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

For nickel--salen complexes with aromatic substituents, see: Bal & Ülküseven (2004[@bb2]). For their activation of O~2~, see: Soto-Garrodo & Salas-Reyes (2000[@bb8]); For their catalytic activity: Silva *et al.* (2002[@bb7]); Santos *et al.* (2000[@bb5]); Yoon & Burrows (1988[@bb9]). For the mesogenic properties of substituted complexes, see: Blake *et al.* (1995[@bb3]). For bond-length data, see: Allen *et al.* (1987[@bb1]).

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

 {#sec2.1}

### Crystal data {#sec2.1.1}

\[Ni(C~20~H~22~N~2~O~6~)\]*M* *~r~* = 445.11Monoclinic,*a* = 7.41599 (12) Å*b* = 15.6945 (2) Å*c* = 15.7203 (2) Åβ = 91.9153 (13)°*V* = 1828.67 (5) Å^3^*Z* = 4Cu *K*α radiationμ = 1.91 mm^−1^*T* = 110 K0.53 × 0.15 × 0.12 mm

### Data collection {#sec2.1.2}

Oxford Diffraction Xcalibur Ruby Gemini diffractometerAbsorption correction: multi-scan (*CrysAlis PRO*; Oxford Diffraction, 2007[@bb4]) *T* ~min~ = 0.602, *T* ~max~ = 1.0006746 measured reflections3603 independent reflections3370 reflections with *I* \> 2σ(*I*)*R* ~int~ = 0.022

### Refinement {#sec2.1.3}

*R*\[*F* ^2^ \> 2σ(*F* ^2^)\] = 0.036*wR*(*F* ^2^) = 0.098*S* = 1.043603 reflections266 parametersH-atom parameters constrainedΔρ~max~ = 0.42 e Å^−3^Δρ~min~ = −0.47 e Å^−3^

 {#d5e463}

Data collection: *CrysAlis PRO* (Oxford Diffraction, 2007[@bb4]); cell refinement: *CrysAlis PRO*; data reduction: *CrysAlis PRO*; program(s) used to solve structure: *SHELXS97* (Sheldrick, 2008[@bb6]); program(s) used to refine structure: *SHELXL97* (Sheldrick, 2008[@bb6]); molecular graphics: *SHELXTL* (Sheldrick, 2008[@bb6]); software used to prepare material for publication: *SHELXTL*.

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

Crystal structure: contains datablocks I, global. DOI: [10.1107/S1600536810016041/bt5260sup1.cif](http://dx.doi.org/10.1107/S1600536810016041/bt5260sup1.cif)

Structure factors: contains datablocks I. DOI: [10.1107/S1600536810016041/bt5260Isup2.hkl](http://dx.doi.org/10.1107/S1600536810016041/bt5260Isup2.hkl)

Additional supplementary materials: [crystallographic information](http://scripts.iucr.org/cgi-bin/sendsupfiles?bt5260&file=bt5260sup0.html&mime=text/html); [3D view](http://scripts.iucr.org/cgi-bin/sendcif?bt5260sup1&Qmime=cif); [checkCIF report](http://scripts.iucr.org/cgi-bin/paper?bt5260&checkcif=yes)

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: [BT5260](http://scripts.iucr.org/cgi-bin/sendsup?bt5260)).

RJB wishes to acknowledge the NSF-MRI program (grant CHE-0619278) for funds to purchase the diffractometer.

Comment
=======

Complexes of Ni(II) with N~2~O~2~ Schiff bases derived from salicylaldehyde have been studied for a long time as homogeneous catalysts due to their high activity and selectivity (Silva *et al.* 2002, Santos *et al.* 2000). These types of complexes have been described in the literature as catalytically active in oxidation and reduction reactions both as homogeneous and heterogeneous catalysts (Yoon & Burrows, 1988). Other areas where coordination chemistry has found application are in the areas of molecular adsorption, liquid-liquid extraction, ion exchange and metalloenzymes. They have been designed as potential transition metal host systems in host-guest chemistry in the similar way to that of enzyme substrate.

The importance of nickel salen complexes with aromatic substituents range from biological (Bal and Ülküseven, 2004), activation of O~2~ under very mild conditions (Soto-Garrodo, & Salas-Reyes, 2000) and mesogenic properties of substituted complexes. (Blake *et al.* 1995) reported metallomesogens based on nickel alkyl and alkoxy substituted salen.

The central Ni is in a square planar coordination environment of O1 O2, N1 and N2 with rms deviation of 0.0461 (6) Å (deviation from plane for Ni of 0.0034 (7) Å). The Ni---N and Ni---O bond distances are in the normal range for Ni-salen type complexes (Allen *et al.*, 1987) at 1.8448 (14), and 1.8478 (14) Å for Ni---N and 1.8536 (12) Å and 1.8520 (12) Å for Ni---O. There is a slight twist in the two phenyl rings at each end of the complex (dihedral angle of 11.11 (5)°. All the atoms of the methoxy substitutents are in the plane of the ring to which they are attached except C19 which deviates slightly (0.365 (3) °). There are weak C---H···O intermolecular interactions connecting the molecules in the solid state.

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

The ligand synthesis was accomplished by adding a solution of (2 g, 33.3 mmol) ethylenediamine in 25 mls of methanol to a solution of (12.13 g, 66.6 mmol) 4,6-dimethoxysalicylaldehyde in 40 ml of methanol. The mixture was refluxed overnight while stirring. Then the mixture was evaporated under reduced pressure to afford yellow solids.

The complex was synthesized by mixing a solution of (0.38 g, 1 mmol) *N*,*N*-ethylenebis(4,6-dimethoxysalicylaldimine) in 5 ml of CH~2~Cl~2~ with a solution of (0.29 g, 1 mmol) nickel nitrate hexahydrate in 5 ml methanol. The solution mixture was stirred for 1 hour then filtered and layered with diethyl ether for crystallization. Single crystals of X-ray quality were obtained.

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

H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with a C---H distances of 0.95 and 0.99 Å *U*~iso~(H) = 1.2*U*~eq~(C) and 0.98 Å for CH~3~ \[*U*~iso~(H) = 1.5*U*~eq~(C)\].

Figures
=======

![Diagram of the square planar nickel complex C20H22N2NiO6 showing atom labeling.](e-66-0m620-fig1){#Fap1}

![The molecular packing for C20H22N2NiO6 viewed down the a axis.](e-66-0m620-fig2){#Fap2}

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

  ---------------------------- ---------------------------------------
  \[Ni(C~20~H~22~N~2~O~6~)\]   *F*(000) = 928
  *M~r~* = 445.11              *D*~x~ = 1.617 Mg m^−3^
  Monoclinic, *P*2~1~/*c*      Cu *K*α radiation, λ = 1.54184 Å
  Hall symbol: -P 2ybc         Cell parameters from 5663 reflections
  *a* = 7.41599 (12) Å         θ = 5.6--74.0°
  *b* = 15.6945 (2) Å          µ = 1.91 mm^−1^
  *c* = 15.7203 (2) Å          *T* = 110 K
  β = 91.9153 (13)°            Needle, red
  *V* = 1828.67 (5) Å^3^       0.53 × 0.15 × 0.12 mm
  *Z* = 4                      
  ---------------------------- ---------------------------------------

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

  ------------------------------------------------------------------------------ --------------------------------------
  Oxford Diffraction Xcalibur Ruby Gemini diffractometer                         3603 independent reflections
  Radiation source: Enhance (Cu) X-ray Source                                    3370 reflections with *I* \> 2σ(*I*)
  graphite                                                                       *R*~int~ = 0.022
  Detector resolution: 10.5081 pixels mm^-1^                                     θ~max~ = 74.2°, θ~min~ = 5.6°
  ω scans                                                                        *h* = −9→8
  Absorption correction: multi-scan (*CrysAlis PRO*; Oxford Diffraction, 2007)   *k* = −11→19
  *T*~min~ = 0.602, *T*~max~ = 1.000                                             *l* = −18→19
  6746 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*\[*F*^2^ \> 2σ(*F*^2^)\] = 0.036   Hydrogen site location: inferred from neighbouring sites
  *wR*(*F*^2^) = 0.098                  H-atom parameters constrained
  *S* = 1.04                            *w* = 1/\[σ^2^(*F*~o~^2^) + (0.0641*P*)^2^ + 1.0294*P*\] where *P* = (*F*~o~^2^ + 2*F*~c~^2^)/3
  3603 reflections                      (Δ/σ)~max~ \< 0.001
  266 parameters                        Δρ~max~ = 0.42 e Å^−3^
  0 restraints                          Δρ~min~ = −0.47 e Å^−3^
  ------------------------------------- -------------------------------------------------------------------------------------------------

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

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

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

  ------ -------------- --------------- --------------- -------------------- --
         *x*            *y*             *z*             *U*~iso~\*/*U*~eq~   
  Ni     0.25525 (4)    0.522587 (16)   0.436449 (16)   0.01249 (11)         
  O1     0.25637 (17)   0.49637 (8)     0.32150 (7)     0.0166 (2)           
  O2     0.25493 (17)   0.63580 (7)     0.40321 (7)     0.0168 (2)           
  O3     0.36236 (18)   0.33461 (8)     0.07279 (8)     0.0209 (3)           
  O4     0.45100 (16)   0.20821 (7)     0.34353 (7)     0.0183 (3)           
  O5     0.10218 (18)   0.76296 (8)     0.66590 (7)     0.0192 (3)           
  O6     0.13141 (19)   0.93215 (8)     0.41651 (8)     0.0230 (3)           
  N1     0.26710 (19)   0.41000 (9)     0.46989 (8)     0.0143 (3)           
  N2     0.24084 (18)   0.54755 (10)    0.55089 (9)     0.0145 (3)           
  C1     0.3028 (2)     0.42368 (10)    0.28756 (10)    0.0142 (3)           
  C2     0.3067 (2)     0.41965 (10)    0.19756 (10)    0.0158 (3)           
  H2A    0.2743         0.4682          0.1643          0.019\*              
  C3     0.3576 (2)     0.34513 (11)    0.15833 (10)    0.0163 (3)           
  C4     0.4124 (2)     0.27279 (11)    0.20515 (11)    0.0171 (3)           
  H4A    0.4539         0.2233          0.1771          0.020\*              
  C5     0.4047 (2)     0.27513 (10)    0.29228 (11)    0.0150 (3)           
  C6     0.3462 (2)     0.34938 (10)    0.33579 (11)    0.0152 (3)           
  C7     0.3154 (2)     0.34535 (10)    0.42475 (11)    0.0145 (3)           
  H7A    0.3313         0.2920          0.4526          0.017\*              
  C8     0.2141 (2)     0.39623 (11)    0.55814 (10)    0.0164 (3)           
  H8A    0.2732         0.3445          0.5820          0.020\*              
  H8B    0.0818         0.3891          0.5605          0.020\*              
  C9     0.2745 (2)     0.47426 (10)    0.60768 (11)    0.0171 (3)           
  H9A    0.2051         0.4801          0.6601          0.020\*              
  H9B    0.4044         0.4702          0.6239          0.020\*              
  C10    0.2071 (2)     0.62123 (11)    0.58443 (10)    0.0155 (3)           
  H10A   0.1973         0.6239          0.6445          0.019\*              
  C11    0.1837 (2)     0.69804 (11)    0.53782 (10)    0.0155 (3)           
  C12    0.1328 (2)     0.77404 (11)    0.58121 (10)    0.0165 (3)           
  C13    0.1162 (2)     0.85044 (11)    0.53987 (11)    0.0188 (3)           
  H13A   0.0831         0.9005          0.5695          0.023\*              
  C14    0.1498 (2)     0.85285 (11)    0.45184 (11)    0.0171 (3)           
  C15    0.1950 (2)     0.78148 (11)    0.40677 (10)    0.0165 (3)           
  H15A   0.2138         0.7853          0.3474          0.020\*              
  C16    0.2134 (2)     0.70230 (10)    0.44895 (10)    0.0144 (3)           
  C17    0.3271 (3)     0.40816 (12)    0.02106 (11)    0.0264 (4)           
  H17A   0.3333         0.3925          −0.0391         0.040\*              
  H17B   0.4174         0.4521          0.0347          0.040\*              
  H17C   0.2065         0.4302          0.0322          0.040\*              
  C18    0.5069 (3)     0.13184 (11)    0.30218 (12)    0.0213 (4)           
  H18A   0.5485         0.0903          0.3451          0.032\*              
  H18B   0.6056         0.1450          0.2643          0.032\*              
  H18C   0.4050         0.1080          0.2688          0.032\*              
  C19    0.0109 (2)     0.83006 (11)    0.70858 (11)    0.0203 (4)           
  H19A   −0.0207        0.8109          0.7655          0.030\*              
  H19B   −0.0992        0.8453          0.6759          0.030\*              
  H19C   0.0901         0.8799          0.7136          0.030\*              
  C20    0.1620 (3)     0.93901 (11)    0.32755 (12)    0.0232 (4)           
  H20A   0.1452         0.9983          0.3094          0.035\*              
  H20B   0.0763         0.9025          0.2958          0.035\*              
  H20C   0.2855         0.9209          0.3164          0.035\*              
  ------ -------------- --------------- --------------- -------------------- --

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

  ----- -------------- -------------- -------------- -------------- -------------- --------------
        *U*^11^        *U*^22^        *U*^33^        *U*^12^        *U*^13^        *U*^23^
  Ni    0.01826 (18)   0.00876 (17)   0.01067 (17)   0.00064 (10)   0.00377 (11)   −0.00065 (9)
  O1    0.0266 (6)     0.0109 (5)     0.0127 (5)     0.0024 (5)     0.0038 (4)     −0.0009 (4)
  O2    0.0253 (6)     0.0111 (5)     0.0144 (6)     0.0006 (5)     0.0071 (4)     −0.0013 (4)
  O3    0.0311 (7)     0.0181 (6)     0.0139 (6)     0.0004 (5)     0.0046 (5)     −0.0034 (5)
  O4    0.0253 (6)     0.0112 (5)     0.0185 (6)     0.0045 (5)     0.0019 (5)     −0.0026 (4)
  O5    0.0298 (7)     0.0148 (6)     0.0135 (6)     0.0034 (5)     0.0054 (5)     −0.0033 (4)
  O6    0.0381 (8)     0.0110 (6)     0.0205 (6)     0.0021 (5)     0.0089 (5)     0.0003 (5)
  N1    0.0170 (7)     0.0130 (6)     0.0130 (6)     0.0002 (5)     0.0033 (5)     0.0006 (5)
  N2    0.0174 (7)     0.0133 (7)     0.0129 (6)     0.0001 (5)     0.0024 (5)     0.0007 (5)
  C1    0.0143 (7)     0.0117 (7)     0.0167 (8)     −0.0022 (6)    0.0027 (6)     −0.0022 (6)
  C2    0.0188 (8)     0.0128 (8)     0.0158 (8)     −0.0016 (6)    0.0029 (6)     −0.0002 (6)
  C3    0.0162 (8)     0.0180 (8)     0.0149 (8)     −0.0035 (6)    0.0045 (6)     −0.0033 (6)
  C4    0.0178 (8)     0.0137 (8)     0.0200 (8)     −0.0006 (6)    0.0042 (6)     −0.0061 (6)
  C5    0.0138 (7)     0.0118 (7)     0.0195 (8)     −0.0010 (6)    0.0020 (6)     −0.0022 (6)
  C6    0.0156 (7)     0.0127 (8)     0.0175 (8)     −0.0012 (6)    0.0023 (6)     −0.0025 (6)
  C7    0.0154 (8)     0.0103 (7)     0.0178 (8)     0.0005 (6)     0.0012 (6)     −0.0004 (6)
  C8    0.0229 (8)     0.0131 (8)     0.0134 (8)     0.0023 (6)     0.0046 (6)     0.0025 (6)
  C9    0.0229 (9)     0.0161 (8)     0.0122 (7)     0.0024 (6)     0.0023 (6)     0.0011 (6)
  C10   0.0176 (8)     0.0164 (8)     0.0128 (7)     −0.0002 (6)    0.0031 (6)     −0.0025 (6)
  C11   0.0173 (8)     0.0127 (8)     0.0166 (8)     −0.0009 (6)    0.0022 (6)     −0.0030 (6)
  C12   0.0192 (8)     0.0159 (8)     0.0145 (7)     −0.0010 (6)    0.0028 (6)     −0.0039 (6)
  C13   0.0244 (9)     0.0127 (8)     0.0196 (8)     0.0001 (6)     0.0044 (6)     −0.0051 (6)
  C14   0.0202 (8)     0.0109 (7)     0.0204 (8)     −0.0006 (6)    0.0027 (6)     0.0006 (6)
  C15   0.0213 (8)     0.0131 (8)     0.0154 (7)     −0.0019 (6)    0.0050 (6)     −0.0012 (6)
  C16   0.0148 (7)     0.0118 (7)     0.0169 (8)     −0.0026 (6)    0.0037 (6)     −0.0023 (6)
  C17   0.0445 (12)    0.0206 (9)     0.0144 (8)     −0.0075 (8)    0.0067 (7)     0.0003 (7)
  C18   0.0266 (9)     0.0127 (8)     0.0249 (9)     0.0053 (7)     0.0051 (7)     −0.0042 (6)
  C19   0.0239 (9)     0.0187 (8)     0.0186 (8)     0.0024 (7)     0.0061 (6)     −0.0051 (6)
  C20   0.0318 (10)    0.0153 (8)     0.0231 (9)     0.0041 (7)     0.0105 (7)     0.0053 (7)
  ----- -------------- -------------- -------------- -------------- -------------- --------------

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

  -------------------- -------------- ----------------------- --------------
  Ni---N1              1.8448 (14)    C8---C9                 1.511 (2)
  Ni---N2              1.8478 (14)    C8---H8A                0.9900
  Ni---O2              1.8520 (12)    C8---H8B                0.9900
  Ni---O1              1.8536 (12)    C9---H9A                0.9900
  O1---C1              1.310 (2)      C9---H9B                0.9900
  O2---C16             1.310 (2)      C10---C11               1.418 (2)
  O3---C3              1.356 (2)      C10---H10A              0.9500
  O3---C17             1.431 (2)      C11---C16               1.423 (2)
  O4---C5              1.361 (2)      C11---C12               1.431 (2)
  O4---C18             1.4316 (19)    C12---C13               1.368 (2)
  O5---C12             1.369 (2)      C13---C14               1.415 (2)
  O5---C19             1.4311 (19)    C13---H13A              0.9500
  O6---C14             1.368 (2)      C14---C15               1.373 (2)
  O6---C20             1.428 (2)      C15---C16               1.413 (2)
  N1---C7              1.295 (2)      C15---H15A              0.9500
  N1---C8              1.4705 (19)    C17---H17A              0.9800
  N2---C10             1.299 (2)      C17---H17B              0.9800
  N2---C9              1.472 (2)      C17---H17C              0.9800
  C1---C2              1.418 (2)      C18---H18A              0.9800
  C1---C6              1.422 (2)      C18---H18B              0.9800
  C2---C3              1.381 (2)      C18---H18C              0.9800
  C2---H2A             0.9500         C19---H19A              0.9800
  C3---C4              1.406 (2)      C19---H19B              0.9800
  C4---C5              1.373 (2)      C19---H19C              0.9800
  C4---H4A             0.9500         C20---H20A              0.9800
  C5---C6              1.426 (2)      C20---H20B              0.9800
  C6---C7              1.426 (2)      C20---H20C              0.9800
  C7---H7A             0.9500                                 
                                                              
  N1---Ni---N2         85.95 (6)      N2---C9---H9B           110.5
  N1---Ni---O2         177.34 (6)     C8---C9---H9B           110.5
  N2---Ni---O2         94.11 (6)      H9A---C9---H9B          108.7
  N1---Ni---O1         93.64 (6)      N2---C10---C11          124.68 (15)
  N2---Ni---O1         176.89 (6)     N2---C10---H10A         117.7
  O2---Ni---O1         86.44 (5)      C11---C10---H10A        117.7
  C1---O1---Ni         126.87 (11)    C10---C11---C16         121.80 (15)
  C16---O2---Ni        127.42 (10)    C10---C11---C12         119.46 (15)
  C3---O3---C17        117.05 (13)    C16---C11---C12         118.73 (15)
  C5---O4---C18        116.65 (13)    C13---C12---O5          123.95 (15)
  C12---O5---C19       117.32 (13)    C13---C12---C11         121.68 (15)
  C14---O6---C20       116.69 (13)    O5---C12---C11          114.37 (14)
  C7---N1---C8         119.28 (14)    C12---C13---C14         118.19 (15)
  C7---N1---Ni         127.27 (12)    C12---C13---H13A        120.9
  C8---N1---Ni         113.45 (10)    C14---C13---H13A        120.9
  C10---N2---C9        118.73 (13)    O6---C14---C15          123.75 (15)
  C10---N2---Ni        127.03 (12)    O6---C14---C13          113.77 (15)
  C9---N2---Ni         114.24 (11)    C15---C14---C13         122.48 (15)
  O1---C1---C2         117.36 (14)    C14---C15---C16         119.78 (15)
  O1---C1---C6         123.69 (15)    C14---C15---H15A        120.1
  C2---C1---C6         118.94 (14)    C16---C15---H15A        120.1
  C3---C2---C1         119.91 (15)    O2---C16---C15          117.64 (14)
  C3---C2---H2A        120.0          O2---C16---C11          123.25 (15)
  C1---C2---H2A        120.0          C15---C16---C11         119.11 (15)
  O3---C3---C2         124.24 (16)    O3---C17---H17A         109.5
  O3---C3---C4         113.82 (15)    O3---C17---H17B         109.5
  C2---C3---C4         121.94 (15)    H17A---C17---H17B       109.5
  C5---C4---C3         118.66 (15)    O3---C17---H17C         109.5
  C5---C4---H4A        120.7          H17A---C17---H17C       109.5
  C3---C4---H4A        120.7          H17B---C17---H17C       109.5
  O4---C5---C4         123.50 (15)    O4---C18---H18A         109.5
  O4---C5---C6         114.92 (14)    O4---C18---H18B         109.5
  C4---C5---C6         121.58 (15)    H18A---C18---H18B       109.5
  C1---C6---C7         121.24 (15)    O4---C18---H18C         109.5
  C1---C6---C5         118.77 (15)    H18A---C18---H18C       109.5
  C7---C6---C5         119.70 (15)    H18B---C18---H18C       109.5
  N1---C7---C6         123.96 (15)    O5---C19---H19A         109.5
  N1---C7---H7A        118.0          O5---C19---H19B         109.5
  C6---C7---H7A        118.0          H19A---C19---H19B       109.5
  N1---C8---C9         106.45 (13)    O5---C19---H19C         109.5
  N1---C8---H8A        110.4          H19A---C19---H19C       109.5
  C9---C8---H8A        110.4          H19B---C19---H19C       109.5
  N1---C8---H8B        110.4          O6---C20---H20A         109.5
  C9---C8---H8B        110.4          O6---C20---H20B         109.5
  H8A---C8---H8B       108.6          H20A---C20---H20B       109.5
  N2---C9---C8         106.22 (13)    O6---C20---H20C         109.5
  N2---C9---H9A        110.5          H20A---C20---H20C       109.5
  C8---C9---H9A        110.5          H20B---C20---H20C       109.5
                                                              
  N1---Ni---O1---C1    −16.22 (14)    O4---C5---C6---C7       −8.9 (2)
  N2---Ni---O1---C1    −98.5 (11)     C4---C5---C6---C7       171.01 (15)
  O2---Ni---O1---C1    161.12 (14)    C8---N1---C7---C6       171.34 (15)
  N1---Ni---O2---C16   −105.1 (12)    Ni---N1---C7---C6       −8.6 (2)
  N2---Ni---O2---C16   −13.82 (14)    C1---C6---C7---N1       −8.2 (3)
  O1---Ni---O2---C16   163.11 (14)    C5---C6---C7---N1       177.99 (16)
  N2---Ni---N1---C7    −165.37 (15)   C7---N1---C8---C9       146.29 (15)
  O2---Ni---N1---C7    −73.9 (12)     Ni---N1---C8---C9       −33.74 (16)
  O1---Ni---N1---C7    17.72 (15)     C10---N2---C9---C8      151.31 (15)
  N2---Ni---N1---C8    14.66 (12)     Ni---N2---C9---C8       −29.43 (16)
  O2---Ni---N1---C8    106.1 (12)     N1---C8---C9---N2       38.49 (17)
  O1---Ni---N1---C8    −162.25 (11)   C9---N2---C10---C11     175.76 (15)
  N1---Ni---N2---C10   −171.54 (15)   Ni---N2---C10---C11     −3.4 (3)
  O2---Ni---N2---C10   11.12 (15)     N2---C10---C11---C16    −6.4 (3)
  O1---Ni---N2---C10   −89.0 (11)     N2---C10---C11---C12    175.06 (16)
  N1---Ni---N2---C9    9.28 (12)      C19---O5---C12---C13    14.1 (2)
  O2---Ni---N2---C9    −168.06 (11)   C19---O5---C12---C11    −165.63 (15)
  O1---Ni---N2---C9    91.8 (11)      C10---C11---C12---C13   177.11 (16)
  Ni---O1---C1---C2    −175.30 (11)   C16---C11---C12---C13   −1.5 (3)
  Ni---O1---C1---C6    5.7 (2)        C10---C11---C12---O5    −3.2 (2)
  O1---C1---C2---C3    178.92 (15)    C16---C11---C12---O5    178.18 (14)
  C6---C1---C2---C3    −2.0 (2)       O5---C12---C13---C14    −179.25 (16)
  C17---O3---C3---C2   5.6 (2)        C11---C12---C13---C14   0.4 (3)
  C17---O3---C3---C4   −173.47 (16)   C20---O6---C14---C15    −0.1 (3)
  C1---C2---C3---O3    178.78 (15)    C20---O6---C14---C13    −179.51 (15)
  C1---C2---C3---C4    −2.2 (3)       C12---C13---C14---O6    −179.43 (16)
  O3---C3---C4---C5    −177.02 (15)   C12---C13---C14---C15   1.1 (3)
  C2---C3---C4---C5    3.9 (2)        O6---C14---C15---C16    179.13 (16)
  C18---O4---C5---C4   −1.1 (2)       C13---C14---C15---C16   −1.5 (3)
  C18---O4---C5---C6   178.73 (14)    Ni---O2---C16---C15     −170.27 (11)
  C3---C4---C5---O4    178.62 (15)    Ni---O2---C16---C11     8.7 (2)
  C3---C4---C5---C6    −1.2 (2)       C14---C15---C16---O2    179.34 (15)
  O1---C1---C6---C7    9.7 (3)        C14---C15---C16---C11   0.3 (2)
  C2---C1---C6---C7    −169.32 (15)   C10---C11---C16---O2    3.6 (3)
  O1---C1---C6---C5    −176.52 (15)   C12---C11---C16---O2    −177.85 (15)
  C2---C1---C6---C5    4.5 (2)        C10---C11---C16---C15   −177.45 (15)
  O4---C5---C6---C1    177.22 (14)    C12---C11---C16---C15   1.1 (2)
  C4---C5---C6---C1    −2.9 (2)                               
  -------------------- -------------- ----------------------- --------------

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

  --------------------- --------- --------- ----------- ---------------
  *D*---H···*A*         *D*---H   H···*A*   *D*···*A*   *D*---H···*A*
  C8---H8B···O2^i^      0.99      2.61      3.587 (2)   169
  C17---H17A···O4^ii^   0.98      2.60      3.484 (2)   150
  --------------------- --------- --------- ----------- ---------------

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

###### Hydrogen-bond geometry (Å, °)

  *D*---H⋯*A*           *D*---H   H⋯*A*   *D*⋯*A*     *D*---H⋯*A*
  --------------------- --------- ------- ----------- -------------
  C8---H8*B*⋯O2^i^      0.99      2.61    3.587 (2)   169
  C17---H17*A*⋯O4^ii^   0.98      2.60    3.484 (2)   150

Symmetry codes: (i) ; (ii) .
