cis-Bis(nitrato-κ²O,O′)bis­­(tri­ethyl­phosphine oxide-κO)nickel(II)

In the title compound, [Ni(NO₃)₂(C₆H₁₅OP)₂], the Ni^II ion, lying on a crystallographic twofold axis, adopts a distorted octa­hedral coordination, consisting of O-donor atoms of two symmetry-related triethyl­phospine oxide and two bidentate nitrate ligands.

Related literature

For the synthesis and the crystal structure of the isotypic Co^II complex, see: Alnaji et al. (1991). For the preparation of the precursor trans-[NiCl₂(Et₃P)₂] (Et₃P = triethyl­phosphine), see: Jensen (1936). For the synthesis of cis-[Pt(NO₃)₂(Et₃P)₂], see: Kuehl et al. (2001).

Experimental

Crystal data

• [Ni(NO₃)₂(C₆H₁₅OP)₂]

• M_r = 451.03

• Monoclinic, C 2/c

• a = 16.954 (2) Å

• b = 7.8494 (5) Å

• c = 15.9905 (9) Å

• β = 92.419 (5)°

• V = 2126.1 (3) ų

• Z = 4

• Mo Kα radiation

• μ = 1.10 mm⁻¹

• T = 294 K

• 0.31 × 0.26 × 0.24 mm

Data collection

• Siemens P4 four-circle diffractometer

• Absorption correction: ψ scan (ABSPsiScan in PLATON; Spek, 2009) T_min = 0.719, T_max = 0.770

• 2351 measured reflections

• 1829 independent reflections

• 1641 reflections with I > 2σ(I)

• R_int = 0.047

• 3 standard reflections every 97 reflections intensity decay: none

Refinement

• R[F² > 2σ(F²)] = 0.029

• wR(F²) = 0.073

• S = 1.05

• 1829 reflections

• 118 parameters

• H-atom parameters constrained

• Δρ_max = 0.22 e Å⁻³

• Δρ_min = −0.28 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

Ni1—O1	1.9741 (16)
Ni1—O2	2.0738 (16)
Ni1—O3	2.1429 (17)

O1—Ni1—O1^i	94.2 (1)
O1—Ni1—O2^i	96.97 (7)
O1—Ni1—O2	102.19 (6)
O2^i—Ni1—O2	151.7 (1)
O1—Ni1—O3^i	91.95 (7)
O2—Ni1—O3^i	97.47 (7)
O1—Ni1—O3	162.74 (7)
O2—Ni1—O3	61.00 (7)
O3^i—Ni1—O3	86.8 (1)
Symmetry code: (i) .

Data collection: XSCANS (Bruker, 1999); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Supporting information

S1. Comment

The title complex, cis-[Ni(NO₃)₂(OPEt₃)] (OPEt₃ = triethylphosphine oxide), exhibits C₂ point symmetry and is located on a twofold crystallographic axis. An ORTEP diagram is depicted in Fig. 1.

As previously observed in the isotypic Co^II complex (Alnaji et al., 1991), the triethylphosphine oxide and the nitrate ligands are arranged in a cis geometry about the Ni^II ion. The bond lengths are comparable to those reported for the Co^II complex. The bidentate nitrate ligand binds asymmetrically with Ni—O distances of 2.0738 (16) and 2.1429 (17) Å. This leads to differences in the N—O bond lengths. The N—O distances of the coordinated oxygen atoms are considerably longer than that of the free one (Table 1). The magnitude of the asymmetric bidentate binding is slightly smaller than that reported for the Co^II complex.

The O2—Ni1—O3 angle is small, as is expected for a bidentate chelating nitrate ion. The remaining angles about the Ni^II ion show large deviations from the regular octahedral geometry (see table 1). The P—O—Ni angle exhibits a typical value of 140.8 (1)°.

Related literature

For the synthesis and the crystal structure of the isotypic Co^II complex, see Alnaji et al. (1991). For the preparation of the precursor trans-[NiCl₂(Et₃P)₂] (Et₃P = triethylphosphine), see: Jensen (1936). For the synthesis of cis-[Pt(NO₃)₂(Et₃P)₂], see: Kuehl et al. (2001).

S2. Experimental

The title compound was obtained as an oxidation product of the metathesis reaction of trans-[NiCl₂(Et₃P)₂] with AgNO₃. The synthetic procedure was adapted from the preparation of cis-[Pt(NO₃)₂(Et₃P)₂] (Kuehl et al., 2001). trans-[NiCl₂(Et₃P)₂] was prepared according to the literature (Jensen, 1936). 33 mg (0.197) AgNO₃ was added to a stirred solution of 36 mg (0.098 mmol) trans-[NiCl₂(Et₃P)₂] in 40 ml acetone. The mixture was stirred 12 h in the dark. The colour changed from red to yellow. The solvent was removed in vacuum and the residue was suspended in 40 ml dichloromethane. Filtration and subsequent evaporation of the solvent yielded a yellow powder. A single-crystal suitable for X-ray diffraction was obtained from methanol-d4 when the solvent was allowed to evaporate slowly at ambient temperature.

S3. Refinement

Hydrogen atoms were placed at geometrically calculated positions and refined with U_iso 1.2 times (1.5 for methyl groups) of their parent atoms and allowing to ride on them. The initial torsion angles of the methyl groups were determined via a difference Fourier analysis and refined, while retaining the tetrahedral geometry.

Computing details

Data collection: XSCANS (Bruker, 1999); cell refinement: XSCANS (Bruker, 1999); data reduction: XSCANS (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 2008); software used to prepare material for publication: enCIFer (Allen et al., 2004).

Figures

Fig. 1. ORTEP diagram of the title compound. Displacement ellipsoids are drawn at the 30% probability level. Hydrogen atoms are drawn with arbitrary size. Symmetry codes: (i) -x,y,-z + 1/2.

cis-Bis(nitrato-κ²O,O')bis(triethylphosphine oxide-κO)nickel(II)

Crystal data

[Ni(NO3)2(C6H15OP)2]	F(000) = 952
Mr = 451.03	Dx = 1.409 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 50 reflections
a = 16.954 (2) Å	θ = 4.7–16.8°
b = 7.8494 (5) Å	µ = 1.10 mm^−1
c = 15.9905 (9) Å	T = 294 K
β = 92.419 (5)°	Prism, yellow
V = 2126.1 (3) Å^3	0.31 × 0.26 × 0.24 mm
Z = 4

Data collection

Siemens P4 four-circle diffractometer	1641 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.047
Graphite monochromator	θmax = 25.0°, θmin = 2.9°
ω scans	h = −1→20
Absorption correction: ψ scan (ABSPsiScan in PLATON; Spek, 2009)	k = −1→9
Tmin = 0.719, Tmax = 0.770	l = −18→18
2351 measured reflections	3 standard reflections every 97 reflections
1829 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.029	H-atom parameters constrained
wR(F^2) = 0.073	w = 1/[σ^2(Fo^2) + (0.0309P)^2 + 1.435P] where P = (Fo^2 + 2Fc^2)/3
S = 1.05	(Δ/σ)max < 0.001
1829 reflections	Δρmax = 0.22 e Å^−3
118 parameters	Δρmin = −0.28 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0039 (5)

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.

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.

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

	x	y	z	Uiso*/Ueq
Ni1	0.0000	0.58558 (5)	0.2500	0.04465 (16)
P1	0.10851 (4)	0.30215 (8)	0.15778 (3)	0.04913 (18)
O1	0.08156 (10)	0.4144 (2)	0.22694 (10)	0.0585 (4)
O2	−0.04216 (10)	0.6501 (2)	0.13055 (10)	0.0596 (4)
O3	−0.08635 (10)	0.7839 (2)	0.23545 (11)	0.0644 (5)
O4	−0.12961 (13)	0.8501 (3)	0.10934 (14)	0.0895 (6)
N1	−0.08784 (12)	0.7647 (3)	0.15682 (13)	0.0587 (5)
C11	0.13399 (18)	0.4234 (3)	0.06864 (16)	0.0681 (7)
H11A	0.1582	0.3481	0.0290	0.082*
H11B	0.0860	0.4682	0.0418	0.082*
C12	0.18933 (19)	0.5692 (4)	0.0880 (2)	0.0799 (8)
H12A	0.1668	0.6427	0.1286	0.120*
H12B	0.1977	0.6323	0.0377	0.120*
H12C	0.2389	0.5256	0.1100	0.120*
C13	0.19220 (15)	0.1817 (3)	0.19631 (17)	0.0642 (7)
H13A	0.2336	0.2609	0.2137	0.077*
H13B	0.1772	0.1198	0.2457	0.077*
C14	0.22625 (19)	0.0551 (4)	0.1355 (2)	0.0910 (10)
H14A	0.1884	−0.0334	0.1233	0.137*
H14B	0.2736	0.0059	0.1602	0.137*
H14C	0.2383	0.1127	0.0847	0.137*
C15	0.03471 (17)	0.1488 (4)	0.12138 (18)	0.0722 (7)
H15A	0.0588	0.0715	0.0826	0.087*
H15B	0.0189	0.0820	0.1689	0.087*
C16	−0.03782 (17)	0.2241 (4)	0.0791 (2)	0.0831 (9)
H16A	−0.0620	0.3019	0.1166	0.125*
H16B	−0.0744	0.1347	0.0641	0.125*
H16C	−0.0235	0.2838	0.0296	0.125*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0491 (2)	0.0437 (2)	0.0416 (2)	0.000	0.00704 (16)	0.000
P1	0.0584 (4)	0.0457 (3)	0.0434 (3)	0.0050 (3)	0.0032 (2)	0.0001 (2)
O1	0.0626 (9)	0.0619 (10)	0.0511 (9)	0.0137 (8)	0.0046 (7)	−0.0072 (8)
O2	0.0711 (11)	0.0575 (10)	0.0502 (9)	0.0081 (9)	0.0033 (8)	0.0022 (8)
O3	0.0675 (11)	0.0579 (10)	0.0683 (11)	0.0082 (8)	0.0083 (9)	−0.0071 (9)
O4	0.0899 (14)	0.0704 (12)	0.1056 (16)	0.0125 (11)	−0.0261 (12)	0.0235 (12)
N1	0.0599 (12)	0.0473 (11)	0.0682 (14)	−0.0036 (10)	−0.0041 (10)	0.0072 (10)
C11	0.096 (2)	0.0589 (15)	0.0500 (13)	−0.0035 (14)	0.0058 (13)	0.0047 (12)
C12	0.087 (2)	0.0734 (19)	0.0802 (19)	−0.0169 (16)	0.0137 (16)	0.0077 (15)
C13	0.0660 (16)	0.0587 (15)	0.0683 (16)	0.0138 (13)	0.0091 (12)	0.0080 (12)
C14	0.082 (2)	0.0632 (18)	0.129 (3)	0.0169 (15)	0.025 (2)	−0.0113 (18)
C15	0.0865 (19)	0.0573 (15)	0.0721 (17)	−0.0088 (14)	−0.0049 (14)	0.0011 (14)
C16	0.086 (2)	0.0774 (19)	0.084 (2)	−0.0173 (17)	−0.0143 (16)	−0.0025 (16)

Geometric parameters (Å, º)

Ni1—O1	1.9741 (16)	C12—H12A	0.9600
Ni1—O1^i	1.9741 (16)	C12—H12B	0.9600
Ni1—O2^i	2.0738 (16)	C12—H12C	0.9600
Ni1—O2	2.0738 (16)	C13—C14	1.521 (4)
Ni1—O3^i	2.1429 (17)	C13—H13A	0.9700
Ni1—O3	2.1429 (17)	C13—H13B	0.9700
P1—O1	1.5001 (16)	C14—H14A	0.9600
P1—C11	1.782 (2)	C14—H14B	0.9600
P1—C13	1.793 (2)	C14—H14C	0.9600
P1—C15	1.814 (3)	C15—C16	1.499 (4)
O2—N1	1.270 (3)	C15—H15A	0.9700
O3—N1	1.266 (3)	C15—H15B	0.9700
O4—N1	1.217 (3)	C16—H16A	0.9600
C11—C12	1.503 (4)	C16—H16B	0.9600
C11—H11A	0.9700	C16—H16C	0.9600
C11—H11B	0.9700
O1—Ni1—O1^i	94.2 (1)	H11A—C11—H11B	107.6
O1—Ni1—O2^i	96.97 (7)	C11—C12—H12A	109.5
O1^i—Ni1—O2^i	102.19 (6)	C11—C12—H12B	109.5
O1—Ni1—O2	102.19 (6)	H12A—C12—H12B	109.5
O1^i—Ni1—O2	96.97 (7)	C11—C12—H12C	109.5
O2^i—Ni1—O2	151.7 (1)	H12A—C12—H12C	109.5
O1—Ni1—O3^i	91.95 (7)	H12B—C12—H12C	109.5
O1^i—Ni1—O3^i	162.74 (7)	C14—C13—P1	116.2 (2)
O2^i—Ni1—O3^i	61.00 (7)	C14—C13—H13A	108.2
O2—Ni1—O3^i	97.47 (7)	P1—C13—H13A	108.2
O1—Ni1—O3	162.74 (7)	C14—C13—H13B	108.2
O1^i—Ni1—O3	91.95 (7)	P1—C13—H13B	108.2
O2^i—Ni1—O3	97.47 (7)	H13A—C13—H13B	107.4
O2—Ni1—O3	61.00 (7)	C13—C14—H14A	109.5
O3^i—Ni1—O3	86.8 (1)	C13—C14—H14B	109.5
O1—P1—C11	111.57 (12)	H14A—C14—H14B	109.5
O1—P1—C13	108.53 (11)	C13—C14—H14C	109.5
C11—P1—C13	109.97 (13)	H14A—C14—H14C	109.5
O1—P1—C15	113.50 (12)	H14B—C14—H14C	109.5
C11—P1—C15	106.55 (13)	C16—C15—P1	115.1 (2)
C13—P1—C15	106.58 (13)	C16—C15—H15A	108.5
P1—O1—Ni1	140.8 (1)	P1—C15—H15A	108.5
N1—O2—Ni1	93.42 (13)	C16—C15—H15B	108.5
N1—O3—Ni1	90.36 (13)	P1—C15—H15B	108.5
O4—N1—O3	122.7 (2)	H15A—C15—H15B	107.5
O4—N1—O2	122.1 (2)	C15—C16—H16A	109.5
O3—N1—O2	115.21 (19)	C15—C16—H16B	109.5
C12—C11—P1	114.3 (2)	H16A—C16—H16B	109.5
C12—C11—H11A	108.7	C15—C16—H16C	109.5
P1—C11—H11A	108.7	H16A—C16—H16C	109.5
C12—C11—H11B	108.7	H16B—C16—H16C	109.5
P1—C11—H11B	108.7

Symmetry code: (i) −x, y, −z+1/2.