[2,6-Bis(di-tert-butyl­phosphinometh­yl)­phen­yl-κ3 P,C 1,P′](nitrato-κO)nickel(II)

Brian J Boro; Diane A Dickie; Eileen N Duesler; Karen I Goldberg; Richard A Kemp

doi:10.1107/S1600536808032376

. 2008 Oct 15;64(Pt 11):m1402. doi: 10.1107/S1600536808032376

[2,6-Bis(di-tert-butylphosphinomethyl)phenyl-κ³ P,C ¹,P′](nitrato-κO)nickel(II)

Brian J Boro ^a, Diane A Dickie ^a, Eileen N Duesler ^a, Karen I Goldberg ^b, Richard A Kemp ^a,^c,^*

PMCID: PMC2959575 PMID: 21580852

Abstract

The Ni^II atom in the title compound, [Ni(C₂₄H₄₃P₂)(NO₃)], adopts a distorted square-planar geometry with the P atoms in a trans arrangement. The compound contains a twofold rotational axis with the nitrate group offset from this axis, except for an O atom of the nitrate group, generating two positions of 50% occupancy for the other atoms of the nitrate group.

Related literature

The synthetic preparation was adopted from that employed to prepare the Pd analogue (Cámpora et al., 2004 ▶). For the crystallographic characterization of the Pd analogue, see: Olsson et al. (2007 ▶). For the crystallographic characterization of the starting {2,6-bis[(di-tert-butylphosphino)methyl]phenyl}chloridonickel complex, see: Boro et al. (2008 ▶). For related literature, see: Denney et al. (2006 ▶); Johansson et al. (2007 ▶); Keith et al. (2006 ▶).

Experimental

Crystal data

[Ni(C₂₄H₄₃P₂)(NO₃)]
M _r = 514.24
Orthorhombic,
a = 24.0023 (14) Å
b = 12.6350 (6) Å
c = 17.6528 (6) Å
V = 5353.5 (4) Å³
Z = 8
Mo Kα radiation
μ = 0.87 mm⁻¹
T = 225 (2) K
0.50 × 0.40 × 0.20 mm

Data collection

Bruker X8 APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2004 ▶) T _min = 0.671, T _max = 0.846
33484 measured reflections
4078 independent reflections
3703 reflections with I > 2σ(I)
R _int = 0.037

Refinement

R[F ² > 2σ(F ²)] = 0.030
wR(F ²) = 0.099
S = 0.81
4078 reflections
156 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.38 e Å⁻³
Absolute structure: Flack (1983 ▶), 1976 Freidel pairs
Flack parameter: 0.012 (10)

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: APEX2; data reduction: APEX2; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: publCIF (Westrip, 2008 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808032376/at2643sup1.cif

e-64-m1402-sup1.cif^{(18.3KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808032376/at2643Isup2.hkl

e-64-m1402-Isup2.hkl^{(200.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Funding was provided by the Natural Sciences and Engineering Research Council of Canada (NSERC PDF to DAD) and the Department of Energy (DE-FG02-06ER15765). The diffractometer was purchased via a National Science Foundation CRIF:MU award to the University of New Mexico (CHE-0443580). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US Department of Energy under contract No. DE-AC04-94AL85000.

supplementary crystallographic information

Comment

The title compound, (I) (Fig. 1), was prepared from {2,6-bis[(di-tert-butylphosphino)methyl]phenyl}chloridonickel(II) (Boro et al., 2008) via a synthesis adopted from the preparation of the Pd analogue (Cámpora et al., 2004). Our research has been directed towards the activation of molecular oxygen using pincer complexes of the late transition metals (Denney et al., 2006; Keith et al., 2006). Compound (I) was prepared as a precursor along the path of the attempted synthesis of a Ni^II-hydroperoxide.

The compound is bisected by a twofold rotational axis running through C4, C1, Ni1, and O3. The nitrate group is offset from this axis with a C1—Ni1—O1 angle of 164.64 (11)°. As a result of this symmetry induced disorder the nitrate group occupies two positions each with 50% occupancy. The Ni1—O1 bond length 1.976 (3) Å is significantly shorter than the corresponding Pd—O bond length 2.164 (2) Å in the Pd analogue (Johansson et al. 2007). This not surprising, given the smaller size of the Ni atom. The M—C and M—P bonds were also shorter in the Ni compound compared to the Pd. The P—M—P angle, however was closer to the ideal linear geometry with Ni (168.87 (3)°) than Pd (163.41 (3)°).

In their report on the Pd analogue of (I), Johansson et al. (2007) observed non-traditional hydrogen bonding between one of the nitrato O atoms and a hydrogen from the methylene arm of the pincer ligand to form a zigzag chain. The C—H···O interaction measured 3.263 (4) Å (C···O) with an angle of 137°. The same pattern is observed in I (Fig. 2) between C5—H5b···O2, with corresponding measurements of 3.5616 (54) Å and 171.81 (18)°.

Experimental

{2,6-Bis[(di-tert-butylphosphino)methyl]phenyl}chloronickel(II) (0.135 g, 0.28 mmol) and AgNO₃ (0.05 g, 0.29 mmol) were combined with THF (20 ml) and the solution was stirred at room temperature for 48 h. The THF was then removed under vacuum and the product was extracted into diethyl ether (15 ml). After filtering, the solution was layered with hexanes and placed in a 238 K freezer. The product crystallized as orange-brown prisms.

Yield 0.118 g, 82%. ¹H NMR (250 MHz, C₆D₆): 6.93 (d, J_HH = 7.5 Hz, 1H, Ar-H_para), 6.68 (t, J_HH = 7.5 Hz, 2H, Ar-H_meta), 2.80 (virtual t, 4H, J_HP = 7.15 Hz,CH₂), 1.25 (virtual t, 36H, J = 13.1 Hz C(CH₃)₃) p.p.m.. ¹³C{¹H} (63 MHz, C₆D₆): 152.8 (t, ²J_PC = 11.6 Hz, Ar-C_ipso), 147.1 (virtual t, J_CP= 32.3 Hz, Ar-C_ortho), 125.8 (s, Ar-C_para), 122.1 (virtual t, J_CP = 15.8 Hz, Ar-C_para), 34.5 (virtual t, J_CP = 13.2 Hz, PCH₂), 32.7 (virtual t, J_CP = 24.6 Hz, PC(CH₃)₃), 29.6 (s, CH₃) p.p.m.. ³¹P{¹H} (101 MHz, C₆D₆): 69.5 (s) p.p.m..