Benchmarking magnetic and spectroscopic properties on highly stable 3d metal complexes with tuneable bis(benzoxazol-2-yl)methanide ligands

Abstract

Two series a and b of 3d metal based complexes 1–4 [MII{(4-R-NCOC6H4)2CH}2], (with M = Mn (1), Fe (2), Co (3), Ni (4) and R = H (a) or Me (b)) were synthesised and structurally as well as magnetically characterized.

Structural and Magnetic Studies on Lanthanide Bis(benzoxazol‐2‐yl)methanides

“…1 H-NMR data demonstrate a trend in the HÀ C2 shifts, 88.8 ppm for 1, 77.2 ppm for 2, 62.0 ppm for 3, and 55.8 ppm for 4, respectively. 13 C-NMR signals are not resolved due to strong signal broadening (for detailed data see SI). However, well-defined differentiation between complex 1-4 is achieved via mass spectrometry, which shows m/z: 906.…”

“…The ligands were synthesized according to the previously reported procedure. [3a] The corresponding lanthanide-HMDS compounds were synthesized according to established methods from Hart et al [16] 1 H-and 13 C-NMR experiments were carried out on Bruker Avance 500 MHz, Bruker Avance 400 MHz, and Bruker Avance 300 MHz spectrometers. NMR data were referenced to the deuterated solvent (thf-d 8 ), which was dried over activated molecular sieves.…”

“…(bs, 2H, H), À 6. 13 [Ho{N(Si(CH 3 ) 3 ) 2 } 3 ] (3'):(modified approach of Hart et al [16] ) K(HMDS) (440 mg, 2.21 mmol, 3.00 eq.) in thf was dropwise added to HoCl 3 (200 mg, 0.74 mmol, 1.00 eq.)…”

“…p-1 H NMR (500 MHz, toluene-d 8 , ppm): δ À 72.46 (bs, 54 H, (Si(CH 3 ) 3 ) 6 ). 13 [(THF)Er{(NCOC 6 H 4 ) 2 CH}] (4): Er(HMDS) 3 (86.4 mg, 0.13 mmol, 1 eq.) in thf was dropwise added to Box (100 mg, 0.40 mmol, 3 eq.)…”

“…Only this year, we investigated the first d-metal Box compounds. [13] Those qualify for spectroscopic and magnetic benchmark systems and display easily adjustable model systems for a deep understanding of the structural and magnetic correlation. Since lanthanides usually outperform transition metals in the absolute values of magnetic anisotropy and magnetic moments, we strived to investigate the analogous f-metal complexes.…”