Enhanced Kinetic Lability of Ru(III) Centers in Oxo-Centered Mixed-Metal Ru₂M Trinuclear Complexes (M = Zn and Mg)

Abstract

Terminal pyridine (py)/pyridine-d 5 (py-d 5) exchange reactions have been investigated for oxo-centered mixed-metal trinuclear complexes, [Ru2Zn(O)(CH3CO2)6(py)3] (1) and [Ru2Mg(O)(CH3CO2)6(py)2(H2O)] (2), using 1H NMR spectroscopy. The exchange reaction of pyridine at Zn(II) with a solvated pyridine in 1·py takes place on the NMR time scale, while dissociative py/py-d 5 exchange reactions at Ru(III) in 1 and 2 proceed much more slowly but are substantially enhanced (480×, 25 °C) compared to the analogous reactions observed for (μ3-oxo)triruthenium(III) analogues.

Propriedades e aplicações de clusters trinucleares de carboxilatos de rutênio

“…A proximidade dos ions metálicos propicia a ocorrência de interações magnéti-cas e eletrônicas entre os sítios metálicos, tanto em compostos homonucleares, como em compostos heteronucleares do tipo [Ru 2 MO(CH 3 CO 2 ) 6 L 3 ] (M (II) = Mg [10][11][12] , Mn 8,11,13 , Co 8,11,[13][14][15] , Ni 8,11,13 , Zn 8,10-12 e M (III) = Cr 13,16 , Fe 13 , Co 14 , Rh 12,[17][18][19] ). A variedade de estados de oxidação leva a uma extensa química de valência mista.…”

Synthetic Design of Heterometallic Cluster Compounds with Site‐Selective and Stepwise Substitution of Bridging Carboxylates

“…[5][6][7][8] This feature has been solely demonstrated by kinetic studies for the substitution of monodentate ancillary ligands. [6, 7] Here we report that this site-selectivity is extended to the substitution of the bridging carboxylates in this class of compounds, through which more diverse, synthetic derivatization of the heterometallic clusters should be amenable. We show that the acetato ligands at the hetrometallic Ru···Mg sites are selectively substituted in the {Ru 2 MgOA C H T U N G T R E N N U N G (CH 3 COO) 6 } core in a stepwise manner, and the individual substituted products thus formed have been successfully separated and characterized.…”

“…[5][6][7][8] This feature has been solely demonstrated by kinetic studies for the substitution of monodentate ancillary ligands. [6, 7] Here we report that this site-selectivity is extended to the substitution of the bridging carboxylates in this class of compounds, through which more diverse, synthetic derivatization of the heterometallic clusters should be amenable.…”

“…Oxo-centered, acetato-bridged trinuclear complexes [Ru 6 (py) 3 ], where M = the first-row transition-metal divalent ions and Mg II and py = pyridine, constitute a rare but crucial class of heterometallic compounds, in which two distinct metal centers with remarkably different degrees of substitution-lability are incorporated. [5][6][7][8] This feature has been solely demonstrated by kinetic studies for the substitution of monodentate ancillary ligands.…”

“…[6,7] Here we report that this site-selectivity is extended to the substitution of the bridging carboxylates in this class of compounds, through which more diverse, synthetic derivatization of the heterometallic clusters should be amenable. We show that the acetato ligands at the hetrometallic Ru···Mg sites are selectively substituted in the {Ru 2 MgOA C H T U N G T R E N N U N G (CH 3 COO) 6 } core in a stepwise manner, and the individual substituted products thus formed have been successfully separated and characterized. The substitution-lability-dependent synthetic strategy described here will lead to a new generation of "multi-chromophore" compounds, in which the functional subunits are immobilized in the molecular framework in well-defined number and geometrical location.…”