Synthesis, mixed valence aspects and non-linear optical properties of the triruthenium complexes [{(bpy)2RuII}3(L)] 3+ and [{(phen)2RuII}3(L)] 3+ (bpy = 2,2′-bipyridine, phen = 1, 10-phenanthroIine and L3- = 1,3,5-triazine-2,4,6-trithiol)

Sanjib Kar, Thomas A. Miller, Soma Chakraborty, Biprajit Sarkar, Biswajit Pradhan, Rajeev K. Sinha, Tapanendu Kundu, Michael D. Ward, Goutam Kumar Lahiri

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The triruthenium complexes [{(bpy)2RuII}L] 3+ [1]3+ and [{(phen)2RuII} 3L]3+ [2]3+ have been synthesized via the reactions of [RuII(bpy)2(EtOH)2]2+ and [RuII(phen)2EtOH)2]2+ with the trisodium salt of 1,3,5-triazine-2,4,6 trithiol (Na3L) respectively. In CH3CN, the complexes [1]3+ and [2]3+exhibit three reversible one-electron redox processes corresponding to successive Ru(II)/Ru(III) couples. The 190-250 mV separation in potential between the successive Ru(II)/Ru(III) couples is indicative of moderate intermetallic electronic coupling in the mixed valence states. The bipyridine and phenanthroline based reductions are observed at -1.58, -1.86 V and -1.77, -2.01, -2.43 V versus SCE respectively. The spectroelectrochemical study on the bipyridine derivative [1]n+ (n = 3-6) in acetonitrile medium at 243 K shows a broad and relatively weak intervalence charge-transfer transition (IVCT) near 1900 nm for both the mixed valence states RuIIRu IIRuIII [1]4+ and RuIIRu IIIRuIII [1]5+, characteristic of class II behaviour. The calculated coupling constant (Vab), 560 cm -1 is also supportive of class II mixed-valence states. The electrochemically generated one-electron oxidised species [1]4+ or [2]4+ exhibits an EPR spectrum characteristic of low-spin Ru III ion in a distorted octahedral environment (g1 = 2.246, g2 = 1.993 for [1]4+ and g1 = 2.469, g 2 = 2.191 for [2]4+). The complexes are moderately strongly luminescent at 77 K. Both the complexes have also shown third order non-linear optical properties with γ = -4.5 × 10-29 esu for [1]3+ and -5.09 × 10-29 esu for [2] 3+.

Original languageEnglish
Pages (from-to)2591-2596
Number of pages6
JournalDalton Transactions
Issue number12
Publication statusPublished - 21-06-2003

All Science Journal Classification (ASJC) codes

  • Inorganic Chemistry

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