, respectively) occupy different positions and the Pt atoms reside on the respective Si sites because silicon and platinum atoms are the most electronegative atoms in the two systems. The new phase Sr2CdPt2 contains 26 valence electrons and, as already mentioned, is isotypic with Ca2GaCu2. However, in comparison the structure of Sr2CdPt2 is appreciably distorted along the platinum chains, presumably because Ca2GaCu2 contains much smaller Cu atoms and a larger valence electron count of 29. Coordination spheres of each atomic site in the title structure are illustrated in Fig. 1. The Sr atom is coordinated by five other Sr, four Cd, and four Pt atoms. The Sr—Sr bond lengths vary from 3.674 (3) to 3.854 (1) Å, the Sr—Cd distances range from 3.490 (1) to 3.577 (1) Å, whereas the Sr—Pt values vary only slightly, from 3.188 (1) to 3.231 (1) Å. Six Sr atoms construct a square-planar pyramid, Sr@Sr5. The existence of Sr—Sr strong bonds is observable in SrCdPt (Gulo & Köhler, 2014) but not in SrCd4Pt2 (Samal et al., 2013). The Cd atom exhibits a coordination number of twelve and has eight Sr and four Pt atoms in its environment with Cd—Pt distances of 2.785 (1) Å. The Pt atom is surrounded by six Sr, two Cd and one Pt atom with a Pt—Pt distance of 2.734 (1) Å. This distance is slightly longer than those found in Ca2CdPt2 (2.659 Å; Samal & Corbett, 2012) or Sr2InPt2 (2.707 Å; Muts et al., 2007) but shorter than those in Pu2SnPt2 (Pereira et al., 1997), U2CdPt2 (Gravereau et al., 1994) or Ce2CdPt2 (Pöttgen et al., 2000). All other inter­atomic distances (Sr—Cd, Sr—Pt, and Cd—Pt) are in agreement with those found in some ternary compounds in Cd/Pt/A systems (A = alkaline earth metal).

Packing features top

Sr atoms are bound together into corrugated sheets consisting of edge-sharing Sr4-units. These sheets spread parallel to (001) and are linked by another Sr—Sr bond of 3.674 (3) Å along [001]. (Fig. 2). The crystal structure is also characterized by the existence of linear (Pt—Pt···Pt—Pt)n chains along [010] with longer distances of 3.2010 (14) Å between the tightly bound Pt—Pt dumbbells, a significant distortion in the direction of dimerization. The platinum chains are condensed into (001) sheets through Cd atoms, forming Cd-centred re­cta­ngles with composition Pt2Cd2/2 (Fig 3). The Pt2Cd2/2 layers are stacked along [001] and are linked through the corrugated sheets of Sr atoms.

Database survey top

A search of the Pearson's Crystal Data – Crystal Structure Database for Inorganic Compounds (Villars & Cenzual, 2015) for the Sr/Cd/Pt family of compounds returned two compounds only: SrCd4Pt2 (Samal et al., 2013) and SrCdPt (Gulo & Köhler, 2014).

Synthesis and crystallization top

The title compound was synthesized from starting materials of Sr granules (99.9+%, Alfa Aesar), Cd powder (99.9+%, Alfa Aesar) and Pt powder (99.95%, Chempur). A stoichiometric mixture of these elements was loaded into a Nb ampoule in an Ar-filled dry box. The Nb ampoule was then weld-sealed under an Ar atmosphere and subsequently enclosed in an evacuated silica jacket. The sample was then heated to 1123 K for 15 h, equilibrated at 923 K for 4 days, and followed by slow cooling to room temperature.

Refinement top

Crystal data, data collection and structure refinement details are summarized in Table 1. The maximum and minimum remaining electron densities are located 1.66 and 0.81 Å, respectively, from the Pt site.

Structure description top

A large number of transition metal-based ternary inter­metallic phases have been studied in terms of metal–metal inter­actions and structure–property relationships (Corbett, 2010). Exploratory synthetic approaches in systems Pt/Cd/A (A = alkaline earth metal) has revealed a great compositional and structural diversity. The calcium phase Ca6Cd16Pt8 contains a three-dimensional array of isolated Cd8 tetra­hedral stars (TS) and a face-centred cube of Pt@Ca6 o­cta­hedra (Samal et al., 2013) whilst the structure of Ca6Cd11Pt crystallizes in its own structure type consisting of apically inter­bonded Cd7 penta­gonal bipyramids and five-membered rings of Ca atoms (Gulo et al., 2013). The strontium phase SrCd4Pt2 is made up of chains of edge-sharing Cd4 tetra­hedra bridged by four-bonded Sr atoms (Samal et al., 2013) and SrCdPt presents six-membered rings of Sr atoms in a chair conformation (Gulo & Köhler, 2014). The barium phase BaCd2Pt exhibits zigzag chains of Ba atoms and Pt-centred boat and anti-boat conformations formed by six-membered rings of Cd atoms (Gulo & Köhler, 2015). The Pt-based ternary inter­metallic compounds with general formula A2XPt2 (A = alkaline-earth or rare-earth metal; X = diel, triel, or tetrel element) adopt five different structure types. Sr2InPt2 (Muts et al., 2007) crystallizes in the monoclinic Ca2Ir2S type (Schoolaert & Jung, 2002), Pu2SnPt2 (Pereira et al., 1997) in the tetra­gonal Mo2FeB2 type (Gladyshevskii et al., 1996) while U2CdPt2 has its own structure type (Gravereau et al., 1994). Ce2CdPt2 (Pöttgen et al., 2000) adopts the tetra­gonal U3Si2 type (Zachariasen, 1948), and Ca2CdPt2 (Samal & Corbett, 2012) the orthorhombic Ca2GaCu2 type (Fornasini & Merlo, 1988).

In this article we present the crystal structure of the novel inter­metallic phase Sr2CdPt2 containing linear (Pt—Pt···Pt—Pt)n chains as a principal structural motif.

The ternary inter­metallic title phase adopts the orthorhombic Ca2GaCu2 structure type (Fornasini & Merlo, 1988) with the Ca, Ga, and Cu sites replaced by Sr, Cd, and Pt sites, respectively. The three atoms occupy three independent sites in the unit cell. The Sr atom resides on a special position with site symmetry mm2 (Wyckoff site 4 j), the Cd atom occupies a special positions with site symmetry mmm (2 a) and the Pt atom is on a special positions with site symmetry m2m (4 h). In the two structures, the transition metals (platinum and copper, respectively) occupy the same positions. In contrast, in the structure of SrCd4Pt2 (Samal et al., 2013) which is isotypic with ZrFe4Si2 (Yarmolyuk et al., 1975), the transition metals (platinum and iron, respectively) occupy different positions and the Pt atoms reside on the respective Si sites because silicon and platinum atoms are the most electronegative atoms in the two systems. The new phase Sr2CdPt2 contains 26 valence electrons and, as already mentioned, is isotypic with Ca2GaCu2. However, in comparison the structure of Sr2CdPt2 is appreciably distorted along the platinum chains, presumably because Ca2GaCu2 contains much smaller Cu atoms and a larger valence electron count of 29. Coordination spheres of each atomic site in the title structure are illustrated in Fig. 1. The Sr atom is coordinated by five other Sr, four Cd, and four Pt atoms. The Sr—Sr bond lengths vary from 3.674 (3) to 3.854 (1) Å, the Sr—Cd distances range from 3.490 (1) to 3.577 (1) Å, whereas the Sr—Pt values vary only slightly, from 3.188 (1) to 3.231 (1) Å. Six Sr atoms construct a square-planar pyramid, Sr@Sr5. The existence of Sr—Sr strong bonds is observable in SrCdPt (Gulo & Köhler, 2014) but not in SrCd4Pt2 (Samal et al., 2013). The Cd atom exhibits a coordination number of twelve and has eight Sr and four Pt atoms in its environment with Cd—Pt distances of 2.785 (1) Å. The Pt atom is surrounded by six Sr, two Cd and one Pt atom with a Pt—Pt distance of 2.734 (1) Å. This distance is slightly longer than those found in Ca2CdPt2 (2.659 Å; Samal & Corbett, 2012) or Sr2InPt2 (2.707 Å; Muts et al., 2007) but shorter than those in Pu2SnPt2 (Pereira et al., 1997), U2CdPt2 (Gravereau et al., 1994) or Ce2CdPt2 (Pöttgen et al., 2000). All other inter­atomic distances (Sr—Cd, Sr—Pt, and Cd—Pt) are in agreement with those found in some ternary compounds in Cd/Pt/A systems (A = alkaline earth metal).

Sr atoms are bound together into corrugated sheets consisting of edge-sharing Sr4-units. These sheets spread parallel to (001) and are linked by another Sr—Sr bond of 3.674 (3) Å along [001]. (Fig. 2). The crystal structure is also characterized by the existence of linear (Pt—Pt···Pt—Pt)n chains along [010] with longer distances of 3.2010 (14) Å between the tightly bound Pt—Pt dumbbells, a significant distortion in the direction of dimerization. The platinum chains are condensed into (001) sheets through Cd atoms, forming Cd-centred re­cta­ngles with composition Pt2Cd2/2 (Fig 3). The Pt2Cd2/2 layers are stacked along [001] and are linked through the corrugated sheets of Sr atoms.

A search of the Pearson's Crystal Data – Crystal Structure Database for Inorganic Compounds (Villars & Cenzual, 2015) for the Sr/Cd/Pt family of compounds returned two compounds only: SrCd4Pt2 (Samal et al., 2013) and SrCdPt (Gulo & Köhler, 2014).

Synthesis and crystallization top

The title compound was synthesized from starting materials of Sr granules (99.9+%, Alfa Aesar), Cd powder (99.9+%, Alfa Aesar) and Pt powder (99.95%, Chempur). A stoichiometric mixture of these elements was loaded into a Nb ampoule in an Ar-filled dry box. The Nb ampoule was then weld-sealed under an Ar atmosphere and subsequently enclosed in an evacuated silica jacket. The sample was then heated to 1123 K for 15 h, equilibrated at 923 K for 4 days, and followed by slow cooling to room temperature.

Refinement details top

Crystal data, data collection and structure refinement details are summarized in Table 1. The maximum and minimum remaining electron densities are located 1.66 and 0.81 Å, respectively, from the Pt site.

Computing details top

Data collection: XSCANS (Bruker, 2001); cell refinement: XSCANS (Bruker, 2001); data reduction: XSCANS (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2010); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. Coordination of strontium, cadmium, and platinum atoms in Sr2CdPt2. Displacement ellipsoids are displayed at the 90% probability level.
[Figure 2] Fig. 2. Projection of the crystal structure of Sr2CdPt2 approximately along the b axis.
[Figure 3] Fig. 3. Projection of linear platinum chains that are aligned parallel to b-axis direction and condensed via cadmium atoms forming Pt2Cd2/2-rectangles in the ab-plane
Distrontium cadmium diplatinum top
Crystal data top
CdPt2Sr2F(000) = 560
Mr = 677.82Dx = 9.054 Mg m3
Orthorhombic, ImmmMo Kα radiation, λ = 0.71073 Å
Hall symbol: -I 2 2Cell parameters from 25 reflections
a = 4.5596 (9) Åθ = 12–18°
b = 5.9351 (12) ŵ = 81.39 mm1
c = 9.1874 (18) ÅT = 293 K
V = 248.63 (9) Å3Block, brown
Z = 20.08 × 0.06 × 0.05 mm
Data collection top
Bruker P4 4-circle
diffractometer
190 independent reflections
Radiation source: fine-focus sealed tube172 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.025
Detector resolution: 0 pixels mm-1θmax = 28.3°, θmin = 4.1°
ω–scansh = 56
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
k = 77
Tmin = 0.004, Tmax = 0.017l = 1111
1069 measured reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.022 w = 1/[σ2(Fo2) + (0.0337P)2 + 3.9776P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.058(Δ/σ)max < 0.001
S = 1.16Δρmax = 1.84 e Å3
190 reflectionsΔρmin = 2.51 e Å3
13 parametersExtinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
0 restraintsExtinction coefficient: 0.0024 (4)
Crystal data top
CdPt2Sr2V = 248.63 (9) Å3
Mr = 677.82Z = 2
Orthorhombic, ImmmMo Kα radiation
a = 4.5596 (9) ŵ = 81.39 mm1
b = 5.9351 (12) ÅT = 293 K
c = 9.1874 (18) Å0.08 × 0.06 × 0.05 mm
Data collection top
Bruker P4 4-circle
diffractometer
190 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2001)
172 reflections with I > 2σ(I)
Tmin = 0.004, Tmax = 0.017Rint = 0.025
1069 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.02213 parameters
wR(F2) = 0.0580 restraints
S = 1.16Δρmax = 1.84 e Å3
190 reflectionsΔρmin = 2.51 e Å3
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Pt0.00000.23034 (10)0.50000.0172 (3)
Cd0.50000.50000.50000.0172 (4)
Sr0.00000.50000.19995 (16)0.0162 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pt0.0156 (4)0.0205 (4)0.0155 (4)0.0000.0000.000
Cd0.0157 (8)0.0152 (8)0.0207 (9)0.0000.0000.000
Sr0.0171 (8)0.0169 (8)0.0146 (8)0.0000.0000.000
Geometric parameters (Å, º) top
Pt—Pti2.7341 (13)Cd—Srvii3.4901 (10)
Pt—Cdii2.7855 (5)Cd—Srviii3.5773 (12)
Pt—Cd2.7855 (5)Cd—Sriii3.5773 (13)
Pt—Sriii3.1876 (14)Cd—Sr3.5773 (12)
Pt—Sr3.1876 (14)Cd—Srix3.5773 (13)
Pt—Ptiii3.2010 (14)Sr—Ptiii3.1876 (14)
Pt—Sriv3.2312 (10)Sr—Ptiv3.2312 (10)
Pt—Srv3.2312 (10)Sr—Ptxii3.2312 (10)
Pt—Srvi3.2312 (10)Sr—Ptxiii3.2312 (10)
Pt—Srvii3.2312 (10)Sr—Ptv3.2312 (10)
Cd—Ptiii2.7855 (5)Sr—Cdxiv3.4901 (10)
Cd—Ptviii2.7855 (5)Sr—Cdxiii3.4901 (10)
Cd—Ptix2.7855 (5)Sr—Cdii3.5773 (12)
Cd—Sriv3.4901 (10)Sr—Srxv3.674 (3)
Cd—Srx3.4901 (10)Sr—Srxvi3.8535 (9)
Cd—Srxi3.4901 (10)
Pti—Pt—Cdii125.070 (13)Srviii—Cd—Sriii180.0
Pti—Pt—Cd125.070 (13)Ptiii—Cd—Sr58.560 (14)
Cdii—Pt—Cd109.86 (3)Ptviii—Cd—Sr121.440 (14)
Pti—Pt—Sriii120.139 (18)Ptix—Cd—Sr121.440 (14)
Cdii—Pt—Sriii73.232 (13)Pt—Cd—Sr58.560 (14)
Cd—Pt—Sriii73.232 (13)Sriv—Cd—Sr66.071 (12)
Pti—Pt—Sr120.139 (18)Srx—Cd—Sr113.929 (12)
Cdii—Pt—Sr73.232 (13)Srxi—Cd—Sr66.071 (12)
Cd—Pt—Sr73.232 (13)Srvii—Cd—Sr113.929 (12)
Sriii—Pt—Sr119.72 (4)Srviii—Cd—Sr79.18 (3)
Pti—Pt—Ptiii180.0Sriii—Cd—Sr100.82 (3)
Cdii—Pt—Ptiii54.930 (13)Ptiii—Cd—Srix121.440 (14)
Cd—Pt—Ptiii54.930 (13)Ptviii—Cd—Srix58.560 (14)
Sriii—Pt—Ptiii59.861 (18)Ptix—Cd—Srix58.560 (14)
Sr—Pt—Ptiii59.861 (18)Pt—Cd—Srix121.440 (14)
Pti—Pt—Sriv64.971 (13)Sriv—Cd—Srix113.929 (12)
Cdii—Pt—Sriv145.14 (2)Srx—Cd—Srix66.071 (12)
Cd—Pt—Sriv70.466 (13)Srxi—Cd—Srix113.929 (12)
Sriii—Pt—Sriv134.76 (2)Srvii—Cd—Srix66.071 (12)
Sr—Pt—Sriv73.786 (15)Srviii—Cd—Srix100.82 (3)
Ptiii—Pt—Sriv115.029 (13)Sriii—Cd—Srix79.18 (3)
Pti—Pt—Srv64.971 (13)Sr—Cd—Srix180.0
Cdii—Pt—Srv70.466 (13)Ptiii—Sr—Pt60.28 (4)
Cd—Pt—Srv145.14 (2)Ptiii—Sr—Ptiv134.76 (2)
Sriii—Pt—Srv134.76 (2)Pt—Sr—Ptiv106.214 (15)
Sr—Pt—Srv73.786 (15)Ptiii—Sr—Ptxii106.214 (15)
Ptiii—Pt—Srv115.029 (13)Pt—Sr—Ptxii134.76 (2)
Sriv—Pt—Srv89.75 (3)Ptiv—Sr—Ptxii50.06 (3)
Pti—Pt—Srvi64.971 (13)Ptiii—Sr—Ptxiii106.214 (15)
Cdii—Pt—Srvi70.466 (13)Pt—Sr—Ptxiii134.76 (2)
Cd—Pt—Srvi145.14 (2)Ptiv—Sr—Ptxiii110.71 (5)
Sriii—Pt—Srvi73.786 (15)Ptxii—Sr—Ptxiii89.75 (3)
Sr—Pt—Srvi134.76 (2)Ptiii—Sr—Ptv134.76 (2)
Ptiii—Pt—Srvi115.029 (13)Pt—Sr—Ptv106.214 (15)
Sriv—Pt—Srvi129.94 (3)Ptiv—Sr—Ptv89.75 (3)
Srv—Pt—Srvi69.29 (5)Ptxii—Sr—Ptv110.71 (5)
Pti—Pt—Srvii64.971 (13)Ptxiii—Sr—Ptv50.06 (3)
Cdii—Pt—Srvii145.14 (2)Ptiii—Sr—Cdxiv151.90 (4)
Cd—Pt—Srvii70.466 (13)Pt—Sr—Cdxiv91.620 (18)
Sriii—Pt—Srvii73.786 (15)Ptiv—Sr—Cdxiv48.779 (16)
Sr—Pt—Srvii134.76 (2)Ptxii—Sr—Cdxiv93.47 (3)
Ptiii—Pt—Srvii115.029 (13)Ptxiii—Sr—Cdxiv93.47 (3)
Sriv—Pt—Srvii69.29 (5)Ptv—Sr—Cdxiv48.779 (16)
Srv—Pt—Srvii129.94 (3)Ptiii—Sr—Cdxiii91.620 (19)
Srvi—Pt—Srvii89.75 (3)Pt—Sr—Cdxiii151.90 (4)
Ptiii—Cd—Ptviii180.0Ptiv—Sr—Cdxiii93.47 (3)
Ptiii—Cd—Ptix109.86 (3)Ptxii—Sr—Cdxiii48.779 (16)
Ptviii—Cd—Ptix70.14 (3)Ptxiii—Sr—Cdxiii48.779 (16)
Ptiii—Cd—Pt70.14 (3)Ptv—Sr—Cdxiii93.47 (3)
Ptviii—Cd—Pt109.86 (3)Cdxiv—Sr—Cdxiii116.48 (4)
Ptix—Cd—Pt180.0Ptiii—Sr—Cdii48.21 (2)
Ptiii—Cd—Sriv119.245 (13)Pt—Sr—Cdii48.21 (2)
Ptviii—Cd—Sriv60.755 (13)Ptiv—Sr—Cdii152.59 (2)
Ptix—Cd—Sriv119.245 (13)Ptxii—Sr—Cdii152.59 (2)
Pt—Cd—Sriv60.755 (13)Ptxiii—Sr—Cdii89.339 (16)
Ptiii—Cd—Srx60.755 (13)Ptv—Sr—Cdii89.339 (16)
Ptviii—Cd—Srx119.245 (13)Cdxiv—Sr—Cdii113.929 (12)
Ptix—Cd—Srx60.755 (13)Cdxiii—Sr—Cdii113.929 (12)
Pt—Cd—Srx119.245 (13)Ptiii—Sr—Cd48.21 (2)
Sriv—Cd—Srx180.00 (4)Pt—Sr—Cd48.21 (2)
Ptiii—Cd—Srxi60.755 (13)Ptiv—Sr—Cd89.339 (16)
Ptviii—Cd—Srxi119.245 (13)Ptxii—Sr—Cd89.339 (16)
Ptix—Cd—Srxi60.755 (13)Ptxiii—Sr—Cd152.59 (2)
Pt—Cd—Srxi119.245 (13)Ptv—Sr—Cd152.59 (2)
Sriv—Cd—Srxi116.48 (4)Cdxiv—Sr—Cd113.929 (12)
Srx—Cd—Srxi63.52 (4)Cdxiii—Sr—Cd113.929 (12)
Ptiii—Cd—Srvii119.245 (13)Cdii—Sr—Cd79.18 (3)
Ptviii—Cd—Srvii60.755 (13)Ptiii—Sr—Srxv149.861 (18)
Ptix—Cd—Srvii119.245 (13)Pt—Sr—Srxv149.861 (18)
Pt—Cd—Srvii60.755 (13)Ptiv—Sr—Srxv55.35 (2)
Sriv—Cd—Srvii63.52 (4)Ptxii—Sr—Srxv55.35 (2)
Srx—Cd—Srvii116.48 (4)Ptxiii—Sr—Srxv55.35 (2)
Srxi—Cd—Srvii180.0Ptv—Sr—Srxv55.35 (2)
Ptiii—Cd—Srviii121.440 (14)Cdxiv—Sr—Srxv58.24 (2)
Ptviii—Cd—Srviii58.560 (14)Cdxiii—Sr—Srxv58.24 (2)
Ptix—Cd—Srviii58.560 (14)Cdii—Sr—Srxv140.409 (17)
Pt—Cd—Srviii121.440 (14)Cd—Sr—Srxv140.409 (17)
Sriv—Cd—Srviii66.071 (12)Ptiii—Sr—Srxvi53.63 (3)
Srx—Cd—Srviii113.929 (12)Pt—Sr—Srxvi100.38 (5)
Srxi—Cd—Srviii66.071 (12)Ptiv—Sr—Srxvi151.51 (5)
Srvii—Cd—Srviii113.929 (12)Ptxii—Sr—Srxvi103.14 (3)
Ptiii—Cd—Sriii58.560 (14)Ptxiii—Sr—Srxvi52.59 (2)
Ptviii—Cd—Sriii121.440 (14)Ptv—Sr—Srxvi92.53 (2)
Ptix—Cd—Sriii121.440 (14)Cdxiv—Sr—Srxvi141.30 (3)
Pt—Cd—Sriii58.560 (14)Cdxiii—Sr—Srxvi58.05 (2)
Sriv—Cd—Sriii113.929 (12)Cdii—Sr—Srxvi55.88 (3)
Srx—Cd—Sriii66.071 (12)Cd—Sr—Srxvi101.13 (5)
Srxi—Cd—Sriii113.929 (12)Srxv—Sr—Srxvi103.81 (4)
Srvii—Cd—Sriii66.071 (12)
Symmetry codes: (i) x, y, z+1; (ii) x+1, y, z; (iii) x, y+1, z+1; (iv) x1/2, y+1/2, z+1/2; (v) x+1/2, y+1/2, z+1/2; (vi) x+1/2, y1/2, z+1/2; (vii) x1/2, y1/2, z+1/2; (viii) x1, y, z; (ix) x1, y+1, z+1; (x) x1/2, y+1/2, z+1/2; (xi) x1/2, y+3/2, z+1/2; (xii) x1/2, y+1/2, z1/2; (xiii) x+1/2, y+1/2, z1/2; (xiv) x+1/2, y1/2, z1/2; (xv) x, y+1, z; (xvi) x+1/2, y+3/2, z+1/2.

Experimental details

Crystal data
Chemical formulaCdPt2Sr2
Mr677.82
Crystal system, space groupOrthorhombic, Immm
Temperature (K)293
a, b, c (Å)4.5596 (9), 5.9351 (12), 9.1874 (18)
V3)248.63 (9)
Z2
Radiation typeMo Kα
µ (mm1)81.39
Crystal size (mm)0.08 × 0.06 × 0.05
Data collection
DiffractometerBruker P4 4-circle
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2001)
Tmin, Tmax0.004, 0.017
No. of measured, independent and
observed [I > 2σ(I)] reflections
1069, 190, 172
Rint0.025
(sin θ/λ)max1)0.666
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.022, 0.058, 1.16
No. of reflections190
No. of parameters13
Δρmax, Δρmin (e Å3)1.84, 2.51

Computer programs: XSCANS (Bruker, 2001), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 2010).

 

Acknowledgements

Financial support for EN and FG from PNBP Unsri is gratefully acknowledged.

References

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Volume 72| Part 2| February 2016| Pages 144-146
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