Bis[[mu]-6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionato-[kappa]³O⁴,N⁵:O⁵]-di-[mu]-aqua-bis{diaqua[6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionato-[kappa]²N¹,O²]strontium(II)}: centrosymmetric dimers containing nine-coordinate Sr, linked by multiple hydrogen bonds into a three-dimensional framework

The title complex, [Sr₂(C₅H₅N₄O₃)₄(H₂O)₆], forms centrosymmetric dimers in which one water ligand bridges two Sr centres and in which one of the anionic ligands is bidentate and bonded to just one Sr atom, and the other is tridentate and bridges the two Sr centres within the dimer. The dimeric units are linked by an extensive series of O-H...O, O-H...N and N-H...O hydrogen bonds to form a complex three-dimensional framework.

S1. Comment

We recently reported the structure, at 150 K, of the dihydrated sodium salt derived from 6-amino-3-methyl-5-nitrosopyrimidine, (I) (Cuesta et al., 2001). In that salt, the Na cations and (C₅H₄N₄O₃)⁻ anions, L, (II), form a one-dimensional coordination polymer in the form of a molecular ladder, and the ladders are linked into a continuous three-dimensional framework by a combination of O—H···O and O—H···N hydrogen bonds. Within the ladder, the anion utilizes one amidic O atom and the nitroso N atom to coordinate to a single Na atom, while the other amidic O atom bridges a pair of cations, forming a centrosymmetric Na₂O₂ ring. \sch

Extending our earlier study to a salt of a dication, we have now investigated the title strontium salt, (III). While the stoichiometry of (III) is apparently simple, Sr(L)₂·3H₂O, the two anionic ligands adopt entirely different coordination modes and, while one water molecule acts as a bridging ligand between two metal centres, the other two are bonded simply to one metal.

The structures of the two anionic components in (III) are similar, but not identical. Each adopts the usual planar conformation, with the nitroso group trans to the amidic atoms On4 (n = 1 or 2 throughout), and each forms an intramolecular N—H···O hydrogen bond with the nitroso On5 atom as acceptor (Fig. 1). The bond distances (Table 1) show a number of metrical features characteristic of 5-nitrosopyrimidines. In particular, the Cn4—Cn5 and Cn5—Cn6 distances are similar, the difference between the Cn5—Nn5 and Nn5—On5 distances does not exceed 0.05 Å, and the Cn6—Nn6 bonds are very short for a single C—N bond between triply connected atoms of these types (Allen et al., 1987). The C—O distances are all typical of those in neutral amides (Allen et al., 1987) and these observations, taken all together, indicate that the delocalized polarized form (IIa) is a significantly better representation of the anions than the localized form, (II).

The coordination complex of (III) (Fig. 1) takes the form of a centrosymmetric dimer, located for the sake of convenience across the inversion centre at (1/2,1/2,1/2). The anion of type 1 (with n = 1 in the atom labels) at (x, y, z) forms a bridge between the two Sr centres at (x, y, z) and (1 − x, 1 − y, 1 − z), with the amidic O14 and nitroso N15 atoms coordinated to the Sr atom at (x, y, z) and the nitroso O15 atom bonded to the Sr atom at (1 − x, 1 − y, 1 − z). By contrast, the type 2 anion (with n = 2 in the atom labels) is bonded to a single Sr atom, via the amidic O22 and N21 atoms of the pyrimidine ring.

Effectively orthogonal to the (SrNO)₂ ring is an Sr₂O₂ ring, in which water atom O1 acts as a bridging ligand between two Sr centres. The irregular nine-coordination around the Sr is completed by two water molecules, each bonded to just one Sr atom. We have previously observed examples of metal complexes of substituted 5-nitrosopyrimidines in which the nitroso group acts as an η¹ ligand, via O, to Na (Low, Moreno Sánchez et al., 2001), K (Low, Arranz et al., 2001) and Sr (Glidewell et al., 2002), as an η¹ ligand, via N, to Na (Cuesta et al., 2001), and as an η² ligand binding to a single K centre via both N and O (Low, Moreno Sánchez et al., 2001), but no previous examples of this ligand adopting a µ bridging action have been observed. In contrast to the metal-bridging action of the nitroso group of the type 1 ligand, the nitroso group in the type 2 ligand plays no role in the metal-ligand bonding, although both atoms N25 and O25 act as acceptors of hydrogen bonds (Table 2).

In addition to the N—H···O hydrogen bonds within each anionic ligand of (III), there is a third N—H···O hydrogen bond within the dimeric complex (Fig. 1, Table 2). Amino atom N26 in the type 2 anion acts as a hydrogen-bond donor, via atom H26A, to amidic atom O14 in the type 1 anion. This then leaves within the dimer one amino N—H bond and six distinct water O—H bonds, each duplicated by inversion, all of which act as hydrogen-bond donors to acceptors in other dimer units, so linking these units into a single three-dimensional framework. The number of distinct hydrogen bonds leads to some complexity in the framework structure, but the formation of the framework is readily described in terms of a small number of one-dimensional substructures, each in the form of a chain of rings, such that the combination of these substructures necessarily leads to a single framework structure.

The simplest of the hydrogen-bonded substructures in (III) is that running parallel to the [001] direction. Water atom O3 at (x, y, z), which forms part of the complex centred at (1/2,1/2,1/2), acts as a hydrogen-bond donor, via atom H3A, to nitroso atom N25 at (1 − x, 1 − y, 2 − z), which lies in the dimer centred at (1/2,1/2, 3/2), so forming an R₂²(14) ring centred at (1/2,1/2,1) (Fig. 2). Propagation of this hydrogen bond by inversion thus generates a chain of spiro-fused rings along [001].

Three hydrogen bonds are involved in chain formation along [010]. Water atoms O1 and O2 at (x, y, z) both act as hydrogen-bond donors, via atoms H1B and H2A, respectively, to amidic atom O12 at (x, y − 1, z), which lies in the dimer centred at (1/2,-1/2,1/2). At the same time, the water atom O3 at (x, y, z) acts as a hydrogen-bond donor, via atom H3A, to pyrimidine atom N11 at (1 − x, 3 − y, 1 − z), which lies in the dimer centred at (1/2,3/2,1/2). Together, these interactions generate a complex chain along [010] (Fig. 3), which consists, in effect, of cages fused along the Sr···Sr vector. The combination of the [010] and [001] chains generates a (100) sheet and this is reinforced by the single inter-dimer N—H···O hydrogen bond.

Amino atom N16 at (x, y, z) acts as a hydrogen-bond donor, via atom H16A, to amidic atom O24 at (x, 1 + y, z − 1), so generating by translation a C(11) chain running parallel to the [011] direction. Propagation of this hydrogen bond by translation and inversion generates a chain of edge-fused rings, in which the (SrNO)₂ rings alternate with hydrogen-bonded R₂²(24) rings (Fig. 4). Alternatively, this substructure can be regarded as a molecular ladder, in which a pair of antiparallel C(11) chains form the uprights, while the (SrNO)₂ rings form the rungs.

Two further O—H···O hydrogen bonds generate chains running parallel to the [110] and [101] directions. Water atom O1 at (x, y, z), part of the dimer centred at (1/2,1/2,1/2), acts as a hydrogen-bond donor, via atom H1A, to amidic atom O12 at (-x, 2 − y, 1 − z), which lies in the dimer centred at (−1/2,3/2,1/2). Propagation of this hydrogen bond generates a chain of edge-fused rings along [110], in which Sr₂O₂ rings alternate with hydrogen-bonded R₂²(16) rings (Fig. 5). Finally, water atom O2 at (x, y, z) acts as a donor, via atom H2B, to nitroso atom O25 at (-x, 1 − y, 2 − z), which lies in the dimer centred at (−1/2,1/2,3/2), and propagation of this hydrogen bond generates a chain of spiro-fused rings along [101], in which Sr₂O₂ rings alternate with hydrogen-bonded R₂²(16) rings (Fig. 6). The combination of the [010] and [001] chains with either of the [110] or [101] chains is itself sufficient to generate a single three-dimensional framework.

S2. Experimental

Potassium 6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionate was prepared by the addition of water (20 mmol) to a suspension of 6-amino-3,4-dihydro-3-methyl-2-methoxy-5-nitroso-4-oxopyrimidine (20 mmol) and potassium hydroxide (20 mmol) in methanol (50 ml). The product was filtered off and recrystallized once from water. Analysis, found: C 28.6, H 2.5, N 26.6%; C₅H₅KN₄O₃ requires: C 28.8, H 2.4, N 26.9%. The title strontium complex, (III), was obtained by adding strontium chloride hexahydrate (1 mmol) to a solution of the potassium salt (2 mmol) in water (40 ml). The orange product was filtered off, and washed with cold water and then ethanol. Analysis, found: C 24.3, H 3.4, N 21.9%; C₂₀H₃₂N₁₆O₁₈Sr₂ requires: C 25.0, H 3.4, N 23.4%. Crystals of (III) suitable for single-crystal X-ray diffraction were grown by slow evaporation of a dilute solution in water.

S3. Refinement

Compound (III) is triclinic; space group P1 was assumed and confirmed by the analysis. H atoms were treated as riding atoms, with C—H distances of 0.98 Å, N—H distances of 0.88 Å and O—H distances in the range 0.84–0.88 Å.

Computing details

Data collection: KappaCCD Server Software (Nonius, 1997); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2002); software used to prepare material for publication: SHELXL97 and PRPKAPPA (Ferguson, 1999).

Figures

	Fig. 1. The centrosymmetric dimer complex in (III), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii. Atoms labelled with the suffix A are at the symmetry position (1 − x, 1 − y, 1 − z).
	Fig. 2. A stereoview of part of the crystal structure of (III), showing the formation of a chain of spiro-fused rings along [001]. For the sake of clarity, the anions of type 1 and the water ligand containing atom O2 have been omitted, as have H atoms bonded to C atoms.
	Fig. 3. A stereoview of part of the crystal structure of (III), showing the formation of a chain along [010]. For the sake of clarity, the anions of type 2 have been omitted, as have H atoms bonded to C atoms.
	Fig. 4. Part of the crystal structure of (III), showing the formation of a chain of edge-fused rings along [011]. For the sake of clarity, the unit-cell box and the water molecules have been omitted, as have H atoms bonded to C atoms. The atoms marked with an asterisk (*), hash (#), dollar sign (add), ampersand (add) or plus sign (+) are at the symmetry positions (1 − x, 1 − y, 1 − z), (1 − x, 2 − y, −z), (x, 1 + x, z − 1), (x, y − 1, 1 + z) and (1 − x, −y, 2 − z), respectively.
	Fig. 5. A stereoview of part of the crystal structure of (III), showing the formation of a chain of edge-fused rings along [110]. For the sake of clarity, the anions of type 2 and the water ligands containing atoms O2 and O3 have been omitted, as have H atoms bonded to C atoms.
	Fig. 6. A stereoview of part of the crystal structure of (III), showing the formation of a chain of spiro-fused rings along [101]. For the sake of clarity, the anions of type 1 and the water ligands containing atom O3 have been omitted, as have H atoms bonded to C atoms.

Di-µ-aqua-bis[µ-6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dionato- κ³O⁴,N⁵:O⁵]bis{diaqua[6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)- dionato-κ²N¹,O²]strontium(II)}

Crystal data

[Sr2(C5H5N4O3)4(H2O)6]	Z = 1
Mr = 959.86	F(000) = 484
Triclinic, P1	Dx = 1.843 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 6.9388 (2) Å	Cell parameters from 3883 reflections
b = 9.8852 (2) Å	θ = 3.1–27.5°
c = 14.1962 (4) Å	µ = 3.19 mm^−1
α = 69.965 (2)°	T = 120 K
β = 77.518 (2)°	Block, orange
γ = 72.361 (2)°	0.30 × 0.28 × 0.25 mm
V = 864.91 (4) Å^3

Data collection

Nonius KappaCCD area-detector diffractometer	3883 independent reflections
Radiation source: rotating anode	3540 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.031
ϕ scans, and ω scans with κ offsets	θmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan (DENZO-SMN; Otwinowski & Minor, 1997)	h = −8→8
Tmin = 0.391, Tmax = 0.449	k = −12→12
12233 measured reflections	l = −17→18

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)] = 0.028	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.068	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.0297P)^2 + 0.7547P] where P = (Fo^2 + 2Fc^2)/3
3883 reflections	(Δ/σ)max = 0.001
255 parameters	Δρmax = 0.55 e Å^−3
0 restraints	Δρmin = −0.68 e Å^−3

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

	x	y	z	Uiso*/Ueq
Sr1	0.43236 (3)	0.49004 (2)	0.653983 (13)	0.01341 (7)
N11	0.2042 (3)	1.15434 (19)	0.46487 (13)	0.0156 (4)
C12	0.1240 (3)	1.1452 (2)	0.56136 (16)	0.0140 (4)
O12	0.0509 (2)	1.26071 (16)	0.58784 (11)	0.0180 (3)
C13	0.0286 (4)	1.0049 (3)	0.73956 (16)	0.0207 (5)
N13	0.1185 (3)	1.00806 (19)	0.63491 (13)	0.0139 (4)
C14	0.2039 (3)	0.8740 (2)	0.61425 (16)	0.0139 (4)
O14	0.2000 (2)	0.75540 (16)	0.68092 (11)	0.0179 (3)
C15	0.2947 (3)	0.8840 (2)	0.51022 (15)	0.0137 (4)
N15	0.3788 (3)	0.7529 (2)	0.49340 (13)	0.0154 (4)
O15	0.4562 (2)	0.75189 (17)	0.40238 (11)	0.0188 (3)
C16	0.2895 (3)	1.0292 (2)	0.43806 (16)	0.0138 (4)
N16	0.3733 (3)	1.0400 (2)	0.34377 (13)	0.0196 (4)
N21	0.3883 (3)	0.4442 (2)	0.85286 (13)	0.0160 (4)
C22	0.5225 (3)	0.3079 (2)	0.87216 (16)	0.0156 (4)
O22	0.6188 (2)	0.25973 (17)	0.80200 (11)	0.0205 (3)
N23	0.5503 (3)	0.2212 (2)	0.97231 (13)	0.0176 (4)
C23	0.7056 (4)	0.0792 (3)	0.98704 (19)	0.0288 (6)
C24	0.4477 (3)	0.2668 (3)	1.05545 (16)	0.0183 (4)
O24	0.4756 (3)	0.18474 (19)	1.14169 (12)	0.0267 (4)
C25	0.3096 (3)	0.4159 (2)	1.03339 (15)	0.0160 (4)
N25	0.2204 (3)	0.4634 (2)	1.11311 (14)	0.0194 (4)
O25	0.0970 (2)	0.59502 (18)	1.09777 (12)	0.0227 (4)
C26	0.2885 (3)	0.4987 (2)	0.92849 (16)	0.0141 (4)
N26	0.1678 (3)	0.6350 (2)	0.90426 (14)	0.0181 (4)
O1	0.2560 (2)	0.50204 (16)	0.49907 (11)	0.0166 (3)
O2	0.1462 (3)	0.3612 (2)	0.73356 (12)	0.0259 (4)
O3	0.6852 (3)	0.60167 (19)	0.68631 (12)	0.0256 (4)
H13A	−0.0481	0.9283	0.7676	0.031*
H13B	−0.0634	1.1021	0.7398	0.031*
H13C	0.1375	0.9822	0.7807	0.031*
H16A	0.3726	1.1281	0.2997	0.024*
H16B	0.4298	0.9592	0.3250	0.024*
H23A	0.6917	0.0267	0.9425	0.043*
H23B	0.6871	0.0181	1.0575	0.043*
H23C	0.8415	0.0980	0.9709	0.043*
H26A	0.1564	0.6854	0.8404	0.022*
H26B	0.0992	0.6751	0.9521	0.022*
H1A	0.1606	0.5754	0.4768	0.020*
H1B	0.2039	0.4292	0.5177	0.020*
H2A	0.0812	0.3341	0.6991	0.031*
H2B	0.0593	0.3733	0.7870	0.031*
H3A	0.7298	0.5945	0.7418	0.031*
H3B	0.7591	0.6549	0.6379	0.031*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Sr1	0.01849 (11)	0.01170 (11)	0.00886 (11)	−0.00230 (7)	−0.00038 (7)	−0.00369 (7)
N11	0.0197 (9)	0.0122 (9)	0.0135 (9)	−0.0037 (7)	−0.0005 (7)	−0.0030 (7)
C12	0.0155 (10)	0.0115 (10)	0.0148 (10)	−0.0017 (8)	−0.0044 (8)	−0.0036 (8)
O12	0.0236 (8)	0.0126 (7)	0.0171 (8)	−0.0011 (6)	−0.0027 (6)	−0.0065 (6)
C13	0.0270 (12)	0.0199 (11)	0.0118 (10)	−0.0014 (9)	0.0027 (9)	−0.0075 (8)
N13	0.0175 (9)	0.0101 (8)	0.0117 (8)	−0.0005 (7)	−0.0005 (7)	−0.0039 (7)
C14	0.0148 (10)	0.0122 (10)	0.0148 (10)	−0.0012 (8)	−0.0034 (8)	−0.0050 (8)
O14	0.0262 (8)	0.0118 (7)	0.0118 (7)	−0.0024 (6)	0.0000 (6)	−0.0022 (6)
C15	0.0165 (10)	0.0123 (10)	0.0115 (10)	−0.0028 (8)	−0.0020 (8)	−0.0032 (8)
N15	0.0186 (9)	0.0153 (9)	0.0115 (9)	−0.0029 (7)	−0.0002 (7)	−0.0052 (7)
O15	0.0265 (8)	0.0159 (8)	0.0116 (7)	−0.0024 (6)	0.0016 (6)	−0.0060 (6)
C16	0.0139 (9)	0.0129 (10)	0.0142 (10)	−0.0035 (8)	−0.0017 (8)	−0.0035 (8)
N16	0.0284 (10)	0.0124 (9)	0.0131 (9)	−0.0029 (8)	0.0017 (8)	−0.0023 (7)
N21	0.0194 (9)	0.0150 (9)	0.0128 (9)	−0.0032 (7)	−0.0023 (7)	−0.0042 (7)
C22	0.0178 (10)	0.0158 (10)	0.0127 (10)	−0.0043 (8)	−0.0023 (8)	−0.0033 (8)
O22	0.0234 (8)	0.0205 (8)	0.0139 (8)	0.0010 (6)	−0.0006 (6)	−0.0071 (6)
N23	0.0213 (9)	0.0156 (9)	0.0112 (9)	−0.0010 (7)	−0.0034 (7)	−0.0005 (7)
C23	0.0315 (13)	0.0209 (12)	0.0242 (13)	0.0039 (10)	−0.0064 (11)	−0.0021 (10)
C24	0.0216 (11)	0.0208 (11)	0.0129 (10)	−0.0087 (9)	−0.0018 (9)	−0.0029 (8)
O24	0.0351 (10)	0.0264 (9)	0.0121 (8)	−0.0062 (8)	−0.0029 (7)	0.0009 (7)
C25	0.0174 (10)	0.0203 (11)	0.0099 (10)	−0.0083 (9)	0.0010 (8)	−0.0027 (8)
N25	0.0224 (9)	0.0231 (10)	0.0148 (9)	−0.0104 (8)	0.0015 (8)	−0.0066 (8)
O25	0.0259 (8)	0.0259 (9)	0.0176 (8)	−0.0078 (7)	0.0029 (7)	−0.0102 (7)
C26	0.0114 (9)	0.0174 (10)	0.0176 (10)	−0.0073 (8)	0.0012 (8)	−0.0087 (8)
N26	0.0236 (9)	0.0174 (9)	0.0110 (9)	−0.0016 (8)	−0.0004 (7)	−0.0056 (7)
O1	0.0189 (7)	0.0130 (7)	0.0163 (8)	−0.0024 (6)	−0.0028 (6)	−0.0033 (6)
O2	0.0284 (9)	0.0418 (11)	0.0172 (8)	−0.0193 (8)	0.0081 (7)	−0.0181 (7)
O3	0.0384 (10)	0.0300 (9)	0.0131 (8)	−0.0210 (8)	−0.0033 (7)	−0.0012 (7)

Geometric parameters (Å, º)

N11—C12	1.345 (3)	C24—C25	1.465 (3)
C12—N13	1.405 (3)	C25—C26	1.447 (3)
N13—C14	1.382 (3)	C26—N21	1.331 (3)
C14—C15	1.457 (3)	C22—O22	1.229 (3)
C15—C16	1.445 (3)	N23—C23	1.468 (3)
C16—N11	1.344 (3)	C24—O24	1.233 (3)
C12—O12	1.250 (2)	C25—N25	1.330 (3)
C13—N13	1.475 (3)	N25—O25	1.298 (2)
C14—O14	1.232 (3)	C26—N26	1.326 (3)
C15—N15	1.330 (3)	C23—H23A	0.98
N15—O15	1.290 (2)	C23—H23B	0.98
C16—N16	1.321 (3)	C23—H23C	0.98
C13—H13A	0.98	N26—H26A	0.88
C13—H13B	0.98	N26—H26B	0.88
C13—H13C	0.98	Sr1—O1	2.6916 (15)
N16—H16A	0.88	Sr1—O1^i	2.7127 (15)
N16—H16B	0.88	Sr1—O2	2.5331 (16)
Sr1—O14	2.7357 (15)	Sr1—O3	2.5250 (16)
Sr1—N15	2.7946 (18)	Sr1—Sr1^i	4.2169 (4)
Sr1—O15^i	2.6231 (15)	O1—H1A	0.84
Sr1—N21	2.6654 (17)	O1—H1B	0.84
Sr1—O22	2.7175 (15)	O2—H2A	0.88
N21—C22	1.362 (3)	O2—H2B	0.88
C22—N23	1.406 (3)	O3—H3A	0.88
N23—C24	1.382 (3)	O3—H3B	0.88
O3—Sr1—O2	145.21 (5)	N15—C15—C16	127.06 (19)
O3—Sr1—O15^i	122.60 (5)	N15—C15—C14	114.06 (18)
O2—Sr1—O15^i	75.15 (5)	C16—C15—C14	118.87 (18)
O3—Sr1—N21	73.13 (5)	O15—N15—C15	118.02 (17)
O2—Sr1—N21	72.14 (5)	O15—N15—Sr1	120.69 (12)
O15^i—Sr1—N21	115.05 (5)	C15—N15—Sr1	120.79 (13)
O3—Sr1—O1	139.14 (5)	N15—O15—Sr1^i	122.83 (12)
O2—Sr1—O1	74.30 (5)	O15^i—Sr1—N15	113.82 (5)
O15^i—Sr1—O1	64.33 (5)	O1—Sr1—O1^i	77.43 (5)
N21—Sr1—O1	145.00 (5)	N16—C16—N11	118.87 (19)
O3—Sr1—O1^i	71.00 (5)	N16—C16—C15	119.54 (19)
O2—Sr1—O1^i	140.35 (5)	N11—C16—C15	121.58 (19)
O15^i—Sr1—O1^i	67.74 (5)	C16—N16—H16A	120.0
N21—Sr1—O1^i	136.66 (5)	C16—N16—H16B	120.0
O3—Sr1—O22	79.02 (5)	H16A—N16—H16B	120.0
O2—Sr1—O22	80.04 (5)	C26—N21—C22	120.20 (18)
O15^i—Sr1—O22	70.98 (5)	C26—N21—Sr1	144.98 (14)
N21—Sr1—O22	49.29 (5)	C22—N21—Sr1	94.75 (12)
O1—Sr1—O22	132.63 (5)	O22—C22—N21	120.05 (19)
O1^i—Sr1—O22	100.01 (4)	O22—C22—N23	119.72 (19)
O3—Sr1—O14	76.27 (5)	N21—C22—N23	120.22 (18)
O2—Sr1—O14	93.09 (5)	O22—C22—Sr1	60.99 (11)
O15^i—Sr1—O14	159.75 (5)	N21—C22—Sr1	59.21 (10)
N21—Sr1—O14	75.46 (5)	N23—C22—Sr1	175.70 (15)
O1—Sr1—O14	96.89 (4)	C22—O22—Sr1	95.72 (13)
O1^i—Sr1—O14	117.60 (4)	C24—N23—C22	123.39 (18)
O22—Sr1—O14	123.92 (4)	C24—N23—C23	119.40 (18)
O3—Sr1—N15	81.26 (5)	C22—N23—C23	117.12 (18)
O2—Sr1—N15	121.31 (6)	N23—C23—H23A	109.5
N21—Sr1—N15	131.12 (5)	N23—C23—H23B	109.5
O1—Sr1—N15	62.02 (5)	H23A—C23—H23B	109.5
O1^i—Sr1—N15	65.36 (5)	N23—C23—H23C	109.5
O22—Sr1—N15	158.57 (5)	H23A—C23—H23C	109.5
O14—Sr1—N15	58.15 (5)	H23B—C23—H23C	109.5
O3—Sr1—Sr1^i	105.86 (4)	O24—C24—N23	120.5 (2)
O2—Sr1—Sr1^i	108.82 (4)	O24—C24—C25	123.8 (2)
O15^i—Sr1—Sr1^i	58.65 (3)	N23—C24—C25	115.75 (18)
N21—Sr1—Sr1^i	172.21 (4)	N25—C25—C26	126.5 (2)
O1—Sr1—Sr1^i	38.89 (3)	N25—C25—C24	115.74 (18)
O1^i—Sr1—Sr1^i	38.53 (3)	C26—C25—C24	117.76 (18)
O22—Sr1—Sr1^i	122.96 (3)	O25—N25—C25	118.26 (18)
O14—Sr1—Sr1^i	112.00 (3)	N26—C26—N21	117.18 (19)
N15—Sr1—Sr1^i	55.42 (4)	N26—C26—C25	120.22 (19)
C16—N11—C12	119.65 (18)	N21—C26—C25	122.59 (19)
O12—C12—N11	120.14 (19)	C26—N26—H26A	120.0
O12—C12—N13	118.00 (18)	C26—N26—H26B	120.0
N11—C12—N13	121.86 (18)	H26A—N26—H26B	120.0
N13—C13—H13A	109.5	Sr1—O1—Sr1^i	102.57 (5)
N13—C13—H13B	109.5	Sr1—O1—H1A	120.2
H13A—C13—H13B	109.5	Sr1^i—O1—H1A	105.6
N13—C13—H13C	109.5	Sr1—O1—H1B	107.7
H13A—C13—H13C	109.5	Sr1^i—O1—H1B	117.6
H13B—C13—H13C	109.5	H1A—O1—H1B	104.0
C14—N13—C12	122.33 (17)	Sr1—O2—H2A	123.5
C14—N13—C13	118.11 (17)	Sr1—O2—H2B	125.9
C12—N13—C13	119.48 (17)	H2A—O2—H2B	104.8
O14—C14—N13	120.77 (19)	Sr1—O3—H3A	132.7
O14—C14—C15	123.58 (19)	Sr1—O3—H3B	123.6
N13—C14—C15	115.64 (18)	H3A—O3—H3B	103.5
C14—O14—Sr1	121.33 (13)
C16—N11—C12—O12	177.46 (19)	O15^i—Sr1—N21—C22	26.43 (14)
C16—N11—C12—N13	−2.9 (3)	O1—Sr1—N21—C22	106.88 (14)
O12—C12—N13—C14	−176.89 (18)	O1^i—Sr1—N21—C22	−57.02 (15)
N11—C12—N13—C14	3.4 (3)	O22—Sr1—N21—C22	−2.32 (11)
O12—C12—N13—C13	−0.3 (3)	O14—Sr1—N21—C22	−172.00 (13)
N11—C12—N13—C13	−179.96 (19)	N15—Sr1—N21—C22	−153.85 (12)
C12—N13—C14—O14	178.57 (19)	C26—N21—C22—O22	−177.85 (19)
C13—N13—C14—O14	1.9 (3)	Sr1—N21—C22—O22	4.5 (2)
C12—N13—C14—C15	−1.9 (3)	C26—N21—C22—N23	2.6 (3)
C13—N13—C14—C15	−178.56 (18)	Sr1—N21—C22—N23	−175.05 (17)
N13—C14—O14—Sr1	−167.30 (14)	C26—N21—C22—Sr1	177.6 (2)
C15—C14—O14—Sr1	13.2 (3)	O3—Sr1—C22—O22	−95.09 (13)
O3—Sr1—O14—C14	75.99 (16)	O2—Sr1—C22—O22	102.35 (14)
O2—Sr1—O14—C14	−137.55 (16)	O15^i—Sr1—C22—O22	28.24 (13)
O15^i—Sr1—O14—C14	−84.1 (2)	N21—Sr1—C22—O22	−175.5 (2)
N21—Sr1—O14—C14	151.80 (17)	O1—Sr1—C22—O22	73.52 (16)
O1—Sr1—O14—C14	−63.00 (16)	O1^i—Sr1—C22—O22	−36.86 (15)
O1^i—Sr1—O14—C14	16.38 (17)	O14—Sr1—C22—O22	−167.66 (13)
O22—Sr1—O14—C14	142.38 (15)	N15—Sr1—C22—O22	−129.39 (14)
N15—Sr1—O14—C14	−12.16 (15)	Sr1^i—Sr1—C22—O22	2.39 (17)
C22—Sr1—O14—C14	148.23 (16)	O3—Sr1—C22—N21	80.45 (13)
Sr1^i—Sr1—O14—C14	−25.82 (16)	O2—Sr1—C22—N21	−82.10 (13)
O14—C14—C15—N15	−1.6 (3)	O15^i—Sr1—C22—N21	−156.21 (13)
N13—C14—C15—N15	178.84 (17)	O1—Sr1—C22—N21	−110.94 (13)
O14—C14—C15—C16	179.61 (19)	O1^i—Sr1—C22—N21	138.68 (12)
N13—C14—C15—C16	0.1 (3)	O22—Sr1—C22—N21	175.5 (2)
C16—C15—N15—O15	−3.8 (3)	O14—Sr1—C22—N21	7.89 (13)
C14—C15—N15—O15	177.59 (17)	N15—Sr1—C22—N21	46.16 (19)
C16—C15—N15—Sr1	168.21 (16)	Sr1^i—Sr1—C22—N21	177.93 (9)
C14—C15—N15—Sr1	−10.4 (2)	N21—C22—O22—Sr1	−4.4 (2)
O3—Sr1—N15—O15	103.93 (15)	N23—C22—O22—Sr1	175.13 (17)
O2—Sr1—N15—O15	−104.54 (14)	O3—Sr1—O22—C22	79.69 (13)
O15^i—Sr1—N15—O15	−17.94 (18)	O2—Sr1—O22—C22	−72.37 (13)
N21—Sr1—N15—O15	162.34 (13)	O15^i—Sr1—O22—C22	−149.98 (14)
O1—Sr1—N15—O15	−57.52 (14)	N21—Sr1—O22—C22	2.58 (12)
O1^i—Sr1—N15—O15	30.90 (13)	O1—Sr1—O22—C22	−130.02 (13)
O22—Sr1—N15—O15	80.7 (2)	O1^i—Sr1—O22—C22	147.91 (13)
O14—Sr1—N15—O15	−176.86 (16)	O14—Sr1—O22—C22	14.63 (15)
C22—Sr1—N15—O15	137.49 (14)	N15—Sr1—O22—C22	103.08 (17)
Sr1^i—Sr1—N15—O15	−12.29 (12)	Sr1^i—Sr1—O22—C22	−178.42 (12)
O3—Sr1—N15—C15	−67.86 (15)	O22—C22—N23—C24	−179.8 (2)
O2—Sr1—N15—C15	83.68 (16)	N21—C22—N23—C24	−0.3 (3)
O15^i—Sr1—N15—C15	170.28 (14)	O22—C22—N23—C23	3.7 (3)
N21—Sr1—N15—C15	−9.45 (18)	N21—C22—N23—C23	−176.7 (2)
O1—Sr1—N15—C15	130.69 (16)	C22—N23—C24—O24	178.6 (2)
O1^i—Sr1—N15—C15	−140.89 (17)	C23—N23—C24—O24	−5.0 (3)
O22—Sr1—N15—C15	−91.08 (19)	C22—N23—C24—C25	−1.9 (3)
O14—Sr1—N15—C15	11.35 (14)	C23—N23—C24—C25	174.4 (2)
C22—Sr1—N15—C15	−34.3 (2)	O24—C24—C25—N25	3.4 (3)
Sr1^i—Sr1—N15—C15	175.92 (17)	N23—C24—C25—N25	−176.05 (19)
C15—N15—O15—Sr1^i	−168.40 (14)	O24—C24—C25—C26	−178.7 (2)
Sr1—N15—O15—Sr1^i	19.59 (19)	N23—C24—C25—C26	1.9 (3)
C12—N11—C16—N16	−177.85 (19)	C26—C25—N25—O25	2.1 (3)
C12—N11—C16—C15	1.0 (3)	C24—C25—N25—O25	179.80 (18)
N15—C15—C16—N16	0.6 (3)	C22—N21—C26—N26	176.74 (19)
C14—C15—C16—N16	179.21 (19)	Sr1—N21—C26—N26	−7.4 (3)
N15—C15—C16—N11	−178.2 (2)	C22—N21—C26—C25	−2.6 (3)
C14—C15—C16—N11	0.4 (3)	Sr1—N21—C26—C25	173.33 (17)
O3—Sr1—N21—C26	91.3 (2)	N25—C25—C26—N26	−1.3 (3)
O2—Sr1—N21—C26	−86.6 (2)	C24—C25—C26—N26	−179.02 (19)
O15^i—Sr1—N21—C26	−150.0 (2)	N25—C25—C26—N21	178.0 (2)
O1—Sr1—N21—C26	−69.6 (3)	C24—C25—C26—N21	0.3 (3)
O1^i—Sr1—N21—C26	126.5 (2)	O3—Sr1—O1—Sr1^i	39.85 (9)
O22—Sr1—N21—C26	−178.8 (3)	O2—Sr1—O1—Sr1^i	−151.90 (6)
O14—Sr1—N21—C26	11.5 (2)	O15^i—Sr1—O1—Sr1^i	−71.12 (5)
N15—Sr1—N21—C26	29.7 (3)	N21—Sr1—O1—Sr1^i	−168.75 (7)
C22—Sr1—N21—C26	−176.5 (3)	O22—Sr1—O1—Sr1^i	−92.10 (7)
O3—Sr1—N21—C22	−92.23 (13)	O14—Sr1—O1—Sr1^i	116.81 (5)
O2—Sr1—N21—C22	89.83 (13)	N15—Sr1—O1—Sr1^i	68.58 (5)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N16—H16A···O24^ii	0.88	2.13	2.776 (3)	129
N16—H16B···O15	0.88	1.94	2.594 (3)	130
N26—H26A···O14	0.88	2.11	2.964 (3)	164
N26—H26B···O25	0.88	1.94	2.595 (3)	130
O1—H1A···O12^iii	0.84	1.94	2.772 (2)	174
O1—H1B···O12^iv	0.84	2.09	2.920 (2)	169
O2—H2A···O12^iv	0.88	2.02	2.846 (2)	156
O2—H2B···O25^v	0.88	1.82	2.700 (2)	173
O3—H3A···N25^vi	0.88	2.02	2.871 (3)	163
O3—H3B···N11^vii	0.88	2.00	2.806 (3)	152

Symmetry codes: (ii) x, y+1, z−1; (iii) −x, −y+2, −z+1; (iv) x, y−1, z; (v) −x, −y+1, −z+2; (vi) −x+1, −y+1, −z+2; (vii) −x+1, −y+2, −z+1.