A Ditopic Catechol Phosphane as Building Block for Selective Construction of Heterometallic Complexes with Early and Late Transition Metal Centers1. Issue 2 (9th January 2014) - Bauer, Gernot
Abstract: Base‐assisted reaction of catechol phosphane2 (H2 L) with [M′Cl2 (cod)] (cod = 1, 5‐cyclooctadiene, M′ = Pd, Pt) yielded chelate complexes [M′(HL)2 ] (7a, b ). Spectroscopic and single‐crystal X‐ray diffraction studies revealed that both complexes feature cis ‐configuration of the P‐ and O‐donor atoms in solution and in the solid state. Reaction of7a, b with acetylacetonato or alkoxide complexes [MO2 (acac)2 ] (M = Mo, W), [VO(acac)2 ], [{Ti(μ‐O)(acac)2 }2 ], or Ti(O i Pr)4 gave good to excellent yields of early‐late heterometallic complexes [MO n (μ‐L)2 M′] (MO n = MoO2, WO2, VO;8a, b –10a, b ) or [Ti(RO‐1κ O )2 (μ‐L ‐1κ 2 O, O' ‐2κ 2 P, O )2 Pd] (R = Me, i Pr;11a, b ), which were inaccessible via other synthetic routes. Spectroscopic and single‐crystal X‐ray diffraction studies revealed that the early metal centres in8a, b, 9b and in11b feature distorted octahedral coordination spheres with rigid transoid alignment of the catechol ring planes. Vanadium complexes10a, b exhibit a square‐pyramidal coordination sphere with cisoid alignment of the catechol ring planes and evidence for intermolecular pairing via weak VO··· Pd contacts in the solid state; complexes8, 9 do not undergo conformational inversion on the NMR time‐scale. The molecular structure of Ti complex11a is characterized by a different orientation of the catechol moieties, which can be envisaged to picture an intermediate state during a configuration inversion process, and a strong hydrogen bridge between a terminally coordinated catecholato‐oxygen atom and a solvent molecule (MeOH). Solution NMR studies indicate that the (MeO)2 Ti(μ‐L)2 M' framework is in this case conformationally labile and that the MeO ligands undergo intermolecular dynamic exchange with the solvent. Abstract :