Synthesis and crystal structure of bis­(9-mesityl-9,10-di­hydro-10-aza-9-borabenzo[h]quinolinato-κ2N1,N10)zinc(II)

Appiarius, Y.; Puylaert, P.; Staubitz, A.

doi:10.1107/S2056989023009192

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Volume 79| Part 11| November 2023| Pages 1063-1066

https://doi.org/10.1107/S2056989023009192

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Synthesis and crystal structure of bis(9-mesityl-9,10-dihydro-10-aza-9-borabenzo[h]quinolinato-κ²N¹,N¹⁰)zinc(II)

Yannik Appiarius,^a,^b Pim Puylaert ^c and Anne Staubitz ^a,^b ^*

^aUniversity of Bremen, Institute for Organic and Analytical Chemistry, 28359 Bremen, Germany, ^bUniversity of Bremen, MAPEX Center for Materials and Processes, 28359 Bremen, Germany, and ^cUniversity of Bremen, Institute for Inorganic Chemistry and Crystallography, 28359 Bremen, Germany
^*Correspondence e-mail: staubitz@uni-bremen.de

Edited by G. Diaz de Delgado, Universidad de Los Andes Mérida, Venezuela (Received 27 July 2023; accepted 19 October 2023; online 24 October 2023)

The title compound, [Zn(C₂₀H₁₈BN₂)₂] (ZnL₂), is an overall uncharged chelate that consists of two units of an NH-deprotonated 10-aza-9-borabenzo[h]quinoline ligand (L) per Zn^II center. It was synthesized in two steps by treating the protonated ligand HL with lithium bis(trimethylsilyl)amide and further conversion with diethylzinc. Its asymmetric unit comprises one ZnL fragment; the molecule is completed by application of inversion symmetry at Zn. Due to the fourfold coordination with nitrogen atoms, the zinc(II) ion is located in a distorted tetrahedral environment. Besides the relatively short N—Zn bonds, ZnL₂ is characterized by the significant protrusion of the central ion from the plane of the ligand backbone. The crystal structure is consolidated by intra- and intermolecular π–π stacking interactions, while the polarized B—N bond is barely involved in any close atom contacts.

Keywords: crystal structure; 1,2-azaborinine; boron-nitrogen; zinc; bidentate ligand; Hirshfeld analysis.

CCDC reference: 2302109

1. Chemical context

1,2-Azaborinine is an aromatic six-membered ring that consists of a polar boron-nitrogen unit and a butadienyl moiety, making it an isoelectronic congener of benzene. Its strikingly similar geometry in conjunction with a significantly altered electron distribution has promoted research on mono- and polycyclic aromatic hydrocarbons (PAHs) with a BN substitution pattern. Several studies highlighted the BN-induced tailored adjustment of chemical, physical and optical properties, enabling the application of such heteroaromatics for instance as white-emitting layers in organic light-emitting diodes (Hoffmann et al., 2021 ), as reversible hydrogen storage materials (Campbell et al., 2010 ) or as building blocks in pharmaceuticals with increased bioavailability (Zhao et al., 2017 ). Relatively few reports made use of the selectively deprotonable NH group (pK_a ≃ 24) to introduce electrophilic functional groups or metal atoms (Pan et al., 2004 ; Lamm et al., 2011 ; Baggett & Liu, 2017 ; Lindl et al., 2023 ).

In a previous study (Appiarius et al., 2021 ), a BN-substituted benzo[h]quinoline (HL), containing one 1,2-azaborininyl- and one pyridyl subunit with both nitrogen atoms beneficially preorganized for chelation was presented. In the context of this communication, we report on the synthesis and crystal structure of the 2:1 coordination complex of ligand L with zinc(II).

2. Structural commentary

The molecular structure of the title compound (C₄₀H₃₆B₂N₄Zn, ZnL₂) is illustrated in Fig. 1. The coordination complex crystallizes in the monoclinic C2/c centrosymmetric space group with one zinc(II) cation and one ligand molecule in the asymmetric unit, being completed by the application of inversion symmetry at Zn^II. The latter is fourfold coordinated by two types of N donors, namely the azaborinine and pyridine subunits comprised in the BN-benzo[h]quinoline. This results in a significantly distorted tetrahedral configuration [bond angle N1—Zn1—N2 84.72 (4)°; all other N—Zn—N bond angles > 118°, see Table 1]. The bond lengths within the 1,2-azaborinine motif of the ligand [B1—N1: 1.4245 (17) Å, B1—C11: 1.5315 (19) Å, N1—C1: 1.3580 (14) Å] are in characteristic ranges (Paetzold et al., 2004 ; Pan et al., 2009 ), confirming electron delocalization and an elevated aromatic character. The N—Zn bond lengths [N1—Zn1: 1.9606 (10) Å, N2—Zn1: 2.0527 (10) Å] are in excellent agreement with bis(2-(2′-pyridyl)pyrrolyl)zinc [N_pyrrole–Zn 1.9513 (18) Å, N_pyridine–Zn 2.0444 (18) Å; Wang et al., 2009 ], supporting the electronic similarities of 1,2-azaborinine and pyrrole (Davies et al., 2017 ). This contrasts with zinc complexes involving the geometrically similar but uncharged 1,10-phenanthroline ligand (N_pyridine–Zn 2.13–2.20 Å) with higher coordination numbers of the central ion. All aromatic rings within the BN-PAH ligand are close to planar, with an average torsion angle of 2.2° and a maximum deviation of an atom from the mean aromatic plane of 0.0217 (8) Å. In contrast, the Zn^II ion is located 0.365 (2) Å out of the mean N1–C1–C2–N2 plane and points in the direction of the mesityl ring of the second ligand unit. The 1,2-azaborinine motif and the attached planar mesityl group [maximum deviation from the mean aromatic plane: 0.0125 (9) Å] are oriented almost perpendicularly to each other, with an angle between their mean planes of 79.41 (4)°.

Table 1
Selected geometric parameters (Å, °)

Zn1—N1	1.9606 (10)	N2—C2	1.3660 (16)
Zn1—N2	2.0527 (10)	N2—C3	1.3316 (17)
N1—C1	1.3580 (14)	C12—B1	1.5896 (18)
N1—B1	1.4245 (17)	C11—B1	1.5315 (19)

N1ⁱ—Zn1—N1	118.68 (6)	N1—Zn1—N2	84.72 (4)
N1ⁱ—Zn1—N2	122.48 (4)	N2—Zn1—N2ⁱ	128.26 (6)

Zn1—N1—C1—C9	166.76 (9)	Zn1—N1—B1—C12	20.10 (16)
Zn1—N1—C1—C2	−14.38 (13)	Zn1—N1—B1—C11	−163.25 (9)
Symmetry code: (i) $[-x+1, y, -z+{\script{3\over 2}}]$ .

Figure 1
Molecular structure of ZnL₂ with atom labeling. The image was generated with ORTEP-3 for Windows (Farrugia, 2012

). Non-hydrogen atoms as displacement ellipsoids drawn at the 50% probability level. Hydrogen atoms were omitted for clarity. [Symmetry code: (i) −x + 1, y, –z + $[{3\over 2}]$ ].

3. Supramolecular features and Hirshfeld surface analysis

A Hirshfeld surface (Hirshfeld, 1977 , Fig. 2) and the respective two-dimensional fingerprint plots (Fig. 3) were generated using CrystalExplorer21.5 (Spackman et al., 2021 ) to analyze the intermolecular interactions. No close atom contacts involving the boron and zinc heteroatoms and a negligible participation of the nitrogen atom (N⋯H: 1.5%, C⋯N: 0.4%) were found. Therefore, the intermolecular interactions were almost exclusively caused by van der Waals forces involving carbon and hydrogen. In particular, close H⋯H contacts and aromatic interactions dominate the overall intermolecular interactions in a crystal. The `wings' at the top left (d_i ≃ 1.05 Å and d_e ≃ 1.60 Å) and their pseudo-symmetrical counterparts at the bottom right of the two-dimensional fingerprint plot correspond to C—H⋯π interactions. These are also mapped by several red spots on the Hirshfeld surface (Spackman & McKinnon, 2002 ). Moreover, considerable π–π stacking interactions are apparent by the light coloring of the Hirshfeld surface around the PAH backbone and intense C⋯C contacts (5.8%). The crystal packing shows that each aromatic ligand has one ligand unit of another molecule in close proximity, so that pairs of almost parallel but slightly displaced sheets in two dimensions result (Fig. 4). In particular, the phenyl and pyridyl subunits of neighboring molecules show a significant overlap, with an offset of only 1.181 (2) Å and a minimum interplanar distance of 3.3826 (13) Å. On the other hand, the PAH scaffolds and the mesityl π-planes of the inverse ligand units are aligned almost coplanar [mesityl–pyridine interplanar angle: 1.46 (5)°] with a similarly small minimum interplanar distance [3.3996 (10) Å]. Therefore, intramolecular π–π stacking contributes significantly to the overall stabilizing forces. We assume that the discussed, unusual off-plane position of the zinc ion and the increased angle between the mean mesityl plane and the B1—C12 bond [7.93 (8)°] also derives from this favorable stacking geometry.

Figure 2
Hirshfeld surface of ZnL₂, mapped over d_norm in the range between −0.1418 (red) and +1.6402 (blue).

Figure 3
Two-dimensional fingerprint plots, showing the contributions of the individual elements in close atom contacts.

Figure 4
Section of the crystal packing, showing the π–π stacking interactions propagating in two dimensions. BN rings are shown in orange, mesityl rings in yellow, phenyl and pyridyl rings in blue.

4. Database survey

A survey of the Cambridge Structural Database (WebCSD version 1.9.32, accessed in July 2023 ; Groom et al., 2016) revealed that 654 crystal structures of six-membered carbocycles with 1-aza-2-bora substitution patterns have been reported. Among these, 101 structures comprising B-mesityl substituents have been deposited, which involves aromatic 1,2-azaborinine subunits for the most part. The crystal structures of 13 compounds with 1,2-azaborinine substructures and nitrogen–metal bonds have been published, of which different lithium solvates as well as potassium, beryllium, aluminum, gallium and tin complexes are included in one publication (Lindl et al., 2023). Moreover, one study describes several complexes of a bidentate ligand with aluminum (Appiarius et al., 2023 ). However, there are only three reports of 1,2-azaborinines with N–transition-metal bonds, including zirconium (refcode JIZQEP; Pan et al., 2008 ), ruthenium (refcode DOXBEY; Pan et al., 2008) and iridium (refcode NEZXAV; Baschieri et al., 2023 ). Also, the structure of a 6-pyridyl-1,2-azaborinine has been reported, which is structurally similar to HL and was used for the preparation of a dimesitylboron complex (refcode WUGMIW; Baggett et al., 2015 ). The search query for coordination complexes of zinc with 1,2-azaborinine ligands did not yield any results.

5. Synthesis and crystallization

The synthesis of ZnL₂ is shown in Fig. 5. Under argon at 298 K, 9,10-dihydro-9-mesityl-10-aza-9-borabenzo[h]quinoline (HL, 29.8 mg, 100 µmol, 1.00 equiv., prepared according to Appiarius et al., 2021) was dissolved in THF (1.5 mL). A solution of lithium bis(trimethylsilyl)amide (1.0 M in THF, 120 µL, 1.20 equiv.) was added, before a solution of diethylzinc (15% w/w in hexanes, 230 µL, 2.00 equiv.) was added via a syringe. The mixture was heated to 428 K for 17 h while stirring. In a glove box, the volatiles were removed under reduced pressure. The residue was extracted with n-hexane (3 × 2 mL) and the solvent was removed. The crude product was dissolved in THF (500 µL) and n-hexane was allowed to diffuse into this solution over the course of 3 d. The light-yellow product (6.4 mg, 19%) was obtained as air-sensitive crystals suitable for X-ray diffraction analysis by repeating this process twice. ¹H NMR (600 MHz, THF-d₈): δ = 8.37–8.32 (m, 4H, C3-H + C5-H), 8.07 (d, ³J = 11.0 Hz, 2H, C10-H), 7.79 (d, ³J = 8.7 z, 2H, C8-H), 7.38–7.35 (m, 2H, C4-H), 7.33 (d, ³J = 8.7 Hz, 2H, C7-H), 6.90 (d, ³J = 11.0 Hz, 2H, C11-H), 6.04 (s, 2H, C14-H), 5.61 (s, 2H, C16-H), 1.83 (s, 6H, C19-H), 1.79 (s, 6H, C18-H), 1.40 (s, 6H, C20-H) ppm. ¹³C{¹H} NMR (151 MHz, THF-d₈): δ = 147.3 (C3), 145.8 (C1), 143.3 (C2), 143.0 (C10), 139.2 (C17), 139.2 (C5), 139.1 (C13), 134.8 (C15), 134.5 (C11), 131.2 (C8), 129.0 (C6), 127.1 (C14), 126.4 (C16), 126.1 (C9), 122.3 (C4), 116.1 (C7), 24.0 (C18), 23.8 (C20), 21.3 (C19) ppm. ¹¹B{¹H} NMR (193 MHz, THF-d₈): δ = 38.6 ppm. MS (EI): m/z 658.3 (3%) [ZnL₂]⁺, 298.2 (100%) [HL]⁺. HR-MS (EI): m/z calculated for C₄₀H₃₆B₂N₄Zn⁺ 658.24259, found 658.24253 (Dev.: 0.06 mu, 0.09 ppm). UV/Vis: λ_abs = 296, 343, 358 nm. Fluorescence: λ_fl = 488 nm (λ_exc = 350 nm). Further experimental details can be found in the Supporting Information.

Figure 5
Reaction scheme for the synthesis of ZnL₂.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 2. Hydrogen atoms were positioned geometrically and refined using a riding model with C—H bond lengths of 0.95 Å (C—H) or 0.98 Å (C—H₃). Isotropic displacement parameters (U_iso) of these H atoms were fixed to 1.2 (C—H) or 1.5 (C—H₃) of the values of the parent carbon atoms. Idealized methyl groups (C18—H₃, C19—H₃, C20—H₃) were allowed to rotate.

Table 2
Experimental details

Crystal data
Chemical formula	[Zn(C₂₀H₁₈BN₂)₂]
M_r	659.72
Crystal system, space group	Monoclinic, C2/c
Temperature (K)	100
a, b, c (Å)	20.0425 (14), 9.8589 (6), 17.1167 (9)
β (°)	105.172 (4)
V (Å³)	3264.3 (4)
Z	4
Radiation type	Mo Kα
μ (mm⁻¹)	0.79
Crystal size (mm)	0.24 × 0.12 × 0.09

Data collection
Diffractometer	Bruker APEXII CCD
Absorption correction	Multi-scan (SADABS; Krause et al., 2015 )
T_min, T_max	0.677, 0.747
No. of measured, independent and observed [I > 2σ(I)] reflections	95271, 6577, 5466
R_int	0.084
(sin θ/λ)_max (Å⁻¹)	0.784

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.036, 0.097, 1.06
No. of reflections	6577
No. of parameters	216
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.52, −0.40
Computer programs: APEX2 and SAINT (Bruker, 2016 ), SHELXT2018/2 (Sheldrick, 2015a ), SHELXL2018/3 (Sheldrick, 2015b ), OLEX2 (Dolomanov et al., 2009 ), ORTEP-3 for Windows (Farrugia, 2012 ), and publCIF (Westrip, 2010 ).

Supporting information

CCDC reference: 2302109

Crystal structure: contains datablock I. DOI: https://doi.org/10.1107/S2056989023009192/dj2071sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989023009192/dj2071Isup2.hkl

Experimental details, unit cell packing views, NMR spectra, UV vis and fluorescence spectra. DOI: https://doi.org/10.1107/S2056989023009192/dj2071sup4.pdf

checkCIF report

Computing details top

Data collection: APEX2 (Bruker, 2016); cell refinement: SAINT (Bruker, 2016); data reduction: SAINT (Bruker, 2016); program(s) used to solve structure: SHELXT2018/2 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2018/3 (Sheldrick, 2015b); molecular graphics: Olex2 1.5 (Dolomanov et al., 2009), ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: publCIF (Westrip, 2010).

Bis(9-mesityl-9,10-dihydro-10-aza-9-borabenzo[h]quinolinato-κ²N¹,N¹⁰)zinc(II) top

Crystal data top

[Zn(C₂₀H₁₈BN₂)₂]	F(000) = 1376
M_r = 659.72	D_x = 1.342 Mg m⁻³
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 20.0425 (14) Å	Cell parameters from 9897 reflections
b = 9.8589 (6) Å	θ = 2.8–33.4°
c = 17.1167 (9) Å	µ = 0.79 mm⁻¹
β = 105.172 (4)°	T = 100 K
V = 3264.3 (4) Å³	Irregular, light yellow
Z = 4	0.24 × 0.12 × 0.09 mm

Data collection top

Bruker APEXII CCD diffractometer	5466 reflections with I > 2σ(I)
φ and ω scans	R_int = 0.084
Absorption correction: multi-scan (SADABS; Krause et al., 2015)	θ_max = 33.9°, θ_min = 2.8°
T_min = 0.677, T_max = 0.747	h = −31→31
95271 measured reflections	k = −15→15
6577 independent reflections	l = −26→26

Refinement top

Refinement on F²	Primary atom site location: dual
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.036	H-atom parameters constrained
wR(F²) = 0.097	w = 1/[σ²(F_o²) + (0.0416P)² + 3.4887P] where P = (F_o² + 2F_c²)/3
S = 1.06	(Δ/σ)_max < 0.001
6577 reflections	Δρ_max = 0.52 e Å⁻³
216 parameters	Δρ_min = −0.40 e Å⁻³
0 restraints

Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
Zn1	0.500000	0.38978 (2)	0.750000	0.01617 (6)
N1	0.45636 (5)	0.28837 (11)	0.65132 (6)	0.01565 (17)
N2	0.55610 (6)	0.48063 (11)	0.67988 (6)	0.01854 (19)
C16	0.33235 (7)	0.14365 (15)	0.83074 (8)	0.0230 (2)
H16	0.341124	0.087836	0.877572	0.028*
C9	0.48444 (6)	0.22124 (13)	0.52702 (7)	0.0178 (2)
C1	0.49408 (6)	0.30237 (12)	0.59647 (7)	0.01542 (19)
C2	0.54576 (6)	0.40771 (12)	0.60987 (7)	0.0164 (2)
C8	0.52494 (7)	0.24688 (14)	0.47125 (8)	0.0227 (2)
H8	0.519116	0.190173	0.425081	0.027*
C10	0.43285 (7)	0.11731 (14)	0.51402 (8)	0.0217 (2)
H10	0.427219	0.059047	0.468550	0.026*
C7	0.57165 (7)	0.35008 (15)	0.48219 (8)	0.0232 (2)
H7	0.596684	0.366128	0.443013	0.028*
C6	0.58310 (7)	0.43410 (14)	0.55225 (8)	0.0199 (2)
C12	0.35616 (6)	0.19967 (13)	0.70258 (7)	0.0181 (2)
C15	0.28518 (7)	0.24956 (15)	0.82289 (8)	0.0237 (2)
C17	0.36714 (6)	0.11728 (14)	0.77154 (8)	0.0198 (2)
C11	0.39151 (7)	0.09962 (14)	0.56519 (8)	0.0219 (2)
H11	0.356957	0.031157	0.554933	0.026*
C20	0.41803 (7)	0.00090 (15)	0.78396 (9)	0.0250 (3)
H20A	0.463242	0.031778	0.816536	0.038*
H20B	0.422293	−0.031172	0.731288	0.038*
H20C	0.401508	−0.073317	0.812099	0.038*
C14	0.27287 (7)	0.32946 (15)	0.75349 (8)	0.0237 (2)
H14	0.240393	0.401532	0.746658	0.028*
C19	0.24812 (8)	0.27744 (19)	0.88737 (10)	0.0329 (3)
H19A	0.204988	0.225380	0.875753	0.049*
H19B	0.237646	0.374471	0.887957	0.049*
H19C	0.277652	0.250591	0.940294	0.049*
C13	0.30729 (6)	0.30568 (14)	0.69395 (8)	0.0212 (2)
C4	0.64006 (8)	0.61577 (16)	0.63859 (9)	0.0272 (3)
H4	0.672060	0.688821	0.649815	0.033*
C3	0.60226 (7)	0.58083 (14)	0.69353 (8)	0.0240 (2)
H3	0.609776	0.630540	0.742618	0.029*
C18	0.29227 (8)	0.39485 (18)	0.61986 (10)	0.0322 (3)
H18A	0.333702	0.447143	0.619199	0.048*
H18B	0.254432	0.457120	0.621039	0.048*
H18C	0.278912	0.338272	0.571181	0.048*
C5	0.63028 (7)	0.54297 (15)	0.56807 (9)	0.0251 (3)
H5	0.655364	0.566043	0.529928	0.030*
B1	0.40171 (7)	0.19187 (14)	0.63937 (8)	0.0171 (2)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Zn1	0.01813 (9)	0.01939 (10)	0.01154 (8)	0.000	0.00488 (6)	0.000
N1	0.0160 (4)	0.0186 (4)	0.0133 (4)	0.0000 (3)	0.0055 (3)	0.0000 (3)
N2	0.0198 (5)	0.0209 (5)	0.0147 (4)	−0.0022 (4)	0.0042 (4)	0.0009 (3)
C16	0.0220 (6)	0.0303 (7)	0.0188 (5)	−0.0055 (5)	0.0089 (4)	0.0010 (5)
C9	0.0203 (5)	0.0193 (5)	0.0149 (5)	0.0015 (4)	0.0066 (4)	−0.0002 (4)
C1	0.0162 (5)	0.0178 (5)	0.0129 (4)	0.0023 (4)	0.0050 (4)	0.0016 (4)
C2	0.0167 (5)	0.0190 (5)	0.0139 (4)	0.0009 (4)	0.0048 (4)	0.0022 (4)
C8	0.0288 (6)	0.0247 (6)	0.0177 (5)	0.0025 (5)	0.0115 (5)	−0.0008 (4)
C10	0.0274 (6)	0.0212 (6)	0.0171 (5)	−0.0016 (5)	0.0070 (4)	−0.0034 (4)
C7	0.0266 (6)	0.0275 (6)	0.0194 (5)	0.0018 (5)	0.0127 (5)	0.0021 (5)
C6	0.0202 (5)	0.0227 (5)	0.0187 (5)	0.0006 (4)	0.0084 (4)	0.0046 (4)
C12	0.0152 (5)	0.0226 (6)	0.0169 (5)	−0.0034 (4)	0.0049 (4)	−0.0004 (4)
C15	0.0207 (5)	0.0314 (7)	0.0217 (6)	−0.0064 (5)	0.0105 (5)	−0.0050 (5)
C17	0.0174 (5)	0.0237 (6)	0.0192 (5)	−0.0038 (4)	0.0064 (4)	0.0015 (4)
C11	0.0233 (6)	0.0226 (6)	0.0203 (5)	−0.0049 (4)	0.0063 (4)	−0.0026 (4)
C20	0.0254 (6)	0.0256 (6)	0.0258 (6)	0.0007 (5)	0.0098 (5)	0.0059 (5)
C14	0.0183 (5)	0.0282 (7)	0.0265 (6)	−0.0010 (5)	0.0094 (5)	−0.0030 (5)
C19	0.0312 (7)	0.0431 (9)	0.0307 (7)	−0.0054 (6)	0.0191 (6)	−0.0066 (6)
C13	0.0179 (5)	0.0260 (6)	0.0209 (5)	−0.0004 (4)	0.0073 (4)	0.0016 (4)
C4	0.0264 (6)	0.0291 (7)	0.0260 (6)	−0.0084 (5)	0.0068 (5)	0.0041 (5)
C3	0.0266 (6)	0.0245 (6)	0.0195 (5)	−0.0064 (5)	0.0037 (5)	0.0006 (4)
C18	0.0294 (7)	0.0395 (8)	0.0309 (7)	0.0123 (6)	0.0137 (6)	0.0122 (6)
C5	0.0238 (6)	0.0293 (7)	0.0244 (6)	−0.0036 (5)	0.0100 (5)	0.0059 (5)
B1	0.0167 (5)	0.0197 (6)	0.0152 (5)	−0.0004 (4)	0.0045 (4)	0.0004 (4)

Geometric parameters (Å, º) top

Zn1—N1ⁱ	1.9606 (10)	C12—C13	1.4134 (18)
Zn1—N1	1.9606 (10)	C12—B1	1.5896 (18)
Zn1—N2	2.0527 (10)	C15—C14	1.393 (2)
Zn1—N2ⁱ	2.0527 (10)	C15—C19	1.5080 (19)
N1—C1	1.3580 (14)	C17—C20	1.5127 (19)
N1—B1	1.4245 (17)	C11—H11	0.9500
N2—C2	1.3660 (16)	C11—B1	1.5315 (19)
N2—C3	1.3316 (17)	C20—H20A	0.9800
C16—H16	0.9500	C20—H20B	0.9800
C16—C15	1.391 (2)	C20—H20C	0.9800
C16—C17	1.3966 (18)	C14—H14	0.9500
C9—C1	1.4035 (16)	C14—C13	1.3920 (18)
C9—C8	1.4281 (17)	C19—H19A	0.9800
C9—C10	1.4310 (18)	C19—H19B	0.9800
C1—C2	1.4421 (17)	C19—H19C	0.9800
C2—C6	1.4095 (16)	C13—C18	1.507 (2)
C8—H8	0.9500	C4—H4	0.9500
C8—C7	1.362 (2)	C4—C3	1.3964 (19)
C10—H10	0.9500	C4—C5	1.374 (2)
C10—C11	1.3652 (18)	C3—H3	0.9500
C7—H7	0.9500	C18—H18A	0.9800
C7—C6	1.4257 (19)	C18—H18B	0.9800
C6—C5	1.4092 (19)	C18—H18C	0.9800
C12—C17	1.4020 (17)	C5—H5	0.9500

N1ⁱ—Zn1—N1	118.68 (6)	C16—C17—C12	120.32 (12)
N1ⁱ—Zn1—N2ⁱ	84.72 (4)	C16—C17—C20	119.04 (12)
N1ⁱ—Zn1—N2	122.48 (4)	C12—C17—C20	120.62 (11)
N1—Zn1—N2ⁱ	122.48 (4)	C10—C11—H11	120.5
N1—Zn1—N2	84.72 (4)	C10—C11—B1	118.97 (12)
N2—Zn1—N2ⁱ	128.26 (6)	B1—C11—H11	120.5
C1—N1—Zn1	109.89 (8)	C17—C20—H20A	109.5
C1—N1—B1	120.99 (10)	C17—C20—H20B	109.5
B1—N1—Zn1	128.11 (8)	C17—C20—H20C	109.5
C2—N2—Zn1	107.62 (8)	H20A—C20—H20B	109.5
C3—N2—Zn1	133.06 (9)	H20A—C20—H20C	109.5
C3—N2—C2	118.90 (11)	H20B—C20—H20C	109.5
C15—C16—H16	119.2	C15—C14—H14	119.4
C15—C16—C17	121.69 (12)	C13—C14—C15	121.22 (13)
C17—C16—H16	119.2	C13—C14—H14	119.4
C1—C9—C8	119.26 (11)	C15—C19—H19A	109.5
C1—C9—C10	118.26 (11)	C15—C19—H19B	109.5
C8—C9—C10	122.46 (11)	C15—C19—H19C	109.5
N1—C1—C9	123.33 (11)	H19A—C19—H19B	109.5
N1—C1—C2	118.03 (10)	H19A—C19—H19C	109.5
C9—C1—C2	118.63 (10)	H19B—C19—H19C	109.5
N2—C2—C1	117.15 (10)	C12—C13—C18	119.97 (11)
N2—C2—C6	122.03 (11)	C14—C13—C12	120.70 (12)
C6—C2—C1	120.82 (11)	C14—C13—C18	119.32 (12)
C9—C8—H8	119.0	C3—C4—H4	120.5
C7—C8—C9	122.07 (12)	C5—C4—H4	120.5
C7—C8—H8	119.0	C5—C4—C3	119.03 (13)
C9—C10—H10	119.1	N2—C3—C4	122.63 (13)
C11—C10—C9	121.79 (12)	N2—C3—H3	118.7
C11—C10—H10	119.1	C4—C3—H3	118.7
C8—C7—H7	119.9	C13—C18—H18A	109.5
C8—C7—C6	120.21 (11)	C13—C18—H18B	109.5
C6—C7—H7	119.9	C13—C18—H18C	109.5
C2—C6—C7	118.90 (12)	H18A—C18—H18B	109.5
C5—C6—C2	117.29 (12)	H18A—C18—H18C	109.5
C5—C6—C7	123.81 (12)	H18B—C18—H18C	109.5
C17—C12—C13	117.92 (11)	C6—C5—H5	120.0
C17—C12—B1	123.59 (11)	C4—C5—C6	120.08 (12)
C13—C12—B1	118.06 (11)	C4—C5—H5	120.0
C16—C15—C14	118.10 (12)	N1—B1—C12	115.27 (11)
C16—C15—C19	121.23 (13)	N1—B1—C11	116.51 (11)
C14—C15—C19	120.67 (14)	C11—B1—C12	128.12 (11)

Zn1—N1—C1—C9	166.76 (9)	C10—C9—C1—C2	−179.75 (11)
Zn1—N1—C1—C2	−14.38 (13)	C10—C9—C8—C7	176.87 (13)
Zn1—N1—B1—C12	20.10 (16)	C10—C11—B1—N1	−2.14 (19)
Zn1—N1—B1—C11	−163.25 (9)	C10—C11—B1—C12	174.00 (13)
Zn1—N2—C2—C1	7.93 (13)	C7—C6—C5—C4	−177.57 (14)
Zn1—N2—C2—C6	−172.71 (10)	C15—C16—C17—C12	1.2 (2)
Zn1—N2—C3—C4	172.48 (11)	C15—C16—C17—C20	179.74 (13)
N1—C1—C2—N2	4.08 (16)	C15—C14—C13—C12	−0.3 (2)
N1—C1—C2—C6	−175.29 (11)	C15—C14—C13—C18	180.00 (14)
N2—C2—C6—C7	177.35 (12)	C17—C16—C15—C14	0.4 (2)
N2—C2—C6—C5	−2.32 (19)	C17—C16—C15—C19	−179.75 (13)
C16—C15—C14—C13	−0.8 (2)	C17—C12—C13—C14	1.89 (19)
C9—C1—C2—N2	−177.01 (11)	C17—C12—C13—C18	−178.44 (13)
C9—C1—C2—C6	3.63 (17)	C17—C12—B1—N1	−96.44 (15)
C9—C8—C7—C6	2.0 (2)	C17—C12—B1—C11	87.37 (17)
C9—C10—C11—B1	−1.2 (2)	C19—C15—C14—C13	179.30 (13)
C1—N1—B1—C12	−172.61 (11)	C13—C12—C17—C16	−2.33 (18)
C1—N1—B1—C11	4.04 (17)	C13—C12—C17—C20	179.19 (12)
C1—C9—C8—C7	−1.7 (2)	C13—C12—B1—N1	75.93 (15)
C1—C9—C10—C11	2.81 (19)	C13—C12—B1—C11	−100.25 (16)
C1—C2—C6—C7	−3.32 (18)	C3—N2—C2—C1	−178.47 (11)
C1—C2—C6—C5	177.02 (12)	C3—N2—C2—C6	0.89 (18)
C2—N2—C3—C4	0.8 (2)	C3—C4—C5—C6	−0.5 (2)
C2—C6—C5—C4	2.1 (2)	C5—C4—C3—N2	−1.0 (2)
C8—C9—C1—N1	177.72 (11)	B1—N1—C1—C9	−2.63 (18)
C8—C9—C1—C2	−1.14 (17)	B1—N1—C1—C2	176.23 (11)
C8—C9—C10—C11	−175.75 (13)	B1—C12—C17—C16	170.06 (12)
C8—C7—C6—C2	0.5 (2)	B1—C12—C17—C20	−8.42 (19)
C8—C7—C6—C5	−179.86 (14)	B1—C12—C13—C14	−170.92 (12)
C10—C9—C1—N1	−0.89 (18)	B1—C12—C13—C18	8.75 (19)

Symmetry code: (i) −x+1, y, −z+3/2.

Funding information

Funding for this research was provided by: Central Research Development Fund of the University of Bremen (postdoctoral fellowship to Pim Puylaert).

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