N 1-(Thiophen-2-ylmethyl)-N 3,N 3-bis[3-(thiophen-2-ylmethylammonio)propyl]propane-1,3-diammonium hexafluoridosilicate methanol trisolvate

In the title compound, C24H40N4S3 4+·2SiF6 2−·3CH3OH, the central tertiary amine function is protonated and is connected to three thiophen-2-ylmethylamino-n-propyl groups, forming the arms of a T-shaped cation that has two pockets. Each arm contains one protonated secondary amine function, and each pocket is occupied by one SiF6 2− anion bonded via two N—H⋯F interactions with the protonated amine group on the middle arm, while two methanol solvent molecules are N—H⋯O hydrogen-bonded with the other secondary protonated amine groups on the side arms. Weak O—H⋯O and O—H⋯F hydrogen bonds between the solvent molecules and between the solvent molecules and the anions, respectively, are also observed. All three thiophene groups in the arms are disordered over two sets of sites, with occupancy ratios of 0.828 (3):0.172 (3), 0.910 (2):0.090 (2) and 0.890 (3):0.110 (3).

In the title compound, C 24 H 40 N 4 S 3 4+ Á2SiF 6 2À Á3CH 3 OH, the central tertiary amine function is protonated and is connected to three thiophen-2-ylmethylamino-n-propyl groups, forming the arms of a T-shaped cation that has two pockets. Each arm contains one protonated secondary amine function, and each pocket is occupied by one SiF 6 2À anion bonded via two N-HÁ Á ÁF interactions with the protonated amine group on the middle arm, while two methanol solvent molecules are N-HÁ Á ÁO hydrogen-bonded with the other secondary protonated amine groups on the side arms. Weak O-HÁ Á ÁO and O-HÁ Á ÁF hydrogen bonds between the solvent molecules and between the solvent molecules and the anions, respectively, are also observed. All three thiophene groups in the arms are disordered over two sets of sites, with occupancy ratios of 0.828 (3) Table 1 Hydrogen-bond geometry (Å , ).  (Hossain, 2008;Mendy et al., 2010). For example, our group recently reported a tripodal host containing ethylene chains in the arms, which provides the complementary of binding sites for a C 3 -symmetric nitrate anion . A related tripodal host was found to fully encapsulate a dihydrogen phosphate anion within its cavity . In order to obtain the flexible cavity for polyatomic anions, we were interested in synthesizing a tripodal molecule with larger propylene chains. Herein, we report the crystal structure of the title compound, (C 24 H 40 N 4 S 3 )

Related literature
[SiF 6 ] 2 . 3(CH 3 OH), that contains two hexafluoridosilicate anions (SiF 6 2-) which originated from the glass container during the crystallization process of the fluoride salt of the ligand. The formation of SiF 6 2was previously observed by us for a large macrocyclic-based receptor forming a water-fluoride cluster in a molecular box (Hossain et al., 2012).
The cation of the title compound adopts a T-shaped geometry rather than a commonly observed tripodal pocket . All four nitrogen atoms in the amine groups are protonated, and the charges are balanced by two dinegatively charged hexafluoridosilicate anions. As shown in Fig. 1, the cationic unit contains two pockets and each pocket is occupied by a single anion bonded to two NH groups with N-H···F bonds in the range of 2.759 (2) to 3.029 (2) Å ( Table 1)

Experimental
Tris (  The hexafluoride salt was obtained by the dropwise addition of hydrofluoric acid into a glass vial containing free amine (40 mg, 0.08 mmol) in methanol (2 mL) until the pH of the solution became to 2.0. The white precipitate obtained was redissolved in water (1:2, v/v, 1 mL) and the crystals suitable for X-ray analysis were grown after five days from slow evaporation of the solvent at room temperature.

Refinement
H atoms on C were placed in idealized positions with C-H distances 0.95 -0.99 Å and thereafter treated as riding. The coordinates of those on N were refined; H atoms of the hydroxy function of methanol were found from difference syntheses and were refined with a distance restraint of 0.84 Å. U iso for H was assigned as 1.2 times U eq of the attached atom (1.5 for methyl). A torsional parameter was refined for each methyl group. The largest residual density peak was 1.50 Å from O2.
The constraints and restraints used in refinement were as follows. The geometry of 1-2 and 1-3 distances of nonhydrogen atoms in the three thiophene groups and the adjacent carbons were restrained to be similar with a standard deviation of 0.004 Å for 1-2 distances and 0.006-0.008 Å for 1-3 distances. In addition, these same atoms were restrained to be approximately in a plane within a standard deviation of 0.008 Å. The displacement parameters of these atoms were restrained to conform to a "rigid bond", i.e., the components of the displacement parameters in the directions of bonds were restrained to be equal within a standard deviation of 0.006 Å. The displacement parameters of the disordered atoms were also restrained to be similar if the atoms were within 2.0 Å of other disordered atoms with a standard deviation of 0.006. The atoms C11M, C11N, and C11O were restrained to have approximately isotropic displacement parameters with a standard deviation of 0.006. The bond lengths of the N5-H groups were all restrainted to be about 0.80Å with a standard deviation of 0.02. Finally the displacement parameters of the disordered pairs of the C7 atoms, that were very close to each other, were constrained to be equal.

Figure 1
The molecular entities of the title compound, showing the atom-numbering scheme and hydrogen bonding interactions (only the major disordered parts of the thiophene rings are shown). Displacement ellipsoids are drawn at the 50% probability level.

Figure 2
The expanded content of the unit cell of the title compound as  (7) 0.0140 (7) 0.0140 (7