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Magnetic Anisotropy of Mononuclear NiII Complexes: On the Importance of Structural Diversity and the Structural Distortions 下载免费PDF全文
Saurabh Kumar Singh Tulika Gupta Prashi Badkur Prof. Dr. Gopalan Rajaraman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(33):10305-10313
Mononuclear NiII complexes are particularly attractive in the area of single‐molecule magnets as the axial zero‐field splitting (D) for the NiII complexes is in the range of ?200 to +200 cm?1. Despite this advantage, very little is known on the origin of anisotropy across various coordination ligands, coordination numbers, and particularly what factors influence the D parameter in these complexes. To answer some of these questions, herein we have undertaken a detailed study of a series of mononuclear NiII complexes with ab initio calculations. Our results demonstrate that three prominent spin‐conserved low‐lying d–d transitions contribute significantly to the D value. Variation in the sign and the magnitude of D values are found to correlate to the specific structural distortions. Apart from the metal–ligand bond lengths, two different parameters, namely, Δα and Δβ, which are correlated to the cis angles present in the coordination environment, are found to significantly influence the axial D values. Developed magneto–structural D correlations suggest that the D values can be enhanced significantly by fine tuning the structural distortion in the coordination environment. Calculations performed on a series of NiII models with coordination numbers two to six unfold an interesting observation—the D parameter increases significantly upon a reduction in coordination number compared with a reference octahedral coordination. Besides, if high symmetry is maintained, even larger coordination numbers yield large D values. 相似文献
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Prashi Jain Shuyan Yi Patrick Thomas Flaherty 《Journal of heterocyclic chemistry》2013,50(Z1):E166-E173
This article focuses on the utility of organotrifluoroborate salts as coupling partners for Suzuki–Miyaura cross‐coupling with 4‐nitro‐6‐triflyl benzimidazoles using microwave irradiation. The C–C bond formation at the 6‐position of the electron‐rich 1‐,4‐,6‐trisubstituted benzimidazole core is challenging and was not achievable via Kumada, Negishi, Stille, or Heck coupling strategies. Yields of 37–70% could be obtained via palladium coupling strategies utilizing potassium benzyl trifluoroborates as the organometallic coupling partner. 相似文献
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