Synthesis and Oxidation Catalysis of [Tris(oxazolinyl)borato]cobalt(II) Scorpionates. Issue 15 (28th April 2016)

• Record Type: Journal Article
• Authors: Reinig, Regina R.; Mukherjee, Debabrata; Weinstein, Zachary B.; Xie, Weiwei; Albright, Toshia; Baird, Benjamin; Gray, Tristan S.; Ellern, Arkady; Miller, Gordon J.; Winter, Arthur H.; Bud'ko, Sergey L.; Sadow, Aaron D.
• Other Names: Pettinari C. guestEditor.
• Is Part Of: European journal of inorganic chemistry. Issue 15/16(2016)
• Page Start: 2486
• Page End: 2494
• Publication Date: 2016-04-28
• Subjects: Scorpionates -- Oxazolines -- Cobalt -- Structure elucidation -- Oxidation; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.201600237
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract : The reaction of CoCl2 · THF and thallium tris(4, 4‐dimethyl‐2‐oxazolinyl)phenylborate (TlTo M ) in tetrahydrofuran (THF) provides To M CoCl (1 ) in 95 % yield; however, appropriate solvents and starting materials are required to favor1 over two other readily formed side‐products, (To M )2 Co (2 ) and {HTo M }CoCl2 (3 ). ESR, NMR, FTIR, and UV/Vis spectroscopies were used to distinguish these cobalt(II) products and probe their electronic and structural properties. Even after the structures indicated by these methods were confirmed by X‐ray crystallography, the spectroscopic identification of trace contaminants in the material was challenging. The recognition of possible contaminants in the synthesis of To M CoCl in combination with the paramagnetic nature of these complexes provided impetus for the utilization of X‐ray powder diffraction to measure the purity of the To M CoCl bulk sample. The X‐ray powder diffraction results provide support for the bulk‐phase purity of To M CoCl in preparations that avoid2 and3 . Thus, 1 is a precursor for new [tris(oxazolinyl)borato]cobalt chemistry, as exemplified by its reactions with KO t Bu and NaOAc to give To M CoO t Bu (4 ) and To M CoOAc (5 ), respectively. Compound5 is a catalyst for the oxidation of cyclohexane with meta ‐chloroperoxybenzoic acid ( m CPBA), and the rate constants and selectivity for cyclohexanol versus cyclohexanone and ε‐caprolactone were assessed. Abstract : A series of high‐spin [tris(oxazolinyl)borato]cobalt(II) scorpionate complexes are synthesized and characterized by X‐ray diffraction and spectroscopic investigations. The bulk‐phase purity of these complexes is verified by X‐ray powder diffraction.