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Acta Cryst. (2007). E63, m1785    [ doi:10.1107/S160053680702627X ]

A tetragonal polymorph of tetra-[mu]3-chlorido-tetrakis[([eta]5-pentamethylcyclopentadienyl)ruthenium(II)]

P. G. Jones, C. G. Hrib, S. Beer and M. Tamm

Abstract top

A new (third) polymorph of the title complex, [Ru4(C10H15)4Cl4] or [Cp*Ru([mu]3-Cl)]4 [Cp* = [eta]5-C5(CH3)5], crystallizes in the tetragonal system, with imposed \overline{4} symmetry. The complex contains a distorted cubic array of Ru and Cl atoms. The structure is an inversion twin.

Comment top

Fagan et al. (1990) reported two polymorphs of the title complex (I) [Cp*Ru(µ3-Cl)]4. At 201 K the crystal is triclinic with space group P1 (a = 11.281 (5), b = 11.354 (4), c = 18.846 (5) Å, α = 82.20 (2)°, β = 82.03 (3)°, γ = 65.45 (4) °; V = 2166.3 Å3) whereas at room temperature it adopts a monoclinic cell (a = 19.040; b = 12.240; c = 18.850 Å; β = 99.38°; V = 4334.2 Å3). Only the structure of the triclinic form was solved and refined; its Cambridge refcode (Allen, 2002) is JERTIJ.

Here we report the structure of a new, tetragonal polymorph of (I), which crystallizes in space group I4 (a = b = 12.0733 (8), c = 14.9611 (15) Å; V = 2180.8 (3) Å3). It is noteworthy that the new form has a significantly larger cell volume then the triclinic form despite the lower temperature. The tetrameric complex possesses imposed 4 symmetry (Fig. 1) and consists, as does the triclinic form, of a distorted cubic array of four Ru and Cl atoms, with angles at ruthenium ca 82° and angles at chlorine ca 97°. Each Ru atom in the complex adopts an 18-electron configuration in a pseudooctahedral environment. The C5Me5 ligand coordinates in η5 fashion to the Ru atom with a Cp* (centroid)—Ru distance of 1.727 Å, which is slightly longer than the average Cp*—Ru distance (1.720 Å) reported by Fagan et al. The C2—centroid vector eclipses the bond Ru···Cl (torsion angle 2.1°). The structure of the complex is closely similar to that of the triclinic form; a least-squares fit of the Ru4Cl4 core for one of the many possible atom permutations gave a r.m.s. deviation of 0.019 Å. In detail, the Ru—Cl bond lengths (av. 2.534 Å) are also slightly longer than in the triclinic form (av. 2.524 Å). The Ru···Ru distances are 3.8286 (4) to Ruii, 3.7920 (4) Å to Rui and Ruiii, cf. 3.776 (2)–3.821 Å (av. 3.797 Å) in the triclinic form. The thermal parameters of the Cp* rings are normal, but were high in the triclinic form; this and the above-mentioned bond lengthening effects (presumably attributable to reduced libration) may be a result of the lower measurement temperature of the current structure.

Related literature top

For related literature, see: Allen (2002); Fagan et al. (1990).

Experimental top

The reaction between the title compound and four equivalents of the lithium salt of an imidazoline-2-imine in hexane afforded the new polymorph of the ruthenium starting complex as unreacted material, dark red-brown crystals of which were obtained by re-crystallization from hexane solution at −35 °C.

Refinement top

Methyl hydrogen atoms were located in a difference synthesis; the methyl groups were idealized and refined as rigid groups allowed to rotate but not tip, with C—H 0.98 Å, H—C—H 109.5°. U(H) values were fixed at 1.2Ueq(C). The structure was refined as a racemic twin, with components 0.57, 0.43 (3). The twinning (Flack) parameter is based on 1573 Friedel pairs.

Computing details top

Data collection: SMART (Bruker, 1998); cell refinement: SAINT (Bruker, 1998); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: XP (Siemens, 1994); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. The molecule of the title compound in the crystal. Ellipsoids represent 30% probability levels. Symmetry operators are those of Table 1.
tetra-µ3-chlorido-[tetrakis(η5-pentamethylcyclopentadienyl)ruthenium(II)] top
Crystal data top
[Ru4(C10H15)4Cl4]Z = 2
Mr = 1086.96F000 = 1088
Tetragonal, I4Dx = 1.655 Mg m−3
a = 12.0733 (8) ÅMo Kα radiation
λ = 0.71073 Å
b = 12.0733 (8) ÅCell parameters from 5126 reflections
c = 14.9611 (15) Åθ = 2–30º
α = 90ºµ = 1.63 mm−1
β = 90ºT = 133 (2) K
γ = 90ºTablet, dark red
V = 2180.8 (3) Å30.30 × 0.22 × 0.20 mm
Data collection top
Bruker SMART 1000 CCD
diffractometer		3314 independent reflections
Radiation source: fine-focus sealed tube3068 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.034
Detector resolution: 8.192 pixels mm-1θmax = 30.5º
T = 133(2) Kθmin = 2.2º
ω and φ scansh = −16→17
Absorption correction: multi-scan
(SADABS; Bruker, 1998)		k = −16→17
Tmin = 0.530, Tmax = 0.736l = −21→21
13332 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.024  w = 1/[σ2(Fo2) + (0.0202P)2 + 1.4509P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.049(Δ/σ)max = 0.003
S = 1.07Δρmax = 0.84 e Å−3
3314 reflectionsΔρmin = −0.33 e Å−3
115 parametersExtinction correction: none
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1573 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.43 (3)
Crystal data top
[Ru4(C10H15)4Cl4]γ = 90º
Mr = 1086.96V = 2180.8 (3) Å3
Tetragonal, I4Z = 2
a = 12.0733 (8) ÅMo Kα
b = 12.0733 (8) ŵ = 1.63 mm−1
c = 14.9611 (15) ÅT = 133 (2) K
α = 90º0.30 × 0.22 × 0.20 mm
β = 90º
Data collection top
Bruker SMART 1000 CCD
diffractometer		3314 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 1998)		3068 reflections with I > 2σ(I)
Tmin = 0.530, Tmax = 0.736Rint = 0.034
13332 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.024H-atom parameters constrained
wR(F2) = 0.049Δρmax = 0.84 e Å−3
S = 1.07Δρmin = −0.33 e Å−3
3314 reflectionsAbsolute structure: Flack (1983), 1573 Friedel pairs
115 parametersFlack parameter: 0.43 (3)
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
xyzUiso*/Ueq
Ru0.418223 (15)0.864161 (15)0.661262 (12)0.01407 (5)
C10.4531 (2)0.7131 (2)0.59544 (18)0.0208 (5)
C20.4159 (2)0.7947 (2)0.53127 (18)0.0231 (5)
C30.3056 (2)0.8280 (2)0.55638 (18)0.0223 (5)
C40.2743 (2)0.7683 (2)0.63523 (18)0.0220 (5)
C50.3659 (2)0.69705 (19)0.6597 (2)0.0205 (5)
C60.5628 (3)0.6547 (3)0.5945 (2)0.0344 (7)
H6A0.57720.62280.65350.041*
H6B0.62140.70770.57950.041*
H6C0.56130.59550.54960.041*
C70.4806 (3)0.8323 (3)0.4508 (2)0.0405 (8)
H7A0.47300.77750.40290.049*
H7B0.55890.84000.46690.049*
H7C0.45190.90390.43030.049*
C80.2339 (3)0.9097 (3)0.5071 (2)0.0447 (9)
H8A0.18930.87050.46240.054*
H8B0.28090.96450.47710.054*
H8C0.18490.94730.54950.054*
C90.1638 (2)0.7708 (3)0.6811 (2)0.0391 (8)
H9A0.12910.84330.67180.047*
H9B0.17390.75790.74520.047*
H9C0.11610.71280.65610.047*
C100.3684 (3)0.6195 (2)0.7381 (2)0.0333 (7)
H10A0.33440.54880.72120.040*
H10B0.32700.65210.78790.040*
H10C0.44530.60690.75640.040*
Cl0.38208 (4)1.06982 (5)0.67020 (3)0.01539 (10)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ru0.01418 (10)0.01413 (9)0.01390 (7)−0.00059 (7)−0.00012 (8)−0.00179 (8)
C10.0205 (13)0.0188 (13)0.0230 (13)0.0005 (10)0.0001 (10)−0.0097 (10)
C20.0288 (14)0.0238 (14)0.0166 (11)−0.0085 (11)0.0025 (10)−0.0060 (10)
C30.0248 (14)0.0214 (13)0.0208 (12)−0.0013 (10)−0.0061 (10)−0.0066 (10)
C40.0173 (12)0.0229 (13)0.0258 (13)−0.0043 (9)0.0012 (9)−0.0082 (10)
C50.0264 (12)0.0163 (11)0.0188 (11)−0.0017 (8)−0.0010 (11)−0.0056 (11)
C60.0236 (15)0.0338 (17)0.0459 (19)0.0055 (12)−0.0031 (13)−0.0193 (14)
C70.060 (2)0.0366 (18)0.0250 (16)−0.0154 (16)0.0137 (15)−0.0080 (13)
C80.052 (2)0.0400 (19)0.0420 (19)0.0067 (16)−0.0282 (17)−0.0007 (16)
C90.0246 (15)0.0455 (19)0.047 (2)−0.0093 (13)0.0071 (13)−0.0194 (15)
C100.054 (2)0.0184 (14)0.0277 (15)−0.0075 (12)−0.0030 (14)0.0014 (11)
Cl0.0146 (2)0.0162 (2)0.0154 (2)0.00040 (17)0.0002 (2)0.0005 (2)
Geometric parameters (Å, °) top
Ru—C12.115 (3)Cl—Ruiii2.5349 (6)
Ru—C22.118 (3)Cl—Ruii2.5428 (6)
Ru—C32.122 (3)C6—H6A0.9800
Ru—C42.124 (3)C6—H6B0.9800
Ru—C52.114 (2)C6—H6C0.9800
Ru—Cl2.5245 (6)C7—H7A0.9800
Ru—Cli2.5350 (6)C7—H7B0.9800
Ru—Clii2.5427 (6)C7—H7C0.9800
C1—C51.439 (4)C8—H8A0.9800
C1—C21.447 (4)C8—H8B0.9800
C1—C61.500 (4)C8—H8C0.9800
C2—C31.440 (4)C9—H9A0.9800
C2—C71.504 (4)C9—H9B0.9800
C3—C41.433 (4)C9—H9C0.9800
C3—C81.506 (4)C10—H10A0.9800
C4—C51.448 (4)C10—H10B0.9800
C4—C91.500 (4)C10—H10C0.9800
C5—C101.502 (4)
C5—Ru—C139.77 (10)C3—C4—C5107.7 (2)
C5—Ru—C266.93 (11)C3—C4—C9127.0 (3)
C1—Ru—C239.99 (11)C5—C4—C9125.1 (3)
C5—Ru—C366.64 (10)C3—C4—Ru70.17 (15)
C1—Ru—C366.76 (11)C5—C4—Ru69.66 (14)
C2—Ru—C339.73 (11)C9—C4—Ru129.3 (2)
C5—Ru—C439.95 (10)C1—C5—C4108.1 (2)
C1—Ru—C466.90 (10)C1—C5—C10126.2 (3)
C2—Ru—C466.75 (10)C4—C5—C10125.7 (3)
C3—Ru—C439.45 (11)C1—C5—Ru70.13 (14)
C5—Ru—Cl152.55 (7)C4—C5—Ru70.39 (14)
C1—Ru—Cl155.12 (8)C10—C5—Ru125.47 (19)
C2—Ru—Cl115.82 (8)Ru—Cl—Ruiii97.092 (19)
C3—Ru—Cl97.53 (7)Ru—Cl—Ruii98.145 (18)
C4—Ru—Cl113.84 (8)Ruiii—Cl—Ruii96.627 (19)
C5—Ru—Cli96.30 (8)C1—C6—H6A109.5
C1—Ru—Cli121.70 (8)C1—C6—H6B109.5
C2—Ru—Cli161.43 (8)H6A—C6—H6B109.5
C3—Ru—Cli142.17 (8)C1—C6—H6C109.5
C4—Ru—Cli105.99 (7)H6A—C6—H6C109.5
Cl—Ru—Cli82.715 (19)H6B—C6—H6C109.5
C5—Ru—Clii125.67 (7)C2—C7—H7A109.5
C1—Ru—Clii96.09 (8)C2—C7—H7B109.5
C2—Ru—Clii100.65 (7)H7A—C7—H7B109.5
C3—Ru—Clii135.31 (8)C2—C7—H7C109.5
C4—Ru—Clii162.99 (7)H7A—C7—H7C109.5
Cl—Ru—Clii81.533 (18)H7B—C7—H7C109.5
Cli—Ru—Clii82.354 (19)C3—C8—H8A109.5
C5—C1—C2107.9 (2)C3—C8—H8B109.5
C5—C1—C6126.1 (3)H8A—C8—H8B109.5
C2—C1—C6126.0 (3)C3—C8—H8C109.5
C5—C1—Ru70.10 (13)H8A—C8—H8C109.5
C2—C1—Ru70.12 (15)H8B—C8—H8C109.5
C6—C1—Ru125.85 (19)C4—C9—H9A109.5
C3—C2—C1107.6 (2)C4—C9—H9B109.5
C3—C2—C7127.2 (3)H9A—C9—H9B109.5
C1—C2—C7125.1 (3)C4—C9—H9C109.5
C3—C2—Ru70.27 (15)H9A—C9—H9C109.5
C1—C2—Ru69.89 (14)H9B—C9—H9C109.5
C7—C2—Ru127.5 (2)C5—C10—H10A109.5
C4—C3—C2108.6 (2)C5—C10—H10B109.5
C4—C3—C8125.5 (3)H10A—C10—H10B109.5
C2—C3—C8125.9 (3)C5—C10—H10C109.5
C4—C3—Ru70.37 (15)H10A—C10—H10C109.5
C2—C3—Ru70.00 (15)H10B—C10—H10C109.5
C8—C3—Ru126.5 (2)
C2—Ru—C1—C5−118.6 (2)Ru—C3—C4—C5−59.79 (17)
C3—Ru—C1—C5−80.87 (17)C2—C3—C4—C9−175.4 (3)
C4—Ru—C1—C5−37.79 (16)C8—C3—C4—C93.3 (4)
Cl—Ru—C1—C5−134.95 (17)Ru—C3—C4—C9124.8 (3)
Cli—Ru—C1—C557.29 (17)C2—C3—C4—Ru59.79 (18)
Clii—Ru—C1—C5142.05 (14)C8—C3—C4—Ru−121.5 (3)
C5—Ru—C1—C2118.6 (2)C5—Ru—C4—C3−118.6 (2)
C3—Ru—C1—C237.76 (16)C1—Ru—C4—C3−80.99 (17)
C4—Ru—C1—C280.84 (17)C2—Ru—C4—C3−37.32 (15)
Cl—Ru—C1—C2−16.3 (3)Cl—Ru—C4—C371.86 (15)
Cli—Ru—C1—C2175.93 (12)Cli—Ru—C4—C3160.85 (13)
Clii—Ru—C1—C2−99.32 (14)Clii—Ru—C4—C3−81.5 (3)
C5—Ru—C1—C6−120.8 (3)C1—Ru—C4—C537.62 (16)
C2—Ru—C1—C6120.6 (3)C2—Ru—C4—C581.29 (17)
C3—Ru—C1—C6158.4 (3)C3—Ru—C4—C5118.6 (2)
C4—Ru—C1—C6−158.6 (3)Cl—Ru—C4—C5−169.53 (13)
Cl—Ru—C1—C6104.3 (3)Cli—Ru—C4—C5−80.54 (15)
Cli—Ru—C1—C6−63.5 (3)Clii—Ru—C4—C537.1 (4)
Clii—Ru—C1—C621.3 (3)C5—Ru—C4—C9119.3 (4)
C5—C1—C2—C3−0.3 (3)C1—Ru—C4—C9157.0 (3)
C6—C1—C2—C3179.1 (2)C2—Ru—C4—C9−159.4 (3)
Ru—C1—C2—C3−60.42 (18)C3—Ru—C4—C9−122.1 (3)
C5—C1—C2—C7−177.5 (3)Cl—Ru—C4—C9−50.2 (3)
C6—C1—C2—C71.9 (4)Cli—Ru—C4—C938.8 (3)
Ru—C1—C2—C7122.3 (3)Clii—Ru—C4—C9156.4 (2)
C5—C1—C2—Ru60.17 (17)C2—C1—C5—C40.3 (3)
C6—C1—C2—Ru−120.5 (3)C6—C1—C5—C4−179.1 (2)
C5—Ru—C2—C380.69 (16)Ru—C1—C5—C460.43 (17)
C1—Ru—C2—C3118.3 (2)C2—C1—C5—C10179.8 (2)
C4—Ru—C2—C337.07 (16)C6—C1—C5—C100.4 (4)
Cl—Ru—C2—C3−69.24 (15)Ru—C1—C5—C10−120.0 (3)
Cli—Ru—C2—C3107.4 (2)C2—C1—C5—Ru−60.18 (17)
Clii—Ru—C2—C3−154.91 (14)C6—C1—C5—Ru120.5 (3)
C5—Ru—C2—C1−37.61 (15)C3—C4—C5—C1−0.2 (3)
C3—Ru—C2—C1−118.3 (2)C9—C4—C5—C1175.4 (2)
C4—Ru—C2—C1−81.24 (17)Ru—C4—C5—C1−60.27 (17)
Cl—Ru—C2—C1172.45 (13)C3—C4—C5—C10−179.7 (2)
Cli—Ru—C2—C1−10.9 (3)C9—C4—C5—C10−4.2 (4)
Clii—Ru—C2—C186.78 (15)Ru—C4—C5—C10120.2 (3)
C5—Ru—C2—C7−157.0 (3)C3—C4—C5—Ru60.12 (18)
C1—Ru—C2—C7−119.4 (4)C9—C4—C5—Ru−124.4 (3)
C3—Ru—C2—C7122.3 (3)C2—Ru—C5—C137.81 (16)
C4—Ru—C2—C7159.3 (3)C3—Ru—C5—C181.21 (18)
Cl—Ru—C2—C753.0 (3)C4—Ru—C5—C1118.6 (2)
Cli—Ru—C2—C7−130.4 (3)Cl—Ru—C5—C1139.76 (16)
Clii—Ru—C2—C7−32.6 (3)Cli—Ru—C5—C1−133.92 (15)
C1—C2—C3—C40.2 (3)Clii—Ru—C5—C1−48.83 (18)
C7—C2—C3—C4177.3 (3)C1—Ru—C5—C4−118.6 (2)
Ru—C2—C3—C4−60.02 (18)C2—Ru—C5—C4−80.82 (17)
C1—C2—C3—C8−178.6 (3)C3—Ru—C5—C4−37.42 (16)
C7—C2—C3—C8−1.4 (5)Cl—Ru—C5—C421.1 (3)
Ru—C2—C3—C8121.3 (3)Cli—Ru—C5—C4107.45 (15)
C1—C2—C3—Ru60.18 (18)Clii—Ru—C5—C4−167.46 (12)
C7—C2—C3—Ru−122.6 (3)C1—Ru—C5—C10121.0 (3)
C5—Ru—C3—C437.88 (15)C2—Ru—C5—C10158.8 (3)
C1—Ru—C3—C481.36 (17)C3—Ru—C5—C10−157.8 (3)
C2—Ru—C3—C4119.4 (2)C4—Ru—C5—C10−120.4 (3)
Cl—Ru—C3—C4−118.75 (14)Cl—Ru—C5—C10−99.3 (3)
Cli—Ru—C3—C4−30.9 (2)Cli—Ru—C5—C10−13.0 (2)
Clii—Ru—C3—C4155.70 (12)Clii—Ru—C5—C1072.1 (3)
C5—Ru—C3—C2−81.48 (16)C5—Ru—Cl—Ruiii81.26 (18)
C1—Ru—C3—C2−38.00 (16)C1—Ru—Cl—Ruiii−177.91 (18)
C4—Ru—C3—C2−119.4 (2)C2—Ru—Cl—Ruiii170.52 (8)
Cl—Ru—C3—C2121.89 (14)C3—Ru—Cl—Ruiii133.45 (8)
Cli—Ru—C3—C2−150.30 (13)C4—Ru—Cl—Ruiii95.92 (8)
Clii—Ru—C3—C236.34 (19)Cli—Ru—Cl—Ruiii−8.388 (18)
C5—Ru—C3—C8158.1 (3)Clii—Ru—Cl—Ruiii−91.693 (16)
C1—Ru—C3—C8−158.4 (3)C5—Ru—Cl—Ruii179.04 (17)
C2—Ru—C3—C8−120.4 (4)C1—Ru—Cl—Ruii−80.13 (18)
C4—Ru—C3—C8120.2 (3)C2—Ru—Cl—Ruii−91.70 (8)
Cl—Ru—C3—C81.5 (3)C3—Ru—Cl—Ruii−128.78 (8)
Cli—Ru—C3—C889.3 (3)C4—Ru—Cl—Ruii−166.30 (8)
Clii—Ru—C3—C8−84.1 (3)Cli—Ru—Cl—Ruii89.387 (18)
C2—C3—C4—C50.0 (3)Clii—Ru—Cl—Ruii6.08 (2)
C8—C3—C4—C5178.7 (3)
Symmetry codes: (i) −y+3/2, x+1/2, −z+3/2; (ii) −x+1, −y+2, z; (iii) y−1/2, −x+3/2, −z+3/2.
Table 1
Selected geometric parameters (Å, °) top
Ru—C12.115 (3)Ru—C52.114 (2)
Ru—C22.118 (3)Ru—Cl2.5245 (6)
Ru—C32.122 (3)Ru—Cli2.5350 (6)
Ru—C42.124 (3)Ru—Clii2.5427 (6)
Cl—Ru—Cli82.715 (19)Ru—Cl—Ruiii97.092 (19)
Cl—Ru—Clii81.533 (18)Ru—Cl—Ruii98.145 (18)
Cli—Ru—Clii82.354 (19)Ruiii—Cl—Ruii96.627 (19)
Symmetry codes: (i) −y+3/2, x+1/2, −z+3/2; (ii) −x+1, −y+2, z; (iii) y−1/2, −x+3/2, −z+3/2.
references
References top

Allen, F. H. (2002). Acta Cryst. B58, 380–388.

Bruker (1998). SMART (Version 5.0), SAINT (Version 4.0) and SADABS (Version 2.0). Bruker AXS Inc., Madison, Wisconsin, USA.

Fagan, P. J., Mahoney, W. S., Calabrese, J. C. & Williams, I. D. (1990). Organometallics, 9, 1843–1852.

Flack, H. D. (1983). Acta Cryst. A39, 876–881.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.

Siemens (1994). XP. Version 5.03. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA.