Models for Cooperative Catalysis: Oxidative AdditionReactions of Dimethylplatinum(II) Complexes with Ligands Having BothNH and OH Functionality

摘要

The role of NH and OH groups in the oxidative addition reactions of the complexes [PtMe2(κ²-N,N′->L)], >L = 2-C5H4NCH2NH-x-C6H4OH [>3, x = 2, >L = >L1; >4, x = 3, >L = >L2; >5, x = 4, >L = >L3], has been investigated. Complex >3 is the most reactive. It reacts with CH2Cl2 to give a mixture of isomers of [PtMe2(CH2Cl)(κ³-N,N′,O-(>L1-H)], >6, and decomposes in acetone to give [PtMe3(κ³-N,N′,O-(>L1-H)], >7, both of which contain the fac tridentate deprotonated ligand. Complex >3 reacts with MeI to give complex >7, whereas >4 and >5 react to give [PtIMe3(κ²-N,N′->L2))], >8, or [PtIMe3(κ²-N,N′->L3)], >9, respectively. Each complex >3, >4, or >5 reacts with either dioxygen or hydrogen peroxide to give the corresponding complex [Pt(OH)2Me2(κ²-N,N′->L)], >10, >L = >L1; >11, >L = >L2; >12, >L = >L3. The ligand >L3 in complexes >9 and >12 is easily oxidized to the corresponding imine ligand 2-C5H₄NCH=N-4-C₆H₄OH, >L4, in forming the complexes [PtIMe₃(κ²-N,N′->L4)], >13, and [Pt(OH)₂Me₂(κ²-N,N′->L4)], >14, respectively. The NH and OH groups play a significant role in supramolecular polymer or sheet structures of the complexes, formed through intermolecular hydrogen bonding, and these structures indicate how either intramolecular or intermolecular hydrogen bonding may assist some oxidative addition reactions.