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Recueil des Trauau Chimiques des Pays-Bas, 114/07, July 1995 337 01 65-05 13/95/07337-02$09.50 Red. Trav. Chim. Pays-Bas 114,337-338 (1995) Preliminary Communication Synthesis and crystal structure of [Bu,N] [Ni(mdt)2], a novel nickel dithiolene complex ( H p d t = 2H-1,3-dithiole-4,5-dithiol). Yvonne S. J. Veldhuizen; Nora Veldman: Anthony L. Spek,b Jaap G. Haasnoof,*' and Jan Reedijk' a Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands (Received April 19, 1995) Abstract: [Bu4N]@i(rndt),] (H2mdt = 2H- 1,3-dithiole-4,5-dithiol) has been prepared in a three-step synthesis from [B~,N]~[Zn(drmt)~] (H2drmt = 2-thione- 1,3-dithlole-4,5-dithiol). The crystal structure is reported which shows that the Ni(mdt), anion is distorted significantlyfrom planarity. The synthesis of the first conducting metal dithiolene complex in 1983, [Bu,N],@i(drmt),],.2CH3CN (H,dmit = 2-hone- 1,3-dithiole-4,5-dihol)', initiated intensive research in the area of conducting coordination compounds based on dmit. Variation of the counterion of the anionic M(dmit), complex resulted in the synthesis of a large variety of conductingcompounds during the last decade2. Variation of the sulfur ligand is currently the topic of interest of many research groups. A way of varying the ligand system is by substituting one or more of the sulfur atoms by the larger selenium atoms. [Me,NI@i(drmse),], was for instance the first conducting complex in which the k o n e function of the drmt ligand was substituted b a selenone here the synthesis of a completely new variation of the nickel diholene complex, [B~~N]wi(rndt)~] (H2mdt = 2H- 1,3-di- -hole-4,5-dihol) in whch the hone function of the drmt ligand is substituted bf two hydrogen atoms. In fact Ni(mdt), is the inorganic analog of the organic donor BMDT-TTF (bis(methylenedithl0)-tetrathdulvalene), which was first synthesized in 1984'. With this donor several conducting compounds have been synthesized, among whch (BMDT-TTF),Au(CN), was one of the most successful conductors (a(RT) = 300 S/cm, with metallic behaviour down to 80 Q6. In a way the new complex can be considered as a variation on @i(dddt),] (H2dddt = 5,6-dihydro-1,4-dithiin-2,3- dithiol), first synthesized in 1985' as the inorganic analog of BEDT-TTF (bis(ethy1enediho)-tetrahafblvalene). So far @i(dddt),], (HS04)2 is the best conductor synthesized with thls unit (+T) = 60-300 S/cm, metallic behaviour down to 25 K)8. The route to the synthesis of ~u,N]@i(rndt),] is shown in Scheme 1. All reactions were carried out under a dinitrogen atmosphere. Ligand precursors 1 and 2 were synthesized by a combination of the methods described in refs. 9 and 10. The final product was synthesized according to the (H2dmtse = 2-selenone-1,3-dittuole-4,5-dithiol) 3y4 7 . We report method described by Faulmann et al. for the synthesis of M(dddt), compounds' '. Orange-brown crystals precipitated hm the dark red solution at - 18 "C. The oxidation state of - 1 for Ni(mdt), was shown by the C=C vibration of 1325 cm- ' in the infrared spectrum and was confirmed by elemental analyses 12. Scheme I Recrystallisation ffom a 1:l mixture of acetone and iso-propanol resulted in sin le crystals suitable for X-ray structure deter~nination'~~''. The crystallographically independent unit consists of one Ni(mdt), anion and one Bu4N cation. Figure 1 shows the labelling scheme of the heavy atoms in the Ni(mdt), unit. The observed Ni- S bond lengths vary from 2.154(2) to 2.170(2) A. This variation is slightly larger than usually found for [Ni(dddt),]-, e.g. 2.130(6) - 2.145(9) A for [B~,NJ[Ni(dddt)~]'~. The observed C=C bonds lengths are 1.372(11) and 1.349(10) A for C(2)-C(3) and C(4)-C(5), respectively.

Synthesis and crystal structure of [Bu4N][Ni(mdt)2], a novel nickel dithiolene complex (H2mdt = 2H-1,3-dithiole-4,5-dithiol)

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Page 1: Synthesis and crystal structure of [Bu4N][Ni(mdt)2], a novel nickel dithiolene complex (H2mdt = 2H-1,3-dithiole-4,5-dithiol)

Recueil des Trauau Chimiques des Pays-Bas, 114/07, July 1995 337

01 65-05 13/95/07337-02$09.50 Red. Trav. Chim. Pays-Bas 114,337-338 (1995)

Preliminary Communication

Synthesis and crystal structure of [Bu,N] [Ni(mdt)2], a novel nickel dithiolene complex ( H p d t = 2H-1,3-dithiole-4,5-dithiol).

Yvonne S. J. Veldhuizen; Nora Veldman: Anthony L. Spek,b Jaap G. Haasnoof,*' and Jan Reedijk'

a Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands

Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands

(Received April 19, 1995)

Abstract: [Bu4N]@i(rndt),] (H2mdt = 2H- 1,3-dithiole-4,5-dithiol) has been prepared in a three-step synthesis from [B~,N]~[Zn(drmt)~] (H2drmt = 2-thione- 1,3-dithlole-4,5-dithiol). The crystal structure is reported which shows that the Ni(mdt), anion is distorted significantly from planarity.

The synthesis of the first conducting metal dithiolene complex in 1983, [Bu,N],@i(drmt),],.2CH3CN (H,dmit = 2-hone- 1,3-dithiole-4,5-dihol)', initiated intensive research in the area of conducting coordination compounds based on dmit. Variation of the counterion of the anionic M(dmit), complex resulted in the synthesis of a large variety of conducting compounds during the last decade2.

Variation of the sulfur ligand is currently the topic of interest of many research groups. A way of varying the ligand system is by substituting one or more of the sulfur atoms by the larger selenium atoms. [Me,NI@i(drmse),], was for instance the first conducting complex in which the kone function of the drmt ligand was substituted b a selenone

here the synthesis of a completely new variation of the nickel diholene complex, [B~~N]wi(rndt)~] (H2mdt = 2H- 1,3-di- -hole-4,5-dihol) in whch the hone function of the drmt ligand is substituted bf two hydrogen atoms.

In fact Ni(mdt), is the inorganic analog of the organic donor BMDT-TTF (bis(methylenedithl0)-tetrathdulvalene), which was first synthesized in 1984'. With this donor several conducting compounds have been synthesized, among whch (BMDT-TTF),Au(CN), was one of the most successful conductors (a(RT) = 300 S/cm, with metallic behaviour down to 80 Q6. In a way the new complex can be considered as a variation on @i(dddt),] (H2dddt = 5,6-dihydro- 1,4-dithiin-2,3- dithiol), first synthesized in 1985' as the inorganic analog of BEDT-TTF (bis(ethy1enediho)-tetrahafblvalene). So far @i(dddt),], (HS04)2 is the best conductor synthesized with thls unit (+T) = 60-300 S/cm, metallic behaviour down to 25 K)8.

The route to the synthesis of ~u,N]@i(rndt),] is shown in Scheme 1 . All reactions were carried out under a dinitrogen atmosphere. Ligand precursors 1 and 2 were synthesized by a combination of the methods described in refs. 9 and 10. The final product was synthesized according to the

(H2dmtse = 2-selenone-1,3-dittuole-4,5-dithiol) 3y4 7 . We report

method described by Faulmann et al. for the synthesis of M(dddt), compounds' '. Orange-brown crystals precipitated h m the dark red solution at - 18 "C. The oxidation state of - 1 for Ni(mdt), was shown by the C=C vibration of 1325 cm- ' in the infrared spectrum and was confirmed by elemental analyses 12.

Scheme I

Recrystallisation ffom a 1:l mixture of acetone and iso-propanol resulted in sin le crystals suitable for X-ray structure deter~nination'~~''. The crystallographically independent unit consists of one Ni(mdt), anion and one Bu4N cation. Figure 1 shows the labelling scheme of the heavy atoms in the Ni(mdt), unit.

The observed Ni- S bond lengths vary from 2.154(2) to 2.170(2) A. This variation is slightly larger than usually found for [Ni(dddt),]-, e.g. 2.130(6) - 2.145(9) A for [B~,NJ[Ni(dddt)~]'~. The observed C=C bonds lengths are 1.372(11) and 1.349(10) A for C(2)-C(3) and C(4)-C(5), respectively.

Page 2: Synthesis and crystal structure of [Bu4N][Ni(mdt)2], a novel nickel dithiolene complex (H2mdt = 2H-1,3-dithiole-4,5-dithiol)

338 YXJ. Veldhuizen et al. /Synthes& and structure of [Bu,N][Ni(mdt),]

S(3) S(5) S(7) Figure 1: ORTEP 50% probability plot (PLATON'S) of

Ijvi(md9J- with the labelling scheme of the heavy atoms.

The side view of Ni(mdt), in figure 2 shows the unusual distortion from planarity of the anion. The NiS, coordination geometry is distorted from a square-planar towards a tetrahedral configuration, the twist between the planes S(3)-Ni(l)-S(4) and S(S)-Ni(l)-S(6) being 14.77(13)". Furthermore the plane S(l)-S(2)-C(2)-C(3)- S(3)-S(4) is tilted 24.84(9)' from the plane of Ni( 1)- S(5)- S(6)- C(4)- C(5)- S(7)- S(8). This distortion is quite unusual as the central unit in BMDT-TTF, as well as in comparable nickel dithiolene complexes, shows only minor deviations from planarity. The trans orientation of C(l) towards C(6) is also found in the crystal structures of BMDT- TTFSa6.

Figure 2: Side view showing the distortion @om planarity of the Ni(mdg2 anion.

Figure 3 shows the arrangement of Ni(mdt), in the unit cell. The shortest intermolecular S-S distance of 3.779(3) A, which is slightly larger than the sum of the Van der Waals radii (3.70 A), is shown by a dashed line. No stacking of Ni(mdt), units is present.

Figure 3: Arrangement ofNi(mdo2 units in the unit cell. Dashed line shows S-S of 3.779(3) A. [Bu,,N]' species omitted.

The electrochemical properties and the scope of h s new complex are currently subject of our research. Given the significant distortion from square planar for the 1 - ion, it is to be expected that the further oxidued species (neutral or even cationic) may result in unusual S-S contacts, which could give rise to new phenomena in the conduction. Such oxidation experiments are also underway.

Acknowledgements

This work was supported in part (A.L.S. and.N.V.) by the Netherlands Foundation of Chemical Research (SON) with

financial aid from the Netherlands Organization for Scientific Research (NWO) and in part (Y.S.J.V., J.G.H., J.R.) by WFMO (Werkgroep Fundamenteel Materialen Onderzoek of Leiden University). Financial support by the European Community, allowing exchange of preliminary results with several European colleagues, under contract ERBCHRXCT920080 is thankfully acknowledged.

References and notes

1. L. Valade, P. Cassoux, A . Gleizes and L.V. Znterrante, J. Phys. Colloq. 44C3, 1183 (1983).

2. a) P. Cassoux, L. Valade, H. Kobayashi, A. Kobayashi, R.A. C1arkandA.E. Underhill, Coord. Chem. Rev. 110, 115 (1991). b) R.-M. Olk, B. Olk, M Dietzsch, R. Kirmse and E. Hoyeq Coord. Chem. Rev. 117,99 (1992).

3 . J.P. Cornelissen, D. Reefman, J.G. Haasnoot, A.L. Spek and J. Reedijk, Recl. Trav. Chim. Pays-Bas 110,345 (1991).

4. J.P. Cornelissen, B. Pomaride, A.L. Spek, D . Reefman, J.G. Haasnoot and J. Reedijk, Inorg. Chem. 32,3720 (1993).

5. R Kato, A. Kobayashi, Y. Sasaki and H. Kobayashi, Chem. Lett., 993 (1984).

6. P.J. Nigrey, B. Morosin, J.F. Kwak, E.L. Venturini and R.J. Baughman, Synthestic Metals 19,617 (1987).

7. C.T. Vance, R.D. Bereman, J. Bordner, ME. Hatfield and J.H. Helms, Inorg. Chem. 24,2905 (1985).

8. RP. Shibaeva and Y E . Zavodnik, Kristallografiya 38,84 (1993). 9. G.C. Papavassiliou, V.C. Kakoussis, J.S. Zambounis and G.A.

Mousdis, Chemica Scripta 29,123 (1989). 10. P.J. Nigrey, B. Morosin, J.F. Kwak, E.L. Venturini and R.J.

Baughman, Synthetic Metals 16,1 (1986). 11. C. Faulmann, P. Cassoux, E.B. Yagubskii and L. V. Vetoshkina,

New J. Chem. 17,385 (1993). 12. To a suspension of 1 mmol of 2 in 4 ml methanol was added a

slight excess of a 1 M NaOMe solution. After one hour stirring 0.5 mmol of NiCl2.6H,O in 10 ml methanol was added, followed, after another hour of stirring, by 0.5 mmol Bu4NBr in 5 ml methanol. The product crystallized overnight at -18 C. Yield 85%. Synthesis was carried out under a dinitrogen atmosphere. Anal. calcd. for NiC,,S,NH,, (633.79): C 4 1.69, H 6.36,N 2.21, S 40.47; found: C 41.91, H 6.44,N 2.19, S 39.44.

13. Crystal data for Pu4N][Ni(mdt),]: M, = 633.79, (0.25 x 0.25 x

0.25 mm), orthorhombic, space group Pna2, (no. 33) with a =

17.2633(6) A, b = 18.4274(9) A, c = 9.01 16(8) A, V = 2866.8(3) A3, Z = 4 , D , = 1.4685(2) g/cmi F(000) = 1340, p(h40 Ka) =

12.7 cm-', 5766 reflections measured, 2949 independent (1.6' ( 8 ( 26.5', w scan, Aw = 0.50 + 0.35 tan8, T = 150 K, Mo Ka radiation, graphite monochromator, h = 0.71073 A) on an Enraf- Nonius CAD4-T diffractometer on rotating anode. The structure was solved by Patterson methods (DIRDIF-92). Refinement on F2 was carried out by full-matrix least-squares techniques (SHELXL-93). Final R1 value 0.500, for 2071 reflections with F, ) 4.0a(FO), wR2 = 0.0825 for all 2949 data, w = I/[$(@) + (0.0233P)2], with P = (Max(Fi,O) + 2 F 3 3 , S = 1.003, for 294 parameters. Flack absolute structure parameter: 0.02(0.06). All non-hydrogen atoms were refined with anisotropic thermal parameters. The hydrogen atoms were refined with a fixed isotropic thermal parameter related to the value of the equivalent isotropic thermal parameter of their carrier atoms, by a factor of 1.5 for the methyl, and 1.2 for the other hydrogen atoms, respectively. Weights were optimized in the final refinement cycles.

14. Further details of the crystal structure investigation may be obtained from one of the authors (A.L.S.).

15. A.L. Spek, Acta Cystallogr. A46, C34 (1990). 16. A.J. Schultz, H.H. Wang, L.C. Soderholm, T.L. Siffer, J.M.

Williams, K. Bechgaard and M.H. Whangbo Inorg. Chem. 26, 3757 (1987).