Axial binding of 2-methylimidazole to the tetraarylcarboxylatodiruthenium (II, III) core: X-ray crystal structure of [Ru₂(O₂CC₆H₄-<em>p</em>-OMe)₄ (2-mimH)₂](CIO₄). 1.75CH₂CI₂.H₂O

Abstract

Diruthenium (II. III) complexes of the type [RU₂(O₂CAr)₄ (2- mimH)₂](CIO₄) (Ar = C₆H₄-<em>P</em>-X : X=OMe.l: X=Me. 2: 2-mimH=2- methylimidazole) have been isolated from the reaction of RU₂CI(O₂CAr)₄ with 2- mimH in CH₂Ch followed by the addition of NaCIO_4. The crystal structure of 1. 1.75CH₂CI₂.H₂O has been determined, The crystal belongs to the monoclinic space group <em>p</em>21/c with the following unit cell dimensions for the C₄₀H₄₀N₄O₁₆CIRu₂. I.75CH₂CI₂.H₂O (M= 1237.0) : a = 12.347 (3)&Aring;. <em>b</em> = 17615(5) &Aring;,<em>c</em> = 26.148(2) &Aring;.b = 9288(l)⁰,v = 5679(2) &Aring; '. <em>Z</em>=4. D_c = 1.45 g cm^-3 &lambda; (Mo- Ka) = 0.7107 &Aring;. &micro;(Mo-Ka) = 8.1 cm^-1. <em>T</em>= 293 K. R = 0.0815 (wR² =0.2118) for 5834 reflections with 1 &gt; 2 s(I). The complex has a tetracarboxylatodiruthenium (II. III) core and two axially bound 2-methylimidazole ligands. The Ru-Ru bond length is 2.290( I) &Aring;. The Ru-Ru bond order is 2.5 and the complex is three-electron paramagnetic. The complex shows an irreversible RU₂(II, III)&nbsp;RU₂(II, II) reduction near -0.2 V vs SCE in CH₂CI₂-0.1 <em>M</em>TBAP. The complexes exemplify the first adduct of the tetracarboxylatodiruthenium (II,III) core having N-donor ligands.