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

For the biological activity of indole derivatives, see: Gribble (2000[@bb7]); Knölker & Reddy (2002[@bb12]); Kawasaki & Higuchi (2005[@bb11]); Bennasar *et al.* (1993[@bb4]); Hong *et al.* (2006[@bb8]); Lacoume *et al.* (1972[@bb13]); Joseph *et al.* (1998[@bb10], 2000[@bb9]). For related crystallographic studies of cyclo­hept\[*b*\]indoles, see: Archana *et al.* (2010[@bb2], 2011[@bb3]). For hydrogen-bond motifs, see: Bernstein *et al.* (1995[@bb5]).

Experimental   {#sec2}
==============

 {#sec2.1}

### Crystal data   {#sec2.1.1}

C~13~H~12~ClNO*M* *~r~* = 233.69Monoclinic,*a* = 11.6354 (4) Å*b* = 6.3798 (2) Å*c* = 14.4513 (5) Åβ = 92.767 (3)°*V* = 1071.49 (6) Å^3^*Z* = 4Mo *K*α radiationμ = 0.33 mm^−1^*T* = 150 K0.40 × 0.30 × 0.30 mm

### Data collection   {#sec2.1.2}

Agilent Xcalibur Ruby Gemini diffractometerAbsorption correction: multi-scan *CrysAlis PRO* (Agilent, 2011[@bb1]) *T* ~min~ = 0.879, *T* ~max~ = 0.9074977 measured reflections2274 independent reflections1836 reflections with *I* \> 2σ(*I*)*R* ~int~ = 0.026

### Refinement   {#sec2.1.3}

*R*\[*F* ^2^ \> 2σ(*F* ^2^)\] = 0.039*wR*(*F* ^2^) = 0.096*S* = 1.042274 reflections149 parametersH atoms treated by a mixture of independent and constrained refinementΔρ~max~ = 0.27 e Å^−3^Δρ~min~ = −0.26 e Å^−3^

 {#d5e537}

Data collection: *CrysAlis PRO* (Agilent, 2011[@bb1]); cell refinement: *CrysAlis PRO*; data reduction: *CrysAlis PRO*; program(s) used to solve structure: *SHELXS97* (Sheldrick, 2008[@bb14]); program(s) used to refine structure: *SHELXL97* (Sheldrick, 2008[@bb14]); molecular graphics: *ORTEP-3* (Farrugia, 1997[@bb6]) and *PLATON* (Spek, 2009[@bb15]); software used to prepare material for publication: *PLATON*.

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

Crystal structure: contains datablock(s) global, I. DOI: [10.1107/S1600536812022945/tk5099sup1.cif](http://dx.doi.org/10.1107/S1600536812022945/tk5099sup1.cif)

Structure factors: contains datablock(s) I. DOI: [10.1107/S1600536812022945/tk5099Isup2.hkl](http://dx.doi.org/10.1107/S1600536812022945/tk5099Isup2.hkl)

Supplementary material file. DOI: [10.1107/S1600536812022945/tk5099Isup3.cdx](http://dx.doi.org/10.1107/S1600536812022945/tk5099Isup3.cdx)

Supplementary material file. DOI: [10.1107/S1600536812022945/tk5099Isup4.cml](http://dx.doi.org/10.1107/S1600536812022945/tk5099Isup4.cml)

Additional supplementary materials: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?tk5099&file=tk5099sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?tk5099sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?tk5099&checkcif=yes)

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: [TK5099](http://scripts.iucr.org/cgi-bin/sendsup?tk5099)).

RJB acknowledges the NSF MRI program (grant No. CHE-0619278) for funds to purchase an X-ray diffractometer.

Comment
=======

An indole nucleus coupled with prenylated indoles, carbazoles, indoloquinoline and cyclohept\[*b*\]indole alkaloids show high levels of biological activities including anti-fungal, anti-bacterial, anti-tumour and anti-HIV activities, as well as DNA interaction properties (Gribble, 2000; Knölker & Reddy, 2002; Kawasaki & Higuchi, 2005; Bennasar *et al.*, 1993; Hong *et al.*, 2006; Lacoume *et al.*, 1972; Joseph *et al.*, 1998; Joseph *et al.*, 2000). Recently, we reported related crystallographic studies for some cyclohept\[*b*\]indoles from our laboratory (Archana *et al.*, 2010; Archana *et al.*, 2011).

In the title molecule, Fig. 1, the dihedral angle between the benzene and pyrrole rings is 1.38 (9)°. The cycloheptene ring adopts a distorted twist chair and sofa conformation. Intermolecular N5---H5···O6 hydrogen bonds form a *R*^2^~2~(10) (Bernstein *et al.*, 1995) rings in the crystal structure. A weak C9---H9A···O6 intermolecular hydrogen bond along with a C7---H7A···π interaction, involving the benzene (C1--C4,C4A,C10B) ring, are also found in the crystal structure, Fig. 2 and Table 1.

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

A solution of 2-(2-(4-chlorophenyl)hydrazono)cycloheptanone (0.486 g, 0.001 mol) in a mixture of acetic acid (20 ml) and hydrochloric acid (5 ml) was refluxed on an oil bath pre-heated to 398 K for 2 h. The contents were then cooled and poured onto cold water with stirring. The brown solid which was separated by passing through a column of silica gel and eluted with (98:2, *v*/*v*) petroleum ether-ethyl acetate mixture yielded the title compound (0.167 g, 72%). This was recrystallized from ethanol.

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

The N---H atom was located in a difference Fourier map and refined freely. Other H atoms were positioned geometrically and allowed to ride on their parent atoms, with C---H = 0.95--0.99 Å and *U*~iso~(H) = 1.2*U*~eq~(parent atom).

Figures
=======

![The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. H atoms are shown as small spheres of arbitrary radius.](e-68-o1887-fig1){#Fap1}

![The crystal structure of (I), viewed down the b axis, showing the formation of a R22(10) ring by N---H···O hydrogen bonding (dashed lines). H atoms not involved in hydrogen bonding have been omitted.](e-68-o1887-fig2){#Fap2}

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

  ------------------------- ---------------------------------------
  C~13~H~12~ClNO            *F*(000) = 488
  *M~r~* = 233.69           *D*~x~ = 1.449 Mg m^−3^
  Monoclinic, *P*2~1~/*n*   Melting point: 389 K
  Hall symbol: -P 2yn       Mo *K*α radiation, λ = 0.71073 Å
  *a* = 11.6354 (4) Å       Cell parameters from 2495 reflections
  *b* = 6.3798 (2) Å        θ = 3.2--28.4°
  *c* = 14.4513 (5) Å       µ = 0.33 mm^−1^
  β = 92.767 (3)°           *T* = 150 K
  *V* = 1071.49 (6) Å^3^    Block, colourless
  *Z* = 4                   0.40 × 0.30 × 0.30 mm
  ------------------------- ---------------------------------------

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

  ------------------------------------------------------------------ --------------------------------------
  Agilent Xcalibur Ruby Gemini diffractometer                        2274 independent reflections
  Radiation source: Enhance (Mo) X-ray Source                        1836 reflections with *I* \> 2σ(*I*)
  Graphite monochromator                                             *R*~int~ = 0.026
  Detector resolution: 10.5081 pixels mm^-1^                         θ~max~ = 28.4°, θ~min~ = 3.5°
  ω scans                                                            *h* = −14→15
  Absorption correction: multi-scan *CrysAlis PRO* (Agilent, 2011)   *k* = −8→7
  *T*~min~ = 0.879, *T*~max~ = 0.907                                 *l* = −12→19
  4977 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*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.039   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.096                  H atoms treated by a mixture of independent and constrained refinement
  *S* = 1.04                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.0373*P*)^2^ + 0.4689*P*\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  2274 reflections                      (Δ/σ)~max~ = 0.001
  149 parameters                        Δρ~max~ = 0.27 e Å^−3^
  0 restraints                          Δρ~min~ = −0.26 e Å^−3^
  ------------------------------------- -------------------------------------------------------------------------------------------------

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

  ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Geometry. Bond distances, angles *etc*. have been calculated using the rounded fractional coordinates. All su\'s are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.\'s are taken into account in the estimation of distances, angles and torsion angles
  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~   
  Cl2    0.59361 (4)    −0.24239 (8)   0.08648 (3)    0.0357 (2)           
  O6     0.57812 (10)   0.3697 (2)     0.60006 (8)    0.0280 (4)           
  N5     0.56976 (12)   0.2648 (3)     0.42004 (10)   0.0225 (5)           
  C1     0.63668 (14)   −0.1524 (3)    0.26774 (12)   0.0244 (5)           
  C2     0.58717 (14)   −0.0838 (3)    0.18511 (12)   0.0262 (5)           
  C3     0.53084 (14)   0.1108 (3)     0.17503 (12)   0.0275 (6)           
  C4     0.52189 (15)   0.2416 (3)     0.24985 (12)   0.0256 (5)           
  C4A    0.56937 (14)   0.1720 (3)     0.33521 (12)   0.0223 (5)           
  C5A    0.62720 (14)   0.1378 (3)     0.48468 (11)   0.0211 (5)           
  C6     0.63461 (14)   0.2152 (3)     0.58029 (12)   0.0229 (5)           
  C7     0.71201 (15)   0.1148 (3)     0.65476 (12)   0.0273 (5)           
  C8     0.80230 (15)   −0.0440 (3)    0.62766 (12)   0.0258 (5)           
  C9     0.75353 (15)   −0.2421 (3)    0.58213 (12)   0.0254 (5)           
  C10    0.73457 (16)   −0.2246 (3)    0.47726 (12)   0.0254 (5)           
  C10A   0.66477 (13)   −0.0419 (3)    0.44109 (12)   0.0214 (5)           
  C10B   0.62718 (14)   −0.0218 (3)    0.34549 (12)   0.0220 (5)           
  H1     0.67583        −0.28293       0.27228        0.0293\*             
  H3     0.49882        0.15197        0.11609        0.0330\*             
  H4     0.48492        0.37398        0.24388        0.0307\*             
  H5     0.5389 (17)    0.380 (3)      0.4311 (14)    0.031 (6)\*          
  H7A    0.66192        0.04481        0.69880        0.0328\*             
  H7B    0.75270        0.22911        0.68916        0.0328\*             
  H8A    0.85431        0.02420        0.58455        0.0309\*             
  H8B    0.84908        −0.08411       0.68393        0.0309\*             
  H9A    0.67922        −0.27558       0.60929        0.0305\*             
  H9B    0.80688        −0.35980       0.59647        0.0305\*             
  H10A   0.81089        −0.21821       0.44992        0.0305\*             
  H10B   0.69653        −0.35477       0.45448        0.0305\*             
  ------ -------------- -------------- -------------- -------------------- --

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

  ------ ------------ ------------- ------------ ------------- ------------- -------------
         *U*^11^      *U*^22^       *U*^33^      *U*^12^       *U*^13^       *U*^23^
  Cl2    0.0376 (3)   0.0460 (3)    0.0233 (2)   0.0078 (2)    0.0001 (2)    −0.0094 (2)
  O6     0.0322 (7)   0.0244 (7)    0.0275 (7)   0.0012 (5)    0.0032 (5)    −0.0036 (6)
  N5     0.0242 (8)   0.0205 (8)    0.0229 (8)   0.0027 (7)    0.0009 (6)    −0.0004 (7)
  C1     0.0213 (8)   0.0259 (9)    0.0261 (9)   0.0005 (8)    0.0008 (7)    −0.0003 (8)
  C2     0.0241 (9)   0.0336 (10)   0.0209 (9)   −0.0007 (8)   0.0026 (7)    −0.0058 (8)
  C3     0.0219 (9)   0.0382 (11)   0.0222 (9)   0.0016 (8)    0.0002 (7)    0.0042 (8)
  C4     0.0231 (8)   0.0269 (10)   0.0267 (9)   0.0039 (8)    0.0013 (7)    0.0035 (8)
  C4A    0.0182 (8)   0.0245 (9)    0.0242 (9)   −0.0027 (7)   0.0016 (7)    −0.0005 (8)
  C5A    0.0187 (8)   0.0209 (9)    0.0235 (8)   −0.0033 (7)   0.0003 (6)    0.0007 (7)
  C6     0.0224 (8)   0.0220 (9)    0.0245 (9)   −0.0069 (7)   0.0031 (7)    −0.0008 (7)
  C7     0.0322 (9)   0.0287 (10)   0.0208 (9)   −0.0034 (8)   −0.0011 (7)   0.0004 (8)
  C8     0.0255 (9)   0.0280 (10)   0.0234 (9)   −0.0028 (8)   −0.0037 (7)   0.0025 (8)
  C9     0.0259 (9)   0.0229 (9)    0.0269 (9)   0.0003 (7)    −0.0039 (8)   0.0035 (8)
  C10    0.0272 (9)   0.0222 (9)    0.0265 (9)   0.0021 (7)    −0.0023 (7)   −0.0013 (8)
  C10A   0.0175 (8)   0.0236 (9)    0.0230 (9)   −0.0036 (7)   0.0005 (6)    −0.0005 (7)
  C10B   0.0177 (8)   0.0244 (9)    0.0238 (8)   −0.0024 (7)   0.0009 (7)    0.0002 (8)
  ------ ------------ ------------- ------------ ------------- ------------- -------------

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

  ------------------------ -------------- ------------------------- --------------
  Cl2---C2                 1.7525 (19)    C8---C9                   1.522 (3)
  O6---C6                  1.226 (2)      C9---C10                  1.525 (2)
  N5---C4A                 1.361 (2)      C10---C10A                1.500 (3)
  N5---C5A                 1.384 (2)      C10A---C10B               1.435 (2)
  N5---H5                  0.837 (19)     C1---H1                   0.9500
  C1---C10B                1.407 (3)      C3---H3                   0.9500
  C1---C2                  1.372 (2)      C4---H4                   0.9500
  C2---C3                  1.408 (3)      C7---H7A                  0.9900
  C3---C4                  1.374 (3)      C7---H7B                  0.9900
  C4---C4A                 1.399 (2)      C8---H8A                  0.9900
  C4A---C10B               1.412 (3)      C8---H8B                  0.9900
  C5A---C6                 1.466 (2)      C9---H9A                  0.9900
  C5A---C10A               1.389 (3)      C9---H9B                  0.9900
  C6---C7                  1.512 (2)      C10---H10A                0.9900
  C7---C8                  1.524 (3)      C10---H10B                0.9900
                                                                    
  C4A---N5---C5A           109.50 (16)    C1---C10B---C10A          133.14 (17)
  C4A---N5---H5            124.8 (14)     C2---C1---H1              121.00
  C5A---N5---H5            125.7 (14)     C10B---C1---H1            121.00
  C2---C1---C10B           117.39 (17)    C2---C3---H3              120.00
  Cl2---C2---C3            117.57 (13)    C4---C3---H3              120.00
  Cl2---C2---C1            119.41 (14)    C3---C4---H4              121.00
  C1---C2---C3             123.02 (17)    C4A---C4---H4             121.00
  C2---C3---C4             120.45 (16)    C6---C7---H7A             107.00
  C3---C4---C4A            117.35 (17)    C6---C7---H7B             107.00
  N5---C4A---C4            129.78 (18)    C8---C7---H7A             107.00
  N5---C4A---C10B          107.77 (15)    C8---C7---H7B             107.00
  C4---C4A---C10B          122.44 (17)    H7A---C7---H7B            107.00
  N5---C5A---C6            116.33 (16)    C7---C8---H8A             109.00
  C6---C5A---C10A          134.44 (16)    C7---C8---H8B             109.00
  N5---C5A---C10A          109.23 (15)    C9---C8---H8A             109.00
  O6---C6---C7             118.84 (16)    C9---C8---H8B             109.00
  C5A---C6---C7            122.28 (16)    H8A---C8---H8B            108.00
  O6---C6---C5A            118.86 (16)    C8---C9---H9A             109.00
  C6---C7---C8             119.54 (15)    C8---C9---H9B             109.00
  C7---C8---C9             114.57 (15)    C10---C9---H9A            109.00
  C8---C9---C10            113.70 (15)    C10---C9---H9B            109.00
  C9---C10---C10A          116.94 (15)    H9A---C9---H9B            108.00
  C5A---C10A---C10B        105.96 (15)    C9---C10---H10A           108.00
  C10---C10A---C10B        122.67 (16)    C9---C10---H10B           108.00
  C5A---C10A---C10         131.32 (16)    C10A---C10---H10A         108.00
  C4A---C10B---C10A        107.53 (16)    C10A---C10---H10B         108.00
  C1---C10B---C4A          119.33 (16)    H10A---C10---H10B         107.00
                                                                    
  C5A---N5---C4A---C4      −180.00 (18)   N5---C5A---C6---C7        −168.77 (16)
  C5A---N5---C4A---C10B    0.65 (19)      C10A---C5A---C6---O6      −169.76 (18)
  C4A---N5---C5A---C6      −179.61 (15)   C10A---C5A---C6---C7      12.0 (3)
  C4A---N5---C5A---C10A    −0.2 (2)       N5---C5A---C10A---C10     177.14 (17)
  C10B---C1---C2---Cl2     −178.65 (13)   N5---C5A---C10A---C10B    −0.37 (19)
  C10B---C1---C2---C3      1.6 (3)        C6---C5A---C10A---C10     −3.6 (3)
  C2---C1---C10B---C4A     −0.8 (2)       C6---C5A---C10A---C10B    178.93 (18)
  C2---C1---C10B---C10A    178.53 (18)    O6---C6---C7---C8         −166.26 (16)
  Cl2---C2---C3---C4       179.40 (14)    C5A---C6---C7---C8        12.0 (3)
  C1---C2---C3---C4        −0.8 (3)       C6---C7---C8---C9         −63.1 (2)
  C2---C3---C4---C4A       −0.8 (3)       C7---C8---C9---C10        88.01 (18)
  C3---C4---C4A---N5       −177.70 (17)   C8---C9---C10---C10A      −52.9 (2)
  C3---C4---C4A---C10B     1.6 (3)        C9---C10---C10A---C5A     11.6 (3)
  N5---C4A---C10B---C1     178.59 (15)    C9---C10---C10A---C10B    −171.28 (16)
  N5---C4A---C10B---C10A   −0.87 (19)     C5A---C10A---C10B---C1    −178.59 (18)
  C4---C4A---C10B---C1     −0.8 (3)       C5A---C10A---C10B---C4A   0.75 (19)
  C4---C4A---C10B---C10A   179.72 (16)    C10---C10A---C10B---C1    3.6 (3)
  N5---C5A---C6---O6       9.5 (2)        C10---C10A---C10B---C4A   −177.02 (15)
  ------------------------ -------------- ------------------------- --------------

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

Cg2 is the centroid of the C1--C4,C4A,C10B ring.

  ------------------------- ------------ ---------- ------------- ---------------
  *D*---H···*A*             *D*---H      H···*A*    *D*···*A*     *D*---H···*A*
  N5---H5···O6^i^           0.837 (19)   2.13 (2)   2.904 (2)     153.2 (19)
  C9---H9*A*···O6^ii^       0.99         2.55       3.228 (2)     125
  C7---H7*A*···*Cg*2^iii^   0.99         2.95       3.7969 (19)   144
  ------------------------- ------------ ---------- ------------- ---------------

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

###### Hydrogen-bond geometry (Å, °)

*Cg*2 is the centroid of the C1--C4,C4*A*,C10*B* ring.

  *D*---H⋯*A*             *D*---H      H⋯*A*      *D*⋯*A*       *D*---H⋯*A*
  ----------------------- ------------ ---------- ------------- -------------
  N5---H5⋯O6^i^           0.837 (19)   2.13 (2)   2.904 (2)     153.2 (19)
  C9---H9*A*⋯O6^ii^       0.99         2.55       3.228 (2)     125
  C7---H7*A*⋯*Cg*2^iii^   0.99         2.95       3.7969 (19)   144

Symmetry codes: (i) ; (ii) ; (iii) .
