The crystal structure of trans-[((bis)triethylphosphine)(bis(phenylselenato))platinum (II)] has been determined by single crystal X-ray diffraction. Crystallization occurs in the triclinic space group P-1 (No. 2) with a = 8.9964(2) Å, b = 11.5103(2) Å, c = 14.9335(3) Å; α = 85.8750(10)°, β = 72.5350(10)°, γ = 68.4450(10)°. Details of the structure and spectroscopic results are presented and discussed and comparisons are made with related square planar platinum (II) structures

Lindeman, Sergey V.

Rudd, Martin D.

English

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Marquette Universitye-Publications@MarquetteChemistry Faculty Research and Publications Chemistry, Department of5-1-2007Synthesis and Characterization of platinum –selenium Derivatives: X-ray Structure of trans-Pt(Pet3)2(SePh)2Martin D. RuddUniversity of Wisconsin - Fox ValleySergey V. LindemanMarquette University, sergey.lindeman@marquette.eduAccepted version. Journal of Chemical Crystallography, Vol. 37, No. 5 (May 2007): 375-379. DOI. ©2007 Springer Science+Business Media, LLC. Used with permission.Shareable Link. Provided by the Springer Nature SharedIt content-sharing initiative. Marquette University e-Publications@Marquette  Chemistry Faculty Research and Publications/College of Arts and Sciences  This paper is NOT THE PUBLISHED VERSION; but the author’s final, peer-reviewed manuscript. The published version may be accessed by following the link in the citation below.  Journal of Chemical Crystallography, Vol. 37, No. 5 (May 2007): 375-379. DOI. This article is © Springer Science+Business Media, LLC and permission has been granted for this version to appear in e-Publications@Marquette. Springer Science+Business Media, LLC does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Springer Science+Business Media, LLC.   Synthesis and characterization of platinum – selenium derivatives: X-ray structure of trans-Pt(PEt3)2(SePh)2  Martin D. Rudd Department of Chemistry, University of Wisconsin – Fox Valley, Menasha, WI Sergey V. Lindeman Department of Chemistry, Marquette University, Milwaukee, WI  The crystal structure of trans-[((bis)triethylphosphine)(bis(phenylselenato))platinum (II)] has been determined by single crystal X-ray diffraction. Crystallization occurs in the triclinic space group P-1 (No. 2) with a = 8.9964(2) Å, b = 11.5103(2) Å, c = 14.9335(3) Å; α = 85.8750(10)°, β = 72.5350(10)°, γ = 68.4450(10)°. Details of the structure and spectroscopic results are presented and discussed and comparisons are made with related square planar platinum (II) structures. KEY WORDS: Platinum, selenium, phosphine, square planar.  Introduction The coordination chemistry of platinum (II) is well developed and is characterized by many interesting square planar complexes exhibiting both cis and trans geometries. In addition, there has been considerable recent interest in the chemistry of organoselenides and selenium containing ligands because of the catalytic,1 conducting2 and biomedical3 properties of their compounds. Selenides also exhibit a range of common coordination modes to transition metals such as η1 (this work) and μ2 (e.g. [Pt2(μ-Se)2(PPh3)4].4 There are two straightforward synthetic preparations for mononuclear platinum complexes containing selenolato ligands: firstly, the addition of diaryl diselenides (R2Se2) to Pt(0) complexes results in an oxidative addition reaction, and secondly a metathesis reaction of Pt(II) halides with NaSeR. An increasingly large amount of work is being focused on the behavior of coordinated selenide with regards to its functionalization and transformation. Relatively few square planar Pt(II) complexes containing a “PtP2Se2” core have been synthesized and structurally characterized. Of the compounds that have been structurally characterized, only Pt(PPh3)(SePh)2 has been reported as a pair of geometrical isomers (cis and trans).5 – 7 In the oxidative addition process of adding Ph2Se2 to Pt(PPh3)4, the two isomers were reported to be formed at different temperatures: 80°C for the trans isomer and room temperature for the cis isomer with low temperature isolation (−5°C) needed to obtain crystals of the cis product. Interestingly, the usual way for observing both isomers is through the oxidative addition pathway to a Pt(0) center: a slow isomerization is seen at room temperature with a decrease in the monitored 31P resonances for the cis isomer and a corresponding increase in signal height for the trans isomer.7 It has been found, until recently, that the metathesis reaction of NaSePh with cis-[PtCl2(L)2] (L = monodentate ligand) produced only the trans isomer.5 , 8 However, in a few cases Jain et al. 9 reported that multinuclear NMR spectra indicated a slow cis to trans isomerization even when NaER (E = Se, Te, R = Ph, substituted Ph) reacted with mononuclear Pt complexes. In our manuscript, we report the synthesis and crystal structure of trans-Pt(PEt3)2(SePh)2 along with some multi-nuclear NMR data and an attempted isolation of the cis isomer. The synthetic scheme is shown below in Eq. 1.   Equation 1. Synthesis of trans-Pt(PEt3)2(SePh)2. Experimental All manipulations were carried out using conventional vacuum/Schlenk techniques under an atmosphere of argon. Cis-dichlorobis (triethylphosphine)platinum (II) was prepared according to a literature method.10 NMR spectra were recorded on a Bruker AMX-360 spectrometer operating at 360 MHz (1H), 90.5 MHz (13C) and 145 MHz (31P). Elemental analysis was performed at Atlantic Microlab (Norcross, GA). A sample of cis-dichlorobis (triethylphosphine)platinum (II) (0.50 g, 1.0 mmol) was dissolved in dry tetrahydrofuran (15 mL). To this solution was added a tetrahydrofuran solution of NaSePh11 (0.37 g, 2.1 mmol) and the mixture was warmed to 50°C for 1 h. The solvent was removed in vacuoand the residue was re-dissolved in methylene chloride. It was filtered to remove insoluble NaCl and reduced to ca. 5mL. Upon layering with n-hexane and cooling to −10°C, small yellow crystals of the title compound were obtained. Yield 0.77 g (65%). In addition, we attempted to synthesize the cis isomer of Pt(PEt3)2(SePh)2in an NMR tube at low temperature and record its NMR spectrum. In a dry NMR tube containing 1 mL d8-thf at −20°C, was added cis-PtCl2(PEt3)2(10 mg) followed by NaSePh (7 mg). The mixture was shaken and allowed to stand at this temperature for 1 hour. The NMR spectrum was also recorded at −20°C. Characterization Trans-Pt(PEt3)2(SePh)2: 1H NMR (d8-thf): 1.00 (d of t, 18H, P-CH2CH 3), 2.00 (d of d, P-CH 2-CH3), 7.02 – 7.65 (10H, arom); 13C NMR: 8.36 (P-CH2CH3), 14.57 (P-CH2CH3), 123.46 – 139.11 (arom); 31P NMR: 6.4 ppm (J (PtP) = 2474 Hz). Elemental Analysis: Found C: 38.94 (Requires 38.77%); Found H: 5.39 (Requires 5.42%) Cis-Pt(PEt3)2(SePh)2: 31P NMR (d8-thf): 7.7 ppm (J(PtP) = 2740 Hz). X-Ray Crystal and data collection parameters for Pt(PEt3)2(SePh)2 are given in Table 1. Diffracted intensities were collected on a Bruker APEX2 CCD detector using graphite monochromated Mo Kα X-radiation at −150°C. Final unit cell dimensions were determined from the 6837 reflections for 1. The data were corrected for absorption effects using a semi-empirical multi-scan method.12 Table 1. Crystal Data and Structure Refinement CCDC deposit no. 602972 Color/shape Yellow/prism Crystal size (mm) 0.22 × 0.17 × 0.12 Empirical formula C24H40P2PtSe2 Formula weight 743.51 Temperature (K) 123(2) Crystal system Triclinic Space group P-1  a (Å) 8.9964(2)  b (Å) 11.5103(2)  c (Å) 14.9335(3)  α (°) 85.8750(10)  β (°) 72.5350(10)  γ (°) 68.4450(10)  V (Å)3 1370.65(5)  Z 2 Dc (mg m−3) 1.802 μ (Mo Kα) (mm−1) 7.900 Theta range for collection 1.90 to 32.93 Reflections collected 8073 Independent reflections 6837 [R (int) = 0.0294] Data/restraints/parameters 6837 / 0 / 272 Goodness of fit on F 2 1.016 Final R indices [I > 2σ(I)] R1 = 0.0417, wR2 = 0.1034 R indices (all data) R1 = 0.0538, wR2 = 0.1085 Extinction coefficient 0.0069(4) Largest difference peak/hole 2.515 / −2.264 e/A3 The structure was solved by direct methods which gave the location of all non-hydrogen atoms using SHELXTL ver. 6.12.13 Refinements were made by using a full-matrix least squares on all F 2 data using SHELXL.14 Anisotropic thermal parameters were included for all non-hydrogen atoms. All hydrogen atoms were included in calculated positions and allowed to ride on their parent carbon atom with fixed isotopic thermal parameters [Uiso(H) = 1.2U iso(parent)]. Results and discussion Figure 1 shows a thermal ellipsoid plot for one of the independent molecules in the unit cell for compound 1. An analysis of the structure reveals there are two independent molecules in the unit cell with each molecule located on a crystallographic inversion center. As expected the molecules are approximately square planar in shape [(P-Pt-Se) angles 85.85°/94.15° and 86.39°/93.61°]. Bond lengths around the central Pt atom are within the range typically found in this type of complex: Pt-P 2.3231(12)  and 2.3252(14)  . In a similar reported compound, a Pt-P distance of 2.304(2)  was found in trans-[Pt(PEt3)2(4-MeSeBzo)2]15 [(4-MeSeBzo)=4=methylbenzenecarboselenoato)].  Fig. 1. Thermal ellipsoid (50% probability) plot and labeling diagram of trans-Pt(PEt3)2 (SePh)2.  In this, and closely related complexes reported in their paper, Kawahara et al. found [J(PtP) ≈ 2450 Hz], comparable to the value in this study and indicative of a trans geometry. In their synthetic method of using NaSeC(O)R’ with cis or trans-[PtCl2(PEt3)2], their products obtained had only trans stereochemistry. Similarly for the Pt-Se distances, there are several related compounds available for comparison. Some of the data relating to pertinent bond distances and lengths is summarized in Table 2. The longer Pt-P bond lengths observed in the structure of 1 (compared to cis structural characterizations) confirm previous reports that the selenolato ligand (PhSe−) has a slightly stronger trans influence than the phosphine ligand.   Table 2. Comparison of Selected Bond Distances (  ) and Angles (°)   [Pt(PEt3)2(4-MeSeBzo)2]13 [Pt(PPh3)2(SePh)2]6 [Pt(PPh3)2(SePh)2]6 [Pt(PPh3)2(SePh)2]5 [Pt(dppe)(SePy)2]15 [Pt(PEt3)2(SePh)2] Geometry/Notes trans trans/An earlier report of this structure is of limited accuracy7 cis cis cis/Standard deviations not reported for all measurements trans/This work – two independent molecules Bond distance             Pt-P 2.304(2) 2.3144(12)/2.3249(12) 2.2900(6)/2.2937(6) 2.310(2)/2.3111(19) 2.271/2.244 2.3231(12)/2.3252(14) Pt-Se 2.452(1) 2.4525(5)/2.4548(5) 2.4885(3)/2.4506(3) 2.4604(10)/2.4970(9) 2.4335(13)/2.4980(14) 2.4692(5)/2.4744(5) Se-C 1.913(6) (Not reported) (Not reported) 1.916(8)/1.937(8)   1.916(5)/1.918(5) Bond Angle             P(1)-Pt-Se(1)/ P(2)-Pt-Se(2) 87.33(5)/92.67(5) 93.93(3)/95.21(3) 82.21(2)/85.85(2) 82.25(1)/85.75(6) 104.65/88.00 85.85(4)/86.39(3) Pt-Se-C(1) 98.3(1) (Not reported) (Not reported) 106.8(2) 115.64 104.69(17)/102.59(14)  Pt(II) does not form complexes with six donor ligands, although there are instances of weak Pt-Pt interactions in square planar complexes with planar ligands; for example in the complex Pt(bipy)Cl2, there are observed Pt-Pt separations of approx. 3.5  .16 In our reported structure, there are no such “short” contacts: the Pt atoms on adjacent molecules are >8.5 apart. The NMR tube experiment did indeed form cis-PtCl2(PEt3)2 at low temperatures (−20°C) but we were unable to isolate crystals from this reaction. However, the 31P NMR signal at 7.7 ppm [J(PtP) = 2740 Hz) is clearly indicative of the presence of the cis isomer. In their synthesis of Pt(SePh)2(PPh3)2, Hannu et al. 6 report 31P resonances at 19.1 and 20.8 ppm for the cis and trans isomers respectively, again with the J(PtP) value higher in the cis isomer. Comparable results are observed in this work. Notes Acknowledgments MDR would like to thank the University of Wisconsin Fox Valley’s Professional Development Committee for their generous funding of this research and to Marquette University for the use of their X-ray diffraction facilities. Supplementary materials Crystallographic data for the structural analysis of compound 1 has been deposited at the Cambridge Crystallographic Data Center (CCDC number 602972). Copies of the information may be obtained free of charge from The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk). References 1Wang, K.; Stiefel, E. I., Science, 2001, 291, 106.  2Batsanov, A. S.; Bryce, M. R.; Dhindsa, A. S.; Howard, J. A.; Underhill, A. E., Polyhedron, 2001, 20, 537. 3Scott, M. L.; Martin, J. L.; Shapiro, J. R.; Klayman, D. L.; Shrift, A. Organic Selenium Compounds: Their Chemistry and Biology: Wiley Interscience: New York, 1973; Ch. 13, p 629.  4Bencini, A.; Vaira, M. D.; Morassi, R.; Stoppioni, P., Polyhedron, 1996, 15, 2079.  5Ananikov, V. P.; Beletskaya, I. P.; Aleksandrov, G. C.; Eremenko, I. L., Organometallics, 2003, 22, 1414.  6Hannu, M. S.; Oilunkaniemi, R.; Laitinen, R. S.; Ahlgén, M., Inorg. Chem. Commun., 2000, 3, 397. 7Jain, V. K.; Kannan, S.; Tiekink, E. R. T., J. Chem Res., 1994, 85. 8Gupta, S. K.; Khandelwal, Indian J. Chem., 1990, 29A, 977  9Jain, V. K.; Singhal, A.; Narayan, S.; Phosphorus Sulfur Silicon, 1998, 136, 483  10Parshall, G. W., Inorg. Synth., 1970, 12, 26.  11Jain, V. K.; Kannan, S., J. Organomet. Chem., 1991, 405, 265.  12Sheldrick, G. M., SADABS, version 2004–1; Bruker-Nonius Area Detector Absorption and Other Corrections. Bruker-Nonius X-ray Analytical Systems: Madison, WI, 2005.  13Sheldrick, G. M. SHELXTL, Version 6.12, Bruker AXS: Madison, WI, 2001.  14Sheldrick, G. M. SHELXL 97, Program for Crystal Structure Refinement, University of Göttingen: Germany, 1997.  15Kawahara, Y.; Kato, S.; Kanda, T.; Murai, T.; Miki, K., J. Chem. Soc. Dalton Trans., 1996, 79.  16Sartori, D. A.; Hurst, S. K.; Wood, N.; Larsen, R. D.; Abbott, E. H., J. Chem. Crystallogr., 2005, 35, 995.  17Lokanath, N. K.; Devarajegowda, H. C.; Anadalwar, S. M.; Prasad, J. S.; Narayan, S.; Jain, V. K., Anal. Sci., 2001, 17, 565.   

Synthesis and Characterization of platinum – selenium Derivatives: X-ray Structure of \u3cem\u3etrans\u3c/em\u3e-Pt(Pet\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e(SePh)\u3csub\u3e2\u3c/sub\u3e

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Synthesis and Characterization of platinum – selenium Derivatives: X-ray Structure of \u3cem\u3etrans\u3c/em\u3e-Pt(Pet\u3csub\u3e3\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e(SePh)\u3csub\u3e2\u3c/sub\u3e

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