Sodium, magnesium and zinc complexes of mono(phenolate) heteroscorpionate ligands

Journal article

The reaction of bis(3,5-dimethylpryrazolyl)methylphenol N₂O^ArH (1) with NaH in THF formed dimeric [Na(κ²-N₂O^Ar)(THF)]₂ (2), which contains a κ²(N,O)-bound bidentate N₂O^Ar)ligand. The reactopm of 1 with MgⁿBu₂ gave the four-coordinate monomeric butyl compound Mg(N₂O^Ar)ⁿBu (3), whereas with ⁿBuMgCl, a mixture of products was formed, including the six-coordinate homoleptic species Mg(N₂O^Ar)₂ (4). The reaction of [Na(κ²-N₂O^Ar)(THF)]₂ with ⁿBuMgCl also gave 3, as did the redistribution reaction of MgⁿBu₂ with 4. The reaction of 1 with Mg{N(SiRMe₂)₂}₂ afforded the four-coordinate amide derivatives Mg(N₂O^Ar){N(SiRMe₂)₂} (R = Me (6) or H (7)), together with 4. The reactions of 1 with ZnMe₂ or Zn{N(SiMe₃)₂}₂ gave the monomeric compounds Zn(N₂O^Ar)Me (8) and Zn(N₂O^Ar){N(SiMe₃)₂} (9) respectively. The reaction of 9 with HCl formed Zn(N₂O^Ar)Cl (11), and subsequent addition of LiN(SiHMe₂)₂ to 11 led to Zn(N₂O^Ar){N(SiHMe₂)₂} (12). The reaction of 1 with either Zn{N(SiMe₃)₂}2 or 9 gave Zn(N₂O^Ar)₂. The compounds 2, 3, 4, 6, 8, 9 and 11 were crystallographically characterized. Compound 7 was very active for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) but the process was very poorly controlled as judged by the Mn and polydispersity index of the polymer. Compounds 3, 8, 9 and 12 gave poor conversions to poly(ε-CL) over extended periods. N₂0^ArH = 2,4-di-tert-butyl-6-(bis(3,5-dimethylpryrazolyl)methyl)phenol.

Authors: Schofield, A; Barros, M; Cushion, M; Schwarz, A; Mountford, P

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Royal Society of Chemistry Publishing
• Journal: Dalton Transactions
• Issue: 1
• Pages: 85-96
• Publication date: 2009-01-01
• DOI: 10.1039/b813116c
• EISSN: 1477-9234
• ISSN: 1477-9226
• Language: English
• Subjects: Chemistry & allied sciences