Synthese und Eigenschaften neuartiger Alkalimetall‐Alkoxo‐ und ‐Aroxocobaltate(II)

Abstract

Synthesis and Properties of Novel Alkali Metal Alkoxo‐ and Aroxocobaltates(II). By reaction of CoBr2 or CoBr2 · 2THF with 4–5 moles of MOR in THF, M  Li, Na, K, R = iso‐propyl (iPr), phenyl (Ph), 2‐naphthyl (2‐Naph), the following novel alkali metal alkoxo‐ and aroxocobaltates(II) have been prepared. Li2Co(OiPr)4 · LiBr · 3THF (1), Na2Co(OiPr)4 · THF (2), KCo(OiPr)3 · THF (3), Li2Co(OPh)4 · 4THF (4), Na2Co(OPh)4 · 5THF (5), K2Co(OPh)4·0,75THF (6), Li2Co(O‐2‐Naph)4 · 4THF (7), Na2Co(O‐2‐Naph)4 · 5THF (8), K2Co(O‐2‐Naph)4 · 2THF (9), and K3Co(O‐2‐Naph)5 · 2THF (10). The blue and violet, crystalline and very air‐sensitive (i.e. protolytically sensitive) compounds, some with good solubilities in organic solvents, eliminate THF in vacuo at temperatures between 50 and 100°C to yield the corresponding THF‐free compounds (1a) to (10a). Electronic spectra (VIS/NIR) and the results of magnetic measurements at 293 K point to preferred (but not exclusive) tetrahedral coordination of cobalt(II).

Homoleptic Cobalt and Copper Phenolate A2[M(OAr)4] Compounds: The Effect of Phenoxide Fluorination

“…A previous report of some [M(OAr F ) 4 ] 2anions provided spectroscopic characterization 60 and proposed metal coordination 61 geometries, some of which are shown to be incorrect (vide infra). An earlier report 62 exists of the compounds Li 2 Co(OPh) 4 ‚4THF, Na 2 Co(OPh) 4 ‚5THF, and K 2 Co(OPh) 4 ‚0.75THF but no structural characterization was performed, and substantial color changes from blue to red were observed upon loss of THF, suggesting metal coordination environment changes from tetrahedral to octahedral, vide infra. No data were provided to distinguish M 2 [Co(OPh) 4 ] structures from [MOPh]/ [MCo(OPh) 3 ] mixtures.…”