2,2,7,7,12,12,17,17-Octamethyl-21,22,23,24-tetrathia-2,7,12,17-tetragermapentacyclo[16.2.1.13,6.18,11.113,16]tetracosa-3,5,8,10,13,15,18,20-octaene

The title compound, [Ge4(CH3)8(C4H2S)4], crystallizes with one-half molecule in the asymmetric unit, the whole molecule being generated by inversion symmetry. The dihedral angle between adjacent thiophene rings is 72.84 (14)°. In the crystal, molecules are linked by C—H⋯π interactions, leading to the formation of chains along [100].

The title compound, [Ge 4 (CH 3 ) 8 (C 4 H 2 S) 4 ], crystallizes with one-half molecule in the asymmetric unit, the whole molecule being generated by inversion symmetry. The dihedral angle between adjacent thiophene rings is 72.84 (14) . In the crystal, molecules are linked by C-HÁ Á Á interactions, leading to the formation of chains along [100].
Cg1 is the centroid of the S1/C3-C6 ring. The asymmetric unit of the title compound contains one half-molecule, the other half being related by a crystallographic inversion center (Fig. 1). In the asymmetric unit, the dihedral angle between adjacent thiophene rings is 72.84 (14)°. It is noteworthy that a C-H···π interaction between the hydrogen H10 and the π cloud of the thiophene ring S1/C3-C6 is observed giving stacks of the title compound along the a axis (Table 1 and Fig.2).

Experimental
The title compound was prepared according to the following procedure: In a first step, to a solution of thiophene (5.09 g, 60 mmol) and TMEDA (9.10 ml, 60 mmol) in dry diethyl ether (150 ml) was added a solution of n-BuLi (37.50 ml, 60 mmol, 1.6 M in hexanes). The mixture was stirred for 2 h at room temperature. A solution of Me 2 GeCl 2 (5.20 g, 30 mmol) in dry diethyl ether (30 ml) was added slowly, the mixture was stirred for an additional 2 h. The reaction mixture was then filtered and the solvents removed by evaporation under reduced pressure. The residue was distillated to afford Me 2 Ge(C 4 H 3 S) 2 (4.90 g, 61% yield).
In a second step, to a solution of Me 2 Ge(C 4 H 3 S) 2 (2.69 g, 10 mmol) and TMEDA (3.0 ml, 20 mmol) in dry pentane (150 ml) cooled to 193 K was slowly added a solution of n-BuLi (12.50 ml, 20 mmol, 1.6 M in hexanes). The mixture was allowed to rise to room temperature and stirred for 2 h. To the formed precipitate in suspension was slowly added at 233 K a solution of Me 2 GeCl 2 (1.75 g, 10 mmol) in dry pentane (50 ml). The mixture was allowed to rise to room temperature and stirred for 1h, and one additional hour at reflux. The reaction mixture was filtered and the solvents removed by evaporation under reduced pressure. The solid was washed by pentane. Crystals of the title compound were obtained by slow evaporation of a solution in CH 2 Cl 2 . Both the intermediate and the title compound were fully characterized, and spectroscopic and other data are available in the archived CIF.

Refinement
All the H atoms were included in calculated positions and treated as riding atoms: C-H = 0.95 Å (aromatic), and 0.98 Å (methyl) with U iso (H) = 1.2U eq (aromatic) and U iso (H) = 1.5U eq (methyl).   A partial view of the crystal packing of the title compound, showing the C-H··· π interactions (dashed lines; see Table 1 for details). H atoms not involved in these interactions have been omitted for clarity.   , 3073, 2976, 2907, 1497, 1402, 1214, 1080H, 4.57 2960, 2915, 1643, 1490, 1406, 1270, 1240, 1200H, 4.42. Calc. for C 24 H 32 S 4 Ge 4 : C, 39.00; H, 4.33. Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.