1212 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Znorg. Chem. 1994, 33, zyxwvu 1212-1216 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK "Se Solid-state NMR Studies of [M(Se4)2I2-Anions (M zyxw = Zn, Cd, Hg) Patrick J. Barrie, Robin J. H. Clark,' and Robert Withnallt Christopher Ingold Laboratories, University College London, 20 Gordon Street, London WClH OAJ, U.K. Duck-Young Chung, Kang-Woo zyxwvu Kim, and Mercouri G. Kanatzidis Department of Chemistry, Michigan State University, East Lansing, Michigan 48824 Received September 22, 19930 77Se solid-state N M R spectra have been recorded with cross-polarization and magic-angle spinning on [M(Se4)2]2- complexes with [Me4N]+ (M = Zn, Cd, Hg) and [EtlN]+ (M = Cd, Hg). The large chemical shift anisotropies (of the order of 1000 ppm) mean that fast spinning speeds (9-1 1 kHz) are needed in order to reveal the number of crystallographic selenium sites present within the solid. The spectra enable the principal components of the 'Be shielding tensor to be calculated from the spinning sideband intensities. Differences between the 77Seisotropic chemical shifts observed for the [Et4N]+ complexes and for the [Me4N]+complexes reflect small structural changes in the [M(Se4)2I2- geometry with cation. J-coupling to 199Hg and II1/II3Cd are also observed. The solid-state NMR results are compared with similar work in solution. A single-crystal X-ray structure determination of [Me4NI2- [Hg(Se4)2].0.5DMF is reported (monoclinic crystal system, space group C2/c). The Hg atom is tetrahedrally coordinated by two chelating tetraselenide ligands with both HgSe4 rings adopting the envelope conformation. The IT Raman spectrum of [Me4N]2[Cd(Se&] is also reported. Introduction There has been significant research interest recently in the chemistry of metal polyselenides and polytellurides due to the extensiverange of complexes with novel and interesting structures that can be Thus far, characterization of these complexes has depended principally on single-crystal X-ray diffraction studies, though there has been a certain amount of 77Se/IZSTe NMR workon these species in solution.2 In this paper we report high-resolution solid-state 77Se NMR results on [M(Se4)2I2-complexes with [Me4N]+ (M = Zn, Cd, Hg) and [Et4N]+ (M = Cd, Hg) (DMF solvates in each case; DMF = dimethylformamide). Solution N M R results on some [ M(Se4)2] *- complexes have been reported previously by Ansari e? ale3 Recording the spectra in the solid state has the advantage that it slows down any fluxional processes that may occur in solution and allows direct comparison between N M R chemical shifts and the crystal structure. It has the added advantage that it can provide a measure of the anisotropy of the shielding tensor, which is in general a more sensitive probe of local geometry than is the isotropic chemical shift measured in solution. There have thus far been very few published 77Sesolid-state N M R studies,47 and this is the first report of solid-state N M R results on polyselenide complexes. It is anticipated that the results on these model compounds will prove useful in recording and interpreting 77Se NMR spectra of new polychalcogenide solids.* Also included in f Current address: University of Greenwich, Wellington St., Woolwich, *Abstract published in Aduance ACS Absrracrs. February 15, 1994. (1) (a) Roof, L. C.; Kolis, J. W. Chem. Reu. 1993, 93, 1037. (b) Huang, (2) (a) Kanatzidis, M. zyxwvutsrq G. Commentslnorg. Chem. 1990,10,161. (b) Ansari, (3) Ansari, M. A.; Mahler, C. H.; Chorghade, G. S.; Lu, Y.-J.; Ibers, J. A. (4) Collins, M. J.; Ratcliffe, C. I.; Ripmeester, J. A. J. zyxwvu Magn. Reson. 1986, (5) Harris, R. K.; Sebald, A. Magn. Reson. Chem. 1987, 25, 1058. (6) Gay, I. D.; Jones, C. H. W.; Sharma, R. D. J. Magn. Reson. 1989,84, (7) Batchelor, R. J.; Einstein, F. W. B.; Gay, I. D.; Gu, J.-H.; Pinto, B. M. London SEI8 6PF, U.K. S.-P.; Kanatzidis, M. G. Coord. Chem. Reo., in press. M. A.; Ibers, J. A. Coord. Chem. Rev. 1990, 100, 223. Inorg. Chem. 1990, 29, 3832. 68, 172. 501. J. Organomet. Chem. 1991, 411, 147. 0020-1669/94/ 1333-1212%04.50/0 this paper are the results of an X-ray crystallographic study of [Me4N]2[Hg(Se4)2]-OSDMF, since this proved to be relevant to the interpretation of the solid-state NMR spectra of this and related complexes, and brief comments on the FT Raman spectra of the complexes. Experimental Section Syntheses. [Me4N]2[Hg(Se&OSDMFwas prepared by the following method.9 To a 50-cm3 DMF solution of 0.53 g (1.5 mmol) of Na2Sed and 0.16 g (1.5 mmol) of [MedNJCl was added dropwise for I5 mina 10 cm3 DMF solution of 0.20 g (0.74 mmol) of HgC12, resulting in a dark reddish brown solution. After removal of undissolved precipitates by filtration, 60 cm3 of ether was slowly layered over the filtrate solution to yield, in 1 day, reddish black chunky crystals. These crystals were isolated and washed with ether several times. Morecrystals wereobtained upon layering an additional 30 cm3 of ether over the filtrate solution. Overall yield: 54%. Quantitative microprobe analyses of the complexes were performed on a JEOL 35CF scanning electron microscope (SEM) equipped with a Tracor Northern TN 5500 X-ray microanalysis attachment. Single crystals were mounted on an aluminum stub using conducting silver paint to help dissipate charges that develop on the sample surface during the measurement of energy dispersive spectra (EDS). A correction factor was applied to the analyses based on EDS results on compoundsof known chemical composition. The analyses were an average of four to six individual measurements on different crystals of each compound. The chemical composition of [Me4N]2[Hg(Se4)2].OSDMF determined by this method showed a HgSe ratio of 1:6.9. The density of the crystals was measured to be 2.66 g cm-) using a mixture of CHBr3 and n-heptane. The syntheses of [Me4N]2[M(Se&] (M = Cd, Zn) and [EhNJz- [M(Se&] (M = Hg, Cd) were accomplished by following the same procedure as above, using the appropriate metal chlorides and [Me4N]Cl or [EtdNIBr salts. All samples were stored under nitrogen prior to the NMR measurements. Crystallography. A single crystal of [Me4N]2[Hg(Se4)2J.O.SDMP was placed inside a glass capillary and sealed in using a flame. The crystallographic data were collected on a Nicolet P3 four-circle automated (8) Kanatzidis, M. G. Chem. Mater. 1990, 2, 353. (9) The DMF-free [Me,N]2[Hg(Se,)z] das also prepared and structurally characterized.It crystallizes in theortborhombicspace group Pbca (No. 61) with (I = 15.898(2) A, b = 15.321(2) A, c = 18.523(3) A, V = 4512(1) A3, and Z = 8. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQP 0 1994 American Chemical Society