Crystal structure of (2,11-diaza[3.3](2,6)pyridinophane-κ 4 N,N′,N′′,N′′′)(1,6,7,12-tetraazaperylene-κ 2 N 1,N 12)ruthenium(II) bis(hexafluoridophosphate) acetonitrile 1.422-solvate

The highlighted ruthenium complex forms discrete dimers by π–π stacking interactions and hydrogen bonds. This combination of interactions results in an unusual nearly face-to-face π–π stacking mode.

In the title compound, [Ru(C 14 H 16 N 4 )(C 16 H 8 N 4 )](PF 6 ) 2 Á1.422CH 3 CN, discrete dimers of complex cations,  H 2 )tape] 2+ are formed {L-N 4 H 2 = 2,11diaza[3.3](2,6)pyridinophane; tape = 1,6,7,12-tetraazaperylene}, held together bystacking interactions via the tape ligand moieties with a centroidcentroid distance of 3.49 (2) Å , assisted by hydrogen bonds between the noncoordinating tape ligand , 0 -diimine unit and the amine proton of a 2,11diaza[3.3](2,6)-pyridinophane ligand of the opposite complex cation. The combination of these interactions leads to an unusual nearly face-to-facestacking mode. Additional weak C-HÁ Á ÁN, C-HÁ Á ÁF, N-HÁ Á ÁF and P-FÁ Á Áring (tape, py) (with FÁ Á Ácentroid distances of 2.925-3.984 Å ) interactions are found, leading to a three-dimensional architecture. The Ru II atom is coordinated in a distorted octahedral geometry, particularly manifested by the N amine -Ru-N amine angle of 153.79 (10) . The counter-charge is provided by two hexafluoridophosphate anions and the asymmetric unit is completed by acetonitrile solvent molecules of crystallization. Disorder was observed for both the hexafluoridophosphate anions as well as the acetonitrile solvate molecules, with occupancies for the major moieties of 0.801 (6) for one of the PF 6 anions, and a shared occupancy of 0.9215 (17) for the second PF 6 anion and a partially occupied acetonitrile molecule. A second CH 3 CN molecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

Chemical context
Heteroaromatic ligands with more than three fused rings are commonly called large-surface ligands. Such ligands have attracted attention due to their use as connecting building blocks for supramolecular assemblies. If large-surface ligands feature more than one ligand donor site, connection between neighboring complexes can be realized through normal metal coordination (Ishow et al., 1998), but the large system also allows for strongstacking interactions. (Kammer et al., 2006;Gut et al., 2002). In order to study the properties of ruthenium complexes containing large-surface ligands, we have recently reported an easy entry to such complexes (Brietzke, Mickler, Kelling, Schilde et al., 2012). Therein, we formulated the advantages of the 2,11-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane (L-N 4 Me 2 ) macrocycle over bipyridine (bpy)-type ligands in saturating the coordination sphere of an octahedral ruthenium complex containing the large-surface ligand of interest. The microwave-assisted synthesis of the precursor  Me 2 )] 2+ , starting from [Ru(DMSO) 4 Cl 2 ] and L-N 4 Me 2 , in an ethanolic solution finished within 30 min. It is not only fast, but also reproducible ISSN 1600-5368 with only few byproducts, and hence requires no laborintensive workup. Moreover, using the C 2v symmetric macrocycle rather than bipyridine-type ligands avoids the formation of mono-and dinuclear complexes with multiple stereoisomeric forms Brietzke et al., 2014). To test the applicability of our microwave-assisted synthetic strategy for use with other related macrocyclic ligands, we choose the unmethylated parent compound of L-N 4 Me 2 , 2,11-diaza[3.3](2,6)-pyridinophane (L-N 4 H 2 ) as a new ligand for Ru II . Herein, we present the structure of the complex [Ru(L-N 4 H 2 )tape](PF 6 ) 2 , (tape = 1,6,7,12-tetraazaperylene), obtained as its acetonitrile solvate.  (Table 1) are very close to those reported earlier for  Me 2 )tape] 2+ (Brietzke, Mickler, Kelling, Schilde et al., 2012). The deviation of the N amine -Ru-N amine angle [153.79 (10) ] from the idealized value of 180 is slightly larger than for analogous ruthenium L-N 4 Me 2 complexes [155.46 (9)-155.93 (17) ; Brietzke, Mickler, Kelling, Schilde et al., 2012].

Supramolecular features
In the crystal structure, the cations form discrete centrosymmetric dimers, similar to those seen previously in mononuclear ruthenium-tape complexes. The molecular structure of [Ru(L-N 4 H 2 )tape] 2+ in  H 2 )tape]-(PF 6 ) 2 Á1.422CH 3 CN with the atomic numbering scheme and 30% probability displacement ellipsoids. Anions and solvent molecules are omitted for clarity. tape ligand, the root-mean-square deviation from planarity was calculated to be 0.0211 Å . However, in the case of [Ru(L-N 4 H 2 )tape] 2+ , the dimers are also connected through bifurcated hydrogen bonds between one of the two L-N 4 H 2 ligand amine protons and both nitrogen atoms of the non-coordinating tape ligand , 0 -diimine unit of the second complex cation of the dimer. In the crystal structure, these additional hydrogen bonds result in a short RuÁ Á ÁRu distance of 8.8306 (2) Å , a tape ligand centroid-centroid distance of 3.49 (2) Å and an angle of 13.7 (1.4) between the ring normal and the centroid-to-centroid vector. Therefore, thestacking motif can be described as parallel-displaced, but near to face-to-face (Fig. 2). In metal complexes, a near face-to-face alignment of the polycyclic units is extremely rare (Janiak, 2000). Furthermore, a large number of weak hydrogen bonds connect cations, anions and solvent molecules, stabilizing the crystal packing (Table 2), supported by P-FÁ Á Á-ring (tape, py) interactions with FÁ Á Ácentroid distances from 2.925 to 3.984 Å . In the packing, the dimers are oriented in a herringbone-like motif, surrounded by hexafluoridophosphate anions. The solvent acetonitrile molecules fill the space between complex moieties (Fig. 3). For a description of the disorder of the anions and solvent molecules, see the Refinement section.

Synthesis and crystallization
The syntheses of the ligands L-N 4 H 2 (Bottino et al., 1988) and tape   Crystals suitable for X-ray structure analysis were obtained by vapor diffusion of diethyl ether into a saturated acetonitrile solution of [Ru(L-N 4 H 2 )tape](PF 6 ) 2 . The solution was filled into a test tube, which was placed into a diethyl ethercontaining bottle. Dark-green crystals began to form at ambient temperature within a few days.

Refinement
Disorder was observed for both the hexafluoridophosphate anions as well as the acetonitrile solvate molecules. Both PF 6 anions were refined as disordered over one major and one minor moiety each. The geometry of the minor moieties were each restrained to be similar to that of the major moieties (within an estimated standard deviation of 0.02 Å ). The minor research communications Table 2 Hydrogen-bond geometry (Å , ).

Figure 3
A packing diagram of the title compound is displayed along the c axis, illustrating the herringbone-type motif formed by two [Ru(L-N 4 H 2 )tape] 2+ dimers. The disordered minor atoms are omitted for clarity. moieties were subjected to a rigid bond restraint (RIGU command of SHELX2014, estimated standard deviation 0.004 Å 2 ), and the anisotropic displacement parameters of the major and minor phosphorus atoms were each constrained to be identical. Associated with the major moiety of the PF 6 anion of P1 is an acetonitrile molecule that is absent for the minor moiety. Subject to the restraints and constraints used, the occupancy ratios refined to 0.9215 (17) to 0.0785 (17) for the PF 6 units of P1A and P1B, and to 0.801 (6) and 0.199 (6) for those of P2A and P2B.
A second acetonitrile molecule is disordered across a crystallographic inversion center, with substantial overlap for the two carbon atoms of symmetry-related molecules. The geometry of the molecule was restrained to be similar to that of the first acetonitrile molecule, and the ADPs of its C and N atoms were restrained to be have similar U ij components to their neighbors closer than 2 Å , including those of symmetryrelated atoms (SIMU restraint in SHELX2014, estimated standard deviation 0.01 Å 2 ).
All hydrogen atoms connected to C and N atoms were placed in their expected calculated positions and refined as riding with C-H = 0.98 (CH 3 ), 0.99 (CH 2 ), 0.95 (C arom ), N-H = 1.0 Å , and with U iso (H) = 1.2U eq (C) with the exception of methyl hydrogen atoms, which were refined with U iso (H) = 1.5U eq (C).

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.