Notizen: Ein Additionsprodukt des Chrom(II)-acetats mit 2.2′-Dipyridyl: Di-acetato-bis-dipyridyl-Chrom(II), [CrDipy₂(CH₃COO)₂]

New Complexes of Chromium(III) Containing Organic π-Radical Ligands: An Experimental and Density Functional Theory Study

“…Regardless, the electronic structure of 1 is best described as [Cr III (bpy 0 )(bpy • )(CH 3 CO 2 ) 2 ] 0 , with the S = 1 ground state being obtained via antiferromagnetic coupling ( J calcd = −989 cm –1 ) between the Cr III center and unpaired spin of the (bpy • ) 1– ligand (see the qualitative FMO diagram and Mulliken spin density population analysis in Figures S10 and S4, Supporting Information). It most certainly does not contain low-spin Cr II , as suggested in the original reports. , …”

“…The above picture is reflected in the Mulliken spin density population analysis, which displays 3.11 α-spin on the chromium center, 1.00 β-spin on the bpy ligand, and virtually no spin density on the acetate and isopropylamine ligands. Once again, no evidence was found for a low-spin Cr II formulation, , so the electronic structure of 2 is [Cr III (bpy • )(CH 3 CO 2 ) 2 ( i PrNH 2 ) 2 ] 0 .…”

“…Following the procedure outlined in reference , involving reaction of the dimer [Cr II 2 (μ-CH 3 CO 2 ) 4 ] 0 and four equivalents of (bpy 0 ) in THF under strictly anaerobic conditions (eq ), we have been able to synthesize the black mononuclear complex [Cr(bpy) 2 (CH 3 CO 2 ) 2 ] 0 ( 1 ). A temperature-independent magnetic moment of 2.88 μ B in the range of 50–300 K indicates that 1 possesses an S = 1 ground state (Figure S1, Supporting Information).…”

“…Solvents were dried and degassed using literature procedures. The complexes [Cr(bpy) 2 (CH 3 CO 2 ) 2 ] 0 ( 1 ) and [Cr(bpy)( i PrNH 2 ) 2 (CH 3 CO 2 ) 2 ] 0 ( 2 ), and the ligands 1,4-bis(cyclohexyl)-1,4-diaza-1,3-butadiene (DAD 0 ), 2-(2-trifluoromethyl)anilino-4,6-di- tert -butylphenol [CF 3 AP]H 2 , and 2,6-bis[1-(4-methoxyphenyliminoethyl)]pyridine (PDI 0 ) were prepared as previously described. The purity of the complexes was confirmed by elemental analyses.…”

“…In 1963, Herzog et al reported that reaction of the dinuclear complex [Cr II 2 (μ-CH 3 CO 2 ) 4 ] 0 ·2THF (THF = tetrahydrofuran) with 4 equivalents of (bpy 0 ) in THF produces an air sensitive black powder corresponding to mononuclear [Cr(bpy) 2 (CH 3 CO 2 ) 2 ] 0 ( 1 , eq ), which has a magnetic moment of 3.01 μ B at ambient temperature in accord with a S = 1 ground state. , On this basis, the authors formulated 1 as a low-spin Cr II complex. The presence of isopropylamine ( i PrNH 2 ) in the aforementioned reaction led to formation of a different air-sensitive complex, [Cr(bpy)( i PrNH 2 ) 2 (CH 3 CO 2 ) 2 ] 0 ( 2 , eq ), which was also described as a low-spin Cr II species with an S = 1 ground state .…”