Related literature {#sec1}
==================

For background to the synthesis of *N*-(*p*-chloro­phen­yl)acetamidine and related *N*-aryl­acetamidines used as reagents in the formation of anti-leishmanial compounds, see: Shearer *et al.* (1997[@bb10]); Rousselet *et al.* (1993[@bb9]); Patai (1975[@bb8]). For background to leismaniasis, see: Ouellette *et al.* (2004[@bb7]); Croft *et al.* (2006[@bb2]); Ferreira *et al.* (2007[@bb4]); World Health Organization (2010[@bb14]).

Experimental {#sec2}
============

 {#sec2.1}

### Crystal data {#sec2.1.1}

C~8~H~9~ClN~2~*M* *~r~* = 168.62Orthorhombic,*a* = 9.6460 (9) Å*b* = 9.0192 (4) Å*c* = 19.3281 (5) Å*V* = 1681.53 (18) Å^3^*Z* = 8Mo *K*α radiationμ = 0.39 mm^−1^*T* = 120 K0.35 × 0.20 × 0.10 mm

### Data collection {#sec2.1.2}

Nonius KappaCCD area-detector diffractometerAbsorption correction: multi-scan (*SADABS*; Sheldrick, 2007[@bb11]) *T* ~min~ = 0.792, *T* ~max~ = 1.00014006 measured reflections1924 independent reflections1185 reflections with *I* \> 2σ(*I*)*R* ~int~ = 0.081

### Refinement {#sec2.1.3}

*R*\[*F* ^2^ \> 2σ(*F* ^2^)\] = 0.047*wR*(*F* ^2^) = 0.150*S* = 1.051924 reflections107 parametersH atoms treated by a mixture of independent and constrained refinementΔρ~max~ = 0.34 e Å^−3^Δρ~min~ = −0.33 e Å^−3^

 {#d5e476}

Data collection: *COLLECT* (Hooft, 1998[@bb5]); cell refinement: *DENZO* (Otwinowski & Minor, 1997[@bb6]) and *COLLECT*; data reduction: *DENZO* and *COLLECT*; program(s) used to solve structure: *SHELXS97* (Sheldrick, 2008[@bb12]); program(s) used to refine structure: *SHELXL97* (Sheldrick, 2008[@bb12]); molecular graphics: *ORTEP-3* (Farrugia, 1997[@bb3]) and *DIAMOND* (Brandenburg, 2006[@bb1]); software used to prepare material for publication: *publCIF* (Westrip, 2010[@bb13]).

Supplementary Material
======================

Crystal structure: contains datablocks global, I. DOI: [10.1107/S1600536810011013/hg2664sup1.cif](http://dx.doi.org/10.1107/S1600536810011013/hg2664sup1.cif)

Structure factors: contains datablocks I. DOI: [10.1107/S1600536810011013/hg2664Isup2.hkl](http://dx.doi.org/10.1107/S1600536810011013/hg2664Isup2.hkl)

Additional supplementary materials: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?hg2664&file=hg2664sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?hg2664sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?hg2664&checkcif=yes)

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: [HG2664](http://scripts.iucr.org/cgi-bin/sendsup?hg2664)).

The use of the EPSRC X-ray crystallographic service at the University of Southampton, England, and the valuable assistance of the staff there is gratefully acknowledged. JLW acknowledges support from CAPES and FAPEMIG (Brazil).

Comment
=======

*N*-(*p*-Chlorophenyl)acetamidine and related *N*-arylacetamidines (Shearer *et al.* 1997; Rousselet *et al.* 1993; Patai, 1975) were synthesized for use as reagents in the formation of 5-(difluoromethyl)-2-methyl-1-(substituted-phenyl)-1*H*-imidazoles, which are active anti-leishmanial compounds (Ferreira *et al.*, 2007). Leishmaniasis is caused by several species of protozoan parasites transmitted by the bite of the female phlebotomine sand fly. This neglected disease is currently prevalent in four continents, being endemic in 88 countries, 72 of which are developing countries, threatening 350 millions worldwide (World Health Organization, 2010). The treatment of Leishmaniasis, currently, is dependent on old and highly toxic drugs (Croft *et al.*, 2006). In addition, the development of clinical resistance and the increase of co-infections leishmaniasis AIDS, in some countries is causing further worries. Thus, the development of new, efficient, and safe drugs for the treatment of this disease is imperative (Ouellette *et al.*, 2004; Croft *et al.*, 2006; Ferreira *et al.*, 2007). This contribution describes the synthesis and crystallographic characterisation of an *N*-(*p*-chlorophenyl)acetamidine derivative, (I).

The molecular structure of (I), Fig. 1, is twisted about the C1--N1 bond as seen in the value of the C2--C1--N1--C7 torsion angle of -118.6 (2) °; the dihedral angle formed between the benzene ring and ethanimidamide residue is 66.54 (14) °. The molecule has approximate mirror symmetry with the non-hydrogen atoms of the ethanimidamide lying on the putative plane and the benzene ring being bisected by the plane. The conformation about the C7═ N1 double bond \[1.299 (3) Å\] is *Z*.

The crystal packing is dominated by N--H···N and N--H···Cl hydrogen bonding interactions, Table 1. These lead to the formation of 22-membered {···HNH···ClC~4~NCNH···ClC~4~N···HNCN}~2~ synthons that are connected into supramolecular arrays in the *ac* plane, Fig. 2; these have a zig-zag topology.

Experimental {#experimental}
============

To a stirred solution of *p*-chloroaniline (10.75 mmol) in acetonitrile (40 ml) was bubbled hydrogen chloride. A precipitate was formed immediately. The resulting suspension was refluxed and became homogeneous. Upon complete reaction, as shown by TLC, the mixture was rotary evaporated and the residue partitioned between CH~2~Cl~2~ and saturated aqueous NaHCO~3~. The aqueous layer was washed (3 times) with CH~2~Cl~2~, and the combined organic layers were dried over sodium sulfate, filtered, and the filtrate concentrated under reduced pressure to yield a white solid; yield 96%, m.p. 389--390 K. The sample used in the X-ray study was slowly grown from an ethanol solution of (I). IR (KBr, cm^-^1): 3451, 3295, 3079, 1640, 1586, 1482. ^1^H NMR (500 MHz, CDCl~3~): δ 1.99 (*s*, 3H, CH~3~); 4.53 (*br s*, 2H, 2); 6.77 (*d*, 2H, J = 8.0 Hz); 7.24 (*d*, 2H, J = 8.0 Hz) p.p.m. ^13^C NMR (125 MHz, CDCl~3~): δ 21.59 (CH~3~); 122.5 121.1; 128.6; 144.6; 155.3 (H~2~N---C=N) p.p.m. EI---MS (m/z): 168 (M^+^, 68%); 153 (M^+^-15, 38%); 127 (M^+^-41, 100%); 111 (M^+^ -57, 54%); 75 (M^+^-93, 42%).

Refinement {#refinement}
==========

The C-bound H atoms were geometrically placed (C--H = 0.95--0.98 Å) and refined as riding with *U~iso~*(H) = 1.2-1.5*U~eq~*(C). The positions of the N--H atoms were refined with *U~iso~*(H) = 1.2*U~eq~*(N).

Figures
=======

![The molecular structure of (I) showing the atom-labelling scheme and displacement ellipsoids at the 50% probability level.](e-66-0o958-fig1){#Fap1}

![A view of a supramolecular array in (I) in the ac plane. The N--H···N and N--H···Cl hydrogen bonding interactions are shown as orange dashed lines. Colour code: Cl, cyan; N, blue; C, grey; and H, green.](e-66-0o958-fig2){#Fap2}

Crystal data {#tablewrapcrystaldatalong}
============

  ------------------------- ---------------------------------------
  C~8~H~9~ClN~2~            *F*(000) = 704
  *M~r~* = 168.62           *D*~x~ = 1.332 Mg m^−3^
  Orthorhombic, *Pbca*      Mo *K*α radiation, λ = 0.71073 Å
  Hall symbol: -P 2ac 2ab   Cell parameters from 2182 reflections
  *a* = 9.6460 (9) Å        θ = 2.9--27.5°
  *b* = 9.0192 (4) Å        µ = 0.39 mm^−1^
  *c* = 19.3281 (5) Å       *T* = 120 K
  *V* = 1681.53 (18) Å^3^   Block, colourless
  *Z* = 8                   0.35 × 0.20 × 0.10 mm
  ------------------------- ---------------------------------------

Data collection {#tablewrapdatacollectionlong}
===============

  --------------------------------------------------------------- --------------------------------------
  Nonius KappaCCD area-detector diffractometer                    1924 independent reflections
  Radiation source: Enraf Nonius FR591 rotating anode             1185 reflections with *I* \> 2σ(*I*)
  10 cm confocal mirrors                                          *R*~int~ = 0.081
  Detector resolution: 9.091 pixels mm^-1^                        θ~max~ = 27.5°, θ~min~ = 3.0°
  φ and ω scans                                                   *h* = −11→12
  Absorption correction: multi-scan (*SADABS*; Sheldrick, 2007)   *k* = −11→9
  *T*~min~ = 0.792, *T*~max~ = 1.000                              *l* = −25→21
  14006 measured reflections                                      
  --------------------------------------------------------------- --------------------------------------

Refinement {#tablewraprefinementdatalong}
==========

  ------------------------------------- ------------------------------------------------------------------------------------
  Refinement on *F*^2^                  Primary atom site location: structure-invariant direct methods
  Least-squares matrix: full            Secondary atom site location: difference Fourier map
  *R*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.047   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.150                  H atoms treated by a mixture of independent and constrained refinement
  *S* = 1.05                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.081*P*)^2^\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  1924 reflections                      (Δ/σ)~max~ = 0.001
  107 parameters                        Δρ~max~ = 0.34 e Å^−3^
  0 restraints                          Δρ~min~ = −0.33 e Å^−3^
  ------------------------------------- ------------------------------------------------------------------------------------

Special details {#specialdetails}
===============

  --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Geometry. All s.u.\'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.\'s are taken into account individually in the estimation of s.u.\'s in distances, angles and torsion angles; correlations between s.u.\'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.\'s is used for estimating s.u.\'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^ \> 2σ(*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.
  --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å^2^) {#tablewrapcoords}
==================================================================================================

  ----- -------------- ------------- -------------- -------------------- --
        *x*            *y*           *z*            *U*~iso~\*/*U*~eq~   
  Cl1   0.43525 (8)    0.20450 (7)   0.43084 (3)    0.0430 (3)           
  N1    0.36389 (19)   0.4659 (2)    0.71058 (10)   0.0308 (5)           
  N2    0.1234 (2)     0.4244 (2)    0.70948 (11)   0.0305 (5)           
  H1N   0.044 (3)      0.438 (3)     0.7313 (13)    0.037\*              
  H2N   0.124 (3)      0.379 (3)     0.6740 (14)    0.037\*              
  C1    0.3774 (2)     0.4032 (3)    0.64327 (12)   0.0274 (6)           
  C2    0.4543 (2)     0.2746 (3)    0.63454 (14)   0.0316 (6)           
  H2    0.4938         0.2272        0.6738         0.038\*              
  C3    0.4741 (3)     0.2144 (3)    0.56933 (13)   0.0317 (6)           
  H3    0.5266         0.1260        0.5638         0.038\*              
  C4    0.4169 (2)     0.2837 (3)    0.51261 (13)   0.0286 (6)           
  C5    0.3428 (3)     0.4144 (3)    0.51965 (12)   0.0342 (6)           
  H5    0.3054         0.4627        0.4802         0.041\*              
  C6    0.3243 (3)     0.4736 (3)    0.58491 (13)   0.0348 (6)           
  H6    0.2745         0.5638        0.5901         0.042\*              
  C7    0.2408 (2)     0.4770 (3)    0.73731 (13)   0.0269 (6)           
  C8    0.2239 (3)     0.5538 (3)    0.80540 (14)   0.0367 (6)           
  H8A   0.3153         0.5706        0.8261         0.055\*              
  H8B   0.1680         0.4919        0.8364         0.055\*              
  H8C   0.1774         0.6492        0.7983         0.055\*              
  ----- -------------- ------------- -------------- -------------------- --

Atomic displacement parameters (Å^2^) {#tablewrapadps}
=====================================

  ----- ------------- ------------- ------------- -------------- -------------- --------------
        *U*^11^       *U*^22^       *U*^33^       *U*^12^        *U*^13^        *U*^23^
  Cl1   0.0537 (5)    0.0446 (5)    0.0307 (4)    0.0051 (3)     0.0060 (3)     −0.0034 (3)
  N1    0.0210 (11)   0.0449 (13)   0.0264 (12)   −0.0010 (9)    −0.0007 (9)    −0.0032 (9)
  N2    0.0205 (11)   0.0461 (14)   0.0248 (12)   −0.0033 (9)    0.0019 (9)     −0.0061 (10)
  C1    0.0171 (11)   0.0372 (14)   0.0280 (14)   −0.0036 (10)   −0.0002 (10)   0.0003 (11)
  C2    0.0286 (13)   0.0340 (14)   0.0321 (15)   −0.0010 (11)   −0.0040 (11)   0.0052 (11)
  C3    0.0297 (13)   0.0288 (13)   0.0367 (16)   0.0031 (10)    0.0014 (11)    0.0001 (11)
  C4    0.0284 (13)   0.0306 (15)   0.0266 (14)   −0.0016 (10)   0.0072 (10)    0.0012 (10)
  C5    0.0327 (14)   0.0437 (16)   0.0263 (14)   0.0074 (11)    0.0018 (11)    0.0068 (11)
  C6    0.0296 (14)   0.0403 (15)   0.0345 (15)   0.0119 (11)    0.0047 (12)    0.0019 (11)
  C7    0.0233 (12)   0.0329 (13)   0.0246 (14)   −0.0026 (10)   −0.0006 (10)   0.0029 (10)
  C8    0.0281 (13)   0.0512 (16)   0.0307 (14)   −0.0059 (12)   0.0014 (11)    −0.0066 (12)
  ----- ------------- ------------- ------------- -------------- -------------- --------------

Geometric parameters (Å, °) {#tablewrapgeomlong}
===========================

  ---------------- ------------- ---------------- -----------
  Cl1---C4         1.743 (3)     C3---C4          1.377 (4)
  N1---C7          1.299 (3)     C3---H3          0.9500
  N1---C1          1.425 (3)     C4---C5          1.385 (3)
  N2---C7          1.340 (3)     C5---C6          1.381 (3)
  N2---H1N         0.89 (3)      C5---H5          0.9500
  N2---H2N         0.80 (3)      C6---H6          0.9500
  C1---C2          1.387 (3)     C7---C8          1.496 (4)
  C1---C6          1.393 (3)     C8---H8A         0.9800
  C2---C3          1.386 (4)     C8---H8B         0.9800
  C2---H2          0.9500        C8---H8C         0.9800
                                                  
  C7---N1---C1     118.52 (19)   C6---C5---C4     119.1 (2)
  C7---N2---H1N    119.4 (17)    C6---C5---H5     120.5
  C7---N2---H2N    121 (2)       C4---C5---H5     120.5
  H1N---N2---H2N   119 (3)       C5---C6---C1     121.0 (2)
  C2---C1---C6     118.7 (2)     C5---C6---H6     119.5
  C2---C1---N1     119.5 (2)     C1---C6---H6     119.5
  C6---C1---N1     121.6 (2)     N1---C7---N2     125.8 (2)
  C3---C2---C1     120.8 (2)     N1---C7---C8     119.0 (2)
  C3---C2---H2     119.6         N2---C7---C8     115.2 (2)
  C1---C2---H2     119.6         C7---C8---H8A    109.5
  C4---C3---C2     119.4 (2)     C7---C8---H8B    109.5
  C4---C3---H3     120.3         H8A---C8---H8B   109.5
  C2---C3---H3     120.3         C7---C8---H8C    109.5
  C3---C4---C5     121.0 (2)     H8A---C8---H8C   109.5
  C3---C4---Cl1    119.65 (19)   H8B---C8---H8C   109.5
  C5---C4---Cl1    119.4 (2)                      
  ---------------- ------------- ---------------- -----------

Hydrogen-bond geometry (Å, °) {#tablewraphbondslong}
=============================

  -------------------- ---------- ---------- ----------- ---------------
  *D*---H···*A*        *D*---H    H···*A*    *D*···*A*   *D*---H···*A*
  N2---H1n···N1^i^     0.88 (3)   2.08 (3)   2.965 (3)   176 (3)
  N2---H2n···Cl1^ii^   0.80 (3)   2.83 (3)   3.464 (2)   138 (3)
  -------------------- ---------- ---------- ----------- ---------------

Symmetry codes: (i) *x*−1/2, *y*, −*z*+3/2; (ii) *x*−1/2, −*y*+1/2, −*z*+1.

###### Hydrogen-bond geometry (Å, °)

  *D*---H⋯*A*        *D*---H    H⋯*A*      *D*⋯*A*     *D*---H⋯*A*
  ------------------ ---------- ---------- ----------- -------------
  N2---H1n⋯N1^i^     0.88 (3)   2.08 (3)   2.965 (3)   176 (3)
  N2---H2n⋯Cl1^ii^   0.80 (3)   2.83 (3)   3.464 (2)   138 (3)

Symmetry codes: (i) ; (ii) .

[^1]: Additional correspondence author, e-mail: j.wardell\@abdn.ac.uk.
