| 释义 |
arachno, a. Chem.|əˈræknəʊ|
Usu. italicized.
[f. Gr. ἀράχν-η spider + -o1.]
Designating (the structure of) a boron compound in whose molecules boron atoms occupy all vertices but two of a notional triangulated polyhedron. Also (with hyphen) as a word-forming element.
1971Inorg. Chem. X. 214/2 Of the many icosahedral fragment arachno structures which may be imagined the simple removal of a high-coordination vertex from the open face of the related nido structure empirically yields the correct or presumed to be correct structure in every case. 1984Greenwood & Earnshaw Chem. of Elements (1986) vi. 185 Arachno-boranes: BnHn+6 , n corners of an (n+2) cornered polyhedron. 1988Jrnl. Chem. Soc.: Dalton Trans. 1467/1 The factors that influence nuclear magnetic shielding in polyhedral boron compounds are not understood, and few reliable structure-shielding correlations that are useful in the general case have emerged. An exception to this generalization is in the C2v open ten-vertex cluster type..in which a change from nido character, exemplified by B10H14 , to arachno character, exemplified by [B10H14]2- is characterized by an inversion of the ordering of the 11B resonance positions and an increase in the mean 11B shielding of several p.p.m. |