Identification of Zr(iv)-based architectures generated from ligands incorporating the 2,2′-biphenolato unit

Abstract

The structural identification in solution of the Zr(iv) complexes involving two 2,2-biphenol-based proligands is reported. The proligand L(1)H2 contains one 2,2-biphenol unit whereas L(2)H4 incorporates two 2,2-biphenol units linked by a para-phenylene bridge. Diffusion Ordered Spectroscopy (DOSY) combined with electrospray mass spectrometry analysis and density functional theory (DFT) allowed for determining the molecular structures of such Zr(iv)-based architectures. It is proposed that [Zr(OPr(i))4(HOPr(i))] in the presence of L(1)H2 generates an octahedral complex formulated as [ZrL(1)3H2]. Concerning the self-assembled architecture incorporating the L(2) ligand, the analytical data highlight the formation of an unprecedented neutral Zr(iv) triple-stranded helicate ([Zr2L(2)3H4]). Insight into the geometry of these complexes is obtained via DFT calculations. Remarkably, the helicate structure characterized in solution strongly contrasts with the triple-stranded structure of the complex that crystallizes.

Synthesis, structure and functions of discrete titanium-based multinuclear architectures

“…The configuration of all the palladium fragments in the molecules displayed Fig. 67 was trans; this could be ascertained by NMR spectroscopy and/or crystallography (101a-d), or by far-IR spectroscopy (102). With regard to the configuration of titanium, the homochiral isomer 102 (D,D or L,L) was the most stable one according to molecular modeling, as for 99a;[243] by contrast, 101b was a mesocate (D,L) according to its crystal structure, and molecular modeling confirmed its stability on the basis of steric considerations.…”

“…Instead of a double-stranded helicate as observed with Ti(O i Pr)4, the formation of a triple-stranded architecture formulated as [Zr2L 1 2(L 1 H4)] (17) was highlighted. [102] Several binuclear double-stranded helicates constructed around TiO4N2 units and incorporating the bis-biphenolato strand L 1 have been described. These complexes were generated by applying a multicomponent self-assembly approach in presence of the pro-ligand L 1 H4, Ti(O i Pr)4 and monodentate or bidentate nitrogen ligands.…”