The First Cobalt Metallacrowns:  Preparation and Characterization of Mixed-Valence Cobalt(II/III), Inverse 12-Metallacrown-4 Complexes

Abstract

Aerobic reactions of Co(O(2)CMe)(2).4H(2)O with di-2-pyridyl ketone oxime (Hpko) in the presence of counterions (ClO(4)(-), PF(6-)) give the tetranuclear, mixed-valence cobalt(II/III) clusters [Co(II)(2)Co(III)(2)(OR)(2)(O(2)CMe)(2)(pko)(4)S(2)]X(2) [R = H, S = MeOH, X = ClO(4) (1); R = Me, S = EtOH, X = PF(6) (2)] depending on the solvent mixture. Complexes 1 and 2 are the first Co members in the family of metallacrowns adopting the extremely rare inverse 12-metallacrown-4 motif.

A rare mixed-valence state manganese(II/IV) tetranuclear cage formed using phenyl 2-pyridyl ketone oxime and azide as ligands

“…Complex 1 is only the second example of a tetranuclear mixed-valent manganese cage with a 2e À difference between the oxidation states, the first being a cluster with the [Mn 4 (l 4 -O)(g 1 , l 2 -OR)] 7+ core (R = PhCO) [12], as well as a rare example of a tetranuclear manganese complex containing azide ligands [13]. The first crystallographically characterized metal complexes of (ph)(py)CNOH were the carbonyl compounds [Os 3 (CO) 8 Solid state dc magnetic susceptibility studies measurements were performed on a polycrystalline sample of 1 in the range 2.0-300 K, under a field of 0.3 T (Fig. 2, inset).…”

Synthesis and Structural Characterization of a New Tetranuclear Nickel(II) Sulfato Complex Containing the Anionic Form of Di-2-Pyridyl Ketone Oxime

“…There is currently a renewed interest in the coordination chemistry of oximes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. 2-pyridyl oximes (Scheme 1) are popular ligands in coordination chemistry [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. The anions of these molecules are versatile ligands for a variety of research objectives, including μ 2 and μ 3 behaviour [21,22]; the activation of 2-pyridyl oximes by 3d-metal centers towards further reactions is also becoming a fruitful area of research [21,22,26].…”

Use of the 2‐Pyridinealdoxime/N,N′‐Donor Ligand Combination in Cobalt(III) Chemistry: Synthesis and Characterization of Two Cationic Mononuclear Cobalt(III) Complexes

“…Reaction schemes involving di-2-pyridyl ketone oxime, dpkoxH (Figure 1), and various Co carboxylate sources led [16] to the first mixed-valence Co(II,III), inverse 12-metallacrown-4 complexes, namely, [Co 2 II Co 2 III (OR) 2 (O 2 CR′) 2 (dpkox) 4 S 2 ]X 2 (R = H, CH 3 ; R ′ = CH 3 , C 6 H 5 , (CH 3 ) 3 ; S = solvent; X = ClO 4 , PF 6 ). The use of phenyl 2-pyridyl ketone oxime, phpkoxH (Figure 1), methyl 2-pyridyl ketone oxime, MepaoH (Figure 1), and 2-pyridinealdoxime, paoH (Figure 1) in Co carboxylate chemistry yielded [17] the trinuclear, mixed-valence, carboxylate-free Co(II,III) complexes [Co 3 (phpkox) 6 ](PF 6 ) 2 , [Co 3 (Mepao) 6 ](ClO 4 ) 2 , and [Co 3 (pao) 6 ](ClO 4 ) 2 .…”