Single-crystal EPR and 15N powder ENDOR studies of [(C4H9)4N][TcVINBr4/TcVOBr4]

K. Köhler; R. Kirmse; R. Böttcher; U. Abram

doi:10.1016/0301-0104(92)80128-I

Single-crystal EPR and ¹⁵N powder ENDOR studies of [(C₄H₉)₄N][Tc^VINBr₄/Tc^VOBr₄]

K. Köhler, R. Kirmse, R. Böttcher, U. Abram

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Abstract

Single-crystal EPR and ¹⁵N powder ENDOR studies of tetra-n-butylammoniumtetrabromonitrido-technetate(VI), (Bu₄N)[TcNBr₄], diamagnetically diluted by the isostructural oxotechnetate(V) complex are reported. The EPR spectra are typical of an ion with 4d¹ configuration and confirm an "in-plane" π-type molecular orbital of the unpaired electron (C_4v, symmetry). At low temperatures very complex ⁹⁹Tc and ^79,81Br hyperfine patterns are observed in the single-crystal EPR spectra. The ¹⁵N hyperfine tensor has been derived from powder ENDOR measurements. Hyperfine and ligand hyperfine data are analyzed to evaluate the electron spin delocalization and compared to those obtained from molecular orbital calculations (EHMO and NDDO). The nitrogen coupling is mainly determined by spin polarization. The fraction of the unpaired electron that is delocalized over ligand orbitals is larger in the bromo than in the corresponding chloro complex [TcNCl₄]^-.

Original language	English
Pages (from-to)	281-287
Number of pages	7
Journal	Chemical Physics
Volume	160
Issue number	2
DOIs	https://doi.org/10.1016/0301-0104(92)80128-I
State	Published - 1 Mar 1992
Externally published	Yes

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@article{946559611f964ea49dd7b83ec596fe98,

title = "Single-crystal EPR and 15N powder ENDOR studies of [(C4H9)4N][TcVINBr4/TcVOBr4]",

abstract = "Single-crystal EPR and 15N powder ENDOR studies of tetra-n-butylammoniumtetrabromonitrido-technetate(VI), (Bu4N)[TcNBr4], diamagnetically diluted by the isostructural oxotechnetate(V) complex are reported. The EPR spectra are typical of an ion with 4d1 configuration and confirm an {"}in-plane{"} π-type molecular orbital of the unpaired electron (C4v, symmetry). At low temperatures very complex 99Tc and 79,81Br hyperfine patterns are observed in the single-crystal EPR spectra. The 15N hyperfine tensor has been derived from powder ENDOR measurements. Hyperfine and ligand hyperfine data are analyzed to evaluate the electron spin delocalization and compared to those obtained from molecular orbital calculations (EHMO and NDDO). The nitrogen coupling is mainly determined by spin polarization. The fraction of the unpaired electron that is delocalized over ligand orbitals is larger in the bromo than in the corresponding chloro complex [TcNCl4]-.",

author = "K. K{\"o}hler and R. Kirmse and R. B{\"o}ttcher and U. Abram",

year = "1992",

month = mar,

day = "1",

doi = "10.1016/0301-0104(92)80128-I",

language = "English",

volume = "160",

pages = "281--287",

journal = "Chemical Physics",

issn = "0301-0104",

publisher = "Elsevier B.V.",

number = "2",

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TY - JOUR

T1 - Single-crystal EPR and 15N powder ENDOR studies of [(C4H9)4N][TcVINBr4/TcVOBr4]

AU - Köhler, K.

AU - Kirmse, R.

AU - Böttcher, R.

AU - Abram, U.

PY - 1992/3/1

Y1 - 1992/3/1

N2 - Single-crystal EPR and 15N powder ENDOR studies of tetra-n-butylammoniumtetrabromonitrido-technetate(VI), (Bu4N)[TcNBr4], diamagnetically diluted by the isostructural oxotechnetate(V) complex are reported. The EPR spectra are typical of an ion with 4d1 configuration and confirm an "in-plane" π-type molecular orbital of the unpaired electron (C4v, symmetry). At low temperatures very complex 99Tc and 79,81Br hyperfine patterns are observed in the single-crystal EPR spectra. The 15N hyperfine tensor has been derived from powder ENDOR measurements. Hyperfine and ligand hyperfine data are analyzed to evaluate the electron spin delocalization and compared to those obtained from molecular orbital calculations (EHMO and NDDO). The nitrogen coupling is mainly determined by spin polarization. The fraction of the unpaired electron that is delocalized over ligand orbitals is larger in the bromo than in the corresponding chloro complex [TcNCl4]-.

AB - Single-crystal EPR and 15N powder ENDOR studies of tetra-n-butylammoniumtetrabromonitrido-technetate(VI), (Bu4N)[TcNBr4], diamagnetically diluted by the isostructural oxotechnetate(V) complex are reported. The EPR spectra are typical of an ion with 4d1 configuration and confirm an "in-plane" π-type molecular orbital of the unpaired electron (C4v, symmetry). At low temperatures very complex 99Tc and 79,81Br hyperfine patterns are observed in the single-crystal EPR spectra. The 15N hyperfine tensor has been derived from powder ENDOR measurements. Hyperfine and ligand hyperfine data are analyzed to evaluate the electron spin delocalization and compared to those obtained from molecular orbital calculations (EHMO and NDDO). The nitrogen coupling is mainly determined by spin polarization. The fraction of the unpaired electron that is delocalized over ligand orbitals is larger in the bromo than in the corresponding chloro complex [TcNCl4]-.

UR - http://www.scopus.com/inward/record.url?scp=4243960723&partnerID=8YFLogxK

U2 - 10.1016/0301-0104(92)80128-I

DO - 10.1016/0301-0104(92)80128-I

M3 - Article

AN - SCOPUS:4243960723

SN - 0301-0104

VL - 160

SP - 281

EP - 287

JO - Chemical Physics

JF - Chemical Physics

IS - 2

ER -

Single-crystal EPR and ¹⁵N powder ENDOR studies of [(C₄H₉)₄N][Tc^VINBr₄/Tc^VOBr₄]

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