Hexakis(N,N-dimethyl­acetamide)nickel(II) bis­(tetra­fluoro­borate) 0.17-hydrate

The nickel complex of the title compound, [Ni(C₄H₉NO)₆](BF₄)₂·0.17H₂O, has an octa­hedral coordination geometry with symmetry at the Ni ion, in which all six ligands are crystallographically equivalent. The Ni-O-C-N torsion angle [151.2 (3)°] indicates that the Ni-O bond is displaced from the direction of the lone pair of the sp² O atom. This is ascribed to the steric hindrance of the ligand in an octa­hedral environment.

Key indicators

• Single-crystal X-ray study
• T = 149 K
• Mean [sigma](C-C) = 0.006 Å
• Disorder in solvent or counterion
• R factor = 0.060
• wR factor = 0.153
• Data-to-parameter ratio = 20.6

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT305_ALERT_2_A Isolated Hydrogen Atom (Outside Bond Range ??)          <H5

Author Response: H5 is connected to O2 and hydrogen-bonded to O1; see _publ_section_exptl_refinement

Alert level B
PLAT029_ALERT_3_B _diffrn_measured_fraction_theta_full Low .......       0.96

Alert level C
PLAT042_ALERT_1_C Calc. and Rep. MoietyFormula Strings Differ ....          ?
PLAT077_ALERT_4_C Unitcell contains non-integer number of atoms ..          ?
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.64 Ratio
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for         B1
PLAT302_ALERT_4_C Anion/Solvent Disorder .........................       3.00 Perc.
PLAT311_ALERT_2_C Isolated Disordered Oxygen Atom (No H's ?) .....        <O2
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.15 Ratio
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          2
              B F4

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

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

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Computing details

Data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1990); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: MSC/AFC Diffractometer Control Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Hexakis(N,N-dimethylacetamide)nickel(II) bis(tetrafluoroborate) 0.17-hydrate

Crystal data

[Ni(C4H9NO)6](BF4)2·0.17H2O	Dx = 1.359 Mg m^−3
Mr = 758.13	Mo Kα radiation, λ = 0.71069 Å
Trigonal, P3	Cell parameters from 25 reflections
Hall symbol: -P 3	θ = 13.2–14.9°
a = 12.334 (6) Å	µ = 0.61 mm^−1
c = 7.030 (8) Å	T = 149 K
V = 926.2 (12) Å^3	Needle, yellow
Z = 1	0.40 × 0.20 × 0.20 mm
F(000) = 399.7

Data collection

Rigaku AFC-5 diffractometer	Rint = 0.020
Radiation source: fine-focus sealed tube	θmax = 30.1°, θmin = 1.9°
Graphite monochromator	h = 0→17
ω–2θ scans	k = 0→17
1858 measured reflections	l = −9→9
1588 independent reflections	3 standard reflections every 60 min
1468 reflections with I > 2σ(I)	intensity decay: 5.4%

Refinement

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)] = 0.061	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.153	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.105P)^2] where P = (Fo^2 + 2Fc^2)/3
1588 reflections	(Δ/σ)max < 0.001
77 parameters	Δρmax = 0.91 e Å^−3
2 restraints	Δρmin = −0.79 e Å^−3

Special details

Experimental. The crystal was cooled at 149 K during the diffraction measurement, but it broke near the end of the completion so that psi-scan was not possible. Repeated attempts to obtain another crystal of acceptable quality were unsuccessful. Therefore, in spite of the lack of absorption correction, the structure was solved by using the collected data.

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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Data were corrected for Lorentz, polarization and absorption effects. The structure was solved by the direct method and subsequent difference Fourier syntheses. The cell geometry showed that the crystal system is either trigonal or hexagonal. Because of the unusually small cell volume (Z = 1), the possibility of 1/2 or 1/3 reciprocal axes was examined before starting the collection of reflections; moving the detector to such hypothetical positions confirmed the absence of Bragg peaks and the correctness of the unit cell.

No systematic absences were found. Among all the compatible space groups, only P3 gave a chemically reasonable structure, in which the nickel atom was at the origin having the 3 symmetry; however, two crystallographically independent DMA molecules were found, resulting in the twelve coordination instead of the expected six. Thus, the complex appeared to be two superposed octahedrons, one of which could be generated from the other by the 60° rotation about the triad axis. Transformation to other cell geometries (such as the orthorhombic system) was also examined but failed to give a solution.

The triad axis of a trigonal system can function as a twin axis (Buerger, 1960; Phillips, 1963; Kelly & Groves, 1970), and the 6-fold rotation generates a twin by pseudo-merohedry (Koch, 1992); in such cases, the twin index is 1, and the reciprocal lattices of the twins exactly coincide. Accordingly, the data were analyzed in terms of the two-component rotation twinning (h' = -k, k' = h + k, l' = l) via SHELX TWIN and BASF facility. This resulted in a satisfactory octahedral structure, and the optimized twin component factor (0.49) showed nearly perfect twinning. The possibility of P3 was also examined, which gave essentially the same structure as P3 with the doubled number of parameters.

Full-matrix least-squares refinement was performed. All non-H atoms except for O2 were refined anisotropically. Methyl H atoms were placed at idealized positions with a fixed C—H distance and H—C—H angle, and refined using a rotating model via SHELX HFIX 137 facility; the starting torsion angle was taken from the position of the maximum electron density in the loci of possible hydrogen positions, and the displacement parameter was set as 1.5 times the equivalent isotropic displacement parameter of the methyl carbon.

After the complex cation and the counter anion were located, a positive peak (2.44 e A^-3) remained at (0, 0, 1/2). The distance from the peak to the nearest atom (O1), 2.993 (3) Å, suggested a hydrogen-bonded water molecule; however, the inclusion of a fully occupied water molecule in the refinement resulted in a large negative peak in the difference map and a diverging U_eq. Therefore, a partially occupied site for water was assumed, and its occupancy factor was optimized; the oxygen atom (O2) was treated isotropically with U_eq fixed at 0.03, and the hydrogen atom (H5) was placed at the fixed position in the direction toward O1.

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

	x	y	z	Uiso*/Ueq	Occ. (<1)
Ni	0.0000	0.0000	0.0000	0.0164 (3)
O1	0.1630 (2)	0.0635 (2)	0.1549 (4)	0.0234 (6)
N1	0.3495 (3)	0.0919 (3)	0.2445 (5)	0.0290 (7)
C1	0.2254 (3)	0.0190 (3)	0.2236 (5)	0.0212 (7)
C2	0.1655 (4)	−0.1145 (4)	0.2874 (7)	0.0335 (9)
H2A	0.2136	−0.1521	0.2386	0.050*
H2B	0.0796	−0.1610	0.2386	0.050*
H2C	0.1640	−0.1177	0.4267	0.050*
C3	0.4118 (4)	0.2236 (4)	0.1916 (7)	0.0382 (10)
H3A	0.4522	0.2753	0.3040	0.057*
H3B	0.3500	0.2440	0.1411	0.057*
H3C	0.4751	0.2403	0.0943	0.057*
C4	0.4306 (4)	0.0503 (5)	0.3240 (11)	0.0561 (15)
H4A	0.5064	0.1224	0.3747	0.084*
H4B	0.4537	0.0099	0.2246	0.084*
H4C	0.3867	−0.0096	0.4267	0.084*
B1	0.3333	−0.3333	0.2682 (13)	0.0308 (15)
F1	0.3333	−0.3333	0.4634 (9)	0.098 (3)
F2	0.2152 (3)	−0.3713 (4)	0.2020 (7)	0.0736 (12)
O2	0.0000	0.0000	0.5000	0.030*	0.170 (15)
H5	0.0533	0.0208	0.3871	0.040*	0.057 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni	0.0165 (3)	0.0165 (3)	0.0163 (5)	0.00826 (15)	0.000	0.000
O1	0.0217 (12)	0.0242 (12)	0.0247 (13)	0.0118 (10)	−0.0059 (10)	−0.0031 (10)
N1	0.0197 (14)	0.0353 (17)	0.0328 (17)	0.0144 (13)	−0.0029 (13)	−0.0017 (14)
C1	0.0211 (15)	0.0253 (16)	0.0186 (15)	0.0127 (13)	0.0002 (12)	−0.0019 (13)
C2	0.0312 (19)	0.0283 (19)	0.039 (2)	0.0134 (16)	−0.0069 (16)	0.0076 (16)
C3	0.0244 (18)	0.039 (2)	0.039 (2)	0.0067 (17)	−0.0015 (17)	−0.0006 (19)
C4	0.031 (2)	0.053 (3)	0.089 (5)	0.024 (2)	−0.016 (3)	0.003 (3)
B1	0.029 (2)	0.029 (2)	0.035 (4)	0.0144 (11)	0.000	0.000
F1	0.130 (4)	0.130 (4)	0.034 (5)	0.065 (2)	0.000	0.000
F2	0.0427 (18)	0.068 (2)	0.108 (3)	0.0252 (17)	−0.016 (2)	0.005 (2)

Geometric parameters (Å, º)

Ni—O1	2.065 (3)	C2—H2C	0.9800
Ni—O1^i	2.065 (3)	C3—H3A	0.9800
Ni—O1^ii	2.065 (3)	C3—H3B	0.9800
Ni—O1^iii	2.065 (3)	C3—H3C	0.9800
Ni—O1^iv	2.065 (3)	C4—H4A	0.9800
Ni—O1^v	2.065 (3)	C4—H4B	0.9800
O1—C1	1.245 (4)	C4—H4C	0.9800
N1—C1	1.340 (4)	B1—F1	1.372 (11)
N1—C3	1.456 (6)	B1—F2	1.370 (5)
N1—C4	1.446 (6)	B1—F2^vi	1.370 (5)
C1—C2	1.497 (5)	B1—F2^vii	1.370 (5)
C2—H2A	0.9800	O2—H5	0.9800
C2—H2B	0.9800
O1—Ni—O1^i	94.76 (11)	C1—C2—H2B	109.5
O1—Ni—O1^ii	94.76 (11)	C1—C2—H2C	109.5
O1—Ni—O1^iii	180.00 (18)	H2A—C2—H2B	109.5
O1—Ni—O1^iv	85.24 (11)	H2A—C2—H2C	109.5
O1—Ni—O1^v	85.24 (11)	H2B—C2—H2C	109.5
O1^i—Ni—O1^ii	94.76 (11)	N1—C3—H3A	109.5
O1^iii—Ni—O1^i	85.24 (11)	N1—C3—H3B	109.5
O1^iii—Ni—O1^ii	85.24 (11)	N1—C3—H3C	109.5
O1^iii—Ni—O1^iv	94.76 (11)	H3A—C3—H3B	109.5
O1^iv—Ni—O1^i	180.00 (16)	H3A—C3—H3C	109.5
O1^iv—Ni—O1^ii	85.24 (11)	H3B—C3—H3C	109.5
O1^v—Ni—O1^i	85.24 (11)	N1—C4—H4A	109.5
O1^v—Ni—O1^ii	180.00 (16)	N1—C4—H4B	109.5
O1^v—Ni—O1^iii	94.76 (11)	N1—C4—H4C	109.5
O1^v—Ni—O1^iv	94.76 (11)	H4A—C4—H4B	109.5
Ni—O1—C1	137.4 (2)	H4A—C4—H4C	109.5
C1—N1—C3	120.7 (3)	H4B—C4—H4C	109.5
C1—N1—C4	124.4 (4)	F1—B1—F2	109.8 (4)
C3—N1—C4	114.9 (3)	F1—B1—F2^vii	109.8 (4)
O1—C1—N1	119.8 (3)	F1—B1—F2^vi	109.8 (4)
O1—C1—C2	121.8 (3)	F2—B1—F2^vii	109.1 (4)
N1—C1—C2	118.4 (3)	F2—B1—F2^vi	109.1 (4)
C1—C2—H2A	109.5	F2^vi—B1—F2^vii	109.1 (4)
Ni—O1—C1—N1	151.2 (3)	O1^v—Ni—O1—C1	−137.5 (4)
Ni—O1—C1—C2	−29.8 (6)	C3—N1—C1—O1	1.4 (6)
O1^i—Ni—O1—C1	137.7 (3)	C3—N1—C1—C2	−177.6 (4)
O1^ii—Ni—O1—C1	42.5 (4)	C4—N1—C1—O1	179.4 (5)
O1^iv—Ni—O1—C1	−42.3 (3)	C4—N1—C1—C2	0.4 (6)

Symmetry codes: (i) −y, x−y, z; (ii) −x+y, −x, z; (iii) −x, −y, −z; (iv) y, −x+y, −z; (v) x−y, x, −z; (vi) −x+y+1, −x, z; (vii) −y, x−y−1, z.