Dicyanido[tris(2-pyridylmethyl)amine]cobalt(III) hexafluoridophosphate

In the title complex, [Co(CN)2(C18H18N4)]PF6, the CoIII atom together with one of the pyridyl rings and two cyanide anions are located on a mirror plane, while the P atom is located on an inversion centre. The CoIII atom exhibits an octahedral geometry, coordinated by four N atoms from the tris(2-pyridylmethyl)amine ligand with an average Co—N distance of 1.953 (2) Å, and two cyanide C atoms with an average Co—C distance of 1.895 (2) Å. The crystal packing is stabilized by intermolecular C—H⋯N and C—H⋯F interactions.

In the title complex, [Co(CN) 2 (C 18 H 18 N 4 )]PF 6 , the Co III atom together with one of the pyridyl rings and two cyanide anions are located on a mirror plane, while the P atom is located on an inversion centre. The Co III atom exhibits an octahedral geometry, coordinated by four N atoms from the tris(2pyridylmethyl)amine ligand with an average Co-N distance of 1.953 (2) Å , and two cyanide C atoms with an average Co-C distance of 1.895 (2) Å . The crystal packing is stabilized by intermolecular C-HÁ Á ÁN and C-HÁ Á ÁF interactions.

Comment
Transitional metal-cyanide systems have been extensively investigated due to their versatile structure and physical properties, especially in the field of molecular-based magnets. A large number of cyanide-bridged heterobimetallic or homometallic coordination complexes that exhibit excellent magnetic properties has been constructed by using the hexacyanoferrate(III) and hexacyanocobaltate(III) anions as templates (Liu et al., 2010). In constrast, complexes constructed by using the octacyanotungsten(IV) anion are rare. In an attempt to synthesize new complexes, we decided to use octacyanotungsten(IV) anions as template and new compounds containing cyanides have been obtained. The octacyanotungsten(IV) anion was not coordinated to Co atom via cyanide bridges, but acts as source of in situ cyanide generation.
Each cobalt(III) ion is coordinated by four N atoms with average Co-N distance of 1.957 (2) Å and two C atoms with average Co-C distance of 1.895 (2) Å in a rigid octahedral geometry, in accordance with those observed in other [Co(N) 4 (CN) 2 ]units (Guo et al., 2007). The dihedral angle of two types of pyridyl rings is about 80.17°, indicating the nearly perpendicular occupation of these pyridyl rings. The crystal packing is stabilized by C-H···N and C-H···F hydrogen bonding interactons (Table 1, Fig. 2).
Experimental 0.01 mmol K 4 W(CN) 8 in 5 ml H 2 O was added in a tube, and 3 ml H 2 O was layered on as a buffer. A solution containing 0.1 mmol CoCl 2 .6H 2 O, 0.11 mmol tris(2-pyridylmethyl)amine and 0.11 mmol KPF 6 in 5 mL acetone and 1 ml H 2 O was stirred for 30 min and layered on top of the previous solution. After half a year, yellow crystals were obtained.

Refinement
All H atoms were placed geometrically with C-H = 0.93 (aromatic) or 0.96-0.97 Å (CH 2 ) , and refined using a riding atom model with their isotropic displacement factors, U ĩso fixed at 1.2 time the U eq of the parent C atom. Fig. 1. Molecular structure of the title compound showing atomic numbering and 30% probability displacement ellipsoids.Symmetry codes: (i) x,y,-z + 1/2; (ii) x,-y + 1/2,-z.

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.
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 Rfactors(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.