Magnesium iodide-4,4'-bipyridine-water (1/3/4) and strontium iodide-4,4'-bipyridine-propan-1-ol (1/2.5/2)

Both of the title compounds, catena-poly­[[[tetra­aqua­magnesium(I)]-[mu]-4,4'-bi­pyridine-[kappa]²N:N'] diiodide bis(4,4'-bi­pyridine) solvate], {[Mg(C₁₀H₈N₂)(H₂O)₄]I₂·2C₁₀H₈N₂}_n, (I), and catena-poly­[[[[mu]-4,4'-bi­pyridine-bis­[di­iodo­bis­(propan-1-ol)­strontium(I)]]-di-[mu]-4,4'-bi­pyridine-[kappa]⁴N:N'] bis(4,4'-bi­pyri­dine) solvate], {[Sr₂I₄(C₁₀H₈N₂)₃(C₃H₈O)₄]·2C₁₀H₈N₂}_n, (II), are one-dimensional polymers which are single- and double-stranded, respectively, the metal atoms being linked by the 4,4'-bi­pyridine moieties. The Mg complex, (I), is [cis-{(H₂O)₄Mg(N-4,4'-bi­pyridine-N')_(2/2)}]_{([infinity]|[infinity])}I₂·4,4'-bi­pyridine and Mg has a six-coordinate quasi-octahedral coordination environment. The Sr complex, (II), is isomorphous with its previously defined Ba counterpart [Kepert, Waters & White (1996). Aust. J. Chem. 49, 117-135], being [(propan-1-ol)₂I₂Sr(N-4,4'-bi­pyridine-N')_(3/2)]_{([infinity]|[infinity])}·4,4'-bi­pyridine, with the I atoms trans-axial in a seven-coordinate pentagonal-bipyramidal Sr environment.

S1. Comment

In the course of extended studies undertaken some years ago concerning the synthesis and structural characterization of nitrogen base adducts of simple group 2 salts with simple nitrogen base ligands, a hitherto largely unexplored fundamental field, we investigated derivatives formed between the metal halides and the inherently bridging bidentate ligand 4,4'-bipyridine, in the expectation that unusual polymeric arrays might be obtained (Kepert et al., 1996). In doing so, the metal iodides were dissolved with the ligand in 1:2 millimolar stoichiometry in a few ml of alcoholic solvent (propan-1-ol for the heavier metals, methanol for the lighter) under anaerobic conditions, i.e. specifically excluding moisture. At the time, a crystalline deposit was obtained only of a barium complex, which proved to be an adduct of stoichiometry BaI₂:4,4'-bipyridine:propan-1-ol (1:2.5:2), a novel polymer in which seven-coordinate Ba atoms of pentagonal-bipyramidal stereochemistry (environment: BaI₂N₃O₂), comprising the two axial I atoms, three pyridyl N atoms (from different ligands) and two propan-1-ol O atoms, were linked into a one-dimensional double-stranded polymer. After standing for some years, two parallel vials containing magnesium iodide with ligand in methanol, and strontium iodide with ligand in propan-1-ol, deposited significant quantities of colourless well formed crystals, the title complexes, (I) and (II), respectively. The strontium complex, (II), proved to be a counterpart of the previously described barium adduct, while the magnesium complex, (I), is an adduct of the form MgI₂-4,4'-bipyridine-water (1:3:4), presumably consequent upon the slow admission of water from the surroundings over an extended period and/or some presence in the initial mixture. In both complexes, coordinated bridging 4,4'-bipyridine moieties are found, so that polymers result. In both compounds, uncoordinated 4,4'-bipyridine moieties are also found, which are prone to stack or interleave interstitially, being (quasi-)planar but not inflexibly so. \sch

In complex (I), one half of the 1:3:4 MgI₂-4,4'-bipyridine-water formula unit comprises the asymmetric unit of the structure, the Mg atom being disposed on a crystallographic 2 axis, while the mid-point of the central bond of the coordinated 4,4'-bipyridine ligand lies at a crystallographic centre of symmetry, the two C₅N rings necessarily parallel and essentially coplanar, the Mg atom deviant by 0.234 (6) and 0.199 (14) Å. The lattice 4,4'-bipyridine moiety is fully crystallographically independent. The Mg atom environment is six-coordinate and quasi-octahedral in stereochemistry. Symmetry-related 4,4'-bipyridine moieties lie cis in the coordination sphere, bonded through their N atoms and bridging to inversion-related Mg atoms to generate an infinite one-dimensional zigzag polymeric cation along the crystallographic c axis (Fig. 2).

The Mg-coordinated atom distances (Table 1) are unremarkable and are comparable with values recorded for similar bonds in examples of pyridine base and aqua ligand complexes (e.g. Waters & White, 1996), there being no significant difference in the two Mg—OH₂ distances indicative of any significant difference in trans effects of the two ligand types.

Although the polymer of (I) is one-dimensional, its profile is extended in the second dimension (b) by its zigzag aspect, with the overall array having a planar core disposed in the bc face of the cell (Fig. 2 b) and the dihedral angle of the C₅N ligand plane to that face being 51.0 (1)°. One H atom from each water molecule is involved in a strong hydrogen bond projecting out of the plane to the same nearby iodide ion (Table 2), and these interactions are perhaps responsible for the considerable deviations of the angles about the Mg atom from orthogonality. Whereas the coordinated ligand is essentially planar, the uncoordinated moiety is twisted about its central bond, the dihedral angle between the two C₅N planes (χ² 20 and 1) being 33.8 (2)°.

The strontium complex, (II), is isomorphous with its barium counterpart, previously recorded elsewhere (Kepert et al., 1996). One full formula unit, devoid of crystallographic symmetry (but see below), comprises the asymmetric unit of the structure. The coordinated 4,4'-bipyridine complement comprises the two halves of different ligands 1, this ligand bridging to a (b-) unit-translation-related metal atom, and one half of ligand 2, which lies with the midpoint of its central bond disposed at a crystallographic inversion centre. The two rings of the second ligand are necessarily parallel and quasi-coplanar, the metal atom deviating from the C₅N plane (χ² 5.6) by 0.34 (1) Å. The two similar component planes (χ² 6.5 and 0.4) of the first ligand lie twisted about the central bond with respect to each other, with an interplanar dihedral angle of 23.0 (4)° and with the associated Sr atoms considerably [0.81 (1) and 1.23 (3) Å] out of plane in each case. [The third uncoordinated ligand is crystallographically fully independent and is also similarly twisted, the interplanar dihedral angle being 33.7 (4)°].

The metal atoms of (II) are seven-coordinate, the coordination environment approximating nicely to pentagonal-bipyramidal stereochemistry, with the I atoms occupying the trans/axial sites. Two of the five equatorial sites (not cis) are occupied by the propan-1-ol ligand O atoms, which thus define the orientation of the other three pyridine N atoms in the I₂SrO₂N₃ coordination sphere. As implied above, two of the N atoms come from the two independent rings of the symmetry-related ligands 1 which extend the resulting polymer in b; the other is from the independent half of ligand 2 which, by inversion, extends the polymer in the second dimension across the cell diagonal. The resulting planar array (Fig. 3a) comprises a double-stranded polymer running parallel to b (Fig. 3 b).

The metal atom environment of (II) may be compared with that of its barium counterpart, in which the Ba—I(1,2)/O(1 A,B)/N(11,21,11') distances are 3.382 (4), 3.403 (4), 2.69 (2), 2.74 (1), 2.85 (2), 2.94 (2) and 2.91 (2) Å, respectively. Thus the mean differences between Ba and Sr bond lengths for I, O and N donors are 0.13, 0.15, 0.14 Å, respectively, suggesting no outstanding differential between bond types.

S2. Experimental

The complexes were obtained as outlined above. Analysis for (I): found: C 43.7, H 4.0, N 8.4%; C₃₁H₃₆I₂N₅O₂Sr requires: C 43.70, H 4.26, N 8.22%. Analysis for (II): found: C 44.2, H 3.7, N 10.3%; C₃₀H₃₂I₂MgN₆O₄ requires: C 44.01, H 3.94, N 10.26%.

S3. Refinement

The H atoms were located from difference Fourier maps and placed at idealized positions for those on C [C—H = 0.95 Å, U_isoH = 1.25U_eq(C) (CH) and 1.5U_eq(C,O) (CH₃ and OH)], and were refined (in x, y, z and U) for (I) but not refined for (II). Atoms C1A and C2A of one propanol group of (II) were each modelled as disordered over two sites, C1A and C1A', and C2A and C2A', and assigned site occupancy factors of 0.5 after initial trial refinement.

Computing details

For both compounds, data collection: CAD-4 Software (Enraf-Nonius, 1989); cell refinement: CAD-4 Software; data reduction: Xtal3.5 (Hall et al., 1995); program(s) used to solve structure: Xtal3.5; program(s) used to refine structure: CRYLSQ in Xtal3.5; molecular graphics: Xtal3.5; software used to prepare material for publication: BONDLA and CIFIO in Xtal3.5.

Figures

	Fig. 1. (a) The numbering scheme and coordination around the Mg atom for (I). (b) The numbering scheme and coordination around the Sr atom for (II). Displacement ellipsoids are drawn at the 20% probability level in this and other figures and H atoms are shown with arbitrary radii of 0.1 Å.
	Fig. 2. (a) A strand of the polymeric cation of the magnesium complex, (I), projected normal to its plane (bc) and with its axis, parallel to crystallographic c, horizontal in the page. (b) Unit-cell contents of (I) projected down b, showing the disposition of anions and lattice 4,4'-bipyridine moieties between the polymer planes, which lie about the bc face of the cell.
	Fig. 3. (a) The double-stranded array of (II), generated by the unit b-translation, together with inversion (b horizontal in the page). (b) Unit-cell projection of (II) down the polymer axis b, showing its extent and disposition across the cell diagonal.

(I) catena-poly[[[tetraaquamagnesium(I)]-µ-4,4'-bipyridine-κ²N:N'] diiodide bis(4,4'-bipyridine) solvate]

Crystal data

[Mg(C10H8N2)(H2O)4]I2·2C10H8N2	F(000) = 1616
Mr = 818.75	Dx = 1.577 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -c 2yc	Cell parameters from 8 reflections
a = 27.574 (7) Å	θ = 18.1–23.8°
b = 9.018 (4) Å	µ = 1.88 mm^−1
c = 16.974 (3) Å	T = 298 K
β = 125.23 (2)°	Block, colourless
V = 3448 (2) Å^3	0.35 × 0.33 × 0.32 mm
Z = 4

Data collection

Enraf-Nonius CAD4 diffractometer	2964 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.014
Graphite monochromator	θmax = 27.5°, θmin = 1.8°
2θ/ω scans	h = −31→35
Absorption correction: gaussian (ABSORB in Xtal3.5; Hall et al., 1995)	k = −11→0
Tmin = 0.58, Tmax = 0.63	l = −22→4
5196 measured reflections	8 standard reflections every 60 min
3955 independent reflections	intensity decay: none

Refinement

Refinement on F	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.040	All H-atom parameters refined
wR(F^2) = 0.052	w = 1/[σ^2(Fo)] where σ(I) = [σ(I)meas + 0.0004(Inet)^2]^1/2
S = 1.12	(Δ/σ)max = 0.049
2964 reflections	Δρmax = 1.06 e Å^−3
260 parameters	Δρmin = −0.50 e Å^−3
0 restraints	Extinction correction: Zachariasen (1967), Eq. 22, p. 292 Larson, A. C. (1970). Crystallographic Computing, edited by F. R. Ahmed, S. R. Hall & C. P. Huber, pp. 291-294. Copenhagen: Munksgaard.
0 constraints	Extinction coefficient: 35 (4) × 10^3
Primary atom site location: structure-invariant direct methods

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
I	0.348074 (13)	0.25991 (3)	0.18221 (2)	0.0720 (2)
Mg	0.50000	0.93393 (16)	0.25000	0.0319 (6)
O1	0.50749 (14)	1.0905 (3)	0.1695 (2)	0.0507 (12)
O2	0.59105 (11)	0.9392 (3)	0.33903 (19)	0.0429 (12)
N11	0.50337 (14)	0.7565 (3)	0.3442 (2)	0.0389 (13)
C12	0.54224 (17)	0.7632 (4)	0.4405 (3)	0.0419 (16)
C13	0.54253 (16)	0.6666 (4)	0.5031 (2)	0.0423 (16)
C14	0.50118 (15)	0.5527 (4)	0.4679 (2)	0.0368 (14)
C15	0.46123 (19)	0.5447 (4)	0.3679 (3)	0.0494 (15)
C16	0.46372 (18)	0.6460 (4)	0.3104 (3)	0.0478 (15)
N21	0.81720 (15)	0.6904 (5)	0.4969 (3)	0.0591 (17)
C22	0.79385 (19)	0.8247 (6)	0.4673 (3)	0.0586 (18)
C23	0.74719 (17)	0.8558 (5)	0.3731 (3)	0.0518 (16)
C24	0.72406 (16)	0.7438 (4)	0.3051 (3)	0.0482 (16)
C25	0.7476 (2)	0.6022 (5)	0.3357 (3)	0.0601 (15)
C26	0.7934 (2)	0.5833 (6)	0.4325 (3)	0.066 (3)
N21'	0.58234 (15)	0.8219 (5)	0.0100 (2)	0.0577 (17)
C22'	0.58681 (18)	0.8943 (5)	0.0811 (3)	0.056 (2)
C23'	0.63167 (17)	0.8751 (5)	0.1773 (3)	0.051 (2)
C24'	0.67539 (16)	0.7715 (4)	0.2026 (3)	0.0465 (16)
C25'	0.6709 (2)	0.6945 (6)	0.1287 (3)	0.066 (3)
C26'	0.6246 (2)	0.7237 (6)	0.0342 (4)	0.072 (3)
H1A	0.482 (2)	1.128 (5)	0.122 (3)	0.061 (14)*
H1B	0.533 (2)	1.144 (5)	0.194 (3)	0.055 (14)*
H2A	0.604 (2)	1.009 (6)	0.333 (3)	0.074 (17)*
H2B	0.619 (2)	0.881 (5)	0.384 (3)	0.059 (12)*
H12	0.5701 (15)	0.841 (4)	0.462 (2)	0.034 (9)*
H13	0.5711 (17)	0.675 (5)	0.571 (3)	0.053 (11)*
H15	0.431 (2)	0.474 (5)	0.337 (3)	0.062 (12)*
H16	0.4340 (19)	0.647 (5)	0.241 (3)	0.069 (13)*
H22	0.8077 (18)	0.899 (5)	0.509 (3)	0.056 (13)*
H23	0.7314 (15)	0.957 (4)	0.358 (3)	0.040 (10)*
H25	0.7301 (16)	0.519 (4)	0.293 (3)	0.047 (11)*
H26	0.8071 (18)	0.490 (5)	0.453 (3)	0.065 (13)*
H22'	0.5610 (18)	0.968 (5)	0.066 (3)	0.055 (12)*
H23'	0.6330 (17)	0.932 (4)	0.223 (3)	0.046 (11)*
H25'	0.699 (2)	0.630 (6)	0.138 (4)	0.096 (18)*
H26'	0.621 (2)	0.666 (6)	−0.020 (4)	0.086 (16)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
I	0.0525 (2)	0.0580 (2)	0.0736 (3)	0.00823 (13)	0.01793 (17)	−0.01955 (15)
Mg	0.0313 (7)	0.0347 (8)	0.0217 (7)	0.00000	0.0106 (6)	0.00000
O1	0.0409 (15)	0.0555 (16)	0.0314 (14)	−0.0050 (14)	0.0068 (13)	0.0153 (13)
O2	0.0303 (12)	0.0501 (15)	0.0332 (14)	0.0005 (11)	0.0096 (11)	0.0128 (12)
N11	0.0441 (16)	0.0393 (15)	0.0311 (15)	−0.0025 (12)	0.0205 (13)	0.0020 (12)
C12	0.0444 (19)	0.046 (2)	0.0322 (18)	−0.0106 (16)	0.0203 (16)	−0.0028 (15)
C13	0.0417 (19)	0.049 (2)	0.0251 (17)	−0.0075 (16)	0.0129 (15)	−0.0006 (15)
C14	0.0433 (18)	0.0353 (16)	0.0310 (17)	−0.0025 (14)	0.0209 (15)	−0.0011 (13)
C15	0.060 (2)	0.046 (2)	0.0312 (18)	−0.0175 (18)	0.0200 (18)	−0.0053 (16)
C16	0.055 (2)	0.052 (2)	0.0251 (17)	−0.0125 (18)	0.0166 (17)	−0.0017 (16)
N21	0.0374 (17)	0.077 (2)	0.042 (2)	0.0060 (17)	0.0109 (15)	0.0200 (19)
C22	0.043 (2)	0.065 (3)	0.047 (2)	−0.002 (2)	0.014 (2)	0.011 (2)
C23	0.041 (2)	0.058 (2)	0.044 (2)	0.0024 (18)	0.0173 (18)	0.012 (2)
C24	0.0321 (17)	0.061 (2)	0.042 (2)	0.0072 (16)	0.0159 (16)	0.0172 (18)
C25	0.053 (2)	0.058 (2)	0.047 (2)	0.011 (2)	0.016 (2)	0.010 (2)
C26	0.053 (3)	0.067 (3)	0.053 (3)	0.019 (2)	0.016 (2)	0.023 (2)
N21'	0.046 (2)	0.079 (2)	0.0324 (17)	0.0043 (18)	0.0136 (15)	0.0157 (17)
C22'	0.040 (2)	0.071 (3)	0.044 (2)	0.013 (2)	0.0165 (18)	0.023 (2)
C23'	0.042 (2)	0.066 (3)	0.040 (2)	0.0130 (18)	0.0211 (18)	0.014 (2)
C24'	0.0358 (18)	0.060 (2)	0.038 (2)	0.0088 (16)	0.0180 (16)	0.0145 (17)
C25'	0.056 (3)	0.082 (3)	0.048 (3)	0.025 (2)	0.023 (2)	0.007 (2)
C26'	0.068 (3)	0.090 (4)	0.042 (2)	0.009 (3)	0.022 (2)	0.007 (2)

Geometric parameters (Å, º)

Mg—O1	2.056 (4)	N21—C22	1.327 (7)
Mg—O2	2.052 (3)	N21—C26	1.316 (6)
Mg—N11	2.226 (4)	C22—C23	1.385 (5)
Mg—O1	2.056 (4)	C22—H22	0.89 (4)
Mg—O2	2.052 (3)	C23—C24	1.382 (6)
Mg—N11	2.226 (4)	C23—H23	0.98 (4)
O1—H1A	0.78 (4)	C24—C25	1.390 (6)
O1—H1B	0.75 (4)	C24—C24'	1.482 (5)
O2—H2A	0.76 (6)	C25—C26	1.389 (5)
O2—H2B	0.88 (4)	C25—H25	0.96 (4)
N11—C12	1.343 (5)	C26—H26	0.91 (4)
N11—C16	1.339 (5)	N21'—C22'	1.314 (7)
C12—C13	1.370 (6)	N21'—C26'	1.326 (7)
C12—H12	0.94 (4)	C22'—C23'	1.377 (5)
C13—C14	1.388 (5)	C22'—H22'	0.90 (5)
C13—H13	0.95 (4)	C23'—C24'	1.383 (6)
C14—C15	1.394 (5)	C23'—H23'	0.91 (5)
C14—C14	1.475 (6)	C24'—C25'	1.375 (8)
C15—C16	1.367 (7)	C25'—C26'	1.382 (6)
C15—H15	0.93 (4)	C25'—H25'	0.91 (6)
C16—H16	0.97 (4)	C26'—H26'	1.01 (7)
O1—Mg—O2	85.66 (12)	N11—C16—C15	123.8 (3)
O1—Mg—N11	172.90 (14)	N11—C16—H16	115 (3)
O1—Mg—O1	93.28 (15)	C15—C16—H16	121 (3)
O1—Mg—O2	92.52 (13)	C22—N21—C26	117.1 (4)
O1—Mg—N11	89.70 (13)	N21—C22—C23	123.1 (4)
O2—Mg—N11	87.78 (12)	N21—C22—H22	120 (3)
O2—Mg—O1	92.52 (13)	C23—C22—H22	117 (3)
O2—Mg—O2	177.35 (14)	C22—C23—C24	119.4 (4)
O2—Mg—N11	94.13 (13)	C22—C23—H23	118 (2)
N11—Mg—O1	89.70 (13)	C24—C23—H23	123 (2)
N11—Mg—O2	94.13 (13)	C23—C24—C25	117.9 (3)
N11—Mg—N11	88.08 (14)	C23—C24—C24'	121.8 (3)
O1—Mg—O2	85.66 (13)	C25—C24—C24'	120.3 (3)
O1—Mg—N11	172.90 (14)	C24—C25—C26	117.7 (4)
O2—Mg—N11	87.78 (12)	C24—C25—H25	121 (2)
Mg—O1—H1A	128 (4)	C26—C25—H25	121 (2)
Mg—O1—H1B	120 (4)	N21—C26—C25	124.8 (5)
H1A—O1—H1B	107 (5)	N21—C26—H26	118 (2)
Mg—O2—H2A	113 (3)	C25—C26—H26	117 (2)
Mg—O2—H2B	135 (3)	C22'—N21'—C26'	116.6 (4)
H2A—O2—H2B	112 (5)	N21'—C22'—C23'	124.8 (4)
Mg—N11—C12	121.0 (3)	N21'—C22'—H22'	118 (3)
Mg—N11—C16	122.8 (2)	C23'—C22'—H22'	117 (3)
C12—N11—C16	115.9 (4)	C22'—C23'—C24'	118.6 (5)
N11—C12—C13	124.0 (3)	C22'—C23'—H23'	120 (2)
N11—C12—H12	114 (2)	C24'—C23'—H23'	121 (2)
C13—C12—H12	122 (2)	C24—C24'—C23'	121.0 (5)
C12—C13—C14	120.1 (3)	C24—C24'—C25'	122.0 (4)
C12—C13—H13	121 (3)	C23'—C24'—C25'	117.0 (4)
C14—C13—H13	119 (3)	C24'—C25'—C26'	120.0 (5)
C13—C14—C15	116.0 (4)	C24'—C25'—H25'	123 (4)
C13—C14—C14	122.3 (3)	C26'—C25'—H25'	117 (4)
C15—C14—C14	121.7 (3)	N21'—C26'—C25'	123.0 (6)
C14—C15—C16	120.3 (4)	N21'—C26'—H26'	117 (2)
C14—C15—H15	123 (3)	C25'—C26'—H26'	120 (3)
C16—C15—H15	117 (3)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1B···I^i	0.76 (5)	2.88 (4)	3.601 (3)	161 (4)
O2—H2A···I^i	0.75 (6)	2.71 (6)	3.466 (3)	178 (5)

Symmetry code: (i) −x+1, y+1, −z+1/2.

(II) catena-poly[[[[µ-4,4'-bipyridine-bis[diiodobis(propan-1-ol)strontium(I)]]- di-µ-4,4'-bipyridine-κ⁴N:N'] bis(4,4'-bipyridine) solvate] [Sr₂I₄(C₁₀H₈N₂)₃(C₃H₈O)₄]·2C₁₀H₈N₂

Crystal data

[Sr2I4(C10H8N2)3(C3H8O)4]·2C10H8N2	F(000) = 1668
Mr = 1704.2	Dx = 1.612 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -p 2ybc	Cell parameters from 8 reflections
a = 15.365 (2) Å	θ = 16.7–18.5°
b = 12.392 (2) Å	µ = 3.33 mm^−1
c = 20.979 (2) Å	T = 298 K
β = 118.493 (8)°	Prism, colourless
V = 3510.6 (8) Å^3	0.53 × 0.40 × 0.18 mm
Z = 2

Data collection

Enraf-Nonius CAD4 with CCD area-detector diffractometer	6161 independent reflections
Radiation source: sealed tube	4203 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
2θ/ω scans	θmax = 25.0°, θmin = 1.5°
Absorption correction: gaussian (ABSORB in Xtal3.5; Hall et al., 1995)	h = −18→18
Tmin = 0.33, Tmax = 0.56	k = −14→0
11868 measured reflections	l = −24→21

Refinement

Refinement on F	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)] = 0.044	Hydrogen site location: difference Fourier map
wR(F^2) = 0.05	H-atom parameters constrained
S = 1.16	w = 1/[σ^2(Fo)] where σ(I) = [σ(I)meas + 0.0004(Inet)^2]^1/2
4203 reflections	(Δ/σ)max = 0.005
388 parameters	Δρmax = 0.87 e Å^−3
0 restraints	Δρmin = −0.55 e Å^−3
0 constraints

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq	Occ. (<1)
Sr	0.25574 (4)	0.71094 (4)	0.22114 (3)	0.0322 (3)
I1	0.08983 (4)	0.70739 (4)	0.27557 (3)	0.0572 (3)
I2	0.43301 (4)	0.72360 (4)	0.17645 (3)	0.0670 (3)
O1A	0.3664 (4)	0.5844 (4)	0.3238 (3)	0.063 (3)
C1A	0.4693 (15)	0.5601 (17)	0.3459 (9)	0.050 (9)	0.50000
C1A'	0.466 (2)	0.592 (2)	0.386 (3)	0.12 (2)	0.50000
C2A	0.516 (2)	0.545 (2)	0.4318 (10)	0.065 (11)	0.50000
C2A'	0.5318 (18)	0.521 (2)	0.397 (2)	0.117 (18)	0.50000
C3A	0.6272 (8)	0.5221 (12)	0.4597 (6)	0.136 (9)
O1B	0.1329 (4)	0.7077 (4)	0.0833 (3)	0.065 (3)
C1B	0.0794 (8)	0.7947 (8)	0.0349 (6)	0.098 (6)
C2B	0.1317 (11)	0.8404 (9)	−0.0006 (6)	0.130 (9)
C3B	0.0923 (9)	0.9478 (10)	−0.0357 (6)	0.130 (8)
N11	0.2080 (4)	0.5016 (4)	0.1783 (3)	0.052 (3)
C12	0.2825 (6)	0.4417 (5)	0.1812 (4)	0.060 (4)
C13	0.2852 (5)	0.3317 (5)	0.1831 (4)	0.056 (4)
C14	0.2060 (5)	0.2747 (5)	0.1799 (4)	0.044 (3)
C15	0.1254 (5)	0.3348 (5)	0.1741 (4)	0.048 (3)
C16	0.1308 (5)	0.4468 (5)	0.1742 (4)	0.049 (4)
N11'	0.2155 (5)	−0.0713 (4)	0.1952 (3)	0.054 (3)
C12'	0.2691 (6)	−0.0164 (6)	0.1724 (5)	0.065 (4)
C13'	0.2678 (6)	0.0945 (5)	0.1667 (4)	0.061 (4)
C14'	0.2064 (5)	0.1550 (5)	0.1844 (4)	0.044 (3)
C15'	0.1513 (5)	0.0981 (5)	0.2080 (4)	0.056 (4)
C16'	0.1560 (5)	−0.0134 (5)	0.2124 (4)	0.054 (4)
N21	0.3767 (5)	0.8314 (5)	0.3449 (3)	0.061 (3)
C22	0.4382 (7)	0.9094 (7)	0.3487 (4)	0.078 (5)
C23	0.4865 (6)	0.9767 (6)	0.4074 (4)	0.068 (5)
C24	0.4752 (5)	0.9636 (5)	0.4676 (4)	0.050 (4)
C25	0.4137 (6)	0.8801 (6)	0.4655 (4)	0.065 (4)
C26	0.3681 (6)	0.8175 (6)	0.4046 (4)	0.069 (5)
N31	−0.2884 (5)	0.8975 (5)	0.1497 (3)	0.060 (3)
C32	−0.2033 (6)	0.9039 (6)	0.1471 (4)	0.059 (4)
C33	−0.1659 (5)	0.8204 (6)	0.1243 (4)	0.051 (4)
C34	−0.2161 (5)	0.7234 (5)	0.1022 (4)	0.050 (4)
C35	−0.3019 (6)	0.7164 (5)	0.1077 (5)	0.066 (4)
C36	−0.3354 (6)	0.8037 (7)	0.1310 (5)	0.067 (5)
N31'	−0.1235 (5)	0.4614 (5)	0.0145 (4)	0.072 (4)
C32'	−0.1065 (7)	0.5611 (7)	0.0077 (5)	0.080 (6)
C33'	−0.1337 (7)	0.6479 (6)	0.0358 (5)	0.074 (5)
C34'	−0.1815 (5)	0.6332 (6)	0.0748 (4)	0.052 (4)
C35'	−0.1941 (8)	0.5261 (7)	0.0882 (6)	0.097 (6)
C36'	−0.1624 (9)	0.4454 (7)	0.0574 (6)	0.102 (7)
H1OA	0.32536	0.52518	0.31657	0.07300*
H1AA	0.50145	0.62076	0.33515	0.05600*	0.50000
H1AB	0.47739	0.49859	0.32214	0.05600*	0.50000
H2AA	0.48432	0.48343	0.44326	0.07300*	0.50000
H2AB	0.50619	0.60602	0.45609	0.07300*	0.50000
H3AA	0.65643	0.51010	0.50986	0.18200*	0.50000
H3AB	0.65157	0.58238	0.44786	0.18200*	0.50000
H3AC	0.62970	0.45979	0.43503	0.18200*	0.50000
H1A'A	0.46363	0.59164	0.43272	0.13700*	0.50000
H1A'B	0.49959	0.65847	0.38719	0.13700*	0.50000
H2A'A	0.54456	0.52502	0.35513	0.14500*	0.50000
H2A'B	0.50408	0.45037	0.39433	0.14500*	0.50000
H3A'A	0.66288	0.46263	0.45954	0.18200*	0.50000
H3A'B	0.61453	0.51915	0.50082	0.18200*	0.50000
H3A'C	0.65535	0.58750	0.45898	0.18200*	0.50000
H1OB	0.16484	0.68247	0.05808	0.08000*
H1BA	0.06952	0.84974	0.06218	0.11400*
H1BB	0.01790	0.76810	−0.00100	0.11400*
H2BA	0.12891	0.79051	−0.03600	0.13900*
H2BB	0.20040	0.84893	0.03545	0.13900*
H3BA	0.12968	0.97330	−0.05756	0.15300*
H3BB	0.09648	0.99766	0.00015	0.15300*
H3BC	0.02499	0.93924	−0.07130	0.15300*
H12	0.33815	0.47837	0.18209	0.07500*
H13	0.34166	0.29400	0.18659	0.06700*
H15	0.06798	0.29941	0.16994	0.05900*
H16	0.07653	0.48689	0.17138	0.05900*
H12'	0.31127	−0.05595	0.15889	0.07600*
H13'	0.30960	0.12961	0.15116	0.07200*
H15'	0.10953	0.13604	0.22225	0.06700*
H16'	0.11575	−0.05028	0.22867	0.06100*
H22	0.45022	0.91893	0.30871	0.09200*
H23	0.52834	1.03311	0.40642	0.08000*
H25	0.40294	0.86722	0.50608	0.07500*
H26	0.32693	0.75999	0.40458	0.09100*
H32	−0.16758	0.96930	0.16181	0.06800*
H33	−0.10515	0.82864	0.12379	0.06400*
H35	−0.33902	0.65051	0.09537	0.07600*
H36	−0.39581	0.79613	0.13349	0.08200*
H32'	−0.07265	0.57670	−0.01914	0.09600*
H33'	−0.11907	0.71944	0.02730	0.09100*
H35'	−0.22291	0.50853	0.11867	0.11500*
H36'	−0.17239	0.37279	0.06747	0.11800*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sr	0.0416 (3)	0.0160 (3)	0.0442 (3)	−0.0020 (2)	0.0246 (3)	−0.0019 (2)
I1	0.0597 (3)	0.0462 (3)	0.0834 (4)	0.0015 (2)	0.0484 (3)	0.0033 (3)
I2	0.0749 (4)	0.0499 (3)	0.1055 (5)	−0.0035 (3)	0.0666 (4)	−0.0065 (3)
O1A	0.058 (3)	0.044 (3)	0.075 (4)	−0.005 (2)	0.023 (3)	0.012 (3)
C1A	0.031 (10)	0.068 (12)	0.042 (11)	0.001 (8)	0.011 (9)	0.005 (9)
C1A'	0.10 (2)	0.11 (2)	0.13 (3)	0.032 (17)	0.05 (2)	0.03 (2)
C2A	0.084 (16)	0.076 (13)	0.047 (12)	0.022 (11)	0.042 (12)	0.001 (10)
C2A'	0.057 (16)	0.15 (2)	0.13 (3)	0.007 (15)	0.04 (2)	−0.03 (2)
C3A	0.081 (8)	0.227 (15)	0.088 (8)	0.031 (9)	0.029 (7)	−0.020 (9)
O1B	0.092 (4)	0.043 (3)	0.062 (3)	0.012 (3)	0.038 (3)	0.000 (3)
C1B	0.130 (9)	0.069 (6)	0.084 (7)	−0.008 (6)	0.042 (7)	−0.009 (6)
C2B	0.225 (14)	0.072 (7)	0.111 (9)	−0.022 (8)	0.096 (10)	−0.014 (7)
C3B	0.158 (11)	0.099 (9)	0.123 (10)	−0.004 (8)	0.059 (9)	0.031 (7)
N11	0.066 (4)	0.025 (3)	0.067 (4)	0.002 (3)	0.033 (3)	−0.002 (3)
C12	0.070 (5)	0.033 (4)	0.089 (6)	−0.007 (4)	0.049 (5)	−0.001 (4)
C13	0.065 (5)	0.025 (3)	0.091 (6)	0.003 (3)	0.046 (5)	−0.002 (4)
C14	0.052 (4)	0.023 (3)	0.057 (4)	−0.006 (3)	0.026 (4)	−0.002 (3)
C15	0.053 (4)	0.024 (3)	0.064 (5)	−0.008 (3)	0.027 (4)	−0.008 (3)
C16	0.057 (5)	0.032 (4)	0.059 (5)	0.004 (3)	0.028 (4)	−0.004 (3)
N11'	0.071 (4)	0.027 (3)	0.065 (4)	0.001 (3)	0.035 (3)	−0.004 (3)
C12'	0.083 (6)	0.034 (4)	0.099 (6)	0.002 (4)	0.061 (5)	−0.006 (4)
C13'	0.084 (6)	0.029 (4)	0.093 (6)	0.001 (4)	0.060 (5)	−0.001 (4)
C14'	0.051 (4)	0.028 (3)	0.053 (4)	−0.000 (3)	0.025 (4)	−0.002 (3)
C15'	0.067 (5)	0.030 (4)	0.082 (6)	−0.002 (3)	0.046 (4)	−0.004 (4)
C16'	0.071 (5)	0.028 (4)	0.076 (5)	−0.010 (3)	0.045 (4)	−0.000 (3)
N21	0.076 (4)	0.046 (4)	0.052 (4)	−0.012 (3)	0.024 (3)	−0.006 (3)
C22	0.122 (8)	0.062 (5)	0.057 (5)	−0.035 (5)	0.047 (5)	−0.008 (4)
C23	0.093 (6)	0.051 (5)	0.063 (5)	−0.029 (4)	0.039 (5)	−0.006 (4)
C24	0.050 (4)	0.038 (4)	0.054 (5)	−0.004 (3)	0.019 (4)	0.002 (3)
C25	0.079 (6)	0.059 (5)	0.060 (5)	−0.031 (4)	0.035 (4)	−0.022 (4)
C26	0.085 (6)	0.057 (5)	0.067 (6)	−0.031 (4)	0.038 (5)	−0.016 (4)
N31	0.067 (4)	0.048 (4)	0.072 (4)	−0.002 (3)	0.039 (4)	−0.015 (3)
C32	0.072 (5)	0.045 (4)	0.062 (5)	−0.006 (4)	0.033 (4)	−0.012 (4)
C33	0.055 (4)	0.043 (4)	0.062 (5)	−0.003 (3)	0.033 (4)	−0.009 (3)
C34	0.056 (4)	0.037 (4)	0.067 (5)	−0.001 (3)	0.036 (4)	−0.004 (3)
C35	0.083 (6)	0.035 (4)	0.091 (6)	−0.010 (4)	0.051 (5)	−0.018 (4)
C36	0.069 (5)	0.064 (5)	0.087 (6)	−0.010 (4)	0.053 (5)	−0.018 (5)
N31'	0.099 (5)	0.047 (4)	0.097 (5)	−0.006 (4)	0.069 (5)	−0.014 (4)
C32'	0.113 (7)	0.062 (6)	0.100 (7)	−0.006 (5)	0.080 (6)	−0.015 (5)
C33'	0.106 (7)	0.047 (5)	0.093 (6)	−0.011 (5)	0.068 (6)	−0.012 (4)
C34'	0.064 (5)	0.045 (4)	0.062 (5)	−0.010 (4)	0.041 (4)	−0.010 (4)
C35'	0.155 (9)	0.049 (5)	0.147 (9)	0.004 (6)	0.120 (8)	0.002 (5)
C36'	0.163 (10)	0.046 (5)	0.150 (10)	0.003 (6)	0.117 (9)	−0.001 (6)

Geometric parameters (Å, º)

Sr—I1	3.2530 (11)	C14—C14'	1.485 (8)
Sr—I2	3.2801 (11)	C15—C16	1.389 (9)
Sr—O1A	2.549 (4)	C15—H15	0.952
Sr—O1B	2.592 (4)	C16—H16	0.948
Sr—N11	2.729 (5)	N11'—C12'	1.321 (13)
Sr—N21	2.797 (5)	N11'—C16'	1.339 (12)
Sr—N11'	2.764 (5)	C12'—C13'	1.378 (10)
O1A—C1A	1.45 (2)	C12'—H12'	0.958
O1A—C1A'	1.46 (3)	C13'—C14'	1.388 (13)
O1A—H1OA	0.931	C13'—H13'	0.953
C1A—C2A	1.60 (3)	C14'—C15'	1.364 (13)
C1A—H1AA	0.98	C15'—C16'	1.385 (9)
C1A—H1AB	0.95	C15'—H15'	0.951
C1A'—C2A'	1.28 (5)	C16'—H16'	0.954
C1A'—H1A'A	0.99	N21—C22	1.328 (12)
C1A'—H1A'B	0.97	N21—C26	1.331 (13)
C2A—C3A	1.55 (3)	C22—C23	1.375 (11)
C2A—H2AA	1.00	C22—H22	0.949
C2A—H2AB	0.96	C23—C24	1.363 (14)
C2A'—C3A	1.43 (3)	C23—H23	0.956
C2A'—H2A'A	0.98	C24—C25	1.388 (11)
C2A'—H2A'B	0.96	C24—C24	1.503 (9)
C3A—H3AA	0.938	C25—C26	1.369 (11)
C3A—H3AB	0.922	C25—H25	0.955
C3A—H3AC	0.941	C26—H26	0.953
C3A—H3A'A	0.920	N31—C32	1.336 (13)
C3A—H3A'B	0.970	N31—C36	1.324 (10)
C3A—H3A'C	0.922	C32—C33	1.376 (12)
O1B—C1B	1.440 (10)	C32—H32	0.945
O1B—H1OB	0.930	C33—C34	1.384 (9)
C1B—C2B	1.45 (2)	C33—H33	0.944
C1B—H1BA	0.948	C34—C35	1.380 (14)
C1B—H1BB	0.943	C34—C34'	1.467 (11)
C2B—C3B	1.501 (16)	C35—C36	1.383 (13)
C2B—H2BA	0.951	C35—H35	0.958
C2B—H2BB	0.967	C36—H36	0.959
C3B—H3BA	0.945	N31'—C32'	1.286 (11)
C3B—H3BB	0.952	N31'—C36'	1.311 (18)
C3B—H3BC	0.949	C32'—C33'	1.384 (14)
N11—C12	1.341 (11)	C32'—H32'	0.950
N11—C16	1.333 (10)	C33'—C34'	1.348 (16)
C12—C13	1.364 (9)	C33'—H33'	0.952
C12—H12	0.961	C34'—C35'	1.390 (12)
C13—C14	1.381 (11)	C35'—C36'	1.398 (17)
C13—H13	0.958	C35'—H35'	0.960
C14—C15	1.399 (11)	C36'—H36'	0.954
I1—Sr—I2	176.07 (2)	N11—C12—C13	124.5 (8)
I1—Sr—O1A	90.77 (16)	N11—C12—H12	118.2
I1—Sr—O1B	96.68 (16)	C13—C12—H12	117.3
I1—Sr—N11	88.27 (17)	C12—C13—C14	119.8 (8)
I1—Sr—N21	88.06 (17)	C12—C13—H13	120.2
I1—Sr—N11'	86.74 (17)	C14—C13—H13	120.0
I2—Sr—O1A	87.76 (15)	C13—C14—C15	117.0 (6)
I2—Sr—O1B	86.76 (16)	C13—C14—C14'	122.0 (7)
I2—Sr—N11	94.66 (17)	C15—C14—C14'	121.0 (7)
I2—Sr—N21	88.01 (17)	C14—C15—C16	118.8 (7)
I2—Sr—N11'	92.03 (17)	C14—C15—H15	120.3
O1A—Sr—O1B	140.38 (15)	C16—C15—H15	120.8
O1A—Sr—N11	70.08 (15)	N11—C16—C15	124.0 (7)
O1A—Sr—N21	70.34 (16)	N11—C16—H16	117.7
O1A—Sr—N11'	139.79 (15)	C15—C16—H16	118.3
O1B—Sr—N11	71.32 (15)	C12'—N11'—C16'	116.4 (6)
O1B—Sr—N21	148.43 (16)	C12'—N11'—Sr	117.0 (5)
O1B—Sr—N11'	79.64 (15)	C16'—N11'—Sr	126.0 (5)
N11—Sr—N21	140.18 (16)	N11'—C12'—C13'	124.0 (9)
N11—Sr—N11'	149.72 (15)	N11'—C12'—H12'	118.1
N21—Sr—N11'	69.46 (16)	C13'—C12'—H12'	117.9
Sr—O1A—C1A	125.7 (9)	C12'—C13'—C14'	119.9 (9)
Sr—O1A—C1A'	135.0 (14)	C12'—C13'—H13'	120.1
Sr—O1A—H1OA	102.7	C14'—C13'—H13'	120.0
C1A—O1A—H1OA	116.0	C14—C14'—C13'	120.4 (8)
C1A'—O1A—H1OA	122.1	C14—C14'—C15'	123.7 (8)
O1A—C1A—C2A	102.6 (19)	C13'—C14'—C15'	115.9 (6)
O1A—C1A—H1AA	111.0	C14'—C15'—C16'	121.2 (9)
O1A—C1A—H1AB	113.2	C14'—C15'—H15'	119.2
C2A—C1A—H1AA	110.0	C16'—C15'—H15'	119.6
C2A—C1A—H1AB	113.3	N11'—C16'—C15'	122.6 (9)
H1AA—C1A—H1AB	107	N11'—C16'—H16'	118.8
O1A—C1A'—C2A'	121 (3)	C15'—C16'—H16'	118.6
O1A—C1A'—H1A'A	112	Sr—N21—C22	125.7 (6)
O1A—C1A'—H1A'B	113	Sr—N21—C26	119.0 (5)
C2A'—C1A'—H1A'A	103	C22—N21—C26	115.2 (7)
C2A'—C1A'—H1A'B	102	N21—C22—C23	124.1 (10)
H1A'A—C1A'—H1A'B	104	N21—C22—H22	118.1
C1A—C2A—C3A	106 (2)	C23—C22—H22	117.9
C1A—C2A—H2AA	110.7	C22—C23—C24	120.3 (8)
C1A—C2A—H2AB	114.0	C22—C23—H23	120.3
C3A—C2A—H2AA	110.2	C24—C23—H23	119.4
C3A—C2A—H2AB	111.6	C23—C24—C25	116.5 (7)
H2AA—C2A—H2AB	105	C23—C24—C24	122.2 (7)
C1A'—C2A'—H2A'A	107	C25—C24—C24	121.3 (8)
C1A'—C2A'—H2A'B	108	C24—C25—C26	119.3 (9)
H2A'A—C2A'—H2A'B	106	C24—C25—H25	120.2
C2A—C3A—H3AA	107.9	C26—C25—H25	120.6
C2A—C3A—H3AB	105.5	N21—C26—C25	124.7 (8)
C2A—C3A—H3AC	105.7	N21—C26—H26	117.4
C2A'—C3A—H3A'A	109.7	C25—C26—H26	117.9
C2A'—C3A—H3A'B	106	C32—N31—C36	116.5 (8)
C2A'—C3A—H3A'C	106.0	N31—C32—C33	123.3 (7)
H3AA—C3A—H3AB	11313	N31—C32—H32	117.8
H3AA—C3A—H3AC	111.3	C33—C32—H32	118.9
H3AB—C3A—H3AC	112.8	C32—C33—C34	120.7 (8)
H3A'A—C3A—H3A'B	110.2	C32—C33—H33	120.2
H3A'A—C3A—H3A'C	114.7	C34—C33—H33	119.1
H3A'B—C3A—H3A'C	110.1	C33—C34—C35	115.4 (7)
Sr—O1B—C1B	129.9 (5)	C33—C34—C34'	123.0 (8)
Sr—O1B—H1OB	109.8	C35—C34—C34'	121.6 (6)
C1B—O1B—H1OB	97.4	C34—C35—C36	120.7 (7)
O1B—C1B—C2B	112.7 (10)	C34—C35—H35	119.9
O1B—C1B—H1BA	108.3	C36—C35—H35	119.3
O1B—C1B—H1BB	108.6	N31—C36—C35	123.3 (9)
C2B—C1B—H1BA	108.5	N31—C36—H36	118.4
C2B—C1B—H1BB	108.5	C35—C36—H36	118.3
H1BA—C1B—H1BB	110.2	C32'—N31'—C36'	113.9 (9)
C1B—C2B—C3B	113.9 (13)	N31'—C32'—C33'	125.5 (12)
C1B—C2B—H2BA	108.5	N31'—C32'—H32'	117.3
C1B—C2B—H2BB	107.8	C33'—C32'—H32'	117.2
C3B—C2B—H2BA	109.7	C32'—C33'—C34'	121.1 (8)
C3B—C2B—H2BB	108.8	C32'—C33'—H33'	119.8
H2BA—C2B—H2BB	108.0	C34'—C33'—H33'	119.1
C2B—C3B—H3BA	109.7	C34—C34'—C33'	122.7 (7)
C2B—C3B—H3BB	109.2	C34—C34'—C35'	122.5 (10)
C2B—C3B—H3BC	108.7	C33'—C34'—C35'	114.9 (9)
H3BA—C3B—H3BB	109.8	C34'—C35'—C36'	118.5 (12)
H3BA—C3B—H3BC	110.0	C34'—C35'—H35'	120.3
H3BB—C3B—H3BC	109.4	C36'—C35'—H35'	121.2
Sr—N11—C12	114.9 (4)	N31'—C36'—C35'	125.7 (9)
Sr—N11—C16	126.7 (5)	N31'—C36'—H36'	117.9
C12—N11—C16	115.8 (6)	C35'—C36'—H36'	116.4