Electronic Structures of Ruthenium and Osmium Complexes of 9,10-Phenanthrenequinone

Biswas, Manas Kumar; Patra, Sarat Chandra; Maity, Amarendra Nath; Ke, Shyue-Chu; Adhikary, Nirmal Das; Ghosh, Prasanta

doi:10.1021/ic300327x

Cited by 30 publications

(23 citation statements)

References 108 publications

(63 reference statements)

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“…1, 2 and 3 were isolated in good yields. 4 was prepared by the reported procedure 4 and the diffusion of iodine in n-hexane to 4 in CH 2 Cl 2 produces 4 + I 3 − in lower yields.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

“…3 Recently, the electronic structures of a paramagnetic family of PQ of type trans-[M(PQ)(PPh 3 ) 2 (CO)(X)] and cis-[M(PQ)(PPh 3 ) 2 (CO)(X)] with the redox-active metal ions (M = Ru, Os; X = Cl, Br) incorporating triphenyl phosphine (PPh 3 ), carbonyl and halide as co-ligands were reported. 4 The article disclosed that trans-[M(PQ)(PPh 3 ) 2 (CO)(X)] and cis-[M(PQ)(PPh 3 ) 2 (CO)(X)] are PQ˙− complexes of ruthenium(II) and osmium(II), as shown by A, defined as trans-[M II (PQ˙−)(PPh 3 ) 2 (CO)X] and cis-[M II (PQ˙−)-(PPh 3 ) 2 (CO)X] with a minor contribution of the alternate resonance form, trans or cis-[M I (PQ)(PPh 3 ) 2 (CO)X], as illustrated by B of Scheme 1. Significant observations documented in the article are: (i) all the anionic complexes are PQ 2− complexes of ruthenium(II)/osmium(II) (ii) all the cationic complexes are neutral PQ complexes of ruthenium(II)/osmium(II) (iii) the ground state electronic structure of the neutral paramagnetic complexes is best described by a superposition of the valence tautomers of PQ˙− coordinated to ruthenium(II)/osmium(II) and PQ coordinated to ruthenium(I)/osmium(I) ions and (iv) PQ˙−/PQ 2− redox couple of the cis-analogues is irreversible even at 253 K due to the PPh 3 dissociation.…”

Section: Introductionmentioning

confidence: 99%

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9,10-Phenanthrenesemiquinone radical complexes of ruthenium(iii), osmium(iii) and rhodium(iii) and redox series

Biswas¹,

Patra²,

Maity

et al. 2013

Dalton Trans.

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Reactions of 9,10-phenanthrenequinone (PQ) in toluene with [M(II)(PPh3)3X2] at 298 K afford green complexes, trans-[M(PQ)(PPh3)2X2] (M = Ru, X = Cl, 1; M = Os, X = Br, 2) in moderate yields. Reaction of anhydrous RhCl3 with PQ and PPh3 in boiling ethanol affords the dark brown paramagnetic complex, cis-[Rh(PQ)(PPh3)2Cl2] (3) in good yields. Diffusion of iodine solution in n-hexane to the trans-[Os(PQ) (PPh3)2(CO)(Br)] solution in CH2Cl2 generates the crystals of trans-[Os(PQ)(PPh3)2(CO)(Br)](+)I3(-), (4(+))I3(-)), in lower yields. Single crystal X-ray structure determinations of 1·2toluene, 2·CH2Cl2 and 4(+)I3(-), UV-vis/NIR absorption spectra, EPR spectra of 3, electrochemical activities and DFT calculations on 1, 2, trans-[Ru(PQ)(PMe3)2Cl2] (1Me), trans-[Os(PQ)(PMe3)2Br2] (2Me), cis-[Rh(PQ)(PMe3)2Cl2] (3Me) and their oxidized and reduced analogues including trans-[Os(PQ)(PMe3)2(CO)(Br)](+) (4Me(+)) substantiated that 1-3 are the 9,10-phenanthrenesemiquinone radical (PQ(˙-)) complexes of ruthenium(III), osmium(III) and rhodium(III) and are defined as trans/cis-[M(III)(PQ(˙-))(PPh3)2X2] with a minor contribution of the resonance form trans/cis-[M(II)(PQ)(PPh3)2X2]. Two comparatively longer C-O (1.286(4) Å) and the shorter C-C lengths (1.415(7) Å) of the OO-chelate of 1·2toluene and 2·CH2Cl2 and the isotropic fluid solution EPR signal at g = 1.999 of 3 are consistent with the existence of the reduced PQ(˙-) ligand in 1-3 complexes. Anisotropic EPR spectra of the frozen glasses (g11 = g22 = 2.0046 and g33 = 1.9874) and solids (g11 = g22 = 2.005 and g33 = 1.987) instigate the contribution of the resonance form, cis-[Rh(II)(PQ)(PPh3)2Cl2] in 3. DFT calculations established that the closed shell singlet (CSS) solutions of 1Me and 2Me are unstable due to open shell singlet (OSS) perturbation. However, the broken symmetry (BS) (1,1) Ms = 0 solutions of 1Me and 2Me are respectively 22.6 and 24.2 kJ mole(-1) lower in energy and reproduced the experimental bond parameters well prompting the coordination of PQ(˙-) to the M(III) ions. The comparatively shorter C-O lengths, 1.268(4) and 1.266(5) Å and the longer C-C length, 1.466(6) Å, are consistent with the PQ chelation to osmium(II) ion in 4(+). The reversible anodic waves at 0.22, 0.22, and 0.18 V of 1-3, referenced by the Fc(+)/Fc couple, are assigned to the PQ(˙-)/PQ couple forming PQ complexes as trans/cis-[M(III)(PQ)(PPh3)2X2](+) while the cathodic waves at -0.92 and -0.89 V of 2 and 3 are due to formations of PQ(2-) complexes as trans-[M(III)(PQ(2-))(PPh3)2X2](-). 1 displays two overlapping cathodic waves at -0.72(89), -1.0(120) V. EPR spectrum of the frozen glass of 1(-) along with DFT calculations detected the contribution of both the valence tautomers, trans-[Ru(III)(PQ(2-))(PPh3)2Cl2](-) (g1 = g2 = 2.456; g3 = 1.983) and trans-[Ru(II)(PQ(˙-))(PPh3)2X2](-) (g(iso) = 1.999) in the anion. The characteristic lower energy absorption bands of 1 and 2 at 700 nm were assigned to CSS-OSS perturbation MLCT those are absent in paramagnetic 3, 1(+), 2(+), 1(-), 2(-) and 4(+)...

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“…1, 2 and 3 were isolated in good yields. 4 was prepared by the reported procedure 4 and the diffusion of iodine in n-hexane to 4 in CH 2 Cl 2 produces 4 + I 3 − in lower yields.…”

Section: Dalton Transactions Papermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

9,10-Phenanthrenesemiquinone radical complexes of ruthenium(iii), osmium(iii) and rhodium(iii) and redox series

Biswas¹,

Patra²,

Maity

et al. 2013

Dalton Trans.

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“…The Ru–Cl length is 2.333(2) Å, which is relatively shorter than Ru II –Cl lengths. 13 Similarly, the Ru–O length, 2.104(4) Å, is relatively shorter. 14 The Ru–N IQ length is 2.072(4) Å.…”

Section: Resultsmentioning

confidence: 99%

Orthometalated N-(Benzophenoxazine)-o-aminophenol: Phenolato versus Phenoxyl States

Mondal¹,

Bera²,

Maity³

et al. 2018

ACS Omega

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The molecular and electronic structures of the orthometalated ruthenium(III) and osmium(III) complexes of N -(benzophenoxazine)- o -aminophenol ( OX LH 2 ) that exhibits versatile redox activities are reported. The redox chemistry of OX LH 2 is remarkably different from that of N -(aryl)- o -aminophenol ( AP LH 2 ). The study established that OX LH 2 is redox noninnocent and is a precursor of a phenoxyl radical. One of the C–H bonds of OX LH 2 is activated by ions, and OX LH 2 reveals three different redox states as dianionic phenolato ( OX L 2– ), monoanionic phenoxyl radical ( OX L •– ), and zwitterionic phenoxium cation ( OX L ± ) states. The reaction of OX LH 2 with [Ru II (PPh 3 ) 3 Cl 2 ] in boiling toluene in air affords an orthometalated OX L 2– complex of ruthenium(III), trans -[( OX L 2– )Ru III (PPh 3 ) 2 (Cl)] ( 1 ), whereas the similar reaction with [Os II (PPh 3 ) 3 Br 2 ] yields an orthometalated OX L •– complex, cis -[( OX L •– )Os III (PPh 3 )Br 2 ] ( 2 ). 1 and 2 exhibit ligand-based reversible redox waves due to OX L •– / OX L 2– , OX L ± / OX L •– , and M III /M II couples. The 1 + ion is a OX L •– complex of ruthenium(III). 2 – exhibits temperature-dependent valence tautomerism due to [Os II ( OX L •– ) ↔ Os III ( OX L 2– )] equilibrium. 2 2– is a OX L 2– ...

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“…These transitions are diagnostic of the singly-reduced radical pd À , [17][18][19] as also observed for related 9,10-phenanthrenesemiquinone (pq À ) complexes [MX(pq À )(PPh 3 ) 2 (CO)] (M = Ru, X = Cl; M = Os, X = Br) where the dominant feature is also assigned as a pp* ILCT. 21,22 In conclusion, this work represents the discovery and success of a novel approach to the synthesis of rare earth-transition metal complexes. The stability of the bridging pd À ligand, and the selectivity of N,N 0 -binding for Y(III) have been demonstrated.…”

Section: Conflicts Of Interestmentioning

confidence: 89%

The semiquinone radical anion of 1,10-phenanthroline-5,6-dione: synthesis and rare earth coordination chemistry

et al. 2018

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Reduction of 1,10-phenanthroline-5,6-dione (pd) with CoCpR2 resulted in the first molecular compounds of the pd˙- semi-quinone radical anion, [CoCpR2]+[pd]˙- (R = H, (1); R = Me4, (2)). Furthermore compounds 1 and 2 were reacted with [Y(hfac)3(thf)2] (hfac = 1,1,1-5,5,5-hexafluoroacetylacetonate) to synthesise the rare earth-transition metal heterometallic compounds, [CoCpR2]+[Y(hfac)3(N,N'-pd)]˙- (R = H, (3); R = Me4, (4)).

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Electronic Structures of Ruthenium and Osmium Complexes of 9,10-Phenanthrenequinone

Cited by 30 publications

References 108 publications

9,10-Phenanthrenesemiquinone radical complexes of ruthenium(iii), osmium(iii) and rhodium(iii) and redox series

9,10-Phenanthrenesemiquinone radical complexes of ruthenium(iii), osmium(iii) and rhodium(iii) and redox series

Orthometalated N-(Benzophenoxazine)-o-aminophenol: Phenolato versus Phenoxyl States

The semiquinone radical anion of 1,10-phenanthroline-5,6-dione: synthesis and rare earth coordination chemistry

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