[2,6-Bis(di-tert-butyl­phosphinometh­yl)­phen­yl-κ3P,C1,P′](nitrato-κO)nickel(II)

Boro, B.J.; Dickie, D.A.; Duesler, E.N.; Goldberg, K.I.; Kemp, R.A.

doi:10.1107/S1600536808032376

metal-organic compounds

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ISSN: 2056-9890

Volume 64| Part 11| November 2008| Page m1402

doi:10.1107/S1600536808032376

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[2,6-Bis(di-tert-butylphosphinomethyl)phenyl-κ³P,C¹,P′](nitrato-κO)nickel(II)

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

^aDepartment of Chemistry and Chemical Biology, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131, USA, ^bDepartment of Chemistry, University of Washington, Seattle, WA 98195, USA, and ^cAdvanced Materials Laboratory, Sandia National Laboratories, 1001 University Boulevard SE, Albuquerque, NM 87106, USA
^*Correspondence e-mail: rakemp@unm.edu

(Received 29 September 2008; accepted 7 October 2008; online 15 October 2008)

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, F d d 2
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[F² > 2σ(F²)] = 0.030
wR(F²) = 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 ).

Supporting information

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

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

checkCIF report

Comment top

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)°.

Related literature top

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 top

{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..

Computing details top

Data collection: APEX2 (Bruker, 2007); cell refinement: APEX2 (Bruker, 2007); data reduction: APEX2 (Bruker, 2007); 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).

Figures top

	Fig. 1. View of the title compound showing full numbering scheme. Ellipsoids are shown at 50% probability and hydrogen atoms have been removed for clarity. Only one of the two symmetry equivalent positions for the nitrate group is shown.
	Fig. 2. Hydrogen bonding in (I). For clarity the tert-butyl substituents on P have been removed.

[2,6-Bis(di-tert-butylphosphinomethyl)phenyl- κ³P,C¹,P'](nitrato-κO)nickel(II) top

Crystal data top

[Ni(C₂₄H₄₃P₂)(NO₃)]	F(000) = 2208
M_r = 514.24	D_x = 1.276 Mg m⁻³
Orthorhombic, Fdd2	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: F 2 -2d	Cell parameters from 9535 reflections
a = 24.0023 (14) Å	θ = 2.2–30.3°
b = 12.6350 (6) Å	µ = 0.87 mm⁻¹
c = 17.6528 (6) Å	T = 225 K
V = 5353.5 (4) Å³	Cut-prism, orange–brown
Z = 8	0.50 × 0.40 × 0.20 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	4078 independent reflections
Radiation source: fine-focus sealed tube	3703 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.037
ϕ and ω scans	θ_max = 30.5°, θ_min = 2.9°
Absorption correction: multi-scan (SADABS; Bruker, 2004)	h = −34→34
T_min = 0.671, T_max = 0.846	k = −18→18
33484 measured reflections	l = −25→25

Refinement top

Refinement on F²	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F² > 2σ(F²)] = 0.030	H-atom parameters constrained
wR(F²) = 0.099	w = 1/[σ²(F_o²) + (0.1P)² + 0.25P] where P = (F_o² + 2F_c²)/3
S = 0.81	(Δ/σ)_max = 0.001
4078 reflections	Δρ_max = 0.38 e Å⁻³
156 parameters	Δρ_min = −0.38 e Å⁻³
1 restraint	Absolute structure: Flack (1983), 1976 Freidel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.012 (10)

Crystal data top

[Ni(C₂₄H₄₃P₂)(NO₃)]	V = 5353.5 (4) Å³
M_r = 514.24	Z = 8
Orthorhombic, Fdd2	Mo Kα radiation
a = 24.0023 (14) Å	µ = 0.87 mm⁻¹
b = 12.6350 (6) Å	T = 225 K
c = 17.6528 (6) Å	0.50 × 0.40 × 0.20 mm

Data collection top

Bruker SMART CCD area-detector diffractometer	4078 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2004)	3703 reflections with I > 2σ(I)
T_min = 0.671, T_max = 0.846	R_int = 0.037
33484 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.030	H-atom parameters constrained
wR(F²) = 0.099	Δρ_max = 0.38 e Å⁻³
S = 0.81	Δρ_min = −0.38 e Å⁻³
4078 reflections	Absolute structure: Flack (1983), 1976 Freidel pairs
156 parameters	Absolute structure parameter: 0.012 (10)
1 restraint

Special details top

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 (Å²) top

	x	y	z	U_iso*/U_eq	Occ. (<1)
Ni1	0.2500	0.2500	0.594610 (14)	0.02536 (9)
P1	0.232841 (19)	0.07823 (3)	0.58242 (3)	0.02639 (10)
C1	0.2500	0.2500	0.48634 (16)	0.0263 (5)
C2	0.22870 (9)	0.16438 (14)	0.44415 (10)	0.0293 (3)
C3	0.22918 (11)	0.16401 (17)	0.36544 (11)	0.0381 (4)
H3	0.2153	0.1051	0.3390	0.046*
C4	0.2500	0.2500	0.32575 (19)	0.0443 (8)
H4	0.2500	0.2500	0.2725	0.053*
C5	0.20438 (10)	0.07210 (16)	0.48626 (12)	0.0357 (4)
H5A	0.2149	0.0054	0.4618	0.043*
H5B	0.1636	0.0770	0.4875	0.043*
C6	0.17578 (10)	0.02125 (17)	0.64252 (13)	0.0356 (4)
C7	0.15103 (12)	−0.08133 (18)	0.60934 (17)	0.0492 (6)
H7A	0.1803	−0.1337	0.6038	0.074*
H7B	0.1348	−0.0665	0.5602	0.074*
H7C	0.1225	−0.1082	0.6431	0.074*
C8	0.13040 (11)	0.1061 (2)	0.64349 (17)	0.0490 (5)
H8A	0.1001	0.0833	0.6759	0.073*
H8B	0.1166	0.1170	0.5925	0.073*
H8C	0.1458	0.1718	0.6627	0.073*
C9	0.19464 (14)	0.00157 (19)	0.72359 (15)	0.0484 (6)
H9A	0.1623	−0.0057	0.7561	0.073*
H9B	0.2171	0.0607	0.7408	0.073*
H9C	0.2166	−0.0628	0.7256	0.073*
C10	0.29710 (10)	−0.00713 (16)	0.58017 (16)	0.0434 (5)
C11	0.33545 (12)	0.0368 (3)	0.5189 (2)	0.0635 (9)
H11A	0.3615	−0.0176	0.5032	0.095*
H11B	0.3558	0.0970	0.5388	0.095*
H11C	0.3134	0.0590	0.4757	0.095*
C12	0.32896 (19)	0.0019 (4)	0.6540 (3)	0.100 (2)
H12A	0.3293	−0.0663	0.6793	0.150*
H12B	0.3110	0.0538	0.6864	0.150*
H12C	0.3669	0.0240	0.6437	0.150*
C13	0.28517 (17)	−0.1214 (3)	0.5629 (4)	0.106 (2)
H13A	0.2705	−0.1274	0.5118	0.159*
H13B	0.2580	−0.1484	0.5986	0.159*
H13C	0.3193	−0.1621	0.5670	0.159*
N1	0.2619 (2)	0.2312 (5)	0.7546 (2)	0.0478 (13)	0.50
O1	0.22947 (16)	0.2640 (3)	0.70255 (19)	0.0394 (7)	0.50
O2	0.3061 (2)	0.1884 (5)	0.7355 (3)	0.0732 (13)	0.50
O3	0.2500	0.2500	0.8206 (2)	0.0869 (14)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
Ni1	0.03377 (16)	0.01934 (13)	0.02296 (14)	−0.00129 (11)	0.000	0.000
P1	0.0305 (2)	0.01967 (19)	0.0290 (2)	0.00015 (15)	0.00072 (17)	0.00082 (15)
C1	0.0312 (13)	0.0241 (12)	0.0238 (11)	0.0033 (8)	0.000	0.000
C2	0.0344 (8)	0.0280 (8)	0.0256 (8)	0.0006 (7)	−0.0019 (7)	−0.0025 (6)
C3	0.0478 (11)	0.0397 (11)	0.0267 (9)	−0.0013 (8)	−0.0025 (8)	−0.0070 (7)
C4	0.059 (2)	0.0497 (19)	0.0237 (12)	0.0046 (13)	0.000	0.000
C5	0.0468 (11)	0.0289 (9)	0.0314 (9)	−0.0077 (8)	−0.0027 (8)	−0.0030 (7)
C6	0.0378 (10)	0.0323 (8)	0.0368 (10)	−0.0059 (8)	0.0047 (8)	0.0017 (7)
C7	0.0514 (13)	0.0399 (11)	0.0564 (14)	−0.0172 (10)	0.0099 (11)	−0.0066 (9)
C8	0.0387 (11)	0.0530 (13)	0.0552 (14)	0.0026 (10)	0.0096 (10)	−0.0039 (11)
C9	0.0621 (16)	0.0468 (14)	0.0364 (11)	−0.0120 (11)	0.0025 (10)	0.0099 (9)
C10	0.0380 (10)	0.0317 (10)	0.0606 (15)	0.0095 (7)	0.0119 (10)	0.0072 (9)
C11	0.0397 (12)	0.0590 (16)	0.092 (2)	0.0147 (12)	0.0217 (15)	0.0184 (17)
C12	0.061 (2)	0.168 (6)	0.070 (3)	0.056 (3)	−0.0012 (18)	0.028 (2)
C13	0.069 (2)	0.0339 (14)	0.215 (7)	0.0129 (13)	0.034 (3)	−0.011 (2)
N1	0.057 (4)	0.052 (4)	0.0350 (19)	−0.016 (2)	−0.0114 (18)	0.0079 (18)
O1	0.0488 (17)	0.0462 (17)	0.0233 (14)	−0.0022 (15)	0.0012 (13)	−0.0048 (12)
O2	0.054 (2)	0.104 (4)	0.062 (3)	0.012 (3)	−0.011 (2)	0.019 (3)
O3	0.098 (3)	0.137 (4)	0.0265 (13)	−0.012 (2)	0.000	0.000

Geometric parameters (Å, º) top

Ni1—C1	1.911 (3)	C7—H7C	0.9700
Ni1—O1ⁱ	1.976 (3)	C8—H8A	0.9700
Ni1—O1	1.976 (3)	C8—H8B	0.9700
Ni1—P1ⁱ	2.2195 (4)	C8—H8C	0.9700
Ni1—P1	2.2195 (4)	C9—H9A	0.9700
P1—C5	1.831 (2)	C9—H9B	0.9700
P1—C6	1.876 (2)	C9—H9C	0.9700
P1—C10	1.882 (2)	C10—C13	1.503 (4)
C1—C2ⁱ	1.409 (2)	C10—C12	1.516 (6)
C1—C2	1.409 (2)	C10—C11	1.525 (4)
C2—C3	1.389 (3)	C11—H11A	0.9700
C2—C5	1.501 (3)	C11—H11B	0.9700
C3—C4	1.386 (3)	C11—H11C	0.9700
C3—H3	0.9400	C12—H12A	0.9700
C4—C3ⁱ	1.386 (3)	C12—H12B	0.9700
C4—H4	0.9400	C12—H12C	0.9700
C5—H5A	0.9800	C13—H13A	0.9700
C5—H5B	0.9800	C13—H13B	0.9700
C6—C9	1.521 (3)	C13—H13C	0.9700
C6—C8	1.528 (4)	N1—O3	1.223 (5)
C6—C7	1.541 (3)	N1—O2	1.239 (7)
C7—H7A	0.9700	N1—O1	1.273 (5)
C7—H7B	0.9700	O3—N1ⁱ	1.223 (5)

C1—Ni1—O1ⁱ	164.64 (11)	C6—C8—H8B	109.5
C1—Ni1—O1	164.64 (11)	H8A—C8—H8B	109.5
C1—Ni1—P1ⁱ	84.437 (14)	C6—C8—H8C	109.5
O1ⁱ—Ni1—P1ⁱ	97.74 (10)	H8A—C8—H8C	109.5
O1—Ni1—P1ⁱ	93.00 (10)	H8B—C8—H8C	109.5
C1—Ni1—P1	84.435 (14)	C6—C9—H9A	109.5
O1ⁱ—Ni1—P1	93.00 (10)	C6—C9—H9B	109.5
O1—Ni1—P1	97.74 (10)	H9A—C9—H9B	109.5
P1ⁱ—Ni1—P1	168.87 (3)	C6—C9—H9C	109.5
C5—P1—C6	103.63 (10)	H9A—C9—H9C	109.5
C5—P1—C10	105.18 (12)	H9B—C9—H9C	109.5
C6—P1—C10	112.97 (10)	C13—C10—C12	110.1 (3)
C5—P1—Ni1	101.56 (7)	C13—C10—C11	108.7 (3)
C6—P1—Ni1	117.12 (7)	C12—C10—C11	106.1 (3)
C10—P1—Ni1	114.22 (8)	C13—C10—P1	113.5 (2)
C2ⁱ—C1—C2	116.2 (3)	C12—C10—P1	110.6 (2)
C2ⁱ—C1—Ni1	121.90 (13)	C11—C10—P1	107.52 (16)
C2—C1—Ni1	121.90 (13)	C10—C11—H11A	109.5
C3—C2—C1	121.9 (2)	C10—C11—H11B	109.5
C3—C2—C5	119.73 (18)	H11A—C11—H11B	109.5
C1—C2—C5	118.39 (19)	C10—C11—H11C	109.5
C4—C3—C2	120.4 (2)	H11A—C11—H11C	109.5
C4—C3—H3	119.8	H11B—C11—H11C	109.5
C2—C3—H3	119.8	C10—C12—H12A	109.5
C3ⁱ—C4—C3	119.3 (3)	C10—C12—H12B	109.5
C3ⁱ—C4—H4	120.4	H12A—C12—H12B	109.5
C3—C4—H4	120.4	C10—C12—H12C	109.5
C2—C5—P1	106.33 (13)	H12A—C12—H12C	109.5
C2—C5—H5A	110.5	H12B—C12—H12C	109.5
P1—C5—H5A	110.5	C10—C13—H13A	109.5
C2—C5—H5B	110.5	C10—C13—H13B	109.5
P1—C5—H5B	110.5	H13A—C13—H13B	109.5
H5A—C5—H5B	108.7	C10—C13—H13C	109.5
C9—C6—C8	108.4 (2)	H13A—C13—H13C	109.5
C9—C6—C7	109.6 (2)	H13B—C13—H13C	109.5
C8—C6—C7	108.6 (2)	O1ⁱ—N1—O3	165.1 (6)
C9—C6—P1	112.18 (18)	O1ⁱ—N1—O2	64.8 (4)
C8—C6—P1	104.93 (15)	O3—N1—O2	123.0 (4)
C7—C6—P1	112.90 (16)	O3—N1—O1	118.8 (4)
C6—C7—H7A	109.5	O2—N1—O1	117.9 (5)
C6—C7—H7B	109.5	N1ⁱ—O1—O2ⁱ	69.6 (4)
H7A—C7—H7B	109.5	O2ⁱ—O1—N1	104.4 (4)
C6—C7—H7C	109.5	N1ⁱ—O1—Ni1	152.8 (5)
H7A—C7—H7C	109.5	O2ⁱ—O1—Ni1	133.8 (4)
H7B—C7—H7C	109.5	N1—O1—Ni1	121.0 (3)
C6—C8—H8A	109.5

Symmetry code: (i) −x+1/2, −y+1/2, z.

Experimental details

Crystal data
Chemical formula	[Ni(C₂₄H₄₃P₂)(NO₃)]
M_r	514.24
Crystal system, space group	Orthorhombic, Fdd2
Temperature (K)	225
a, b, c (Å)	24.0023 (14), 12.6350 (6), 17.6528 (6)
V (Å³)	5353.5 (4)
Z	8
Radiation type	Mo Kα
µ (mm⁻¹)	0.87
Crystal size (mm)	0.50 × 0.40 × 0.20

Data collection
Diffractometer	Bruker SMART CCD area-detector diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2004)
T_min, T_max	0.671, 0.846
No. of measured, independent and observed [I > 2σ(I)] reflections	33484, 4078, 3703
R_int	0.037
(sin θ/λ)_max (Å⁻¹)	0.714

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.030, 0.099, 0.81
No. of reflections	4078
No. of parameters	156
No. of restraints	1
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.38, −0.38
Absolute structure	Flack (1983), 1976 Freidel pairs
Absolute structure parameter	0.012 (10)

Computer programs: APEX2 (Bruker, 2007), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg, 1999), publCIF (Westrip, 2008).

Acknowledgements

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.

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