[Me₂NN]Co(η⁶-toluene):  OO, NN, and ON Bond Cleavage Provides β-Diketiminato Cobalt μ-Oxo and Imido Complexes

Abstract

The synthesis and structure of a novel beta-diketiminato Co(I) arene adduct [Me2NN]Co(eta6-toluene) (2) are described, that serves as a synthon to the reactive, "naked" 12-electron [Me2NN]Co fragment via loss of toluene in its reactions with dioxygen, organoazides, and a nitrosobenzene. Exposure of 2 to dioxygen in ether leads to {[Me2NN]Co}2(mu-O)2 (3), a rare example of a cobalt-oxo complex thermally stable at room temperature. The X-ray structure of 3 reveals a short Co-Co separation of 2.716(4) A and exhibits positional disorder for the bridging oxo groups; the predominant configuration contains oxygen atoms in square-planar sites with short Co-O distances (1.784(3) and 1.793(4) A). Reaction of 2 with organoazides N3R (R = 3,5-Me2C6H3 (Ar) or 1-adamantyl (Ad)) results in the formation of imido complexes whose structure depends on the nature of the azido substituent. The synthesis and structures of both {Me2NN]Co}2(mu-NAr)2 (4) with arylimido groups in tetrahedral bridging sites or the three-coordinate, 16-electron [Me2NN]CoNAd (5) are described. The X-ray structure of terminal imide 5 reveals a short Co-N bond distance (1.624(4) A) and only somewhat bent imido linkage (Co-N-C = 161.5(3) degrees ) consistent with a significant degree of multiple bond character. Complex 2 cleaves the O=N bond of the nitrosobenzene O=NAr (Ar = 3,5-Me2C6H3) to form the binuclear oxo-imido complex {[Me2NN]Co}2(mu-O)(mu-NAr) (6) that possesses a structure intermediate between square-planar 3 and tetrahedral 4 in which the [Me2NN]Co fragments are mutually orthogonal.

Three-coordinate bis(phosphinimino)methanide derivatives of ‘open shell’ [M(II)] (M=Mn, Fe, Co) transition metals

“…The molecular structure of 2 is illustrated in Although possibly a result of the increased steric demands of the Dipp substituents, this value is some 10-15°wider than the corresponding bite angles of three-coordinate b-diketiminate derivatives containing the same metal and coligand [6][7][8][9]. It is more likely therefore that this bite angle is influenced more directly by the chemical constitution, and hence conformation of the N-P-C-P-N chelate (vide infra).…”

“…As outlined above, b-diketiminato derivatives of the first row transition elements have given rise to a great variety of unusual and striking reaction chemistry [5][6][7][8][9]. ety of transition metal-catalysed processes such as olefin polymerisation, C-H activation and the activation of otherwise inert small molecules [17].…”

“…Use of the anion II, for example, has enabled the synthesis of several electronically and coordinatively unsaturated Ôopen shellÕ (i.e. <10 d electrons) derivatives of the divalent first row transition elements Mn, Fe and Co, some of which have demonstrated a spectacular reaction chemistry [6][7][8][9]. The common entry point for much of this chemistry has been the synthesis of low-coordinate halide and amido complexes.…”

A potential role of a substrate as a base for the deprotonation pathway in Rh-catalysed C–H amination of heteroarenes: DFT insights

“…In fact, metal-nitrenoid species are known to be generated in such reactions and a few examples of C-N bond formation upon treatment of the corresponding metal-nitrenoid species with hydrocarbons have also been reported. [25][26][27][28][29] The Scheme 2. Possible mechanism of C-H amination using phenyl azide as the nitrogen source.…”

Monomeric Thallium(I) Complexes of Fluorinated Triazapentadienyl Ligands

“…[9][10][11][12] Thallium(i) derivatives of triazapentadienyl ligands are of particular interest because they could serve as good ligand-transfer agents (like the commonly used thallium adducts of poly(pyrazolyl)borates and diazapentadienyl systems). [1,3,[13][14][15][16] [10] these protons give rise to nine separate doublets and four separate septets. This is similar to changes observed during the formation of the silver adducts [AgL{N[C(C 3 F 7 )N(dipp)] 2 }] (L = MeCN, tBuNC) from the free ligand.…”