A low-temperature investigation of trans-diiodo­tetra­kis(tetra­hydro­furan)calcium(II)

The asymmetric unit of the title compound, [CaI₂(C₄H₈O)₄], at 100 K comprises half each of two independent mol­ecules, each of which is located on a center of inversion, and in each of these, the central Ca atom is bound by two trans I atoms and four tetra­hydro­furan mol­ecules to give a distorted octa­hedral geometry. This compound undergoes a phase change on cooling from room temperature to 100 K, altering the space group from monoclinic P2₁/c to triclinic P. This change is also accompanied by a reduction in the positional disorder of the coordinated tetra­hydro­furan mol­ecules.

Key indicators

• Single-crystal X-ray study
• T = 100 K
• Mean [sigma](C-C) = 0.018 Å
• Disorder in main residue
• R factor = 0.058
• wR factor = 0.171
• Data-to-parameter ratio = 18.7

checkCIF/PLATON results

No syntax errors found



Alert level A
PLAT029_ALERT_3_A _diffrn_measured_fraction_theta_full Low .......       0.89

Author Response: The crystal is a non-merohedral twin and a number of reflections were omitted to facilitate the refinement. The twinned model provides a much improved structure over that published by Hanusa (1994).

Alert level B
REFLT03_ALERT_3_B  Reflection count < 90% complete (theta max?)
           From the CIF: _diffrn_reflns_theta_max           27.00
           From the CIF: _diffrn_reflns_theta_full          26.99
           From the CIF: _reflns_number_total               4361
           TEST2: Reflns within _diffrn_reflns_theta_max
           Count of symmetry unique reflns         4876
           Completeness (_total/calc)             89.44%
PLAT022_ALERT_3_B Ratio Unique / Expected Reflections too Low ....       0.89

Alert level C
PLAT241_ALERT_2_C Check High      Ueq as Compared to Neighbors for        C16
PLAT301_ALERT_3_C Main Residue  Disorder .........................       8.00 Perc.
PLAT342_ALERT_3_C Low Bond Precision on C-C bonds (x 1000) Ang ...         18
PLAT360_ALERT_2_C Short  C(sp3)-C(sp3) Bond  C15    -   C16    ...       1.43 Ang.
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      29.00 Deg.
              C12  -O3   -C12'    1.555   1.555   1.555
PLAT779_ALERT_2_C Suspect or Irrelevant (Bond) Angle in CIF ......      26.60 Deg.
              C11' -C10  -C11     1.555   1.555   1.555

   1 ALERT level A = In general: serious problem
   2 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   4 ALERT type 2 Indicator that the structure model may be wrong or deficient
   5 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion

---

S1. Comment

As part of our ongoing investigations into the chemistry of the alkaline earth metals (He et al., 2005), we crystallized the title compound, (I). The room-temperature structure of (I) was first reported by Tesh et al. (1994). The original experiment found the monoclinic space group P2₁/c with unit-cell parameters a = 8.201 (7), b = 14.262 (9), c = 10.008 (6) Å, β = 93.93 (6)° and Z = 2. The asymmetric comprised a half-molecule, with the Ca center on an inversion center. Disorder was indicated in the atomic positions of the attached tetrahydrofuran (THF) molecules, as the molecules appear almost planar. We confirmed the identity of the room-temperature unit cell, but found that cooling to 100 K resulted in a phase change to the triclinic space group P1 with unit-cell parameters as listed in the Crystal data section. This phase change proved to be reversible upon warming the crystal to room temperature. The low-temperature structure was refined as a four-component non-merohedral twin. Twin domains were located using Cell_Now (Sheldrick, 2005). The scale factors between component one and subsequent components are 0.331 (2), 0.136 (2) and 0.121 (2).

Two independent half-molecules with similar metrical parameters occupy the asymmetric unit; one of these half-molecules is shown in Fig. 1. Each molecule has a pair of well defined THF ligands and a pair of easily modeled two-site disordered THF ligands. Overlaying one half-molecule on the other shows differences principally in the angles between the attached cis ligands. One of the molecules has these angles in the narrow range 88.55 (19)–91.45 (19)°, whereas these angles in the second molecule are in the range 84.36 (3)–95.65 (3)°. The analogous angles in the room-temperature structure are in the range 89.06 (6)–90.94 (7)°.

S2. Experimental

All experimental manipulations were carried out under a purified nitrogen atmosphere using standard Schlenk techniques. Hexane and THF were dried using a solvent purification system and stored over 4 Å molecular sieves prior to use. CaI₂ was purchased from Aldrich as anhydrous beads and used as received. The NMR data were obtained on a Varian Unity Plus 300 spectrometer at 298 K. X-ray quality crystals of (I) formed at 253 K as a by-product in the reaction of tBuLi with CaI₂ in a hexane/THF solution. ¹H NMR (300 MHz, DMSO-d₆, 298 K): δ 3.59 (m, OCH₂, THF), 1.76 (m, CH₂, THF).

S3. Refinement

H atoms were placed at calculated positions and allowed to ride on the parent C atoms, with C—H set at 0.97 Å and with U_iso(H) = 1.2U_iso(C). Disorder was modeled for the O3 THF molecule in the second independent molecule so that atoms C11 and C12were split over two sites. Anisotropic refinement of these showed that the major component has a site-occupancy factor of 0.63 (4). The four largest residual peaks in the final difference map, 2.27 to 1.34 e Å⁻³, were located near the I-atom positions, approximately perpendicular to the Ca—I bond, and may be alternate sites for these atoms.

Computing details

Data collection: APEX2 (Bruker–Nonius, 2004); cell refinement: APEX2 and SAINT (Bruker–Nonius, 2004); data reduction: SAINT and SHELXTL (Sheldrick, 2004); program(s) used to solve structure: SHELXTL; program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Figures

Fig. 1. The structure and atomic numbering for one independent molecule in (I); the Ca atom is located on a center of inversion. Displacement ellipsoids are drawn at the 50% displacement level and H atoms have been omitted for clarity.

trans-diiodotetrakis(tetrahydrofuran)calcium(II)

Crystal data

[CaI2(C8H16O2)2]	Z = 2
Mr = 582.30	F(000) = 572
Triclinic, P1	Dx = 1.734 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 8.442 (2) Å	Cell parameters from 5033 reflections
b = 9.858 (2) Å	θ = 2.8–26.3°
c = 13.610 (3) Å	µ = 3.06 mm^−1
α = 80.156 (1)°	T = 100 K
β = 89.412 (1)°	Needle, colorless
γ = 87.877 (1)°	0.28 × 0.17 × 0.15 mm
V = 1115.2 (4) Å^3

Data collection

Bruker SMART APEX CCD area-detector diffractometer	4361 independent reflections
Radiation source: fine-focus sealed tube, Siemens KFFMO2K-90	3852 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.053
Detector resolution: 8.33 pixels mm^-1	θmax = 27.0°, θmin = 2.1°
ϕ and ω scans	h = −10→10
Absorption correction: multi-scan (Blessing, 1995)	k = −11→12
Tmin = 0.53, Tmax = 0.64	l = 0→16
4361 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.171	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.1062P)^2 + 6.8251P] where P = (Fo^2 + 2Fc^2)/3
4361 reflections	(Δ/σ)max = 0.002
233 parameters	Δρmax = 2.27 e Å^−3
24 restraints	Δρmin = −1.30 e Å^−3

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	Occ. (<1)
Ca1	0.5000	0.5000	0.0000	0.0307 (7)
I1	0.73189 (9)	0.73484 (8)	−0.07295 (5)	0.0388 (2)
O1	0.6762 (9)	0.3385 (8)	−0.0626 (6)	0.041 (2)
C1	0.8489 (13)	0.3380 (16)	−0.0547 (11)	0.058 (4)
H1A	0.8824	0.3000	0.0127	0.069*
H1B	0.8867	0.4308	−0.0720	0.069*
C2	0.9122 (15)	0.2483 (17)	−0.1279 (11)	0.061 (4)
H2A	0.9245	0.3019	−0.1941	0.073*
H2B	1.0133	0.2039	−0.1061	0.073*
C3	0.7862 (14)	0.1444 (14)	−0.1265 (10)	0.049 (3)
H3A	0.8007	0.0690	−0.0710	0.058*
H3B	0.7859	0.1076	−0.1882	0.058*
C4	0.6354 (14)	0.2282 (13)	−0.1146 (9)	0.042 (3)
H4A	0.5910	0.2658	−0.1794	0.050*
H4B	0.5575	0.1707	−0.0766	0.050*
O2	0.6259 (9)	0.4496 (9)	0.1558 (5)	0.0377 (18)
C5	0.5378 (14)	0.4201 (14)	0.2498 (8)	0.040 (3)
H5A	0.5470	0.3227	0.2775	0.048*
H5B	0.4265	0.4462	0.2396	0.048*
C6	0.6127 (15)	0.5055 (13)	0.3192 (8)	0.041 (3)
H6A	0.6501	0.4474	0.3799	0.050*
H6B	0.5376	0.5746	0.3364	0.050*
C7	0.7502 (14)	0.5724 (13)	0.2587 (8)	0.042 (3)
H7A	0.7216	0.6664	0.2286	0.050*
H7B	0.8424	0.5730	0.3005	0.050*
C8	0.7836 (13)	0.4842 (13)	0.1790 (8)	0.036 (3)
H8A	0.8355	0.5357	0.1213	0.043*
H8B	0.8481	0.4026	0.2047	0.043*
Ca2	0.5000	0.0000	0.5000	0.0364 (7)
I2	0.26678 (11)	−0.19874 (9)	0.43005 (6)	0.0497 (3)
O3	0.3113 (11)	0.1832 (10)	0.4498 (6)	0.056 (3)
C9	0.1868 (15)	0.2028 (13)	0.3798 (10)	0.048 (3)
H9A	0.1082	0.1336	0.3985	0.058*
H9B	0.2276	0.1941	0.3142	0.058*
C10	0.1116 (15)	0.3462 (13)	0.3777 (9)	0.045 (3)
H10A	−0.0010	0.3478	0.3640	0.054*
H10B	0.1620	0.4139	0.3283	0.054*
C11	0.144 (3)	0.373 (2)	0.4888 (17)	0.042 (6)	0.63 (4)
H11A	0.1408	0.4708	0.4927	0.050*	0.63 (4)
H11B	0.0706	0.3257	0.5371	0.050*	0.63 (4)
C12	0.312 (3)	0.309 (2)	0.5005 (15)	0.037 (6)	0.63 (4)
H12A	0.3887	0.3740	0.4689	0.045*	0.63 (4)
H12B	0.3391	0.2828	0.5705	0.045*	0.63 (4)
C11'	0.204 (5)	0.397 (3)	0.453 (3)	0.034 (9)	0.37 (4)
H11C	0.1418	0.4624	0.4840	0.041*	0.37 (4)
H11D	0.2983	0.4409	0.4232	0.041*	0.37 (4)
C12'	0.249 (5)	0.265 (4)	0.530 (3)	0.048 (11)	0.37 (4)
H12C	0.3310	0.2802	0.5760	0.058*	0.37 (4)
H12D	0.1584	0.2240	0.5661	0.058*	0.37 (4)
O4	0.3655 (10)	−0.0220 (11)	0.6568 (6)	0.049 (2)
C13	0.4246 (14)	0.0017 (14)	0.7501 (8)	0.039 (3)
H13A	0.4437	0.0988	0.7474	0.047*
H13B	0.5233	−0.0505	0.7664	0.047*
C14	0.2955 (15)	−0.0461 (16)	0.8290 (9)	0.052 (3)
H14A	0.3142	−0.1415	0.8597	0.062*
H14B	0.2908	0.0109	0.8805	0.062*
C15	0.1499 (17)	−0.0284 (19)	0.7689 (10)	0.065 (4)
H15A	0.0728	−0.0949	0.7971	0.078*
H15B	0.1032	0.0635	0.7665	0.078*
C16	0.1963 (15)	−0.050 (2)	0.6714 (10)	0.075 (6)
H16A	0.1342	0.0113	0.6217	0.090*
H16B	0.1777	−0.1440	0.6640	0.090*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ca1	0.0250 (17)	0.0322 (16)	0.0341 (15)	0.0016 (13)	−0.0039 (12)	−0.0036 (12)
I1	0.0304 (4)	0.0422 (4)	0.0419 (4)	−0.0063 (3)	−0.0054 (3)	−0.0005 (3)
O1	0.021 (4)	0.039 (4)	0.067 (5)	0.004 (3)	−0.007 (4)	−0.019 (4)
C1	0.020 (7)	0.076 (10)	0.089 (10)	0.009 (6)	−0.009 (6)	−0.051 (9)
C2	0.030 (7)	0.088 (12)	0.070 (9)	0.014 (7)	0.000 (7)	−0.030 (8)
C3	0.028 (7)	0.055 (8)	0.068 (8)	−0.005 (6)	0.004 (6)	−0.022 (7)
C4	0.034 (7)	0.042 (7)	0.053 (7)	−0.006 (5)	−0.004 (5)	−0.018 (6)
O2	0.028 (5)	0.047 (5)	0.039 (4)	−0.005 (4)	−0.003 (3)	−0.009 (4)
C5	0.041 (7)	0.051 (8)	0.029 (5)	−0.009 (6)	0.001 (5)	−0.005 (5)
C6	0.044 (8)	0.048 (7)	0.030 (5)	−0.005 (6)	0.005 (5)	0.001 (5)
C7	0.036 (7)	0.042 (7)	0.046 (7)	−0.005 (6)	−0.012 (5)	−0.005 (6)
C8	0.021 (6)	0.045 (7)	0.041 (6)	−0.006 (5)	−0.002 (5)	−0.004 (5)
Ca2	0.0233 (18)	0.052 (2)	0.0330 (16)	0.0062 (14)	−0.0009 (12)	−0.0063 (14)
I2	0.0419 (6)	0.0534 (5)	0.0522 (5)	−0.0089 (4)	0.0018 (4)	−0.0027 (4)
O3	0.051 (6)	0.068 (6)	0.053 (5)	0.030 (5)	−0.027 (4)	−0.026 (5)
C9	0.040 (8)	0.047 (7)	0.062 (8)	0.001 (6)	−0.020 (6)	−0.020 (6)
C10	0.039 (8)	0.048 (7)	0.044 (7)	−0.001 (6)	0.001 (5)	0.006 (6)
C11	0.042 (6)	0.041 (6)	0.042 (6)	−0.001 (2)	−0.001 (2)	−0.007 (2)
C12	0.037 (6)	0.038 (6)	0.038 (6)	−0.001 (2)	0.000 (2)	−0.007 (2)
C11'	0.035 (9)	0.034 (9)	0.034 (9)	−0.001 (2)	0.000 (2)	−0.006 (3)
C12'	0.049 (11)	0.048 (11)	0.048 (11)	−0.002 (2)	−0.001 (2)	−0.008 (3)
O4	0.027 (5)	0.084 (7)	0.036 (4)	0.004 (5)	0.000 (3)	−0.011 (4)
C13	0.028 (7)	0.052 (8)	0.043 (6)	0.003 (6)	−0.008 (5)	−0.022 (6)
C14	0.039 (8)	0.075 (10)	0.043 (7)	−0.004 (7)	0.002 (6)	−0.017 (7)
C15	0.043 (9)	0.097 (13)	0.058 (9)	−0.020 (9)	0.014 (7)	−0.023 (8)
C16	0.024 (8)	0.151 (18)	0.050 (8)	−0.011 (9)	0.000 (6)	−0.017 (9)

Geometric parameters (Å, º)

Ca1—O2	2.349 (7)	Ca2—I2	3.0957 (9)
Ca1—O2^i	2.349 (7)	Ca2—I2^ii	3.0957 (9)
Ca1—O1^i	2.395 (8)	O3—C9	1.411 (13)
Ca1—O1	2.395 (8)	O3—C12	1.52 (2)
Ca1—I1	3.1125 (9)	O3—C12'	1.54 (4)
Ca1—I1^i	3.1125 (9)	C9—C10	1.524 (17)
O1—C4	1.448 (13)	C9—H9A	0.9700
O1—C1	1.463 (13)	C9—H9B	0.9700
C1—C2	1.522 (17)	C10—C11'	1.46 (3)
C1—H1A	0.9700	C10—C11	1.61 (2)
C1—H1B	0.9700	C10—H10A	0.9700
C2—C3	1.501 (18)	C10—H10B	0.9700
C2—H2A	0.9700	C11—C12	1.53 (3)
C2—H2B	0.9700	C11—H11A	0.9700
C3—C4	1.515 (17)	C11—H11B	0.9700
C3—H3A	0.9700	C12—H12A	0.9700
C3—H3B	0.9700	C12—H12B	0.9700
C4—H4A	0.9700	C11'—C12'	1.56 (6)
C4—H4B	0.9700	C11'—H11C	0.9700
O2—C8	1.438 (12)	C11'—H11D	0.9700
O2—C5	1.464 (13)	C12'—H12C	0.9700
C5—C6	1.524 (15)	C12'—H12D	0.9700
C5—H5A	0.9700	O4—C13	1.428 (12)
C5—H5B	0.9700	O4—C16	1.469 (15)
C6—C7	1.520 (16)	C13—C14	1.551 (17)
C6—H6A	0.9700	C13—H13A	0.9700
C6—H6B	0.9700	C13—H13B	0.9700
C7—C8	1.519 (16)	C14—C15	1.472 (18)
C7—H7A	0.9700	C14—H14A	0.9700
C7—H7B	0.9700	C14—H14B	0.9700
C8—H8A	0.9700	C15—C16	1.427 (18)
C8—H8B	0.9700	C15—H15A	0.9700
Ca2—O3^ii	2.378 (8)	C15—H15B	0.9700
Ca2—O3	2.378 (8)	C16—H16A	0.9700
Ca2—O4	2.388 (8)	C16—H16B	0.9700
Ca2—O4^ii	2.388 (8)
O2—Ca1—O2^i	180.0	O3^ii—Ca2—I2^ii	88.5 (2)
O2—Ca1—O1^i	89.9 (3)	O3—Ca2—I2^ii	91.5 (2)
O2^i—Ca1—O1^i	90.1 (3)	O4—Ca2—I2^ii	90.1 (2)
O2—Ca1—O1	90.1 (3)	O4^ii—Ca2—I2^ii	89.9 (2)
O2^i—Ca1—O1	89.9 (3)	I2—Ca2—I2^ii	179.999 (2)
O1^i—Ca1—O1	180.0 (4)	C9—O3—C12	107.9 (10)
O2—Ca1—I1	91.30 (19)	C9—O3—C12'	102.5 (16)
O2^i—Ca1—I1	88.70 (19)	C12—O3—C12'	29.0 (15)
O1^i—Ca1—I1	89.9 (2)	C9—O3—Ca2	133.2 (7)
O1—Ca1—I1	90.1 (2)	C12—O3—Ca2	118.8 (8)
O2—Ca1—I1^i	88.70 (19)	C12'—O3—Ca2	117.4 (15)
O2^i—Ca1—I1^i	91.30 (19)	O3—C9—C10	108.5 (10)
O1^i—Ca1—I1^i	90.1 (2)	O3—C9—H9A	110.0
O1—Ca1—I1^i	89.9 (2)	C10—C9—H9A	110.0
I1—Ca1—I1^i	180.0	O3—C9—H9B	110.0
C4—O1—C1	108.2 (8)	C10—C9—H9B	110.0
C4—O1—Ca1	127.8 (7)	H9A—C9—H9B	108.4
C1—O1—Ca1	123.9 (6)	C11'—C10—C9	101.6 (15)
O1—C1—C2	105.6 (10)	C11'—C10—C11	26.6 (14)
O1—C1—H1A	110.6	C9—C10—C11	102.4 (11)
C2—C1—H1A	110.6	C11'—C10—H10A	133.3
O1—C1—H1B	110.6	C9—C10—H10A	111.3
C2—C1—H1B	110.6	C11—C10—H10A	111.3
H1A—C1—H1B	108.8	C11'—C10—H10B	87.4
C3—C2—C1	103.1 (11)	C9—C10—H10B	111.3
C3—C2—H2A	111.2	C11—C10—H10B	111.3
C1—C2—H2A	111.2	H10A—C10—H10B	109.2
C3—C2—H2B	111.2	C12—C11—C10	97.7 (16)
C1—C2—H2B	111.2	C12—C11—H11A	112.2
H2A—C2—H2B	109.1	C10—C11—H11A	112.2
C2—C3—C4	102.7 (11)	C12—C11—H11B	112.2
C2—C3—H3A	111.2	C10—C11—H11B	112.2
C4—C3—H3A	111.2	H11A—C11—H11B	109.8
C2—C3—H3B	111.2	O3—C12—C11	105.7 (15)
C4—C3—H3B	111.2	O3—C12—H12A	110.6
H3A—C3—H3B	109.1	C11—C12—H12A	110.6
O1—C4—C3	107.4 (9)	O3—C12—H12B	110.6
O1—C4—H4A	110.2	C11—C12—H12B	110.6
C3—C4—H4A	110.2	H12A—C12—H12B	108.7
O1—C4—H4B	110.2	C10—C11'—C12'	104 (3)
C3—C4—H4B	110.2	C10—C11'—H11C	110.9
H4A—C4—H4B	108.5	C12'—C11'—H11C	110.9
C8—O2—C5	107.5 (8)	C10—C11'—H11D	110.9
C8—O2—Ca1	127.0 (6)	C12'—C11'—H11D	110.9
C5—O2—Ca1	122.6 (6)	H11C—C11'—H11D	108.9
O2—C5—C6	105.6 (9)	O3—C12'—C11'	94 (3)
O2—C5—H5A	110.6	O3—C12'—H12C	113.0
C6—C5—H5A	110.6	C11'—C12'—H12C	113.0
O2—C5—H5B	110.6	O3—C12'—H12D	112.9
C6—C5—H5B	110.6	C11'—C12'—H12D	112.9
H5A—C5—H5B	108.7	H12C—C12'—H12D	110.4
C5—C6—C7	103.9 (9)	C13—O4—C16	106.9 (9)
C5—C6—H6A	111.0	C13—O4—Ca2	128.3 (7)
C7—C6—H6A	111.0	C16—O4—Ca2	124.5 (7)
C5—C6—H6B	111.0	O4—C13—C14	106.3 (9)
C7—C6—H6B	111.0	O4—C13—H13A	110.5
H6A—C6—H6B	109.0	C14—C13—H13A	110.5
C8—C7—C6	105.1 (10)	O4—C13—H13B	110.5
C8—C7—H7A	110.7	C14—C13—H13B	110.5
C6—C7—H7A	110.7	H13A—C13—H13B	108.7
C8—C7—H7B	110.7	C15—C14—C13	102.3 (10)
C6—C7—H7B	110.7	C15—C14—H14A	111.3
H7A—C7—H7B	108.8	C13—C14—H14A	111.3
O2—C8—C7	101.3 (9)	C15—C14—H14B	111.3
O2—C8—H8A	111.5	C13—C14—H14B	111.3
C7—C8—H8A	111.5	H14A—C14—H14B	109.2
O2—C8—H8B	111.5	C16—C15—C14	106.1 (12)
C7—C8—H8B	111.5	C16—C15—H15A	110.5
H8A—C8—H8B	109.3	C14—C15—H15A	110.5
O3^ii—Ca2—O3	179.999 (1)	C16—C15—H15B	110.5
O3^ii—Ca2—O4	95.6 (3)	C14—C15—H15B	110.5
O3—Ca2—O4	84.4 (3)	H15A—C15—H15B	108.7
O3^ii—Ca2—O4^ii	84.4 (3)	C15—C16—O4	109.0 (11)
O3—Ca2—O4^ii	95.6 (3)	C15—C16—H16A	109.9
O4—Ca2—O4^ii	180.000 (1)	O4—C16—H16A	109.9
O3^ii—Ca2—I2	91.5 (2)	C15—C16—H16B	109.9
O3—Ca2—I2	88.5 (2)	O4—C16—H16B	109.9
O4—Ca2—I2	89.9 (2)	H16A—C16—H16B	108.3
O4^ii—Ca2—I2	90.1 (2)

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