Diruthenium and triruthenium compounds of the potential redox active non-chelated η¹-N,η¹-N-benzothiadiazole bridge

Abstract

The article dealt with a series of non-chelated BTD (BTD:2,1,3-Benzothiadiazole) bridged diruthenium(II) ([{(CH3CN)(acac)2RuII}2(-BTD)] 1, [{CH3CN(acac)2RuII}(-BTD){RuII(acac)2(1-N-BTD)}] 2, [{(1-N-BTD)(acac)2RuII}2(-BTD)] 3) and triruthenium ([{(acac)2RuII}3(-BTD)2(1-N-BTD)2] 4) complexes with varying ratio of 1-N and -bis-1-N,1-N...

Inner-Sphere Electron Transfer Induced Reversible Electron Reservoir Feature of Azoheteroarene Bridged Diruthenium Frameworks

“…The preferential metal-based reduction (R1, Figure ) of 2a or 2b (Ru III (μ-L4 •– )­Ru II , S = 0) instead of the alternate option of the reduction of L4 •– led to the electronic form of [Ru II (μ-L4 •– )­Ru II ] − for 2a – / 2b – ( S = 1/2) as supported by MOs (Tables S21–S28 in the Supporting Information), spin density, azo bond length (1.372/1.371 Å) (Figures S15 & S16 in the Supporting Information), and radical-based EPR , e, (Figure , Table ). The absence of a second reduction in dinuclear 2a / 2b in contrast to the earlier reported L1/L2/L3-derived analogous diruthenium complexes , could be interpreted in terms of the relatively higher energy of the β-LUMO of L4 •– as in the case of mononuclear 1 (Figure , Figures S14 & S17 in the Supporting Information).…”

“…(v) Unlike mononuclear 1 or 3 , radical state of the NN (1.359–1.374 Å) , function of L4 stabilized in the dimeric complexes, leading to the electronic forms of (acac) 2 Ru III (μ-L4 •– )­Ru II (acac) 2 and [(acac) 2 Ru III (μ-L4 •– )­Ru III (acac) 2 ]­ClO 4 for diastereomeric 2 and [ 2 ]­ClO 4 , respectively. (vi) Almost identical Ru–N­(azo) distances (2.007/2.009 Å) in 2a implied a delocalized mixed-valent (acac) 2 Ru II+0.5 (μ-L4 •– )­Ru II+0.5 (acac) 2 configuration in the solid state . (vii) Nearly planar and twisted N -methyl pyrazole rings of L4 in meso and rac forms of 2b/ [ 2b ]­ClO 4 (0.3°/0.21° (molecule A) and 0.4° (molecule B)) and 2a /[ 2a ]­ClO 4 (6.44°/24.49°) (Figure S11), respectively, were in agreement with the corresponding analogous L1, L2, and L3 derivatives. , (viii) Similar Ru···Ru distance in the dinuclear complexes [ rac - 2a/ [ 2a ]­ClO 4 : 4.833/4.762 Å and meso - 2b /[ 2b ]­ClO 4 : 4.834/4.815 (molecule A) or 4.783 (molecule B) Å] in spite of the twisted L4 bridge in the rac isomer with respect to the corresponding meso form.…”

“…In accordance with the structural authentication, electrically neutral and spin-paired or coupled ( S = 0) L4/L5/ 1/2a / 2b / 3 displayed sharp and distinct proton resonances within the standard chemical shift window of δ = 0–10 ppm (Figure , Figures S2–S4 Experimental Section). Mononuclear 1 or 3 displayed a 1 H NMR signature corresponding to the full molecule (4H (L4)/2H (L5), 2H (CH-acac), 2 CH 3 -L4/L5, 4 CH 3 -acac), while the presence of internal symmetry in 2a or 2b led to the resonances corresponding to the half molecule (2H (L4), 2H (CH-acac), 1 CH 3 -L4, 4 CH 3 -acac). , On the other hand, one-electron paramagnetic [ 2a ]­ClO 4 and [ 2b ]­ClO 4 exhibited 1 H NMR resonances over a wide chemical shift region of δ = +10 to −30 ppm (Figure S5) due to the contact shift effect (Figure S6). , The IR spectra (KBr disk) of L4, L5, 1 , 2a , 2b , [ 2a ]­ClO 4 , [ 2b ]­ClO 4 , 3 , and [ 4 ]­ClO 4 displayed ν­(NN) vibrations at 1376, 1395, 1260, 1232, 1234, 1233, 1231, 1258, and 1259 cm –1 , respectively, and ν­(ClO 4 ) vibrations at 1094/1097 and 1094 cm –1 for [ 2a ]­ClO 4 /[ 2b ]­ClO 4 and [ 4 ]­ClO 4 , respectively (Figure S7 and Experimental Section).…”

Ruthenium Azobis(benzothiazole): Electronic Structure and Impact of Substituents on the Electrocatalytic Single-Site Water Oxidation Process

“…The partial spin accumulation onto the metal ion in 1 – 3 (Table ), however, suggested the mixed electronic form of {Ru II -L •– }(major)/{Ru III -L 2– }(minor) instead of a precise description (Scheme ). , Further, electrochemically generated one-electron reduced 1 – 3 displayed a ligand-based isotropic EPR signal with the g values of 1.997, 1.993, and 1.985, respectively, at 298 K with a slightly structured feature due to metal-based anisotropy (Figure and Figure S10 and Table S6 in the Supporting Information), presumably due to the partial metal contribution at the singly occupied molecular orbital (SOMO) as reflected in the spin density plots . The successive reductions of the azo fragment in [ 1 ]ClO 4 –[ 3 ]ClO 4 led to the elongation and shortening of N azo –N azo and N azo –C8 distances, respectively (Table and Figures S11–S13 in the Supporting Information) as in the case of free L1–L3.…”

Donor–acceptor bridge 2,5-bis(2-oxido-phenyl)thiazolo-[5,4-d]thiazole derived diruthenium and diosmium systems. Structural and competitive electronic events as a function of metal ion, bridge and ancillary ligand

“…Continuing efforts have been devoted to redox-active ligand derived metal complexes due to their intriguing electronic forms 1 and application potential. 2 The primary thrust is to evaluate the redox noninnocence of the ligand moiety in the competitive electron transfer scenario 3,4 under a selectively designed coordination situation, followed by assessing the application aspects in molecular functionalisation, including catalysis.…”