[5,15-Bis(2-methylpropyl)porphyrinato]nickel(II)

The title compound, [Ni(C28H28N4)], crystallizes with two independent molecules in the unit cell, one of which is located on an inversion center. Both macrocycles exhibit a planar conformation with average deviation from the least-squares-plane of the 24 macrocycle atoms of Δ24 = 0.043 Å for the first molecule and 0.026 Å for the molecule located on an inversion center. The average Ni—N bond lengths are 1.955 (2) and 1.956 (2) Å in the two molecules. The molecules form π–π dimers of intermediary strength with a mean plane separation of 3.36 (2) Å.

The title compound, [Ni(C 28 H 28 N 4 )], crystallizes with two independent molecules in the unit cell, one of which is located on an inversion center. Both macrocycles exhibit a planar conformation with average deviation from the least-squaresplane of the 24 macrocycle atoms of Á24 = 0.043 Å for the first molecule and 0.026 Å for the molecule located on an inversion center. The average Ni-N bond lengths are 1.955 (2) and 1.956 (2) Å in the two molecules. The molecules formdimers of intermediary strength with a mean plane separation of 3.36 (2) Å .
Á is the deviation from the least-squares-plane of the 24 macrocycle atoms and N-Ni-Nadj is the angle between neighboring pyrrole units.  Jentzen et al. (1996) Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL. Comment meso-Alkylporphyrins are increasingly used in porphyrin chemistry, but their structural chemistry is less well established . The compound is another example for the expanding body of Ni(II) porphyrins with a planar macrocycle Jentzen et al., 1996;. In the crystal this allows the formation of πaggregates which are characterized by a mean plane separation of 3.36 (2) Å, a center-to-center distance of 4.88 (2) Å, a slip angle of 133.5 (1) ° which, according to the classification given by Scheidt & Lee (1987), results in a lateral shift of the metal centers of 3.54 (2) Å. Thus, the π-π-stacks are of intermediary strength. The compound forms part of a series of Ni(II) 5,15-dialkylporphyrins with different steric demand of the meso residue. The respective tert-butyl derivative (Song et al., 1996) is clearly the most nonplanar one with the shortest Ni-N bond length and largest deviation from planarity ( Table 2). The iso-propyl derivative (Song et al., 1998) shows still significant out-of-plane deformations, while Ni(II)porphyrin without any non-hydrogen residues is planar (Jentzen et al., 1996). The title compound has the sterically least demanding alkyl residue and exhibits an almost planar macrocycle. However, as indicated by the different N-Ni-N adj bond angles, the compound still exhibits some degree of in-plane distortion, which becomes more pronounced with larger meso alkyl residues.

Experimental
The compound was prepared as described by Wiehe et al. (2005) and crystallized from CH 2 Cl 2 /CH 3 OH.

Refinement
All nonhydrogen atoms were refined with anisotropic thermal parameters. Hydrogen atoms were refined with a standard riding model (C-H distance 0.96 Å, U iso = 0.05).

Figure 2
View of the π-aggregates formed by the title compound in the crystal.

[5,15-Bis(2-methylpropylporphyrinato]nickel(II)
Crystal data [Ni(C 28 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 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.