Structural and nonlinear optical properties of aligned heterotrinuclear [RuII-(Spacer)-MII-(Spacer)-RuII] Complexes (M=Pd, Pt; spacer=4-ethynylpyridine)

Abstract

Lewis addition between the metalloligand [RuCpACHTUNGTRENUNG(C≡Cpy-4) ACHTUNGTRENUNG(dppf)] (1) (dppf=(C5H4PPh2) 2Fe) and MCl2 ACHTUNGTRENUNG(CH3CN)2 gives [RuCpACHTUNGTRENUNG(C≡Cpy-4)-ACHTUNGTRENUNG(dppf)] 2ACHTUNGTRENUNG[MCl2] (M=Pd (2) and Pt (3)), all of which have been spectroscopically and crystallographically characterized. The mixed-metal adducts show the d6-d8-d6 metal alignment maintained by the trans disposition of the directionally rigid 4-ethynylpyridine at the centrosymmetric square-planar metal center. Electrochemical studies of these and the related known complexes trans-[RuClACHTUNGTRENUNG(C≡Cpy-4)ACHTUNGTRENUNG(dppm)2] (4) and [trans-RuClACHTUNGTRENUNG(C≡Cpy-4)-ACHTUNGTRENUNG(dppm)2] 2ACHTUNGTRENUNG[MCl2] (dppm=Ph2PCH 2PPh2) (M=Pd (5) and Pt (6)) suggest that the spacer-linked heterotrinuclear network is able to stabilize the oxidized RuIII better than the metalloligand precursor. Cubic nonlinear optical responses are also generally higher for the heterometallic complexes. The greal value of the PdRu2 dppm complex 5 is among the largest for linear organometallic complexes. © 2009 Wiley-VCH Verlag GmbH & Co. KGaA.