(1-Butyl-1,4-diazabicyclo[2.2.2]octon-1-ium-κN 4)trichloridocobalt(II)

The title compound, [Co(C10H21N2)Cl3], was obtained as the by-product of the attempted synthesis of a cobalt sulfate framework using 1,4-diazabicyclo[2.2.2]octane as an organic template. The asymmetric unit comprises two distinct molecules, and in each, the cobalt(II) ions are tetrahedrally coordinated by three chloride anions and one 1-butyldiazabicyclo[2.2.2]octan-1-ium cation. The organic ligands are generated in situ, and exhibit two forms differentiated by the eclipsed and staggered conformations of the butyl groups. These molecules interact by way of C—H⋯Cl hydrogen bonds, forming a three-dimensional hydrogen-bonding array.


Comment
The crystals of Co(C 10 H 21 N 2 )Cl 3 (I) were unintentionally obtained as a by-product from the hydrothermal reaction between cobalt(II) sulfate heptahydrate and 1,4-diazabicyclo[2.2.2]octane in a water/butan-1-ol mixture. The N-butyl-1,4diazabicyclo[2.2.2]octanium ligand was presumably generated in situ under acidic conditions. The structure of I is built up from two distinct [Co(C 10 H 21 N 2 )Cl 3 ] molecules as shown in Fig. 1. They are different in the spatial orientation of the butyl group of the N-butyl-1,4-diazabicyclo[2.2.2]octanium ligand, one of which is in the eclipsed conformation (A) and the other is in the staggered conformation (B). The A molecules are connected by the C-H···Cl hydrogen bonding interactions to form a two-dimensional A sheet in the ab plane ( Fig. 2), whereas the B molecules form the B sheet also in theab plane using similar C-H···Cl hydrogen bonding interactions (Fig. 3). The A and B sheets are then regularly alternated in the ABAB fashion, and linked by way of also the C-H···Cl hydrogen bonding interactions along c to give the infinite three-dimensional hydrogen bonding array (Fig. 4).

Experimental
Crystals of I were obtained as a by-product from the hydrothermal reaction of cobalt(II) sulfate heptahydrate, 1,4diazabicyclo[2.2.2]octane and hydrochloric acid in a water/butan-1-ol mixture at 453 K for 120 h.

Refinement
H atoms were placed in calcluated positions with C-H = 0.99Å or 0.98Å for methyl H atoms and were included in the refinement in a riding-model approximation with U iso (H) = 1.2U eq (C) or 1.5U eq (C) for methyl H atoms.
The examined crystal was found to be twinned, composing of two crystal components which were miss-set by about two degrees. The crystal was therefore treated as a twin and the two components integrated separately using the same unit cell.
Both components were used for the structure refinement and the twin fraction was found to be 0.698:0.302 (1).
Three alerts from checkCIF: The rather weak van der Waals interactions involving the n-butyl chains mean there is considerable freedom for these carbon and hydrogen atoms to vibrate. The slightly enlarged displacement parameters observed are entirely expected on chemical grounds.

PLAT341_ALERT_3_C
The calculated estimated standard uncertainties associated with the unit-cell parameters are faithfully reproduced from the Bruker APEXII suite (Bruker, 2004). All observed data were used in their calculation. These give rise to moderate precision in the C-C bonds. To some extent this is a consequence of the integration procedure which uses two twin components -deconvolution of the low angle components is problematic as the two componenets are miss-set by approximately 2°.