1-Phenylpiperazine-1,4-diium tetrachloridocobalt(II)

In the title molecular salt, (C10H16N2)[CoCl4], the piperazine ring of the phenylpiperazine dication adopts a chair conformation and the phenyl ring occupies an equatorial orientation. In the tetrachloridocobaltate(II) dianion, the Co—Cl bond lengths for the chloride ions not accepting hydrogen bonds are significantly shorter than those for the chloride ions accepting such bonds. In the crystal, the components are linked by N—H⋯Cl hydrogen bonds, generating [001] chains.

We acknowledge the NSF-MRI grant No. 1125975 "MRI Consortium Acquisition of a Single Crystal X-ray Diffractometer for a Regional PUI Molecular Structure Facility".

Comment
Organic-inorganic hybrid materials have received extensive attention in recent years owing to their great fundamental and practical interest such as second-order nonlinear optical (NLO) responses, magnetism, luminescence, photography and drug delivery (Bringley & Rajeswaran, 2006). However, the energetics of NH····Cl-M (M = metal) hydrogen bonds and their possible roles in supramolecular chemistry have only been recently described in detail (Brammer et al., 2002). It is therefore vital to design and synthesize new organic inorganic hybrid compound to explore their various properties.
In this compound, H1A and H2A attached to the N1 nitrogen atom and H2 attached to N2 nitrogen atom play an important role in forming the molecular association through hydrogen bonding. Here two chlorine atoms, Cl1 and Cl4, act as acceptors of N-H···Cl H-bonds. The chlorine atoms Cl2 and Cl3 do not participate in the hydrogen bonding network. The deviation from the perfect tetrahedral arrangement around Co(II) in the title compound can be explained by involvment of the chlorine ions in hydrogen bonding. Three different [CoCl 4 ] 2anions are act as hydrogen-bonding acceptors to each phenylpiperazinium dication forming two different hydrogen-bonding ring motifs, R 2 4 (14) and R 4 4 (12) (Fig.3). As Cl2 and Cl3 do not act as hydrogen-bond acceptors, the bond angles Cl2-Co-Cl3 and Cl2-Co-Cl4 (116.304 (19)° and 112.971 (19)°, respectively) display comparatively large deviations from the expected tetrahedral arrangement around Co(II). Similar features have been also observed in the structure of dimorpholinium tetrachloridocobaltate(II) (Wang et al., 2012), where three chlorine atoms are engaged in the hydrogen-bonding network and distortions from tetrahedral predictions are present in the Cl-Co-Cl angles. The structure of dimorpholinium tetrachloridocobaltate(II) also displays a R 4 4 (12) hydrogen bonding motif, but does not possess a second unique R 2 4 (14) motif that the title compound does exhibit.

Experimental
A mixture of CoCl 2 ·H 2 O and phenylpiperazine was dissolved in an aqueous solution of hydrochloric acid (molar ratio 1:1:1). The obtained solution was stirred for 2 h and then kept at room temperature. Blue prisms of the title compound were obtained two weeks later.

Refinement
Many hydrogen atoms were treated in calculated positions and refined in the model as riding with distances of C-H = 0.95 and 0.99 Å for the phenyl and methylene groups, respectively, and with U iso (H) = k×U eq (C), k = 1.2. Hydrogen atoms H1A, H1B, and H2 were located in the electron density map, and their positions were refined with U iso (H) = k×U eq (C), k =1.2.   Graph-set description of ring types hydrogen bonding. Hydrogen bonds are shown as dashed lines.

1-Phenylpiperazine-1,4-diium tetrachloridocobalt(II)
Crystal data (C 10  Special details Geometry. ENTER SPECIAL DETAILS OF THE MOLECULAR GEOMETRY Refinement. Refinement was performed using all reflections. The weighted R-factor (wR) and goodness of fit (S) are based on F 2 . R-factor (gt) are based on F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).