Supplementary material

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1 Supplementary material Cobalt selenium oxohalides: Catalysts for Water Oxidation Faiz Rabbani a,b, Henrik Svengren a, Iwan Zimmermann a, Shichao Hu a, Tanja Laine c, Wenming Hao a, Björn Åkermark c, Torbjörn Åkermark c, Mats Johnsson a a) Department of Materials and Environmental Chemistry, Stockholm University, SE Stockholm, Sweden b) Permanent address: Department of Chemistry, University of Engineering and Technology, Lahore , Pakistan c) Department of Organic Chemistry, Stockholm University, SE Stockholm, Sweden Table S1 Crystal data and structure refinement parameters for (1) Co 4 Se 3 O 9 Cl 2 and (2) Co 3 Se 4 O 10 Cl 2. Empirical formula Co 4 Se 3 O 9 Cl 2 Co 3 Se 4 O 10 Cl 2 Formula weight (amu) Temperature (k) 292(3) 293(2) Wavelength (Å) Crystal system Orthorhombic Monoclinic Space group Pnma (no. 62) C2/m (no. 12) Unit cell dimensions a = (1) Å b = (2) Å c = (2) Å a = 7.197(1) Å b = (2) Å c = (9) Å β = (2) º Volume (Å 3 ) (3) (14) Z 4 2 Density (calculated) (g cm -3 ) Absorption coefficient (mm -1 ) F(000) Crystal colour Blue Purple Crystal habit Block Block Crystal size (mm 3 ) 0.20x0.04x x 0.05 x 0.03 Ө range for data coll to to Index ranges -11 h 8-21 k l 14-7 h 9-17 k 15-7 l 5 Reflections collected Independent reflections 1576 [R(int) = ] 535 [R(int) = ] Data / restraints / parameters 1938 / 0 / / 0 / 49 Goodness-of-fit on F Final R indices [I > 2Sigma (I)] a R 1 = wr 2 = R 1 = wr 2 = R indices (all data) R 1 = WR 2 = R 1 = wr 2 = Largest diff. peak and hole (e Å -3 ) and and a R 1 = Σ Fo - Fc /Σ Fo ; wr 2 = {Σ[w(F 2 o- F 2 o) 2 ]/ Σ[w(F 2 o)2]} 1/2 1

2 Table S2 Atomic coordinates and Equivalent Isotropic Displacement Parameters (Å 2 ) for (1) Co 4 (SeO 3 ) 3 Cl 2. Atom label Wyckoff x y z Uiso Se1 8d (3) (2) (3) (6) Se2 4c (4) 1/ (4) (8) Co1 8d (5) (3) (4) (8) Co2 8d (4) (2) (4) (8) Cl1 8d (8) (5) (7) (14) O1 8d (2) (13) (19) (4) O2 8d (2) (12) (19) (4) O3 4c (3) 1/ (3) (6) O4 8d (2) (13) (18) (4) O5 8d (2) (13) (19) (4) Table S3 Selected bond lengths (Å) and bond angles for (1) Co 4 (SeO 3 ) 3 Cl 2. Se1 O (2) Se2 O2 x (2) Se1 O (2) Se2 O (3) Se1 O (2) Co2 O (2) Co1 O (2) Co2 O (2) Co1 O (1) Co2 O (2) Co1 O (2) Co2 O4 v 2.139(2) Co1 O (2) Co2 O (2) Co1 Cl (1) Co2 Cl1 v 2.431(1) Co1 Cl iii 2.704(1) O1 Se1 O (8) O3 ii Co1 Cl1 iii 83.87(2) O1 Se1 O (9) O4 Co1 Cl1 iii (5) O5 Se1 O (9) Cl1 Co1 Cl1 iii (3) O2 Se2 O2 i (8) O5 iii Co2 O1 iv 93.63(7) O2 Se2 O3 x (6) O5 iii Co2 O (7) O2 Co1 O (7 O1 iv Co2 O (7) O2 Co1 O3 ii (5) O5 iii Co2 O4 v (7) O5 Co1 O3 ii (6) O1 iv Co2 O4 v 89.13(7) O2 Co1 O (7) O4 Co2 O4 v 77.67(6) O5 Co1 O (7) O5 iii Co2 O (7) O3 ii Co1 O (5) O1 iv Co2 O (7) O2 Co1 Cl (5) O4 Co2 O (7) O5 Co1 Cl (5) O4 v Co2 O (7) O3 ii Co1 Cl (3) O5 iii Co2 Cl1 v 92.89(6) O4 Co1 Cl (5) O1 iv Co2 Cl1 v 94.61(6) O2 Co1 Cl1 iii 86.67(5) O4 Co2 Cl1 v 96.28(5) O5 Co1 Cl1 iii 80.81(5) O4 v Co2 Cl1 v 87.40(5) O2 Co2 Cl1 v (5) (i) x, 0.5-y, z; (ii) 0.5+x, y, 0.5-z; (iii) -0.5+x, y, 0.5-z; (iv) 0.5-x, 1-y, -0.5+z; (v) 1-x, 1-y, -z. 2

3 Table S4 Results from Bond Valence Sum (BVS) calculations for (1) Co 4 (SeO 3 ) 3 Cl 2. Atoms Bonding distance Bond valence Atoms Bonding distance Bond valence Se1 O (2) Cl1-Co (1) Se1 O (2) Cl1 iii -Co (1) Se1 O (2) Cl1 v -Co (1) Se2 O2 x (2) O1-Se (2) Se2 O (3) O1-Co (2) Co1 O (2) O2-Se (2) Co1 O (1) O2-Co (2) Co1 O (2) O2-Co (2) Co1 O (2) Co1 Cl (1) Co1 Cl1 iii 2.704(1) O3-Co1 x (1) O3-Se (3) Co2 O (2) Co2 O (2) O4-Co (2) Co2 O (2) O4 v -Co (2) Co2 O (2) O4-Co (2) Co2 O (2) O4-Se (2) Co2 Cl1 v 2.431(1) O5-Se (2) O5-Co (2) O5-Co (2) The bond valence parameters of two atoms i and j were calculated according to the formula Vij = exp{[r 0 -r ij ] B} where r ij is the inter atomic distance. The r 0 values are for Se-O, for Co-O and for Co-Cl with B = 0.37 [S1]. 3

4 Table S5 Atomic coordinates and Equivalent Isotropic Displacement Parameters (Å 2 ) for (2) Co 3 Se 4 O 10 Cl 2. Atom x y z U(eq) Se(1) (9) (5) (11) (4) Co(1) ½ ½ (5) Co(2) ½ (10) ½ (4) Cl(1) (3) ½ (4) (5) O(1) (7) (4) (9) (11) O(2) (7) (4) (9) (11) O(3) (6) ½ (19) Note. U(eq) is defined as one third of the trace of the orthogonalized U ij tensor. Table S6 Selected Bond Lengths (Å) and Angles (º) for (2) Co 3 Se 4 O 10 Cl 2. Se1 O (5) Co2 O1 x (5) Se1 O (5) Co2 O2 x (5) Se1 O (3) Co2 Cl1 x (1) Co1 O1 x (5) Co1 Cl1 x (2) O2 Se1 O (3) O2 Co2 O1 x2 90.6(2) O2 Se1 O (3) O2 Co2 O1 x2 99.5(2) O1 Se1 O3 96.0(2) O1 iii Co2 O1 viii 164.8(3) O1 Co1 O1 x2 87.2(3) O2 vi Co2 O2 vii 96.7(3) O1 Co1 O1 x (2) O2 Co2 Cl1 x (16) O1 Co1 O1 x2 92.8(3) O2 Co2 Cl1 x (15) O1 Co1 Cl1 x (14) O1 iii Co2 Cl (14) O1 Co1 Cl1 x (14) O1 Co2 Cl1 x (16) O1 Co1 Cl1 x (14) O1 viii Co2 Cl1 iii 80.27(15) Cl1 Co1 Cl1 v 180.0(1) Cl1 Co2 Cl1 iii 89.18(9) Note. Symmetry transformations used to generate equivalent atoms: (i) x, y, -1+z; (ii) 1-x, y, 1-z; (iii) 1-x, 1-y, 1-z; (iv) x, 1-y, -1+z; (v) 1-x, 1-y, -z; (vi) 0.5+x, 0.5+y, z; (vii) 0.5-x, 0.5+y, 1-z; (viii) x, 1-y, z; (ix) x, y, 1+z; (x) -0.5+x, -0.5+y, z; (xi) -x, y, 1-z. 4

5 Table S7 Results from Bond Valence Sum (BVS) calculations of (2) Co 3 Se 4 O 10 Cl 2. Atoms Bonding distance Bond valence Atoms Bonding distance Bond valence Se1 O (5) 1.5 O1 Co (5) 0.33 Se1 O (5) 1.4 O1 Co (5) 0.31 Se1 O (3) 1.1 O1 Se (5) Co1 O1 i 2.091(5) 0.33 O2 Co2 iv 2.060(5) 0.36 Co1 O1 ii 2.091(5) 0.33 O2 Se (5) 1.52 Co1 O1 iii 2.091(5) Co1 O1 iv 2.091(5) 0.33 Co1 Cl (2) 0.33 O3 Se (3) 1.1 Co1 Cl1 v 2.424(2) 0.33 O3 Se1 viii 1.776(3) Co2 O2 vi 2.060(5) 0.36 Cl1 Co (2) 0.33 Co2 O2 vii 2.060(5) 0.36 Cl1 Co (1) 0.25 Co2 O1 iii 2.116(5) 0.31 Cl1 Co2 iv 2.520(1) 0.25 Co2 O1 viii 2.116(5) Co2 Cl (1) 0.25 Co2 Cl1 iii 2.520(1) Figure S1 [Co 3 O 8 Cl 2 ] chains made up of edge charing [Co(1)O 4 Cl 2 ] octahedra and [Co(2)O 4 Cl 2 ] octahedra extend along [001] in (2) Co 3 Se 4 Cl 2 O 10. 5

6 Oxidation experiments Figure S2 Raw pressures from the mass spectrometer from the analysis of Co 3 Se 4 O 10 Cl 2 (2) shown in fig. 3, the oxohalide catalyst showing the lowest oxygen evolution. The graph indicate the stability of the closed system during analysis. The total pressure in the reaction chamber during this experiment was 20 mbar, mainly constituted by partial pressures from H 2 O (15 mbar at 13 C) and the reference gas He (5 mbar). The atmospheric gases N 2 and Ar show constant linear trends during the experiment indicating no addition of atmospheric O 2 after start of the oxygen evolving reaction at time zero. The unchanged H 2 O pressure indicates isothermal conditions. No significant CO 2 evolved during the reaction indicating that the Ru 3+ (bpy) 3 (PF 6 ) 3 complex have not fully oxidized to C 4+. 6

7 Figure S3 Turnover number for a fixed amount of catalyst 1 (1.45 µmol bulk [Co]), as shown in fig. 5, plotted against the amount of Ru 3+ (bpy) 3 (PF 6 ) 3 used. The magnitude of the turnover number follows a linear trend with increasing amount of Ru 3+ (bpy) 3 (PF 6 ) 3. Figure S4 Linear regression fit of the initial kinetic slope of the curve for the selected experiment with TN = 1.0 for compound 1 (1.45 µmol bulk [Co], 22.4µmol Ru III (bpy) 3 (PF 6 ) 3 ) presented in fig. 5 as indicated between brackets at T = 33 sec. and T = 115 sec. and TN =

8 Figure S5 Trends using only Ru 3+ (bpy) 3 (PF 6 ) 3 in 0.1 M phosphate buffer at ph 6.1 and ph 5.7. Neither any significant evolution of O 2 and CO 2 (<0.01 µmol) in relation to the atmospheric gas N 2, nor any significant change of color from green (Ru 3+ ) to orange (Ru 2+ ) could be observed. Blue and red lines indicate ph = 6.1, purple and green lines indicate ph 5.7. Figure S6 Local arrangements around the Co atoms in the three different oxohalide compounds. 1-3 (left to right). The Co(II) octahedra are edge sharing in compounds 1 and 2 and can be depicted to two connected open faced cubanes. Compound 3 is less regular and display both corner- and edge sharing octahedra. 8

9 Table S8 figures. Amount of chemicals used in the water oxidation experiments shown in the Figure Formula Weig hed amou nt (mg) Correspond ing amount bulk Co ( mol) Weighed amount Ru III (bpy) 3 (PF 6 ) 3 oxidant (mg) Correspondi ng amount Ru III ( mol) Phosphate buffer 0.1M ph 6.0 (ml) 3 Co 4 Se 3 O 9 Cl 2 (1) , S2 Co 3 Se 4 O 10 Cl (2) 3 Co 5 Se 4 O 12 Cl (3) 3 CoCl CoO Co 4 Se 3 O 9 Cl 2 (1) ) ) ) ) Co 4 Se 3 O 9 Cl 2 (1) , S3, Co 4 Se 3 O 9 Cl 2 (1) S4 6, S3 Co 4 Se 3 O 9 Cl 2 (1) , 6, S3 Co 4 Se 3 O 9 Cl 2 (1) , S3 Co 4 Se 3 O 9 Cl 2 (1) S ; ph 6.1 S ; ph 5.7 S6 Co 4 Se 3 O 9 Cl 2 (1) ; 15% H 18 2 O 9

10 Figure S7 Evolution of oxygen isotopes from water oxidation performed in presence of 15% H 2 18 O using Ru III (bpy) 3 (PF 6 ) 3 as oxidant and compound Co 4 Se 3 O 9 Cl 2 (1) as catalyst shows that at least 90% of the evolved O 2 (g) was derived from water. 10

11 Figure S8 Thermal gravimetric analysis of decomposition of (1) in air and in nitrogen. The compound starts to decompose at 500 C by giving off SeO 2 and Cl 2. At 600 C CoO is left according to the weight loss (theoretically 43% left). The slight weight increase from 600 C to 850 C (in N 2 ) is most likely due to oxidation of CoO to Co 2 O 3 (theoretically 48% left), reduction of Co 2 O 3 to CoO seems to start at ca 850 C. The reactions are postponed to higher temperatures when taking place in O 2 (g). 11

12 Figure S9 Thermal gravimetric analysis of decomposition of (2) in air and in nitrogen. This compound starts to decompose already below 100 C and SeO 2 and Cl 2 leave the sample in different steps. A mixture of Co 2 O 3 and CoO remains at 600 C according to the weight loss (theoretically 31.1% left in case only CoO remains and 34.4% if only Co 2 O 3 remains). When the decomposition takes place in N 2 a reduction of formed Co 2 O 3 to CoO seems to take place at ca 775 C. 12

13 Quantity Adsorbed (mmol/g) Electronic Supplementary Material (ESI) for Dalton Transactions Nitrogen and carbon dioxide adsorption data of (1) Nitrogen adsorption Nitrogen adsorption isotherms were measured at 77 K using a Micromeritics ASAP 2020 device. Before conducting the adsorption experiments, samples were degassed under conditions of dynamic vacuum at a temperature of 150 ºC for 1 h. Specific surface areas (S BET ) were calculated using standard expressions for Brunauer Emmet Teller (BET) isotherms. For BET analyses, uptake of nitrogen at relative pressures of p/p 0 = were used. The total pore volume (V t ) was estimated from the uptake at a p/p 0 = ,16 0,12 0,08 0,04 0,00 0,0 0,2 0,4 0,6 0,8 1,0 Relative Pressure (p/p o ) Figure S10 N 2 -adsorption isotherm of (1) at 77K BET surface area: 1.94 m²/g Total pore volume: cm³/g Hysteresis starts at relative pressure 0.5 is attributed to the capillary condensation. The big loop at high relative pressure is related to the large pores from accumulation of the particles. The fact that the loop does not close can, speculatively, be related to insufficient degassing. (The samples were degassed at only 150 C). Carbon dioxide adsorption Carbon dioxide adsorption isotherms were measured at 273 K using a Micromeritics ASAP 2020 device. Before conducting the adsorption experiments, samples were degassed under conditions of dynamic vacuum at a temperature of 150 ºC for 1 h. 13

14 Quantity Adsorbed (mmol/g) Electronic Supplementary Material (ESI) for Dalton Transactions 0,030 0,025 0,020 0,015 0,010 0,005 0,000 0,000 0,005 0,010 0,015 0,020 0,025 0,030 Relative Pressure (p/p o ) Figure S11 CO 2 -adsorption isotherm of (1) at 273K The sample does not adsorb much CO 2, so the uptake is very low. 14

15 a) Co 4 Se 3 O 9 Cl 2 (1) b) Co 3 Se 4 O 10 Cl 2 (2) c) Co 5 Se 4 O 12 Cl 2 (3) d) CoO Figure S12 SEM images of compounds 1, 2, 3 and CoO. 15

16 References [S1] I.D. Brown and D. Altermatt, Acta Cryst. (1985) B