A redetermination of chlorido­[hydridotris(3-tert-butyl-5-methyl­pyrazol­yl)borato]nickel(II)

In the title complex, [NiCl(C₂₄H₄₀BN₆)], the Ni atom is coordinated by three N atoms, with the typical facial arrangement imposed by tris­pyrazolylborate ligands, and a chloride ligand in a distorted tetra­hedral geometry. A structure of the title complex was previously reported in a lower symmetry space group [Santi, Romano, Sommazzi, Grande, Bianchini & Mantovani (2005). J. Mol. Catal. A: Chem. 229, 191-197].

Key indicators

• Single-crystal X-ray study
• T = 193 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.018
• wR factor = 0.045
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT063_ALERT_3_C Crystal Probably too Large for Beam Size .......       0.66 mm

Author Response: The crystal had one dimension of 0.66 mm, which is indeed a bit large. Although 0.6 mm or smaller would have been better, the data is of sufficient quality that collection of another data set with a smaller crystal seems unwarranted.

PLAT076_ALERT_1_C Occupancy       0.50 less than 1.0 for Sp.pos  .       H16A

Author Response: The two flagged atoms: H16A and H16D sit on a crystallographic mirror plane, but are properly included as half occupancy. These H atoms were included as members of an idealized disordered methyl group using the HFIX 123 command in SHELX.

PLAT076_ALERT_1_C Occupancy       0.50 less than 1.0 for Sp.pos  .       H16D

Author Response: The two flagged atoms: H16A and H16D sit on a crystallographic mirror plane, but are properly included as half occupancy. These H atoms were included as members of an idealized disordered methyl group using the HFIX 123 command in SHELX.

PLAT222_ALERT_3_C Large Non-Solvent    H     Ueq(max)/Ueq(min) ...       4.00 Ratio

Author Response: T The 4.00 ratio is the result of a small Ueq(Min) for the B-H H atom. The atom resides on three crystallographic mirror planes and a crystallographic 3-fold axis. It refines with a reasonable distance and is expected to be present based on the chemistry.

PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Ni     -   Cl      ..       6.07 su

Author Response: The Ni-Cl bond is being flagged. The atoms are properly assigned and aside from the Hirshfeld flag, seem to have been refined correctly. The metal being 4-coordinate is more restricted in atomic displacement than the attached mono-coordinate chlorine atom.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.34
           From the CIF: _reflns_number_total                964
           Count of symmetry unique reflns          525
           Completeness (_total/calc)            183.62%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured       439
           Fraction of Friedel pairs measured     0.836
           Are heavy atom types Z>Si present        yes

Author Response: So checked and noted. The estimated number was 439 pairs. The actual value is 444 pairs.

PLAT033_ALERT_2_G Flack Parameter Value Deviates 2 * su from zero.       0.03
PLAT794_ALERT_5_G Check Predicted Bond Valency for Ni          (2)       1.91
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   4 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   3 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   1 ALERT type 5 Informative message, check

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S1. Comment

The chemistry of scorpionate supported transition-metal complexes has been the subject of intense research with in excess of 2000 papers published on polypyrazolylborate complexes spanning over seventy elements of the periodic table (Trofimenko, 2004; Trofimenko, 1999). The Cambridge Structural Database includes data for over 2800 crystal structures of trispyrazolylborate (Tp) metal complexes, many with bulky derivatives, including 54 incorporating the tris(3-tert-butyl-5-methylpyrazolyl)borate ligand, Tp^tBu,Me (Allen, 2002). The coordination number of Tp coordinated metals is heavily controlled by the steric properties of the substituents attached to the 3-pyrazolyl carbon atoms. Sterically demanding Tp ligands have been found to be well suited for the isolation of low coordinate metal complexes; those with tert-butyl groups attached to the pyrazolyl 3-positions have been referred to as tetrahedral enforcers (Trofimenko et al. 1987). The title complex, (Tp^tBu,Me)NiCl is consistent with this generalization.

The molecular structure of (I) is shown in Fig. 1. A l l bond distances and angles are indistinguishable from those previously reported. (Santi et al., 2005). The core geometry of (I) is indistinguishable, with few bond distances or angles differing more than within error, from those of the related complexes, including, (Tp^tBu)NiCl (Belderrain et al., 2002), (Tp^iPr,iPr)NiCl (Shirasawa et al., 2001), (Tp^Mes)NiCl (Kunrath et al., 2003), (Tp^Ph,Me)NiCl (Uehara et al., 2002), and (Tp^Me,Me)NiCl (Desrochers et al., 2003). The Ni atom is coordinated by three N atoms, arranged with the typical facial arrangement imposed by trispyrazolylborato ligands, and a chloride ligand in a distorted tetrahedral geometry.

Arguably the most interesting feature of the structure is that the title compound preserves its highest possible, C_3v, point group symmetry in the solid state by residing upon appropriate crystallographic symmetry elements. Specifically, the H—B—Ni—Cl axis lies along a crystallographic threefold axis, and the pyrazolyl ring planes reside on crystallographic mirror planes. About 600 of the over 2800 crystallographically characterized trispyrazolylborate complexes have atomic connectivity capable of idealized C_3v point group symmetry. Of these, less than 65 have a Tp ligand with an H—B axis coincident with a crystallographic threefold axis, and only (Tp^tBu)BeH (Han & Parkin, 1992), (Tp^tBu,Me)CoNO (Thyagarajan et al., 2003), and (Tp^tBu,Me)ZnOH (Alsfasser et al., 1991) additionally lie on the necessary crystallographic mirror planes to display true C_3v symmetry in the solid state. Curiously, these three examples, like the title compound, contain Tp ligands with tert-butyl groups on the 3-pyrazolyl positions.

Related literature

A previously reported structure of the title complex was refined in the R3 space group (Santi et al., 2005). Checking this structure's CCDC deposited. cif with PLATON's (Spek, 2003) ADDSYM suggests R3m to be a better choice of space group. This is consistent with the R3m assignment of our structure; however, without processing the prior structure's data, at room temperature a polymorph cannot be absolutely ruled out. For related literature, see: Allen (2002); Alsfasser et al. (1991); Belderrain et al. (2002); Desrochers et al. (2003); Han & Parkin (1992); Kunrath et al. (2003); Shirasawa et al. (2001); Thyagarajan et al. (2003); Trofimenko (1999, 2004); Trofimenko et al. (1987); & Uehara et al. (2002).

S2. Experimental

Synthesis of (Tp^tBu,Me)NiCl was carried out according to the procedure previously reported for (Tp^tBu)NiCl, substituting KTp^tBu,Me for KTp^tBu (Trofimenko et al. 1987). An X-ray quality crystal was selected from crystals grown by slow evaporation of a mixture (2:1 ratio) of methylene chloride and acetonitrile).

S3. Refinement

The H atom attached to the B atom was identified through difference Fourier synthesis and refined with an isotropic displacement parameter. All other H atoms were included in the refinement in the riding-model approximation, with respective isotropic aromatic and methyl displacement parameters fixed at 1.2Ueq and 1.5Ueq of the parent atom (C–H = 0.95 and 0.98 Å). Atom C16 was refined as an idealized disordered methyl group with H atoms included using the HFIX 123 instruction in SHELXL97.

Computing details

Data collection: SMART (Bruker, 1999); cell refinement: SMART (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Bruker, 2000); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999) and publCIF (Westrip, 2007).

Figures

Fig. 1. The molecular structure of compound (I), with the atomic numbering scheme [symmetry codes: (i) 1 - y, x-y, z; (ii) x, x-y, z; (iii) 1 - x + y, y, z; (iv) 1 - y, 1 - x, z; (v) x, x-y, z]. H atoms except H1 are omitted for clarity. Displacement ellipsoids are drawn at the 50% probability level. Unlabeled atoms are related to the respective atoms C13, C14, C15, C17, and C18 of the asymmetric unit by 1 - y, x-y, z.

chlorido[hydridotris(3-tert-butyl-5-methylpyrazolyl)borato]nickel(II)

Crystal data

[NiCl(C24H40BN6)]	Dx = 1.247 Mg m^−3
Mr = 517.59	Mo Kα radiation, λ = 0.71073 Å
Trigonal, R3m	Cell parameters from 5297 reflections
Hall symbol: R 3 -2"	θ = 2.6–26.3°
a = 15.8900 (4) Å	µ = 0.82 mm^−1
c = 9.4584 (5) Å	T = 193 K
V = 2068.22 (13) Å^3	Prism, violet
Z = 3	0.66 × 0.4 × 0.31 mm
F(000) = 828

Data collection

CCD area detector diffractometer	964 reflections with I > > 2σ(I)
φ and ω scans	Rint = 0.020
Absorption correction: multi-scan SADABS (Sheldrick, 1996)	θmax = 26.3°, θmin = 3.7°
Tmin = 0.682, Tmax = 0.785	h = −19→19
4349 measured reflections	k = −19→19
964 independent reflections	l = −11→10

Refinement

Refinement on F^2	0 constraints
Least-squares matrix: full	H atoms treated by a mixture of independent and constrained refinement
R[F^2 > 2σ(F^2)] = 0.018	w = 1/[σ^2(Fo^2) + (0.0143P)^2 + 0.6826P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.045	(Δ/σ)max < 0.001
S = 1.08	Δρmax = 0.23 e Å^−3
964 reflections	Δρmin = −0.14 e Å^−3
69 parameters	Absolute structure: Flack (1983), 444 Friedel pairs
1 restraint	Absolute structure parameter: 0.033 (11)

Special details

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

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Cl	0.6667	0.3333	0.42261 (9)	0.0350 (2)
Ni	0.6667	0.3333	0.65602 (2)	0.01925 (10)
N11	0.71951 (5)	0.43902 (11)	0.91467 (16)	0.0216 (3)
N12	0.72792 (5)	0.45584 (11)	0.77144 (18)	0.0220 (3)
B	0.6667	0.3333	0.9718 (4)	0.0219 (7)
C13	0.77645 (7)	0.55289 (13)	0.7537 (2)	0.0266 (4)
C14	0.79873 (7)	0.59746 (13)	0.8855 (3)	0.0329 (4)
H14	0.8327	0.6654	0.9035	0.039*
C15	0.76206 (7)	0.52412 (14)	0.9853 (2)	0.0272 (4)
C16	0.76527 (8)	0.53054 (16)	1.1429 (2)	0.0381 (5)
H16A	0.7324	0.4649	1.1831	0.057*	0.5
H16B	0.7324	0.5655	1.1745	0.057*	0.25
H16C	0.8331	0.5654	1.1745	0.057*	0.25
H16D	0.7995	0.599	1.1716	0.057*	0.5
H16E	0.7996	0.4984	1.1803	0.057*	0.25
H16F	0.6989	0.4985	1.1803	0.057*	0.25
C17	0.80046 (7)	0.60092 (14)	0.6087 (2)	0.0333 (4)
C18	0.85597 (9)	0.71194 (17)	0.6292 (3)	0.0613 (8)
H18A	0.8719	0.7439	0.5367	0.092*
H18B	0.916	0.7313	0.6819	0.092*	0.5
H18C	0.8153	0.7312	0.6822	0.092*	0.5
C19	0.70656 (13)	0.57256 (12)	0.52716 (18)	0.0420 (4)
H19A	0.7227	0.604	0.4342	0.063*
H19B	0.6674	0.5937	0.5802	0.063*
H19C	0.6696	0.5019	0.515	0.063*
H1	0.6667	0.3333	1.090 (4)	0.023 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl	0.0435 (3)	0.0435 (3)	0.0179 (4)	0.02173 (16)	0	0
Ni	0.02115 (12)	0.02115 (12)	0.01547 (18)	0.01057 (6)	0	0
N11	0.0241 (5)	0.0220 (7)	0.0181 (8)	0.0110 (3)	−0.0006 (3)	−0.0012 (6)
N12	0.0254 (5)	0.0219 (7)	0.0176 (7)	0.0110 (3)	0.0005 (3)	0.0011 (6)
B	0.0238 (10)	0.0238 (10)	0.0181 (18)	0.0119 (5)	0	0
C13	0.0279 (6)	0.0237 (8)	0.0268 (10)	0.0118 (4)	0.0010 (4)	0.0020 (7)
C14	0.0403 (8)	0.0192 (8)	0.0321 (11)	0.0096 (4)	−0.0022 (4)	−0.0043 (8)
C15	0.0297 (7)	0.0252 (8)	0.0251 (10)	0.0126 (4)	−0.0021 (4)	−0.0041 (7)
C16	0.0498 (9)	0.0322 (10)	0.0263 (11)	0.0161 (5)	−0.0037 (4)	−0.0073 (8)
C17	0.0434 (8)	0.0236 (9)	0.0263 (11)	0.0118 (5)	0.0024 (4)	0.0047 (8)
C18	0.0949 (18)	0.0235 (10)	0.0418 (15)	0.0117 (5)	0.0036 (5)	0.0072 (10)
C19	0.0557 (9)	0.0446 (8)	0.0340 (9)	0.0314 (7)	−0.0017 (8)	0.0066 (7)

Geometric parameters (Å, º)

Cl—Ni	2.2077 (9)	C16—H16B	0.98
Ni—N12	2.0084 (15)	C16—H16C	0.98
N11—C15	1.348 (2)	C16—H16D	0.98
N11—N12	1.374 (2)	C16—H16E	0.98
N11—B	1.552 (2)	C16—H16F	0.98
N12—C13	1.346 (2)	C17—C19	1.534 (2)
B—H1	1.12 (4)	C17—C18	1.540 (3)
C13—C14	1.389 (3)	C18—H18A	0.98
C13—C17	1.522 (3)	C18—H18B	0.98
C14—C15	1.382 (3)	C18—H18C	0.98
C14—H14	0.95	C19—H19A	0.98
C15—C16	1.493 (3)	C19—H19B	0.98
C16—H16A	0.98	C19—H19C	0.98
N12^i—Ni—N12	93.26 (6)	C15—C16—H16D	109.5
N12—Ni—Cl	122.93 (5)	C15—C16—H16E	109.5
C15—N11—N12	110.02 (15)	H16C—C16—H16E	56.3
C15—N11—B	129.89 (19)	H16D—C16—H16E	109.5
N12—N11—B	120.08 (18)	C15—C16—H16F	109.5
C13—N12—N11	106.84 (15)	H16C—C16—H16F	141.1
C13—N12—Ni	139.93 (14)	H16D—C16—H16F	109.5
N11—N12—Ni	113.23 (11)	H16E—C16—H16F	109.5
N11^i—B—N11	108.53 (15)	C13—C17—C19	110.04 (11)
N11—B—H1	110.40 (14)	C19—C17—C19^ii	111.36 (19)
N12—C13—C14	109.06 (18)	C13—C17—C18	108.5 (2)
N12—C13—C17	122.88 (18)	C19—C17—C18	108.41 (12)
C14—C13—C17	128.06 (18)	C17—C18—H18A	109.5
C15—C14—C13	106.89 (17)	C17—C18—H18B	109.5
C15—C14—H14	126.6	H18A—C18—H18B	109.5
C13—C14—H14	126.6	C17—C18—H18C	109.5
N11—C15—C14	107.18 (17)	H18A—C18—H18C	109.5
N11—C15—C16	123.11 (18)	H18B—C18—H18C	109.5
C14—C15—C16	129.71 (19)	C17—C19—H19A	109.5
C15—C16—H16A	109.5	C17—C19—H19B	109.5
C15—C16—H16B	109.5	H19A—C19—H19B	109.5
H16A—C16—H16B	109.5	C17—C19—H19C	109.5
C15—C16—H16C	109.5	H19A—C19—H19C	109.5
H16A—C16—H16C	109.5	H19B—C19—H19C	109.5
H16B—C16—H16C	109.5
C15—N11—N12—C13	0	Ni—N12—C13—C17	0.0000 (10)
B—N11—N12—C13	180	N12—C13—C14—C15	0
C15—N11—N12—Ni	180	C17—C13—C14—C15	180
B—N11—N12—Ni	0	N12—N11—C15—C14	0
N12^i—Ni—N12—C13	133.27 (4)	B—N11—C15—C14	180
Cl—Ni—N12—C13	0	N12—N11—C15—C16	180
N12^i—Ni—N12—N11	−46.73 (4)	B—N11—C15—C16	0.0000 (10)
Cl—Ni—N12—N11	180	C13—C14—C15—N11	0
C15—N11—B—N11^i	−121.12 (18)	C13—C14—C15—C16	180.0000 (10)
N12—N11—B—N11^i	58.88 (18)	N12—C13—C17—C19	61.54 (12)
N11—N12—C13—C14	0	C14—C13—C17—C19	−118.46 (12)
Ni—N12—C13—C14	180	N12—C13—C17—C18	180.0000 (10)
N11—N12—C13—C17	180	C14—C13—C17—C18	0.0000 (10)

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