Alpha shift correlation (ASC) method. Sensitivity of B-11 NMR shifts to halogen substitution in the ten-vertex nido and arachno series of boron clusters. Linear behavior of NMR effects

0483706 - ÚACH 2019 RIV CH eng J - Článek v odborném periodiku
Štíbr, Bohumil
Alpha shift correlation (ASC) method. Sensitivity of B-11 NMR shifts to halogen substitution in the ten-vertex nido and arachno series of boron clusters. Linear behavior of NMR effects.
Inorganica chimica acta. Roč. 471, FEB (2018), s. 615-619. ISSN 0020-1693. E-ISSN 1873-3255
Grant CEP: GA ČR(CZ) GA16-01618S
Institucionální podpora: RVO:61388980
Klíčová slova: Boranes * Dicarbaboranes * NMR shifts- B NMR correlation 11 * Sensitivity factors * Substitution effects
Obor OECD: Inorganic and nuclear chemistry
Impakt faktor: 2.433, rok: 2018

ASC method is applied to all the known monohalogeno derivatives of the 10-vertex nido and arachno series, specifically to those of nido-B10H14 (1), nido-5,6-C2B8H12 (2), [nido-5,6-C2B8H11] (2), and arachno-6,9-C2B8H14 (3). This graphical method confirmed a simple linear correlation between the universal aref shifts and Delta delta(B-11) shifts induced in unsubstituted (u) (beta, gamma, and antipodal = A), positions of individual clusters: Delta delta(B-11) = k. alpha(ref) (where Delta delta= delta(s) - delta(p) and symbols s and p relate to the substituted and parent derivative, respectively, k = correlation slope). The g factor (g = gradient = k center dot 10(2)) then reflects the sensitivity of a given cage position to halogen changes at the substituted B-vertex. The linearity is likewise preserved for the substituted alpha-sites, but only for heavier halogens (Cl, Br, and I). Individual cluster types sharply differ in g values for specific cage positions. The sensitivity of B-11 NMR shifts to halogen changes is descending in the order: alpha >> over-mu > trans (T) > A > beta >= gamma for all the compounds investigated.
Trvalý link: http://hdl.handle.net/11104/0282018