Znorgnnica Chimica Acta, 191 (1992) 7-9 7
In0
Chi*i*
tram-Effect of dialkyl sulfide on a
Pt(III)-Pt(II1)
bond. Synthesis,
spectroscopy and X-ray crystal structure
of
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Chi-Ming Che”*by*, Ming-Chu Chengb, Yu Wangb and Harry B. Gray
“Depament of Chem&y, Universiq of Hong Kong, Pokfulam Road, Hong Kong (Hong Kong)
bDepariment of Chernbtry, National Taiwan University, Taipei (Taiwan)
‘Arthur Amos Noyes Laboratory, California Institute of Technology, Pasadena, CA 91125 (USA)
(Received September 13, 1991)
Recent spectroscopic and structural studies on the [Pt2(P205H&(XY)J’- system (XY= Cl,, Br,, 12, CH,I, (SCN),, (C&H,N,),, (NO,),, (CH,CN),) established sig- nificant axial a-electronic delocalization between the da(Pt) and 0(X)/a(Y) orbitals [l]. The extent of charge- transfer mixing between the Pt-Pt and Pt-X/Pt-Y bonds can be correlated with the Pt-Pt distances where long Pt-Pt bonds are usually found with those axial ligands X and Y having strong o-donor strengths [l, 21. Herein is described the synthesis and X-ray structure of [Ptz(PzO,H,),(SEt,),]*-, illustrating that are neutral Et,S is an even better a-donor to Pt(II1) than are anionic ligands such as SCN- and I-. The photo- chemical reactions of [Pt2(P20,H2),14- with dialkyl sulfides have been described previously [3].
Experimental
[Bu4Nl4[Ptz(P,OSH,)41
was prepared by the literature method [4]. All reagents (analytical grade) for synthesis and spectroscopic measurements were obtained from Aldrich Co. Ltd. UV-Vis and 31P NMR spectra were recorded on a Shimadzu UV-240 spectrophotometer and a Jeol model FX 90Q spectrometer (90 MHz), respectively.*Author to whom correspondence should be addressed.
A methanolic solution (20 ml) containing [Bu4N]4[Pt2(P205H2)4] (0.5 g) and Et,S (1 g) was treated with H,O, (30%, 2 ml) at room temperature. After effervescence ceased, the solution was left to stand in air for 15 min. Addition of diethyl ether to the solution gave the orange product in high yield (> 80%). Crystals of [Bu4N]2[Pt2(P205H2),(SEt2)2] were obtained by vapor difision of diethyl ether into acetonitrile solution.
X-ray structure determination
The [Bu4N]2[Pt2(P205H2)4(SEt2)2] complex was re- crystallized by diffusion of diethyl ether into acetonitrile. Crystal data: k= 1623.25, monoclinic, space grou P2,/c, a = 11.240(2), b = 12.700(3), c =22.101(6) K
p=91.27(2)“, V=3154(1)A3,Z=2,D,,,=1.713gcrn3:
F(OOO) = 1628, crystal dimensions = 0.20 X 0.30 X 0.40 mm. The intensity data were measured on a CAD-4 diffractometer using MO Ka radiation (h =0.7107 A) using the w/20 scan mode at 297 K with 2&,,,,=50“. Cell dimensions were obtained from 25 reflections with 28 angle in the range of 19.28-23.82”. A total of 6142 reflections was measured and 3294 reflections were observed (I> 2.00(I)). Absorption corrections (p = 48 cm-l) were made according to ?P curves of 3 selected reflections. The minimum and maximum transmission factors are 0.73 and 1.0. The structure was solved by the Patterson method and refined by least-squares. Full matrix least-squares refinement on 334 parameters con- verged to yield agreement indices R(F) =0.055, R,(F) = 0.053 and GOF = 2.74. Table 1 lists the atomic coordinates of non-hydrogen atoms.
Results and discussion
As with other [Pt2(P20sH2)4XY]“- complexes [2a], oxidation of [Pt2(P205H2)4]4- with H202 in the presence of excess Et2S gave [Pt2(P205H2)4(SEt2)2]2-. The 31P NMR spectrum of [Pt2(P20,H2),(SEt2),]*- shows a pseudo triplet with 6=25.1 ppm (relative to H,PO,) and J,(Pt-P) =2040 Hz, which are characteristics of the [Pt,(P,O,H,),XY]“- system. Figure 1 shows the ORTEP plot of the complex anion with atom numbering. There are two cations and one complex anion in an asymmetric unit. The [Bu,N]+ ion is in a regular tetrahedral symmetry. The complex anion shown in Fig. 1 has a Ci molecular symmetry with i at the midpoint of the Pt-Pt bond. Four bridging diphosphite ligands are bonded to two Pt atoms in a rough C,, symmetry with two axial Et,S ligands tram to the Pt-Pt bond. The Pt-Pt-S(SEt,) group is essentially linear (Pt-Pt-S= 173.41(14)“). As in the cases of other ]Pt,(P,Q,H,),XYl” - complexes [2], the PtP4 units are
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TABLE 1. Atomic parameters x, Y, z and Bi, (e.s.d.s refer to the last digit printed)
Pt s Pl P2 P3 P4 01 02 011 012 021 022 031 032 041 042 Cl c2 c3 c4 N Cl1 Cl2 Cl3 Cl4 c21 c22 C23 C24 c31 C32 c33 c34 c41 C42 c43 c44 0.10848(6) 0.2908(4) 0.0254(5) 0.0634(6) 0.2022(5) 0.1629(6) -0.1194(12) -0.0771(12) 0.0627( 16) 0.0517(13) 0.0766( 14) 0.1349(14) 0.2313(14) 0.3146(10) 0.2898(12) 0.1611(16) 0.3737(25) 0.4577(23) 0.4067(19) 0.442(3) 0.1881(14) 0.1578(23) 0.2452(22) 0.216(3) 0.305(3) 0.206(3) 0.230(3) 0.255(4) 0.277(4) 0.286(4) 0.400(S) 0.470(3) 0.500(5) 0.058(4) -0.008(S) -0.107(3) -0.171(3) 0.51001(5) 0.5404(4) 0.4532(5) 0.6838(4) 0.5654(5) 0.3351(5) 0.4544( 14) 0.7074(12) 0.3440(12) 0.5337( 14) 0.6990( 12) 0.7669(10) 0.6833(11) 0.4978(16) 0.3315(12) 0.2589( 10) 0.4156(18) 0.4277(20) 0.6164(18) 0.7087( 18) 0.0088(13) -0.1033(19) - 0.1669(22) -0.2631(18) - 0.3338(24) 0.0888(21) 0.1836(24) 0.2423(24) 0.329(3) 0.016(3) 0.068(4) 0.051(3) 0.148(3) 0.0416(21) - 0.0146(23) 0.0430(22) -0.014(3) - essentially planar (Pt-Pt-P 0.03022(3) 0.0930(3) 0.1224(3) 0.0606(3) - 0.0590(3) 0.0037(4) 0.1175(6) 0.0524(7) 0.1411(g) 0.1750(S) 0.1293(7) 0.0227(10) - 0.0598(7) - 0.0727(6) -0.0253(S) 0.0602(9) 0.1106(14) 0.1590(15) 0.0567(9) 0.0845(15) 0.1924(7) 0.2209(12) 0.2488(12) 0.2732( 12) 0.2865(15) 0.2444(14) 0.2521(18) 0.3014(16) 0.3085(19) 0.1424(14) 0.1232(24) 0.0856(12) 0.0538( 18) 0.1693(13) 0.1200(12) 0.0925(13) 0.0507(11) 2.57(3) 5.0(3) 5.8(3) 6.3(4) 5.9(3) 7.2(4) 8.3(11) 8.0(9) 9.8(12) 8.3(10) 8.8( 10) 10.4(13) 8.1(9) 8.4(10) 8.5(10) 10.6(11) 11.8(20) 11.9(20) 6.5(13) 13.9(25) 5.9(9) 9.1(17) 9.5(18) 9.5(18) 13.6(24) 12.2(21) 17.1(30) 17.8(30) 21.7(39) 19.6(32) 35.0(57) 16.1(28) 28.1(48) 16.6(31) 13.0(22) 12.2(20) 14.0(25) angles, 91.39(16)- _ _
91.75(15)“). Th e most interestin structural feature is the Pt-Pt distance of 2.766(l) R . This Pt-Pt distance is the longest reported for the [Pt,(P,O,H,),XY]“- system [l]. It is even longer than that for [Pt,(P,O,H,),(SCN)J- and [Pt,(P,0,H,),IJ4- where the respective Pt-Pt distances are 2.760(l) [2a] and 2.754-2.746(l) [2b] A. This finding suggests that (+- electronic delocalization of the Pt(III)-Pt(II1) with the Pt-SEt, bond is even more pronounced than that with Pt-SCN and Pt-I. The Pt-S(SEt,) distance of 2.479(5) %, is comparable to that of 2.466(4) 8, [2a] for PtS(SCN) in [Pt2(P205H2)4(SCN),]4-. Figure 2 shows the UV-Vis absorption spectrum of [Ptz(Pz0,H,),(SEt&J2- in acetonitrile at room temperature. The intense band at 342 nm with q_=3.2x104 mol-l dm3 cm-’ is un-
Fig. 1. ORTEP plot of [Pt,(PzOsH,),(SEt,),]*- with atom num- bering. Pt-Pt,, 2.766(l); Pt-S, 2.479(5); Pt-P(l), 2.372(6); Pt-P(2), 2.365(5); Pt-P(3), 2.364(6); Pt-P(4), 2.381(6); P(3)-O(l), 1.629(14); P(3)-0(31), 1.533(15); P(3)-0(32), 1.563(15) A. pt,-Pt-S, 173.41(14); Pt,-Pt-P(l), 91.56(14); Pt,-Pt-P(2), 91.75(15); Pt,-Pt-P(3), 91.66(14); Pt,-Pt-P(4), 91.39(16); S-Pt-P(l), 84.41(19); S-Pt-P(2), 82.85(20); S-Pt-P(3), 92.44(19); S-Pt-P(4), 93.96(20); P(l)-Pt-P(2), 87.09(25); P(l)-Pt-P(3), 176.71(20); P(I)-Pt-P(4), 92.0(3); Pt-SC(l), 112.7(g); Pt-S-C(3), 115.2(7); Pt-P(l)-O(l), 110.6(6)“. I .?
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x 40 1 203 300 03 500 A (nm)Fig. 2. UV-Vis absorption spectrum of [Pt2(PZOSH&(SEt&]*- in acetonitrile at room temperature.
doubtedly due to the @Et,) + da*(Pt) charge-transfer transition. This energy is also lower than that for the a(SCN) --) do*(Pt) (337 nm) in [Pt2(P20,H,)4(SCN)2]4- [2a] or u(I)-+da*(Pt) (338 nm) in [Pt2(P20,H2),12J4- [2b]. Thus the spectroscopic data correlate with the X-ray result that the energy of the u(SEt,) orbital is even higher than that for the a(SCN-) and ~(1~) orbitals.
Supplementary material References
Full tables of bond lengths and angles, H-atom co- ordinates, thermal parameters and structure factors are available from Yu Wang (Taiwan).
Acknowiedgements
Financial support from the University of Hong Kong, the Croucher Foundation and the National Research Council of Taiwan is gratefully acknowledged.
1 D. M. Roundhill, H. B. Gray and C. M. Che, Act. Chem.
Rex, 22 (1989) 55.
2 (a) C. M. Che, W. M. Lee, T. C. W. Mak and H. B. Gray, J Am. Chem. Sot., 108 (1986) 4446; (b) K. A. Alexander, S. A. Bryan, F. R. Fronczek, W. C. Fultz, A. L. Rheingold, D. M. Roundhill, P. Stein and S. F. Watkins, Znorg. Chem., 24 (1985) 2803.
3 C. M. Che, L. G. Butler, P. J. Grunthaner and H. B. Gray, Znorg. Chem., 24 (1985) 4662.
4 C. M. Che, H. L. Kwong and K. C. Cho, Zno~ Chem., 27 (1988) 3691.
![Fig. 2. UV-Vis absorption spectrum of [Pt2(PZOSH&(SEt&]*- in acetonitrile at room temperature](https://thumb-ap.123doks.com/thumbv2/9libinfo/8681472.197238/2.832.431.777.521.784/fig-vis-absorption-spectrum-pzosh-set-acetonitrile-temperature.webp)
