The betainic form of (imidazol-2-yl)phenylphosphinic acid hydrate

Kunz, P.C.; Frank, W.

doi:10.1107/S1600536810018337

organic compounds

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Volume 66| Part 6| June 2010| Page o1440

https://doi.org/10.1107/S1600536810018337

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The betainic form of (imidazol-2-yl)phenylphosphinic acid hydrate

Peter C. Kunz ^a ^* and Walter Frank ^a

^aInstitut für Anorganische Chemie und Strukturchemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225 Düsseldorf, Germany
^*Correspondence e-mail: peter.kunz@uni-duesseldorf.de

(Received 25 March 2010; accepted 17 May 2010; online 22 May 2010)

Single crystals of the title compound, (imidazolium-2-yl)phenylphosphinate monohydrate, C₉H₉N₂O₂·H₂O, were obtained from methanol/water after deprotection and oxidation of bis(1-diethoxymethylimidazol-2-yl)phenylphosphane. In the structure, several N–H⋯O and P—O⋯H–O hydrogen bonds are found. π–π interactions between the protonated imidazolyl rings [centroid–centroid distance = 3.977 (2) Å] help to establish the crystal packing. The hydrate water molecule builds hydrogen bridges to three molecules of the phosphinic acid by the O and both H atoms.

Related literature

For structures of related imidazolyl phosphinic acids, see: Ball et al. (1984 ); Britten et al. (1993 ). For the chemistry of imidazolyl phosphanes, see: Enders et al. (2004 ); Kimblin et al. (1996a ,b , 2000a ,b ); Kunz et al. (2003 ).

Experimental

Crystal data

C₉H₉N₂O₂P·H₂O
M_r = 226.17
Monoclinic, P 2₁ /n
a = 8.5890 (6) Å
b = 12.1091 (7) Å
c = 10.9534 (7) Å
β = 111.766 (7)°
V = 1057.99 (12) Å³
Z = 4
Mo Kα radiation
μ = 0.25 mm⁻¹
T = 223 K
0.2 × 0.2 × 0.2 mm

Data collection

Stoe IPDS diffractometer
14882 measured reflections
2069 independent reflections
1606 reflections with I > 2σ(I)
R_int = 0.052

Refinement

R[F² > 2σ(F²)] = 0.037
wR(F²) = 0.092
S = 0.93
2069 reflections
148 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.40 e Å⁻³
Δρ_min = −0.16 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1⋯O1ⁱ	0.87	1.80	2.6302 (19)	160
N2—H2⋯O3ⁱⁱ	0.91 (2)	1.78 (2)	2.684 (2)	168 (2)
O3—H3⋯O2	0.83 (3)	1.94 (3)	2.773 (2)	177 (3)
O3—H4⋯O2ⁱⁱⁱ	0.79 (3)	2.00 (3)	2.777 (2)	164 (3)
Symmetry codes: (i) $[x-{\script{1\over 2}}, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ ; (ii) $[-x+{\script{1\over 2}}, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]$ ; (iii) -x, -y+2, -z+1.

Data collection: EXPOSE in IPDS Software (Stoe & Cie, 2000 ); cell refinement: CELL in IPDS Software; data reduction: INTEGRATE in IPDS Software; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97.

Supporting information

Crystal structure: contains datablocks I, global. DOI: https://doi.org/10.1107/S1600536810018337/nc2181sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810018337/nc2181Isup2.hkl

checkCIF report

Comment top

Imidazolphosphanes of the type PPh_3-n(im)_n (im = imidazol-2-yl) can resemble the chemistry of pyridylphosphanes PPh_3-n(2-py)_n (pyridin-2-yl). In addition, imidazolylphosphanes can not only act as neutral polydentate ligands but due to their N—H functionalities act as (poly)anionic ligands, e.g. a tris(lithium) salt of tris(imidazol-2-yl)phosphane has been described (Enders et al., 2004). Also, tris(imidazolyl)phosphanes and their oxides were used to mimic the tris(histidine) motif found in many metalloenzymes (Kimblin et al. 1996a,b, 2000a,b). The use of of imidazol-2-ylphosphanes is limited due to degradation, e.g. oxidative hydrolysis. Britten reported upon the attempted synthesis of tris(imidazol-2-yl)-phosphane. They yielded unexpectedly the bis(imidazol-2-yl)- phosphinic acid, presumably due to oxidation of the phosphane and subsequent hydrolysis (Britten et al., 1993). Brown reported that the catalytic activity of a catalyst formed by zinc chloride and bis(4,5-diisopropylimidazol- 2-yl)imidazol-2-ylphosphane decreased due to formation of a zinc complex of bis(4,5-diisopropylimidazol-2-yl)phosphinic acid as degradation product (Ball et al., 1984). Here we report that the oxidation of bis(imidazol-2-yl)phosphane using H₂O₂ in methanol did not yield the corresponding phosphane oxide, too. Upon oxidation in the presence of water, hydrolysis occurred to imidazol-2-yl phenylphosphinic acid.

The molecular structure of the title compound is shown in Figure 1. In the crystal structur of the title compound the molecules are connected into chains via N—H···O—P hydrogen bonding between the N—H H atom of the protonated imidazolyl ring and the O atom of the PO₂ group (Figure 2 and Table 1). These chains are further connected by N—H···O and O—H···O hydrogen bonding to the water molecules. Each two water molecules and two symmetry related molecules of the title compounds forms 8-membered hydrogen bonded rings that are located on centres of inversion. Additionally to the hydrogen bonding network, in the solid state packing a pairwise π-π stacking of imidazolyl rings with a centroid distance of 3.977 Å is observed (Figure 3).

Related literature top

For structures of related imidazolyl phosphinic acids, see: Ball et al. (1984); Britten et al. (1993). For the chemistry of imidazolyl phosphanes, see: Enders et al. (2004); Kimblin et al. (1996a,b, 2000a,b); Kunz et al. (2003).

Experimental top

To a solution of 1-diethoxy-2-isopropylimidazole (Kunz et al., 2003) in diethyl ether a solution of tert.-BuLi in hexane (1.5 M, 1.1 equivalents) is added dropwise at – 78 °C. After the solution was stirred for 30 min at – 78 °C and 30 min at room temperature the temperature is lowered again to – 78 °C and half an equivalent of dichlorophenylphosphane in diethyl ether (20 ml) is added drop-wise. After the mixture was stirred over night conc. ammonia was added, the phases were separated and the organic layer washed with bidest. water (3 x 100 ml). The organic layer was dried over anhydrous Na₂SO₄. After filtration and removal of the volatiles in vacuo the protected (imidazolyl)phosphane was obtained. After deprotection in an acetone-water mixture (10:1) perhydrol was added. The product precipitated as white solid which was collected by filtration, washed with acetone and diethyl ether and dried in vacuo. Single crystals were grown from a methanol / water solution. ¹H NMR (200 MHz, [D₄]methanol/D₂O): δ = 7.37 (d, 2H, J_PH = 1.5 Hz, H_im), 7.4 – 7.6 (m, 3 H, Ph), 7.85 – 8.0 (m, 2H, Ph) ppm. ³¹P{¹H} NMR (200 MHz, [D₄]methanol/D₂O): δ = 3 ppm. C₉H₉N₂O₂P.H₂O (214.16): calc. C 47.8 H 4.9 N 12.4, found C 47.2 H 4.9 N 12.1. ¹H and ³¹P NMR spectra were recorded on a Bruker DRX 200 spectrometer. The ¹H NMR spectra were calibrated against the residual proton signals of the solvents as internal references ([D₄]methanol: δ = 5.84 ppm) while the ³¹P{¹H} NMR spectra were referenced to external 85 % H₃PO₄.

Structure description top

For structures of related imidazolyl phosphinic acids, see: Ball et al. (1984); Britten et al. (1993). For the chemistry of imidazolyl phosphanes, see: Enders et al. (2004); Kimblin et al. (1996a,b, 2000a,b); Kunz et al. (2003).

Computing details top

Data collection: EXPOSE (Stoe & Cie, 2000); cell refinement: CELL (Stoe & Cie, 2000); data reduction: INTEGRATE (Stoe & Cie, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top

	Fig. 1. The components of the title compound with their hydrogen bond enviroment. Hydrogen atoms are drawn with an arbitrary radius and displacement ellipsoids at the 30% probability level. Dashed lines indicate hydrogen bonding establishing a three dimensional network.
	Fig. 2. Diagram showing the supramolecular association of the betainic acid and water molecules of I in layers perpendicular to [-1 0 1]; symmetry codes: (A) x +1/2, y – 1/2, z –3/2; (B) x + 1/2, –y + 3/2, z + 1/2 (C) –x + 1, –y + 1, –z + 2; (D) x + 1, y, z + 1; (E) –x + 3/2, y – 1/2, –z + 5/2; the atoms of the unlabeled left part of the figure are generated by translation along [0 0 -1].
	Fig. 3. Packing diagram, view along [1 0 -1], showing the arrangement of layers perpendicular to [-1 0 1]

(imidazolium-2-yl)phenylphosphinate monohydrate top

Crystal data top

C₉H₉N₂O₂P·H₂O	F(000) = 472
M_r = 226.17	D_x = 1.420 Mg m⁻³
Monoclinic, P2₁/n	Mo Kα radiation, λ = 0.71073 Å
a = 8.5890 (6) Å	Cell parameters from 8000 reflections
b = 12.1091 (7) Å	θ = 2.6–26.1°
c = 10.9534 (7) Å	µ = 0.25 mm⁻¹
β = 111.766 (7)°	T = 223 K
V = 1057.99 (12) Å³	Isometric, colourless
Z = 4	0.2 × 0.2 × 0.2 mm

Data collection top

Stoe IPDS diffractometer	1606 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.052
Graphite monochromator	θ_max = 26.1°, θ_min = 2.6°
Detector resolution: 6.67 pixels mm^-1	h = −10→10
φ–scans	k = −14→14
14882 measured reflections	l = −13→13
2069 independent reflections

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.037	Hydrogen site location: difference Fourier map
wR(F²) = 0.092	H atoms treated by a mixture of independent and constrained refinement
S = 0.93	w = 1/[σ²(F_o²) + (0.0664P)²] where P = (F_o² + 2F_c²)/3
2069 reflections	(Δ/σ)_max < 0.001
148 parameters	Δρ_max = 0.40 e Å⁻³
0 restraints	Δρ_min = −0.16 e Å⁻³

Crystal data top

C₉H₉N₂O₂P·H₂O	V = 1057.99 (12) Å³
M_r = 226.17	Z = 4
Monoclinic, P2₁/n	Mo Kα radiation
a = 8.5890 (6) Å	µ = 0.25 mm⁻¹
b = 12.1091 (7) Å	T = 223 K
c = 10.9534 (7) Å	0.2 × 0.2 × 0.2 mm
β = 111.766 (7)°

Data collection top

Stoe IPDS diffractometer	1606 reflections with I > 2σ(I)
14882 measured reflections	R_int = 0.052
2069 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.037	0 restraints
wR(F²) = 0.092	H atoms treated by a mixture of independent and constrained refinement
S = 0.93	Δρ_max = 0.40 e Å⁻³
2069 reflections	Δρ_min = −0.16 e Å⁻³
148 parameters

Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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
P1	0.21068 (5)	0.75986 (4)	0.66209 (4)	0.02580 (15)
O1	0.38922 (15)	0.77558 (11)	0.74699 (13)	0.0357 (3)
O2	0.11462 (16)	0.84520 (10)	0.56559 (13)	0.0348 (3)
O3	−0.03925 (18)	1.01453 (13)	0.64926 (14)	0.0353 (3)
H3	0.007 (3)	0.965 (2)	0.622 (3)	0.054 (7)*
H4	−0.068 (3)	1.063 (3)	0.596 (3)	0.061 (8)*
N1	0.11416 (18)	0.61686 (12)	0.44158 (15)	0.0296 (3)
H1	0.0343	0.6596	0.3921	0.044*
N2	0.3181 (2)	0.55296 (12)	0.60673 (16)	0.0329 (4)
H2	0.399 (3)	0.5492 (17)	0.689 (2)	0.037 (6)*
C1	0.2123 (2)	0.63787 (14)	0.56488 (18)	0.0269 (4)
C2	0.1578 (3)	0.51769 (16)	0.4043 (2)	0.0383 (5)
H10	0.1080	0.4839	0.3216	0.057*
C3	0.2853 (3)	0.47751 (16)	0.5081 (2)	0.0403 (5)
H11	0.3412	0.4101	0.5119	0.060*
C4	0.0927 (2)	0.71894 (14)	0.76010 (18)	0.0276 (4)
C5	−0.0757 (2)	0.74606 (15)	0.7218 (2)	0.0346 (4)
H5	−0.1292	0.7856	0.6435	0.052*
C6	−0.1654 (2)	0.71519 (18)	0.7985 (2)	0.0430 (5)
H6	−0.2793	0.7341	0.7726	0.064*
C7	−0.0874 (3)	0.65688 (18)	0.9125 (2)	0.0436 (5)
H7	−0.1482	0.6361	0.9646	0.065*
C8	0.0794 (3)	0.62866 (18)	0.9510 (2)	0.0428 (5)
H8	0.1316	0.5883	1.0289	0.064*
C9	0.1702 (2)	0.65964 (17)	0.87531 (19)	0.0356 (4)
H9	0.2841	0.6406	0.9018	0.053*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
P1	0.0274 (2)	0.0255 (2)	0.0236 (3)	−0.00120 (16)	0.00835 (18)	−0.00096 (18)
O1	0.0315 (7)	0.0423 (7)	0.0312 (8)	−0.0076 (5)	0.0094 (6)	−0.0054 (6)
O2	0.0456 (7)	0.0294 (6)	0.0305 (8)	0.0057 (5)	0.0154 (6)	0.0035 (5)
O3	0.0428 (8)	0.0301 (7)	0.0295 (8)	0.0019 (6)	0.0092 (6)	−0.0007 (6)
N1	0.0308 (8)	0.0275 (7)	0.0265 (8)	0.0012 (6)	0.0060 (6)	0.0000 (6)
N2	0.0359 (8)	0.0303 (8)	0.0280 (9)	0.0054 (6)	0.0067 (7)	0.0014 (7)
C1	0.0259 (8)	0.0270 (9)	0.0263 (10)	0.0004 (6)	0.0080 (7)	0.0029 (7)
C2	0.0490 (11)	0.0325 (9)	0.0296 (10)	−0.0005 (8)	0.0104 (9)	−0.0088 (8)
C3	0.0495 (11)	0.0293 (10)	0.0380 (12)	0.0088 (8)	0.0116 (9)	−0.0036 (8)
C4	0.0310 (9)	0.0259 (8)	0.0260 (10)	−0.0017 (6)	0.0108 (7)	−0.0034 (7)
C5	0.0321 (9)	0.0321 (9)	0.0387 (11)	0.0035 (7)	0.0122 (8)	0.0000 (8)
C6	0.0351 (10)	0.0423 (11)	0.0571 (14)	−0.0004 (8)	0.0236 (10)	−0.0070 (10)
C7	0.0476 (11)	0.0486 (12)	0.0450 (13)	−0.0119 (9)	0.0291 (10)	−0.0092 (10)
C8	0.0453 (11)	0.0516 (12)	0.0316 (11)	−0.0100 (9)	0.0145 (9)	0.0042 (9)
C9	0.0317 (9)	0.0416 (10)	0.0316 (11)	−0.0012 (7)	0.0095 (8)	0.0045 (8)

Geometric parameters (Å, º) top

P1—O1	1.4815 (13)	C2—H10	0.9400
P1—O2	1.4897 (13)	C3—H11	0.9400
P1—C4	1.7974 (18)	C4—C5	1.388 (3)
P1—C1	1.8240 (18)	C4—C9	1.389 (3)
O3—H3	0.83 (3)	C5—C6	1.385 (3)
O3—H4	0.79 (3)	C5—H5	0.9400
N1—C1	1.325 (2)	C6—C7	1.373 (3)
N1—C2	1.365 (2)	C6—H6	0.9400
N1—H1	0.8700	C7—C8	1.377 (3)
N2—C1	1.335 (2)	C7—H7	0.9400
N2—C3	1.362 (2)	C8—C9	1.385 (3)
N2—H2	0.91 (2)	C8—H8	0.9400
C2—C3	1.344 (3)	C9—H9	0.9400

O1—P1—O2	121.89 (8)	C2—C3—H11	126.5
O1—P1—C4	110.00 (8)	N2—C3—H11	126.5
O2—P1—C4	109.18 (8)	C5—C4—C9	119.45 (17)
O1—P1—C1	103.90 (8)	C5—C4—P1	120.62 (14)
O2—P1—C1	105.65 (8)	C9—C4—P1	119.93 (13)
C4—P1—C1	104.68 (8)	C6—C5—C4	120.30 (19)
H3—O3—H4	109 (3)	C6—C5—H5	119.8
C1—N1—C2	109.43 (15)	C4—C5—H5	119.8
C1—N1—H1	125.3	C7—C6—C5	119.77 (18)
C2—N1—H1	125.3	C7—C6—H6	120.1
C1—N2—C3	109.27 (16)	C5—C6—H6	120.1
C1—N2—H2	123.3 (14)	C6—C7—C8	120.50 (19)
C3—N2—H2	127.4 (14)	C6—C7—H7	119.7
N1—C1—N2	107.26 (16)	C8—C7—H7	119.7
N1—C1—P1	127.65 (13)	C7—C8—C9	120.1 (2)
N2—C1—P1	125.07 (14)	C7—C8—H8	119.9
C3—C2—N1	107.04 (17)	C9—C8—H8	119.9
C3—C2—H10	126.5	C8—C9—C4	119.84 (18)
N1—C2—H10	126.5	C8—C9—H9	120.1
C2—C3—N2	106.99 (17)	C4—C9—H9	120.1

C2—N1—C1—N2	−0.1 (2)	O2—P1—C4—C5	14.52 (17)
C2—N1—C1—P1	178.80 (14)	C1—P1—C4—C5	−98.21 (15)
C3—N2—C1—N1	−0.1 (2)	O1—P1—C4—C9	−29.28 (17)
C3—N2—C1—P1	−179.06 (14)	O2—P1—C4—C9	−165.48 (14)
O1—P1—C1—N1	−145.99 (16)	C1—P1—C4—C9	81.80 (16)
O2—P1—C1—N1	−16.61 (18)	C9—C4—C5—C6	0.6 (3)
C4—P1—C1—N1	98.60 (17)	P1—C4—C5—C6	−179.36 (15)
O1—P1—C1—N2	32.72 (18)	C4—C5—C6—C7	−0.4 (3)
O2—P1—C1—N2	162.09 (15)	C5—C6—C7—C8	−0.1 (3)
C4—P1—C1—N2	−82.69 (17)	C6—C7—C8—C9	0.4 (3)
C1—N1—C2—C3	0.3 (2)	C7—C8—C9—C4	−0.2 (3)
N1—C2—C3—N2	−0.3 (2)	C5—C4—C9—C8	−0.3 (3)
C1—N2—C3—C2	0.3 (2)	P1—C4—C9—C8	179.68 (16)
O1—P1—C4—C5	150.71 (14)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.87	1.80	2.6302 (19)	160
N2—H2···O3ⁱⁱ	0.91 (2)	1.78 (2)	2.684 (2)	168 (2)
O3—H3···O2	0.83 (3)	1.94 (3)	2.773 (2)	177 (3)
O3—H4···O2ⁱⁱⁱ	0.79 (3)	2.00 (3)	2.777 (2)	164 (3)

Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x+1/2, y−1/2, −z+3/2; (iii) −x, −y+2, −z+1.

Experimental details

Crystal data
Chemical formula	C₉H₉N₂O₂P·H₂O
M_r	226.17
Crystal system, space group	Monoclinic, P2₁/n
Temperature (K)	223
a, b, c (Å)	8.5890 (6), 12.1091 (7), 10.9534 (7)
β (°)	111.766 (7)
V (Å³)	1057.99 (12)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.25
Crystal size (mm)	0.2 × 0.2 × 0.2

Data collection
Diffractometer	Stoe IPDS
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	14882, 2069, 1606
R_int	0.052
(sin θ/λ)_max (Å⁻¹)	0.618

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.037, 0.092, 0.93
No. of reflections	2069
No. of parameters	148
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.40, −0.16

Computer programs: EXPOSE (Stoe & Cie, 2000), CELL (Stoe & Cie, 2000), INTEGRATE (Stoe & Cie, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.87	1.80	2.6302 (19)	160.0
N2—H2···O3ⁱⁱ	0.91 (2)	1.78 (2)	2.684 (2)	168 (2)
O3—H3···O2	0.83 (3)	1.94 (3)	2.773 (2)	177 (3)
O3—H4···O2ⁱⁱⁱ	0.79 (3)	2.00 (3)	2.777 (2)	164 (3)

Symmetry codes: (i) x−1/2, −y+3/2, z−1/2; (ii) −x+1/2, y−1/2, −z+3/2; (iii) −x, −y+2, −z+1.

Acknowledgements

We thank Ms E. Hammes and Dr M. Schilling for technical assistance.

References

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