Chlorido[2,15-dimethyl-3,7,10,14,20-pentaazabicyclo[14.3.1]eicosa-1(20),2,14,16,18-pentaene]manganese(II) perchlorate acetonitrile solvate

The Mn ion in the title complex, [MnCl(C17H27N5)]ClO4·CH3CN, is six-coordinated with a geometry intermediate between pentagonal pyramidal and heavily distorted octahedral. In the macrocycle, the pyridinium ring makes a large dihedral angle of 63.70 (9)° with the best plane through the remaining four N atoms. This feature is common for 17-membered N5 rings, in contrast to their 16- and 15-membered analogues which often form planar N5 systems. In the crystal, N—H⋯O and C—H⋯O interactions help to establish the packing. The perchlorate counter-ion is rotationally disordered around the chlorine centre, with occupation factors of 0.74 (1) and 0.26 (1).


Comment
The significance of metal complexes containing synthetic macrocyclic ligands is most obvious as it relates to naturally occurring macrocyclic systems such as the porphyrin core in hemoglobin or chlorophylls, the corrin in vitamin B 12 , cyclic polyether antibiotics. Many of the recent advances in the coordination chemistry of manganese have arisen from the desire to understand and mimic the mechanism of water oxidation and dioxygen evolution during photosynthesis catalyzed by manganese metalloproteins (Grabolle et al., 2006;Isobe et al., 2005). The manganese(II) pentaaza macrocyclic complexes have been considered as synzymes (low molecular weight catalysts which mimic a natural enzymatic function) for superoxide anion dismutation and activity with the goal to design and synthesis better human pharmaceutical agents (Riley, 1999;Aston et al., 2001). The effective method for the synthesis of macrocyclic complexes involves the coordination template effect.
It consists of a metal ion being used to orient the reacting groups of linear substrates in the desired conformation for the condensation process which ultimately ends with ring closure (Radecka-Paryzek et al., 2005). We have recently reported the first examples of 16-membered macrocyclic lanthanide complexes which are able to activate molecular oxygen (Patroniak et al., 2004). Here we present the template action of manganese(II) in the synthesis of 17-membered pentaaza macrocycle.
The N 5 -system in the 17-membered quinquedentate macrocyclic ligand does not form a plane, as it is often a case for 15-and 16-membered analogues (e.g. Patroniak et al., 2004). Four non-pyridine nitrogen atoms N3, N7, N10 and N14 are approximately coplanar -however even for these four atoms the maximum deviation from the least-squares plane is as high as 0.207 (2) Å -and the pyridine nitrogen N20 is 1.369 (3)Å out of this plane (Fig. 1). The pyridine ring makes a dihedral angle of 63.70 (9)° with the mean plane of the remaining N 4 -system; a similar value was found in the thiocyanato-lead complex (63.1°, , while it was smaller, but still significant, in other complexes: 48.8° for bromo-mercury , 49.7° for bromo-cadmium , and 41.8° for bis-isothiocyanato-manganese . This non-planar disposition of five nitrogen atoms results also in an uncommon coordination of the Mn ion, which can be described as intermediate between a heavily distorted pentagonal pyramid (with the Cl atom at the apex and the N 5 system as the base) and a distorted octahedron (cf. Table 1).
The perchlorate counterions are disordered over two positions with site occcupation factors of 0.74 (1) and 0.26 (1). Table 2 for the most relevant ones), a centrosymmetric tetramer is formed around the cell centre, which appears as the building block on which the crystal architecture is based. Two solvent -acetonitrile molecules join to these tetramers by means of a rather linear C-H···O hydrogen bond. These cationanion groups further organize into columns along the [001] direction, probably through second order contacts involving the supplementary materials sup-2 Chlorine atoms (H···Cl ~2.90Å) which might impose some directionality to the main driving force of the crystal packing, the coulombic interaction between charged fragments.
The reaction mixture was evaporated to dryness and the remaining solid dissolved in boiling acetonitrile (15 ml

Refinement
Hydrogen atoms were located geometrically and refined in the 'riding model', with U iso 's set at 1.2 (1.5 for methyl groups) times U eq 's of their appropriate carrier atoms. Weak restraints were applied to both the geometry (DFIX for Cl-O bond lengths and O···O 1,3-distances) and displacement parameters (ISOR) of O atoms from the disordered perchlorate group. Fig. 1. Anisotropic displacement ellipsoid representation (at the 50% probability level) of the asymmetric unit content. Only the larger fraction of the disordered perchlorate is shown.

Special details
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 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ.