Tris(3-nitropentane-2,4-dionato-κ²O,O′)cobalt(III)

Abstract

The structure of the title compound, [Co(C5H6NO4)3], consists of a CoIII ion octahedrally coordinated by three bidentate 3-nitro­pentane-2,4-dionate ligands. The complex was prepared via the nitration of tris­(2,4-penta­nedionato-κ2 O,O′)cobalt(III) with a solution of copper(II) nitrate in glacial acetic acid. The central C atom and the nitro group of one 3-nitro­pentane-2,4-dionate ligand are disordered over two positions with an occupancy ratio of 0.848 (4):0.152 (4). A second nitro group is also disordered over two orientations with an occupancy ratio of 0.892 (7):0.108 (7). Two of the ligand methyl groups form C—H⋯O inter­actions with two different nitro groups to form chains running along the c axis. Additional C—H⋯O inter­actions are found between ligand methyl groups and the cobalt-bound O atoms, also resulting in the formation of chains along the c axis.

Synthesis and Thermal Behavior of Heteroleptic γ‐Substituted Acetylacetonate‐Alkoxides of Titanium

“…[7] The internal (γ-or 3-) position of the acac ligand has often been modified to allow the grafting of metal alkoxide complexes onto oxide surfaces [8,9] but data exploiting this modification to study the thermal degradation of such complexes were scarce and dealt only with homoleptic systems M(β-dik) 3 . [10][11][12][13][14] Herein, we report the syntheses of a series of heteroleptic titanium derivatives [Ti(OiPr) 2 (R-acac) 2 ] with acac ligands modified with different substituents (R = OAc, NO 2 , Me, Et, Cl, Br) at the γ-position and the impact on their thermal stability by thermogravimetric analysis (TGA) and Density Functional Theory (DFT) calculation in order to reach optimal thermal degradation of acac-based titanium complexes. DFT has become the theoretical quantum approach of choice to calculate structure and properties of molecular systems, thanks to its reasonable computational effort required.…”

“…Mass spectrometry studies have shown that [Ti(OiPr) 2 (thd) 2 ] thermally degraded to Ti(thd) 3 or TiO(thd) 2 species demonstrating that the nature of the β‐diketonate played a major role in the complete decomposition of the precursor [3] and that one of the starting point of the decomposition pathway was the cleavage of the external alkyl group (i. e. by β‐elimination) [7] . The internal (γ‐ or 3‐) position of the acac ligand has often been modified to allow the grafting of metal alkoxide complexes onto oxide surfaces [8,9] but data exploiting this modification to study the thermal degradation of such complexes were scarce and dealt only with homoleptic systems M(β‐dik) 3 [10–14] …”

Crystal structures of chloro-, bromo-, and nitro-substituted chromium(III) acetylacetonates

“…The rotation angle is 50-59°, lower than in aromatic analogs: in benzene derivatives, where nitro-group is surrounded by methyl groups, rotation angle is 66-86° [26][27][28]. Mean bond length C γ -N in 3 is 1.45 Å that matches the value for the cobalt complex (1.46 Å, mean value [12]) and lower than in aromatic compounds (1.47-1.49 Å).…”

“…One oxygen of nitro, connected with cycle B, interacts with C β -C γ bond of cycle B of a neighboring molecule, whose nitro interacts with the next molecule, similar to packed molecules of Co(acacNO 2 ) 3 [12]. Unlike Cu(acacNO 2 ) 2 [14], there is no interaction between nitro and metal ion of neighboring molecules in 3 due to isolation of chromium ion coordination sphere in acetylacetonate complexes.…”

“…Three halogen-substituted iridium acetylacetonates were described [10,11]. Recently a communication about Co(acacNO 2 ) 3 [12] has appeared. There are data reported in literature about structures of substituted bisacetylacetonates, e.g.…”