arachnoadj.

/əˈraknəʊ/

Forms: Usually italicized.

Etymology: < Greek ἀράχνη spider + -o- connective.

Chemistry.

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.

ΘΚΠ

the world > matter > chemistry > elements and compounds > metals > specific elements > boron > [noun] > compounds > designating the structure of

arachno1971

1971 Inorg. 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.

1984 N. N. Greenwood & A. Earnshaw Chem. of Elements (1986) vi. 185 Arachno-boranes: B_nH_n+6, n corners of an (n+2) cornered polyhedron.

1988 Jrnl. 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 C_2v 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.

This entry has not yet been fully updated (first published 1993; most recently modified version published online June 2018).

单词	arachno
释义	arachnoadj. /əˈraknəʊ/ Forms: Usually italicized. Etymology: < Greek ἀράχνη spider + -o- connective. Chemistry. 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. ΘΚΠ the world > matter > chemistry > elements and compounds > metals > specific elements > boron > [noun] > compounds > designating the structure of arachno1971 1971 Inorg. 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. 1984 N. N. Greenwood & A. Earnshaw Chem. of Elements (1986) vi. 185 Arachno-boranes: B_nH_n+6, n corners of an (n+2) cornered polyhedron. 1988 Jrnl. 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 C_2v 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. This entry has not yet been fully updated (first published 1993; most recently modified version published online June 2018). < adj.1971
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