Crystal structure and magnetic and EPR properties of bis(.mu.-azido)tetrakis(4-tert-butylpyridine)dicopper(II) perchlorate: a new copper(II) dinuclear complex with a large stabilization of the ground triplet state

Abstract

Wólfel (Technische Hochschule Darmstadt) provided access to the facilities (four-circle diffractometer and computer) of the Stoe + Cie. Application Laboratory, Darmstadt. The authors appreciate discussions on the manuscript with Dr. K. J. Wannowius. Propargylaldehyde was supplied by BASF, Ludwigshafen.Registry No. II, 22119-38-6; IV, 88106-41-6; Cu(TMBC)(C104)2, 88106-43-8; Cu(TMBC)I(C104), 88106-45-0; Cu(TMBC)(N3)(C104), 88106-47-2; Cu(TMBC)Br(C104), 88106-49-4; Cu(TMBC)(N03)2, 88106-51-8; Ni(TMBC)(C104)2, 88106-53-0; Ni(TMBC)Br2, 88106-54-1; Ni(TMBC)(N03)2, 88106-56-3; Cu(TMBC)(H20)2+, 88106-57-4; Cu(TMBC)N3+, 88106-46-1; Cu(TMBC)2+, 88106-58-5.Supplementary Material Available: Listings of observed and calculated structure factors and atomic parameters for TMBC, Cu-(TMBC)(N3)(C104), and Cu(TMBC)(C104)2 (105 pages). Ordering information is given on any current masthead page.

Ferromagnetic Interaction in an Asymmetric End‐to‐End Azido Double‐Bridged Copper(II) Dinuclear Complex: A Combined Structure, Magnetic, Polarized Neutron Diffraction and Theoretical Study

“…[1,2] In an effort to be concise, this work is restricted to the study of azido double-bridge copper(II) dinuclear systems. In these systems, the azido groups bridge the copper(II) ions either through one terminal nitrogen atom (m-1,1), in a socalled end-on coordination mode (abbreviated hereafter EO), [3][4][5][6][7][8][9][10][11][12][13][14][15][16] or through two terminal nitrogen atoms (m-1,3) in an end-to-end coordination mode (EE) as shown in Scheme 1. [11,[17][18][19][20][21][22][23] For both EO and EE systems, the bridge may be either symmetric (Scheme 1 a), when the two N À Cu bonds are Abstract: A new end-to-end azido double-bridged copper(II) complex [Cu 2 L 2 (N 3 ) 2 ] (1) was synthesized and characterized (L = 1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato).…”

“…Some asymmetric EO systems [11][12][13] have now been found that exhibit antiferromagnetic Cu À Cu interactions, while several cases of ferromagnetic couplings have been reported for asymmetric EE systems. [11,22,23] In the early studies, [3][4][5][6][17][18][19][20] the symmetric EO coordination mode behavior seemed intrinsically ferromagnetic and independent of any structural parameters. This is why most previous theoretical studies focused on EO systems to explain such peculiar behavior, [24,[26][27][28][29][30] which was initially attributed to spin polarization effects.…”

La technique classique du rapport de flipping. Application aux aimants moléculaires et aux aimants photo-commutables

“…Pour tous les dimères symétriques di-µ-azido-cu(II) synthétisés jusqu'à présent, on observe soit un fort couplage ferromagnétique, soit un fort couplage antiferromagnétique, selon la manière dont les deux groupes azide pontent les cuivres, soit par une extrémité, 'end-on' (µ − 1, 1-), soit par les deux extrémités, 'end-to-end' (µ − 1, 3-). Jusqu'à récemment, une longue controverse a eu lieu sur l'origine du fort couplage ferromagnétique dans les dimères 'end-on' de composés di-µ-azide cu(II) [29]. Les deux mécanismes principaux invoqués sont :…”

Cluster‐Based CuII–Azide Polymers: Synthesis, Structure, Magnetic Properties, and Effect of Polyamines on Crystal Structures

“…When the angle is smaller than 108°, it propagates ferromagnetic; otherwise, it is antiferromagnetic. [11][12][13][14][15] A more recent study based on theoretical calculations suggests a smaller critical angle (≈104°). [16][17][18] The second bridging mode (EE) usually gives rise to antiferromagnetic coupling and only in a few cases does ferromagnetic coupling occur through this pathway.…”