Isomeric Diruthenium Complexes Bridged by Deprotonated Indigo in cis and trans Configuration

Abstract

Abstract:The doublyd eprotonated form L 2À of indigo = H 2 L can bind two [Ru(acac) 2 ]c omplex fragments in the cis (1) and trans configuration (2), as evidenced from crystal structure analysis. While the latter type of N,O;N ' ,O ' coordination has been observed earlier,f or example, with [Ru(bpy) 2 ] 2 + , leading to two equivalent six-membered ring chelates, the cis arrangementi n1 is observed here fort he first time in a dinuclear complex, producing one five-membered ring chelate with N,N ' coordination and one seven-membered chelate with O,O ' coordination.T he different structures of the isomersr esult in differing electrochemical and spectroelectrochemical (EPR, UV-Vis-NIR) responses for variousa ccessible charges tates 1 n and 2 n , n = -, 0, + ,2+ .T he associated electronic structures were analyzed by DFT( structures, spin density) and TD-DFT calculations (electronic transitions),r evealing mainly metal-based reduction but largely indigo ligand-based oxidation of both neutralprecursors.

Redox‐Induced Oxidative C−C Bond Cleavage of 2,2′‐Pyridil in Diruthenium Complexes

“…The combination of monoanionic picolinate (pic À )l igand and the s-donating acac ancillary fragment favors the high-valent Ru III oxidation state in complex 2 (Scheme 2). [10] The neutral complexes 1, 2,a nd 3a/3 b yielded satisfactory microanalytical and mass-spectral data ( Figure S1, Supporting Information). The diamagnetic compounds 1 and 3a/3 b exhibited sharp and distinct 1 HNMR signals over ac hemical shift range from d = 9.5 to 1ppm in CDCl 3 at 298 K( FigureS2).…”

Metal Complexes of Indigo and of Some Related Ligands

“…Most notable, Kaim and Lahiri and their co‐workers succeeded to synthesize a pair of the isomeric diruthenium complexes with trans ‐ N,O‐N,O and with cis ‐ N,N ‐ O,O coordination of the bridging dianionic indigo ligands (Scheme ). In the complex with cis configuration of the deprotonated indigo ligand a five‐membered and a seven‐membered chelate ring were ascertained by X‐ray structure analysis.…”

Ruthenium‐Hydride Assisted Remarkable Diversity Towards Non‐Spectator Feature of Benzodifuroxan

“…Though isomeric 1 and 2 exhibited almost identical oxidation potential, reasonable variation (160 mV) in potential was noted for the other isomeric pair 3 a/3 b. [9,14] The pertaining…”

“…[7,8] Six-membered chelate involving N,O donating (nitroanilido) L 1 , L 2 , L 4 , L 5 in 1, 2, 4, 5, respectively, exhibited larger chelate bite angle of~82 ο -87 ο with respect to the five-membered N,N' donating (L 3 ) chelate bite angle of~77 ο in 3 a/ 3 b. [9] 1, 2, 3 b, 4, 5, 6 also displayed similar bond parameters involving {Ru(Cl)(CO)(PPh 3 ) 2 } unit. [2b] However, a significant increase in Ru1À N1 bond length was selectively taken place in 3 a owing to the presence of π-accepting CO group trans to σdonating NH À .…”

“…Tunable electronic, redox and reactivity profiles of biochemically relevant benzofuroxan heterocycle [1] -a ring-chain tautomeric form of 1,2-dinitrosobenzene have initiated the recent exploration of its binding feature as a function of electronic modulation at the metal fragment (Scheme 1). [2] It extended ring fission of benzofuroxan, which in effect led to (i) symmetric N,N-binding mode (I) in combination with {Ru(bpy) 2 } (bpy = 2,2'bipyridine)/{Ru(pap) 2 } (pap = 2-phenylazopyridine)/{Ru( [9] aneS3)} ( [9]aneS3 = 1,4,7-trithiacyclononane), (ii) unsymmetric O,N -bonded III in conjunction with {Ru(H)(CO)(Cl)(PPh 3 ) 2 } via the hydrogen bonded monodentate form in intermediate II and (iii) unsymmetric N,N' bonded IV-V with {Ru(acac) 2 } (acac = acetylacetonate).…”