Coordination site-dependent cation binding and multi-responsible redox properties of Janus-head metalloligand, [Mo V(1,2-mercaptophenolato) 3]

Takeshi Matsumoto, Masanori Wakizaka, Hirokazu Yano, Atsushi Kobayashi, Ho Chol Chang, Masako Kato

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

The redox-active fac-[Mo V(mp) 3] - (mp: o-mercaptophenolato) bearing asymmetric O- and S-cation binding sites can bind with several kinds of metal ions such as Na +, Mn II, Fe II, Co II, Ni II, and Cu I. The fac-[Mo V(mp) 3] - metalloligand coordinates to Na + to form the contact ion pair {Na +(THF) 3[fac-Mo V(mp) 3]} (1), while a separated ion pair, n-Bu 4N[fac-Mo V(mp) 3] (2), is obtained by exchanging Na + with n-Bu 4N +. In the presence of asymmetric binding-sites, the metalloligand reacts with Mn IICl 2·4H 2O, Fe IICl 2· 4H 2O, Co IICl 2·6H 2O, and Ni IICl 2·6H 2O to afford UV-vis-NIR spectra, indicating binding of these guest metal cations. Especially, for the cases of the Mn II and Co II products, trinuclear complexes, {M(H 2O)(MeOH)[fac-Mo V(mp) 3] 2}·1.5CH 2Cl 2 (3·1.5CH 2Cl 2 (M = Mn II), 4·1.5CH 2Cl 2 (M = Co II)), are successfully isolated and structurally characterized where the M are selectively bound to the hard O-binding sites of the fac-[Mo V(mp) 3] -. On the other hand, a coordination polymer, {Cu I(CH 3CN)[mer- Mo V(mp) 3]} n (5), is obtained by the reaction of fac-[Mo V(mp) 3] - with [Cu I(CH 3CN) 4]ClO 4. In sharp contrast to the cases of 1, 3·1.5CH 2Cl 2, and 4·1.5CH 2Cl 2, the Cu I in 5 are selectively bound to the soft S-binding sites, where each Cu I is shared by two [Mo V(mp) 3] - with bidentate or monodentate coordination modes. The second notable feature of 5 is found in the geometric change of the [Mo V(mp) 3] -, where the original fac-form of 1 is isomerized to the mer-[Mo V(mp) 3] - in 5, which was structurally and spectroscopically characterized for the first time. Such isomerization demonstrates the structural flexibility of the [Mo V(mp) 3] -. Spectroscopic studies strongly indicate that the association/dissociation between the guest metal ions and metalloligand can be modulated by solvent polarity. Furthermore, it was also found that such association/dissociation features are significantly influenced by coexisting anions such as ClO 4 - or B(C 6F 5) 4 -. This suggests that coordination bonds between the guest metal ions and metalloligand are not too static, but are sufficiently moderate to be responsive to external environments. Moreover, electrochemical data of 1 and 3·1.5CH 2Cl 2 demonstrated that guest metal ion binding led to enhance electron-accepting properties of the metalloligand. Our results illustrate the use of a redox-active chalcogenolato complex with a simple mononuclear structure as a multifunctional metalloligand that is responsive to chemical and electrochemical stimuli.

Original languageEnglish
Pages (from-to)8303-8315
Number of pages13
JournalDalton Transactions
Volume41
Issue number27
DOIs
Publication statusPublished - 2012 Jul 21
Externally publishedYes

ASJC Scopus subject areas

  • Inorganic Chemistry

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