Z. anorg. allg. Chem. 624 (1998) 1400±1404 Zeitschrift fu È r anorganische und allgemeine Chemie  WILEY-VCH Verlag GmbH 1998 The DMSO Solvated octahedro-[W 6 Cl i 12 ]Cl a 6 Cluster Molecule Yue-Qing Zheng* Ningbo/P. R. China, Chemistry Department of Ningbo University Ekaterina Jonas, Ju È rgen Nuss and Hans Georg von Schnering* Stuttgart, Max-Planck-Institut fu È r Festko È rperforschung Received March 18th, 1998. Abstract. Octahedro-hexatungsten octadecachloride, W 6 Cl 18 , is soluble in dimethyl sulfoxide (DMSO). Brownish black crystals of W 6 Cl 18 (DMSO) 4 are formed from the brown so- lution by evaporation of DMSO under dynamic vacuum. The compound crystallizes monoclinically in the space group P2 1 /n (no. 14) with a = 10.420 A Ê , b = 9.271 A Ê , c = 20.828 A Ê , b = 91.10° and Z = 2. The crystal structure is formed by isolated cluster molecules [W 6 Cl i 12 ]Cl a 6 of the hexa- meric tungsten trichloride and DMSO molecules. It is the first hierarchical variant of the tetragonal BaAl 4 type of structure where all atoms of the intermetallic phase are sub- stituted by neutral molecules. The mean bond lengths are d(W±W) = 2.878 A Ê , d(W±Cl i ) = 2.391 A Ê and d(W±Cl a )= 2.447 A Ê . They will be discussed in relation to analogous clus- ters. The two crystallographically independent DMSO mole- cules (d(S±O) = 1.53±1.55 A Ê , d(S±C) = 1.65±1.78 A Ê ) form a 3 D net of condensed < 4 8 6 4 > dodecahedra which envelopes the clusters. Keywords: Hexameric tungsten trichloride; W 6 Cl 18 cluster molecule; solvate; syntheses; crystal structure Das DMSO-solvatisierte Clustermoleku Èl octahedro-[W 6 Cl i 12 ]Cl a 6 Inhaltsu È bersicht. Octahedro-Hexawolframoctadecachlorid W 6 Cl 18 lo È st sich in Dimethylsulfoxid (DMSO) mit brauner Farbe. Aus dieser Lo È sung kristallisiert beim Einengen unter dynamischem Vakuum das Tetrasolvat W 6 Cl 18 (DMSO) 4 in Form braun-schwarzer Kristalle. Die Verbindung kristalli- siert monoklin in der Raumgruppe P2 1 /n (Nr. 14) mit a = 10.420 A Ê , b = 9.271 A Ê , c = 20.828 A Ê , b = 91.10° und Z = 2. Die Kristallstruktur ist aus isolierten Cluster-Moleku È len [W 6 Cl i 12 ]Cl a 6 des hexameren Wolframtrichlorids und DMSO- Moleku È len aufgebaut. Sie ist die erste bekannte hierar- chische Variante des tetragonalen BaAl 4 -Typs, in der sa Èmt- liche Atome der intermetallischen Phase durch neutrale Moleku È le ersetzt sind. Die mittleren Bindungsla È ngen betra- gen d(W±W) = 2.878 A Ê , d(W±Cl i ) = 2.391 A Ê und d(W±Cl a )= 2.447 A Ê . Sie werden im Zusammenhang mit analogen Clu- stern diskutiert. Die beiden kristallographisch unabha È ngigen DMSO-Moleku È le (d(S±O) = 1.53±1.55 A Ê , d(S±C) = 1.65±1,78 A Ê ) umhu È llen die Cluster als ein 3 D-Netz kondensierter Dode- caeder vom Typ < 4 8 6 4 >. 1 Introduction It is well-known for a long time that the formation of the two cluster types octahedro-[M 6 X i 8 ] and octahe- dro-[M 6 X i 12 ] is strongly related to the number of va- lence electrons per M 6 fragment. Magic numbers for these two types are 24 and 16 electrons, respectively. The first type, therefore, is found to be favored with molybdenum, tungsten and rhenium (Mo II ,W II , Re III ) and the second type with niobium and tantalum (M 2.33+ to M 2.67 ) [1±3]. The syntheses and characteri- zation of Nb 6 I 11 and of HNb 6 I 11 by Simon et al. [4, 5] were very important discoveries, because the [M 6 X i 8 ] * Correpondence Addresses: Prof. Dr. H. G. von Schnering Max-Planck-Institut fu È r Festko È rperforschung Heisenbergstraûe 1 D-70569 Stuttgart Prof. Dr. Y.-Q. Zheng Chemistry Department of Ningbo University Ningbo, Zhejiang, 315211, P. R. China