Reduction of biscarborane: molecular structures of [(15-crown-5)3Na2](C2B10H11)2 and [P(C6H5)3CH3]2[.mu.-9,10-CH-(.mu.-9',10'-CH-nido-7'-CB10H11)-nido-7-CB10H11]

Icosahedral metallacarborane/carborane species derived from 1,1′-bis(o-carborane)

“…In Table 1 we list the weighted average 11 B chemical shifts, <δ( 11 B)>, of the conjoined species 1,1′-bis(o-carborane), 2, 4 and 5 along with those of their "components", [1,2-closo-C 2 B 10 Although the spectra of 1,1′-bis(o-carborane) 3,6 and all these "components" have been reported previously we have remeasured some of them here in CDCl 3 for internal consistency. Note that we have not included compound 3 in this These data show that when 1,1′-bis(o-carborane) and the metallacarborane-carborane species 2, 4 and 5 are "constructed" from their constituent parts the <δ( 11 B)> value for the "product" lies to high frequency of the (weighted) average of that of the two "components".…”

“…10 In solution, [PPh 3 Me] + and [(15-crown-5) 3 Na 2 ] 2+ salts of the 2e reduced species are identical, whilst in the solid state the anion of the [PPh 3 Me] + salt has two partially-open 4-atom CBCB faces 11 and the anion of the [(15-crown-5) 3 Na 2 ] 2+ salt has one 4-atom CBCB face which is partially-open and one 5-atom CBCBB face which is rather more open. 10 Double protonation of the 4e reduced form and subsequent work-up caused the linking C atoms to adopt bridging positions on B-B edges above nido 11-vertex [1] and compounds 2-5, respectively). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt00081e cages, in a similar manner to the protonation and work-up of [7,9-nido-C 2 B 10 H 12 ] 2− affording [μ 9,10 -CH 2 -7-nido-CB 10 H 11 ] − .…”

“…10 Double protonation of the 4e reduced form and subsequent work-up caused the linking C atoms to adopt bridging positions on B-B edges above nido 11-vertex [1] and compounds 2-5, respectively). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt00081e cages, in a similar manner to the protonation and work-up of [7,9-nido-C 2 B 10 H 12 ] 2− affording [μ 9,10 -CH 2 -7-nido-CB 10 H 11 ] − . 12 Prior to our recent research 13,14 the only metallacarboranes derived from bis(carboranes) of which we are aware are two 2,1,8-MC 2 B 9 -1′,2′-C 2 B 10 species 15,16 and two bis(metallacarboranes), 17 one of 3,1,2-MC 2 B 9 -3′,1′,2′-MC 2 B 9 geometry and the other of 3,1,2-MC 2 B 9 -2′,1′,8′-MC 2 B 9 geometry.…”

Exo-π-bonding to an ortho-carborane hypercarbon atom: systematic icosahedral cage distortions reflected in the structures of the fluoro-, hydroxy- and amino-carboranes, 1-X-2-Ph-1,2-C2B10H10 (X = F, OH or NH2) and related anions

“…Far more dramatic effects of C-X exo-dative -bonding on cage geometries, particularly on cage C1-C2 distances in derivatives of ortho-carborane, have been found in other systems RCb o X (Fig 1(a)), e.g. in Hawthorne's studies 9,10 PhCH is linked to C1 by an exo C=C double bond (Fig 1(a), R = PhCH 2 , X = PhCH . [12][13][14][15][16][17] Welch carried out systematic studies of aryl-ortho-carboranes bearing substituents of varied bulk 4 on the second carbon atom, enabling him to document both the steric and subtle electronic effects on the cage C1-C2 distance.…”

“…In these last systems, the C1 carbon atom has moved to a distance of ca 2.8 Å away from C2, the carbon atom to which it was attached in the parent neutral ortho-system. This is appropriate for 12-atom nido systems in which the carbon atoms occupy opposite sites on a (folded) six-atom open face as shown in 25 Note that the RCH system, incorporating C1, has an orientation with respect to the CB 10 The bonding environment around C1, the atom bearing the -donor substituent Figure 8 and Table 1 show how the compounds PhCb o X studied here and elsewhere 15,25 now chart relatively fully the progression from a 12-atom closo to a 12-atom near-nido structure that occurs as the degree of -bonding from a substituent X to the hypercarbon atom C1 builds up. The build-up occurs in the sequences X = F<OH<NH 2 or O -<NH -<CHPh -as the electronegativity of the donor atom decreases (and so its -donor capacity increases), and as the C1X unit effectively progresses from a unit with three atomic orbitals available for skeletal bonding to one with two atomic orbitals available for skeletal bonding.…”