pH-induced phase transition and crystallization of soft-oxometalates (SOMs) into polyoxometalates (POMs): a study on crystallization from colloids

In this work, we demonstrate a simple approach for growing 1D (one-dimensional) inorganic chains of K(C₆H₁₆N)₃Mo₈O₂₆·H₂O polyoxometalates (POMs) from its colloidal soft-oxometalate (SOM) phase through the variation of pH. The structure is composed mainly of a 1D inorganic chain with a β-Mo₈O₂₆⁴⁻ binding node linked using K⁺ via Mo—O—K linkages, which results in a cubocta­hedral geometry for the K⁺ ions. Crystal structure and Hirshfeld surface studies reveal the role of tri­ethyl­ammonium cations in restricting the growth of the 1D chain into 2D/3D (two-/three-dimensional) structures. During the nucleation process from the heterogeneous SOM phase, some of the inter­molecular inter­actions in the dispersion phase are retained in the crystal structure, which was evidenced from residual O...O inter­actions. The crystallization of the species from its colloidal form as a function of pH was studied by the use of Raman spectroscopy and it was found that the increase in volume fraction of the β-Mo₈O₂₆⁴⁻ species in the crystallizing colloidal mixture with the decrease in pH is responsible for the nucleation. This was monitored by time-dependent DLS (dynamic light scattering) measurement and zeta-potential studies, revealing the co-existence of both the crystal and the colloidal forms at pH 3–2. This brings us to the conclusion that in the crystallization of POMs, the colloidal SOM phase precedes the crystalline POM phase which occurs via a phase transition. This work could open up avenues for the study of POM formation from the stand-point of colloidal chemistry and SOMs.

Computing details

Data collection: CrysAlis PRO (Rigaku OD, 2015); cell refinement: CrysAlis PRO (Rigaku OD, 2015); data reduction: CrysAlis PRO (Rigaku OD, 2015); program(s) used to solve structure: SHELXT2014 (Sheldrick, 2015a); program(s) used to refine structure: SHELXL2016 (Sheldrick, 2015b); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

Tris(triethylaminium) hemi(dopentacontaoxidopotassiohexadecamolybdate) monohydrate

Crystal data

(C6H16N)3[K2Mo16O52]0.5·H2O	F(000) = 3000
Mr = 1547.23	Dx = 2.413 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 25.1247 (8) Å	Cell parameters from 8571 reflections
b = 10.7583 (3) Å	θ = 2.1–26.8°
c = 18.5442 (5) Å	µ = 2.46 mm^−1
β = 121.835 (3)°	T = 100 K
V = 4258.5 (2) Å^3	Rod, clear colourless
Z = 4	0.3 × 0.1 × 0.05 mm

Data collection

Agilent SuperNova Dual Source diffractometer with an Eos detector	3886 independent reflections
Radiation source: micro-focus sealed X-ray tube, SuperNova (Mo) X-ray Source	3582 reflections with I > 2σ(I)
Detector resolution: 7.9580 pixels mm^-1	Rint = 0.034
ω scans	θmax = 25.4°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −30→28
Tmin = 0.062, Tmax = 0.093	k = −12→12
12607 measured reflections	l = −22→21

Refinement

Refinement on F^2	Hydrogen site location: mixed
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.023	w = 1/[σ^2(Fo^2) + (0.0247P)^2 + 6.8377P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.056	(Δ/σ)max = 0.002
S = 1.06	Δρmax = 0.59 e Å^−3
3886 reflections	Δρmin = −0.52 e Å^−3
304 parameters	Extinction correction: SHELXL2016 (Sheldrick, 2015b), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
43 restraints	Extinction coefficient: 0.00020 (2)

Special details

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 > 2sigma(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)
Mo1	0.60807 (2)	0.46762 (2)	0.48657 (2)	0.01373 (8)
Mo2	0.45907 (2)	0.42819 (2)	0.39963 (2)	0.01256 (8)
Mo3	0.43750 (2)	0.72147 (2)	0.40889 (2)	0.01356 (8)
Mo4	0.58769 (2)	0.76365 (2)	0.49649 (2)	0.01453 (8)
K1	0.500000	0.63056 (8)	0.250000	0.0175 (2)
O6	0.40089 (9)	0.55146 (18)	0.39590 (13)	0.0139 (4)
O5	0.53989 (9)	0.34477 (17)	0.45968 (13)	0.0141 (4)
O7	0.50838 (9)	0.82562 (18)	0.47312 (13)	0.0160 (4)
O8	0.64366 (9)	0.62419 (18)	0.53556 (13)	0.0161 (4)
O2	0.41322 (9)	0.29802 (18)	0.38701 (13)	0.0168 (4)
O4	0.63703 (9)	0.88406 (19)	0.55100 (14)	0.0201 (5)
O13	0.52072 (9)	0.58220 (18)	0.46285 (13)	0.0148 (4)
O3	0.37813 (9)	0.81053 (19)	0.39867 (13)	0.0190 (5)
O11	0.42950 (10)	0.72627 (18)	0.31153 (14)	0.0183 (5)
O10	0.44962 (9)	0.44827 (19)	0.30301 (13)	0.0179 (4)
O1	0.67186 (9)	0.37354 (19)	0.53047 (14)	0.0194 (5)
O12	0.57329 (10)	0.77401 (19)	0.39577 (14)	0.0193 (5)
O9	0.58913 (10)	0.48992 (19)	0.38481 (13)	0.0183 (4)
N2	0.25130 (12)	0.4973 (2)	0.15917 (17)	0.0210 (6)
H1	0.210462	0.542676	0.127437	0.025*
C1	0.24871 (15)	0.3974 (3)	0.1006 (2)	0.0248 (7)
H1A	0.242317	0.436805	0.048327	0.030*
H1B	0.212168	0.343221	0.084083	0.030*
C5	0.30166 (15)	0.5926 (3)	0.1824 (2)	0.0296 (8)
H5A	0.342389	0.549630	0.206001	0.036*
H5B	0.304599	0.647457	0.227237	0.036*
C3	0.25554 (16)	0.4433 (3)	0.2373 (2)	0.0270 (7)
H3A	0.231860	0.364257	0.222124	0.032*
H3B	0.299896	0.424755	0.280303	0.032*
C6	0.28980 (17)	0.6717 (4)	0.1076 (3)	0.0389 (9)
H6A	0.288202	0.618337	0.063712	0.058*
H6B	0.323724	0.732392	0.126479	0.058*
H6C	0.249821	0.715530	0.084411	0.058*
C2	0.30707 (16)	0.3182 (3)	0.1394 (2)	0.0299 (8)
H2A	0.300543	0.249081	0.101172	0.045*
H2B	0.316062	0.285309	0.194034	0.045*
H2C	0.342464	0.368815	0.148274	0.045*
C4	0.2298 (2)	0.5311 (5)	0.2747 (3)	0.0530 (12)
H4A	0.186605	0.553331	0.231346	0.079*
H4B	0.255564	0.606480	0.294639	0.079*
H4C	0.230423	0.490785	0.322551	0.079*
N1	0.4996 (5)	0.0915 (3)	0.2512 (9)	0.0196 (7)	0.5
H0AA	0.520749	0.050747	0.224401	0.024*	0.5
C9	0.4493 (8)	0.1725 (11)	0.1849 (8)	0.023 (3)	0.5
H0AB	0.470038	0.238783	0.171401	0.027*	0.5
H0AC	0.428100	0.213514	0.210813	0.027*	0.5
C12	0.4383 (5)	0.0462 (12)	0.3166 (6)	0.033 (3)	0.5
H3AA	0.415218	−0.018759	0.325802	0.050*	0.5
H3AB	0.409297	0.111835	0.280817	0.050*	0.5
H3AC	0.470371	0.081453	0.371312	0.050*	0.5
C10	0.3986 (8)	0.1162 (16)	0.1011 (9)	0.027 (3)	0.5
H1AA	0.374471	0.182848	0.060966	0.041*	0.5
H1AB	0.370596	0.065029	0.110690	0.041*	0.5
H1AC	0.418044	0.064341	0.077782	0.041*	0.5
C11	0.4696 (3)	−0.0096 (5)	0.2727 (4)	0.0197 (12)	0.5
H2AA	0.501705	−0.070823	0.310657	0.024*	0.5
H2AB	0.438043	−0.053194	0.220312	0.024*	0.5
C7	0.5474 (9)	0.1723 (12)	0.3207 (8)	0.026 (3)	0.5
H7A	0.528306	0.218610	0.347644	0.031*	0.5
H7B	0.564362	0.233025	0.297807	0.031*	0.5
C8	0.5995 (9)	0.0882 (17)	0.3854 (10)	0.044 (5)	0.5
H8A	0.614089	0.034607	0.356608	0.066*	0.5
H8B	0.583510	0.036630	0.413540	0.066*	0.5
H8C	0.634356	0.139158	0.427874	0.066*	0.5
O14	0.4539 (4)	0.0437 (8)	0.3555 (4)	0.0306 (16)	0.5
H13A	0.447491	0.104527	0.379140	0.046*	0.5
H13B	0.472012	−0.010592	0.394479	0.046*	0.5

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Mo1	0.01187 (14)	0.01594 (14)	0.01319 (15)	0.00013 (9)	0.00648 (12)	−0.00076 (10)
Mo2	0.01135 (14)	0.01429 (14)	0.01045 (15)	−0.00077 (9)	0.00466 (12)	−0.00192 (10)
Mo3	0.01196 (14)	0.01438 (14)	0.01315 (15)	0.00001 (9)	0.00580 (12)	−0.00035 (10)
Mo4	0.01237 (14)	0.01536 (14)	0.01447 (15)	−0.00235 (9)	0.00612 (12)	−0.00155 (10)
K1	0.0190 (5)	0.0189 (4)	0.0159 (5)	0.000	0.0100 (4)	0.000
O6	0.0118 (10)	0.0164 (10)	0.0122 (11)	−0.0009 (8)	0.0055 (9)	−0.0017 (8)
O5	0.0118 (10)	0.0153 (10)	0.0143 (11)	−0.0008 (8)	0.0063 (9)	−0.0028 (8)
O7	0.0159 (10)	0.0149 (10)	0.0170 (11)	−0.0017 (8)	0.0084 (10)	−0.0022 (9)
O8	0.0115 (10)	0.0191 (10)	0.0158 (11)	−0.0023 (8)	0.0060 (9)	−0.0013 (9)
O2	0.0148 (10)	0.0181 (10)	0.0150 (11)	−0.0021 (8)	0.0062 (10)	−0.0035 (9)
O4	0.0166 (11)	0.0198 (11)	0.0212 (12)	−0.0036 (8)	0.0081 (10)	−0.0033 (9)
O13	0.0131 (10)	0.0160 (10)	0.0142 (11)	−0.0022 (8)	0.0063 (9)	−0.0023 (8)
O3	0.0168 (11)	0.0200 (10)	0.0208 (12)	0.0016 (9)	0.0105 (10)	0.0020 (9)
O11	0.0189 (11)	0.0203 (11)	0.0163 (12)	−0.0033 (8)	0.0096 (10)	−0.0018 (9)
O10	0.0171 (11)	0.0212 (11)	0.0146 (11)	−0.0017 (8)	0.0078 (10)	−0.0015 (9)
O1	0.0141 (10)	0.0231 (11)	0.0203 (12)	0.0008 (8)	0.0086 (10)	0.0013 (9)
O12	0.0186 (11)	0.0213 (11)	0.0194 (12)	−0.0018 (9)	0.0109 (10)	−0.0001 (9)
O9	0.0180 (11)	0.0216 (11)	0.0168 (12)	0.0005 (9)	0.0102 (10)	−0.0002 (9)
N2	0.0139 (13)	0.0219 (13)	0.0187 (15)	0.0026 (11)	0.0029 (12)	0.0001 (11)
C1	0.0245 (17)	0.0241 (16)	0.0240 (19)	−0.0056 (13)	0.0116 (16)	−0.0066 (14)
C5	0.0182 (17)	0.0227 (16)	0.032 (2)	−0.0012 (13)	0.0026 (17)	0.0004 (15)
C3	0.0192 (17)	0.0347 (18)	0.0180 (18)	0.0003 (14)	0.0035 (15)	0.0003 (15)
C6	0.0263 (19)	0.035 (2)	0.048 (3)	−0.0012 (16)	0.015 (2)	0.0095 (19)
C2	0.0299 (19)	0.0255 (17)	0.041 (2)	0.0010 (15)	0.0232 (18)	0.0001 (16)
C4	0.047 (3)	0.077 (3)	0.027 (2)	0.023 (2)	0.014 (2)	−0.003 (2)
N1	0.0233 (16)	0.0191 (16)	0.0202 (17)	0.004 (3)	0.0141 (14)	0.000 (3)
C9	0.022 (3)	0.023 (4)	0.022 (3)	0.001 (3)	0.011 (2)	0.002 (3)
C12	0.046 (7)	0.028 (4)	0.042 (7)	0.009 (5)	0.035 (6)	0.012 (5)
C10	0.028 (4)	0.017 (6)	0.028 (3)	−0.002 (5)	0.008 (2)	0.001 (4)
C11	0.019 (3)	0.022 (2)	0.015 (3)	0.003 (2)	0.006 (3)	0.003 (2)
C7	0.032 (4)	0.031 (4)	0.015 (3)	−0.004 (3)	0.013 (2)	0.002 (3)
C8	0.034 (4)	0.030 (8)	0.038 (6)	−0.013 (5)	−0.002 (4)	0.007 (5)
O14	0.037 (4)	0.020 (3)	0.041 (5)	−0.001 (3)	0.025 (4)	−0.003 (4)

Geometric parameters (Å, º)

Mo1—O6^i	2.315 (2)	N2—C5	1.504 (4)
Mo1—O5	2.0071 (19)	N2—C3	1.512 (4)
Mo1—O8	1.899 (2)	C1—H1A	0.9900
Mo1—O13	2.3477 (19)	C1—H1B	0.9900
Mo1—O1	1.697 (2)	C1—C2	1.510 (4)
Mo1—O9	1.702 (2)	C5—H5A	0.9900
Mo2—O6	1.9477 (19)	C5—H5B	0.9900
Mo2—O5	1.9452 (19)	C5—C6	1.516 (5)
Mo2—O2	1.749 (2)	C3—H3A	0.9900
Mo2—O13	2.1455 (19)	C3—H3B	0.9900
Mo2—O13^i	2.325 (2)	C3—C4	1.506 (5)
Mo2—O10	1.693 (2)	C6—H6A	0.9800
Mo3—O6	2.0040 (19)	C6—H6B	0.9800
Mo3—O5^i	2.304 (2)	C6—H6C	0.9800
Mo3—O7	1.899 (2)	C2—H2A	0.9800
Mo3—O13	2.3261 (19)	C2—H2B	0.9800
Mo3—O3	1.697 (2)	C2—H2C	0.9800
Mo3—O11	1.709 (2)	C4—H4A	0.9800
Mo4—O7	1.9216 (19)	C4—H4B	0.9800
Mo4—O8	1.918 (2)	C4—H4C	0.9800
Mo4—O2^i	2.272 (2)	N1—H0AA	1.0000
Mo4—O4	1.707 (2)	N1—C9	1.493 (4)
Mo4—O13	2.4340 (19)	N1—C11	1.493 (4)
Mo4—O12	1.708 (2)	N1—C7	1.493 (4)
K1—Mo2^ii	4.0630 (5)	C9—H0AB	0.9900
K1—Mo3^ii	4.1214 (3)	C9—H0AC	0.9900
K1—K1^ii	0.0000 (1)	C9—C10	1.521 (6)
K1—O11	2.763 (2)	C12—H3AA	0.9800
K1—O11^ii	2.763 (2)	C12—H3AB	0.9800
K1—O10	2.780 (2)	C12—H3AC	0.9800
K1—O10^ii	2.780 (2)	C12—C11	1.521 (6)
K1—O12	2.798 (2)	C10—H1AA	0.9800
K1—O12^ii	2.798 (2)	C10—H1AB	0.9800
K1—O9^ii	2.765 (2)	C10—H1AC	0.9800
K1—O9	2.766 (2)	C11—H2AA	0.9900
O6—Mo1^i	2.315 (2)	C11—H2AB	0.9900
O5—Mo3^i	2.304 (2)	C7—H7A	0.9900
O2—Mo4^i	2.272 (2)	C7—H7B	0.9900
O13—Mo2^i	2.325 (2)	C7—C8	1.521 (6)
O11—K1^ii	2.763 (2)	C8—H8A	0.9800
O10—K1^ii	2.780 (2)	C8—H8B	0.9800
O12—K1^ii	2.798 (2)	C8—H8C	0.9800
O9—K1^ii	2.766 (2)	O14—H13A	0.8493
N2—H1	1.0000	O14—H13B	0.8504
N2—C1	1.505 (4)
O6^i—Mo1—O13	71.18 (7)	Mo2—O6—Mo3	109.20 (9)
O5—Mo1—O6^i	71.43 (7)	Mo3—O6—Mo1^i	103.54 (8)
O5—Mo1—O13	73.03 (7)	Mo1—O5—Mo3^i	103.82 (8)
O8—Mo1—O6^i	83.30 (8)	Mo2—O5—Mo1	109.57 (9)
O8—Mo1—O5	145.88 (8)	Mo2—O5—Mo3^i	110.40 (8)
O8—Mo1—O13	77.39 (7)	Mo3—O7—Mo4	117.04 (10)
O1—Mo1—O6^i	91.81 (9)	Mo1—O8—Mo4	116.54 (10)
O1—Mo1—O5	101.11 (9)	Mo2—O2—Mo4^i	116.29 (10)
O1—Mo1—O8	102.26 (9)	Mo1—O13—Mo4	85.49 (6)
O1—Mo1—O13	162.96 (9)	Mo2—O13—Mo1	91.78 (7)
O1—Mo1—O9	104.89 (10)	Mo2^i—O13—Mo1	97.32 (7)
O9—Mo1—O6^i	161.24 (8)	Mo2—O13—Mo2^i	103.84 (8)
O9—Mo1—O5	96.57 (9)	Mo2^i—O13—Mo3	97.44 (7)
O9—Mo1—O8	101.02 (9)	Mo2—O13—Mo3	92.08 (7)
O9—Mo1—O13	91.79 (9)	Mo2^i—O13—Mo4	92.06 (7)
O6—Mo2—O13^i	78.31 (8)	Mo2—O13—Mo4	164.09 (10)
O6—Mo2—O13	78.79 (8)	Mo3—O13—Mo1	163.37 (10)
O5—Mo2—O6	150.67 (8)	Mo3—O13—Mo4	86.37 (6)
O5—Mo2—O13	78.97 (8)	Mo3—O11—K1	132.96 (11)
O5—Mo2—O13^i	77.99 (7)	Mo3—O11—K1^ii	132.96 (11)
O2—Mo2—O6	96.40 (9)	K1^ii—O11—K1	0.00 (3)
O2—Mo2—O5	97.02 (9)	Mo2—O10—K1	128.95 (10)
O2—Mo2—O13^i	81.70 (8)	Mo2—O10—K1^ii	128.95 (10)
O2—Mo2—O13	157.86 (9)	K1^ii—O10—K1	0.00 (3)
O13—Mo2—O13^i	76.16 (8)	Mo4—O12—K1	132.24 (10)
O10—Mo2—O6	101.06 (9)	Mo4—O12—K1^ii	132.24 (10)
O10—Mo2—O5	100.72 (9)	K1^ii—O12—K1	0.00 (3)
O10—Mo2—O2	104.24 (10)	Mo1—O9—K1^ii	134.34 (10)
O10—Mo2—O13^i	174.05 (8)	Mo1—O9—K1	134.34 (10)
O10—Mo2—O13	97.91 (9)	K1^ii—O9—K1	0.0
O6—Mo3—O5^i	71.72 (7)	C1—N2—H1	106.5
O6—Mo3—O13	73.45 (7)	C1—N2—C3	111.8 (2)
O5^i—Mo3—O13	71.43 (7)	C5—N2—H1	106.5
O7—Mo3—O6	146.39 (8)	C5—N2—C1	113.8 (3)
O7—Mo3—O5^i	83.84 (8)	C5—N2—C3	111.4 (3)
O7—Mo3—O13	77.15 (8)	C3—N2—H1	106.5
O3—Mo3—O6	100.44 (9)	N2—C1—H1A	108.9
O3—Mo3—O5^i	90.26 (8)	N2—C1—H1B	108.9
O3—Mo3—O7	102.43 (9)	N2—C1—C2	113.4 (3)
O3—Mo3—O13	161.67 (9)	H1A—C1—H1B	107.7
O3—Mo3—O11	104.97 (10)	C2—C1—H1A	108.9
O11—Mo3—O6	96.31 (9)	C2—C1—H1B	108.9
O11—Mo3—O5^i	162.33 (8)	N2—C5—H5A	109.0
O11—Mo3—O7	101.16 (9)	N2—C5—H5B	109.0
O11—Mo3—O13	92.98 (9)	N2—C5—C6	113.0 (3)
O7—Mo4—O2^i	77.66 (8)	H5A—C5—H5B	107.8
O7—Mo4—O13	74.09 (7)	C6—C5—H5A	109.0
O8—Mo4—O7	145.39 (8)	C6—C5—H5B	109.0
O8—Mo4—O2^i	77.61 (8)	N2—C3—H3A	109.3
O8—Mo4—O13	74.90 (7)	N2—C3—H3B	109.3
O2^i—Mo4—O13	69.94 (7)	H3A—C3—H3B	107.9
O4—Mo4—O7	102.30 (9)	C4—C3—N2	111.7 (3)
O4—Mo4—O8	102.19 (9)	C4—C3—H3A	109.3
O4—Mo4—O2^i	91.54 (9)	C4—C3—H3B	109.3
O4—Mo4—O13	161.48 (9)	C5—C6—H6A	109.5
O4—Mo4—O12	105.47 (10)	C5—C6—H6B	109.5
O12—Mo4—O7	97.72 (9)	C5—C6—H6C	109.5
O12—Mo4—O8	98.88 (9)	H6A—C6—H6B	109.5
O12—Mo4—O2^i	162.98 (9)	H6A—C6—H6C	109.5
O12—Mo4—O13	93.04 (8)	H6B—C6—H6C	109.5
Mo2^ii—K1—Mo3^ii	46.350 (5)	C1—C2—H2A	109.5
K1^ii—K1—Mo2^ii	0 (8)	C1—C2—H2B	109.5
K1^ii—K1—Mo3^ii	0 (7)	C1—C2—H2C	109.5
K1^ii—K1—O11	0 (10)	H2A—C2—H2B	109.5
K1^ii—K1—O11^ii	0 (10)	H2A—C2—H2C	109.5
K1^ii—K1—O10	0 (10)	H2B—C2—H2C	109.5
K1^ii—K1—O10^ii	0 (10)	C3—C4—H4A	109.5
K1^ii—K1—O12^ii	0 (10)	C3—C4—H4B	109.5
K1^ii—K1—O12	0 (10)	C3—C4—H4C	109.5
K1^ii—K1—O9^ii	0 (10)	H4A—C4—H4B	109.5
K1^ii—K1—O9	0 (10)	H4A—C4—H4C	109.5
O11^ii—K1—Mo2^ii	57.94 (4)	H4B—C4—H4C	109.5
O11—K1—Mo2^ii	158.47 (5)	C9—N1—H0AA	106.7
O11—K1—Mo3^ii	140.89 (5)	C11—N1—H0AA	106.7
O11^ii—K1—Mo3^ii	17.66 (4)	C11—N1—C9	108.6 (4)
O11—K1—O11^ii	136.23 (9)	C11—N1—C7	118.9 (16)
O11—K1—O10	66.80 (6)	C7—N1—H0AA	106.7
O11—K1—O10^ii	156.90 (7)	C7—N1—C9	108.5 (4)
O11^ii—K1—O10	156.90 (7)	N1—C9—H0AB	107.4
O11^ii—K1—O10^ii	66.80 (6)	N1—C9—H0AC	107.4
O11—K1—O12	68.53 (6)	N1—C9—C10	119.8 (13)
O11^ii—K1—O12	87.41 (6)	H0AB—C9—H0AC	106.9
O11^ii—K1—O12^ii	68.53 (6)	C10—C9—H0AB	107.4
O11—K1—O12^ii	87.41 (6)	C10—C9—H0AC	107.4
O11—K1—O9	102.73 (6)	H3AA—C12—H3AB	109.5
O11^ii—K1—O9	100.81 (6)	H3AA—C12—H3AC	109.5
O11—K1—O9^ii	100.81 (6)	H3AB—C12—H3AC	109.5
O11^ii—K1—O9^ii	102.73 (6)	C11—C12—H3AA	109.5
O10^ii—K1—Mo2^ii	18.90 (4)	C11—C12—H3AB	109.5
O10—K1—Mo2^ii	100.95 (5)	C11—C12—H3AC	109.5
O10^ii—K1—Mo3^ii	59.89 (4)	C9—C10—H1AA	109.5
O10—K1—Mo3^ii	146.78 (5)	C9—C10—H1AB	109.5
O10^ii—K1—O10	90.26 (9)	C9—C10—H1AC	109.5
O10^ii—K1—O12^ii	103.76 (6)	H1AA—C10—H1AB	109.5
O10—K1—O12	103.76 (6)	H1AA—C10—H1AC	109.5
O10^ii—K1—O12	122.71 (6)	H1AB—C10—H1AC	109.5
O10—K1—O12^ii	122.71 (6)	N1—C11—C12	109.3 (8)
O12^ii—K1—Mo2^ii	84.86 (4)	N1—C11—H2AA	109.8
O12—K1—Mo2^ii	132.90 (4)	N1—C11—H2AB	109.8
O12—K1—Mo3^ii	104.78 (4)	C12—C11—H2AA	109.8
O12^ii—K1—Mo3^ii	58.88 (4)	C12—C11—H2AB	109.8
O12^ii—K1—O12	113.05 (9)	H2AA—C11—H2AB	108.3
O9—K1—Mo2^ii	87.03 (5)	N1—C7—H7A	110.2
O9^ii—K1—Mo2^ii	57.68 (4)	N1—C7—H7B	110.2
O9^ii—K1—Mo3^ii	85.16 (4)	N1—C7—C8	107.5 (11)
O9—K1—Mo3^ii	110.12 (4)	H7A—C7—H7B	108.5
O9—K1—O10^ii	68.35 (6)	C8—C7—H7A	110.2
O9^ii—K1—O10	68.35 (6)	C8—C7—H7B	110.2
O9—K1—O10	66.23 (6)	C7—C8—H8A	109.5
O9^ii—K1—O10^ii	66.23 (6)	C7—C8—H8B	109.5
O9^ii—K1—O12^ii	67.79 (6)	C7—C8—H8C	109.5
O9^ii—K1—O12	168.99 (6)	H8A—C8—H8B	109.5
O9—K1—O12^ii	168.99 (6)	H8A—C8—H8C	109.5
O9—K1—O12	67.79 (6)	H8B—C8—H8C	109.5
O9^ii—K1—O9	113.66 (9)	H13A—O14—H13B	104.6
Mo2—O6—Mo1^i	110.49 (9)

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

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2^iii—H1^iii···O4^iii	1.00	1.81	2.796 (4)	168
N1^iv—H0AA^iv···O14^iv	1.00	1.90	2.826 (17)	153
O14—H13B···O7	0.85	2.16	2.998 (8)	169

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

MicroRaman spectroscopic data analysis of reaction at varying pH from 2 to 6

pH	Mo8O264-	Mo7O246-	SOM
2	241, 292, 498, 545, 620, 732, 829, 851, 895, 917, 973	-	952, 415, 963
3	241, 292, 498, 545, 620, 732, 829, 851, 895, 917, 973	-	952, 415, 963
4	725, 849, 917	215, 365, 561, 903	953, 416
5	725, 851	216, 365, 568, 641, 866, 903, 946	416
6	-	442, 547, 614, 811, 900, 945	-