28 (C7HsN2S2)2 [Pt(C4N2S2)2] AND [(C7I"LICIN2S2)2CI][Pt(C4N2 S2)2] Acta Cryst. (1994). C50, 28-33 t I Structures of [PhCNSSN]2[Pt(mnt)2] and i i [(p-CIC6H4CNSSN)2CI][Pt(mnt)2] (mnt- Maleonitriledithiolato Ligand) WILLIAM CLEGG AND SARA L. BIRKBY Department of Chemistry, University of Newcastle upon Tyne, Newcastle upon Tyne NEI 7RU, England ARTHUR J. BANISTER, JEREMY M. RAWSON AND SIMON T. WArt Department of Chemistry, University Science Laboratories, South Road, Durham DH1 3LE, England PmRRE RIZKALLAH SERC Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, England MAPJORIE M. HARDING Department of Chemistry, University of Liverpool, PO Box 147, Liverpool L69 3BX, England ALEXANDER J. BLAKE Department of Chemistry, The University of Edinburgh, West Mains Road, Edinburgh EH9 3J J, Scotland (Received 14 January 1993; accepted 28 June 1993) Abstract 4-Phenyl- 1,2-dithia-3,5-diaz01ium bis(maleonitriledithi- olato)platinum(II), [PhCNSSI~I]2[Pt(mnt)2] (1), and bis- [4-(4-chlorophenyl)- 1,2-dithia-3,5-diazolium] chloride- bis(maleonitriledithiolato)platinum(III), [(p-CIC6H4- CNSSIQ)2CI][Pt(mnt)2] (2), contain essentially planar [Pt(nmt)z]"- anions In -- 2 for complex (1), n = 1 for complex (2)], with square-planar coordination of Pt. The Pt--S bonds are slightly, but significantly, shorter for the Pt m complex (2). The cations contain planar (~NSSlq five-membered rings with an aryl substituent Ar (Ph or p-CIC6H4) on C. In (1), the cations are discrete, but in (2), they are associated in pairs with a C1- anion to give an approximately planar [(ArCNSS/Q)2C1] ÷ cationic unit, with S-..C1 contacts in the range 2.845 (3)-2.970 (4) A. In (1), the cations and anions are arranged all parallel in mixed cation-anion stacks, each anion being sandwiched between two cations. In (2), the cations and anions form sheets which are buckled into an unusual wave-like con- figuration. © 1994 International Union of Crystallography Printed in Great Britain - all rights reserved Comment During the study of the chemistry of the 4-phenyl-l,2- dithia-3,5-diazolium cation [PhCNSSI~I] ÷, a variety of salts have been prepared. Those which have planar or almost planar cyclic sulfur-nitrogen anions give low- dimensional stacking arrangements in the solid state, generally of an ABBA type, as has been found for [PhCNSS/~][S3N3] (3), [PhCNSS/q]IS3N2]CI (4) and r' i [(PhCNSSN)zC1][S3N3] (5) (Banister, Clegg, Hauptman, Luke & Wait, 1989; Banister, Hansford, Hauptman, Luke, Wait, Clegg & Jorgensen, 1990). In such compounds the rings are held together by secondary interactions between cations and anions within each stack. The lowest unoc- cupied molecular orbital (LUMO) of the [PhI~NSSI~] ÷ cation is antibonding with respect to both the S--N and S--S bonds; consequently, charge-transfer interactions between the anions and cations in these stacked struc- tures take place at the expense of S--N and S--S bond- ing within the cations. These S--N and S--S bonds are observed to be longer than in salts without such interac- tions, for example [PhCNSSlq][AsF6] (Scholz, Roesky, Schimkowiak & Noltemeyer, 1989). However, in some salts, such as the chloride, interactions in the plane of the cation are found (Hazell & Hazell, 1988); these involve a higher-energy molecular orbital of different symmetry, resulting in a shortening of the cation bonds through a net three-centre bonding interaction. As an extension of this work, we have examined other salts containing soft anions, with the aim of enhanc- ing these structurally influential secondary interactions. We report here structures containing [Pt(mnt)2] n- anions (n = 2 and 1) with formal Pt n and Pt m oxidation states, respectively. The asymmetric unit of (1) consists of a complete cation, the Pt and one ligand of the anion. The asymmet- ric unit of (2) comprises four cations, one complete com- plex anion, two half anions with Pt on inversion centres and CI- anions on one general position and two inversion centres. Both structures contain essentially planar [ArCNS SIQ] ÷ cations and [Pt(mnt)2]"- anions, as shown in Figs. 1 and 2. The r.m.s, deviation of the CNSSlq ring atoms from their mean plane is 0.023 A in (1) and 0.008, 0.007, 0.003 o and 0.006 A for the independent cations of (2), with the aryl substituent almost in the same plane [dihedral angles 3.1 ° for (1); 14.0, 14.1, 8.3 and 11.5° for (2)]. In the an- ions, the PtS4 unit is strictly planar in (1) and in some of the anions of (2), with Pt on an inversion centre; the crys- tallographically unconstrained anion in (2) has an r.m.s. deviation of 0.039 A, for the PtS4 atoms from their mean plane. The r.m.s, deviations for the complete anions are 0.064 ~, in (1) and 0.092, 0.041 and 0.030 A, in (2). In each complex anion the coordination geometry of Pt is essentially undistorted square planar, with SwPt--S angles deviating by less than 1 ° from the ideal 90 °. The Acta Crystallographica Section C ISSN 0108-2701 ©1994