# Steric, Activation Method and Solvent Effects on the Structure of Paddlewheel Diruthenium Complexes
## 2 Materials and Methods
### Synthesis  
4.1 Synthesis of [Ru\({}_{2}\)Cl(\(\mu\)-O\({}_{2}\)CC\({}_{6}\)H\({}_{4}\)-o-OMe)\({}_{4}\)]\({}_{\rm{n}}\) (1a)  
The synthesis of this compound was carried out following two different methods:  
_Method a: Microwave assisted solvothermal synthesis._ [Ru\({}_{2}\)Cl(\(\mu\)-O\({}_{2}\)CCH\({}_{3}\))\({}_{4}\)]\({}_{\rm{n}}\) (0.12 g, 0.25 mmol), _o_-methoxybenzoic acid (0.23 g, 1.50 mmol), 8 mL of ethanol and a magnetic stirrer bar were placed into an 85 mL TFM Teflon vessel. The vessel, sealed with a lid equipped with temperature and pressure sensors, was placed in the microwave oven. The reaction mixture was then treated by a three-step program consisting of (i) 15 min heating ramp up to 100 \({}^{\circ}\)C, (ii) 16 h isotherm at 100 \({}^{\circ}\)C and (iii) 20 min cooling ramp up to room temperature. A brown solid is obtained after filtration and washing with 2 \(\times\) 10 mL \begin{table}
\begin{tabular}{c c c} \hline \hline  & **1b** & **1c** \\ \hline Empirical formula & C\({}_{34}\)H\({}_{33}\)ClO\({}_{13}\)Ru\({}_{2}\) & C\({}_{66}\)H\({}_{62}\)Cl\({}_{2}\)O\({}_{26}\)Ru\({}_{4}\) \\ \hline Formula weight & 887.03 & 1746.33 \\ \hline Temperature/K & 293(2) & 293(2) \\ \hline Crystal system & Triclinic & triclinic \\ \hline Space group & _P_-1 & _P_-1 \\ \hline _a_/Å & 8.6893(9) & 10.5091(13) \\ \hline _b_/Å & 14.4399(15) & 10.6029(13) \\ \hline _c_/Å & 14.5070(16) & 15.938(2) \\ \hline _a_/\({}^{\circ}\) & 84.308(2) & 85.170(2) \\ \hline _β_/\({}^{\circ}\) & 79.522(2) & 75.587(2) \\ \hline _γ_/\({}^{\circ}\) & 80.622(2) & 84.125(2) \\ \hline Volume/Å\({}^{3}\) & 1761.4(3) & 1707.8(4) \\ \hline \(Z\) & 2 & 1 \\ \hline _c_calc/g cm\({}^{-3}\) & 1.672 & 1.698 \\ \hline _μ_/mm\({}^{-1}\) & 0.998 & 1.028 \\ \hline Reflections collected & 13207 & 12851 \\ \hline Independent reflections & 6018 & 5837 \\  & [R\({}_{\rm{int}}\) = 0.0387, R\({}_{\rm{sigma}}\) = 0.0568] & [R\({}_{\rm{int}}\) = 0.0871, R\({}_{\rm{sigma}}\) = 0.0883] \\ \hline Goodness-of-fit on F2 & 1.036 & 0.967 \\ \hline Final R indexes & & \\ [I\(>=2\) \(o\) (I)] & R1 = 0.0488, wR2 = 0.1250 & R1 = 0.0387, wR2 = 0.0861 \\ \hline Final R indexes [all data] & R1 = 0.0855, wR2 = 0.1438 & R1 = 0.0673, wR2 = 0.1003 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Crystal and refinement for **1b** and **1c**. of cold ethanol. Finally, it was dried under vacuum. Yield: 76%. Anal. Calcd. (%) for {[Ru2 Cl(\(\mu\)-O2 CC6H4-o-OMe)4]-H2O}n (**1a**-H2O): C, 44.68; H, 3.52. Found (%): C, 44.39; H, 3.69. _Method b: Conventional synthesis._ First, 0.12 g (0.25 mmol) of [Ru2 Cl(\(\mu\)-O2 CC6H3)4]n and 0.23 g (1.50 mmol) of \(o\)-methoxybenzoic acid were added to 24 mL of MeOH/H2O (1:1). The reaction mixture was refluxed for 4 h. The brown precipitate formed was obtained by filtration, washed twice with 10 mL of absolute ethanol and dried under vacuum. Yield: 53%: Anal. Calcd. (%) for {[Ru2 Cl(\(\mu\)-O2 CC6H4-o-OMe)4]-H2O}n (**1a**-H2O): C, 44.68; H, 3.52. Found (%): C, 44.45; H, 3.58. FT-IR (cm\({}^{-1}\)): 3073w, 3021w, 2942w, 2839w, 1608w, 1587w, 1490w, 1473w, 1346m, 1391s, 1315w, 1287m, 1247m, 1181w, 1167w, 1115w, 1085w, 1043m, 996w, 969w, 899w, 887w, 845w, 788m, 755s, 703w, 678m. UV-Vis-NIR (diffuse reflectance): [\(\lambda\), nm] 332 sh, 450, 1088. Mass spectrometry [\(m/z\) (fragment)]: 808 [Ru2(\(\mu\)-O2 CC6H4-o-OMe)4]+. \(\mu_{\rm eff}\) (R.T.) = 3.86 \(\mu_{\rm B}\). _Method c: Solothermal synthesis._ The same reagents and quantities used for the synthesis of **1a** were added to a 23 mL Teflon-lined autoclave and stirred to get a homogenous dispersion. The closed reactor was treated under a three-step program consisting of (i) 2 h heating ramp up to 100 \({}^{\circ}\)C, (ii) 24 h isotherm at 100 \({}^{\circ}\)C and (iii) 40 h cooling ramp down to room temperature. Brown, needle-shaped crystals were obtained after filtration, washed with cold absolute ethanol (2 \(\times\) 10 mL) and dried under vacuum. Yield: 71%. Anal. Calcd. (%) for [Ru2 Cl(\(\mu\)-O2 CC6H4-o-OMe)4(EtOH)]-H2O (**1b**): C, 45.06; H, 4.00. Found (%): C, 45.19; H, 3.80.