104A Sp09 lecture 18

104A Sp09 lecture 18 - And those in the layer below are...

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Elemental boron exists in icosahedral clusters. Although the vertices may be viewed as existing in two pentagons plus additional vertices above the top pentagon and below the bottom pentagon, all vertices are equivalent. The icosahedra arrange themselves in different manners in various allotropes. 1 The B-B distances within each icosahedron vary regularly between 1.73 - 1.79 Å. Dotted lines show the 3-center bonds Between the 6 equatorial boron atoms in each icosahedron to 6 other icosahedra in the same sheet at 2.02 Å. The sheets Are stacked so that each icosahedron is bonded by six 2-center B-B bonds at 1.71 Å (3 above and 3 below the icosahedron). The B 12 units in the layer above are centered over the “1”s
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Unformatted text preview: And those in the layer below are centered under the “2”s. 2 2 2 1 1 High temperature form of elemental boron. Elemental Boron [B 12 H 12 ] 2-Borohydrides Cluster Types - Borohydrides and Carboranes Carboranes ortho-carborane meta-carborane para-carborane nido-B 10 H 14 + 2SEt 2 B 10 H 12 (SEt 2 ) 2 + H 2 B 10 H 12 (SEt 2 ) 2 + HC CH closo-1,2-C 2 B 10 H 12 + 2SEt 2 + H 2 typical synthesis: Neil Bartlett and Noble Gas Compounds High oxidation state fluorine compounds such as PtF 6 1932-2008 O 2 + PtF 6 O 2 + PtF 6-IE 1 = 12.2 eV Xe + PtF 6 Xe + PtF 6-IE 1 = 12.1 eV ?? orange-yellow salt H 2 O Xe (by mass spec) XePtF 6 was later shown to be XeF + PtF 5-...
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This note was uploaded on 09/03/2009 for the course CHEM ???? taught by Professor Tiley during the Spring '09 term at Berkeley.

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104A Sp09 lecture 18 - And those in the layer below are...

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