A pentuply-bridging carbonyl group: crystal and molecular structure of a salt of the 1-oxo-2-phenyl-1,2-dicarbadodecaborate(12) anion, [LH]⁺[O(Ph)C₂B₁₀H₁₀]^–(L = 1,8-N,N,N′,N′-tetramethylnaphthalenediamine)

Abstract

Deprotonation of the C-hydroxy ortho-carborane 1 ,2-HO(Ph)C2BloHlo by 1,8-N,N,N',N'-tetramethylnaphthalenediamine gives a salt whose anion, [O(Ph)C2B10H10]-, effectively consists of a nido-shaped [PhCBloH1~]-residue capped by a pentuply-bridging carbonyl group whose C-0 distance of 1.24513) 8, and position over the open carborane face, 2.001 (3) A from the cage carbon atom, are readily rationalized by frontier orbital considerations.Although the derivative chemistry of icosahedral carboranes [O(R)CzB1OH10] -(2) generated on deprotonation of (1) went C2B 10H1z is now extensive,l-3 C-hydroxy species unremarked. The delocalization of anionic charge into the HO(R)CzBloHlo (1) have received surprisingly little atten-carborane cage expected in (2) allows such anions to be tion, and none has been structurally characterised. In one of regarded as nido-shaped residues [RCBloHlo]-stabilised by the few reported studies of such cornpounds,4 it was noted that pentuply-bridging carbonyl groups (3), an environment conthey are acidic, though the potential interest of the anions sistent with the cluster-forming potential of CO units as

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

“…This paper reports synthetic, spectroscopic, X-ray crystallographic and computational studies on an isoelectronic series of ortho-carborane derivatives 1-X-2-Ph-1,2-C 2 B 10 H 10 (R = Ph, X = F, OH, O -, NH 2 or NH -, Fig. 1(a)).…”

“…Derivatives of phenyl-ortho-carborane were used in order to label the second carbon atom with a group whose influence was already understood; without such a label, CH/BH disorder problems can make X-ray structure determination difficult. Here, our work on PhCb o X systems (some aspects of which have appeared in preliminary accounts [1][2][3][4][5] ) is intended to provide a definitive account of the systematically more pronounced cage distortions that occur near the cage carbon atom C1 as exo C1-X -bonding builds up. In 2-phenyl-ortho-carborane itself, PhCb o H (Fig 1(a), R = Ph, X = H), the hypercoordinated carbon ('hypercarbon' 6 ) atom C1 forms a single bond to the exohydrogen atom and bonds of lower order to the five neighbouring cage atoms (one carbon, four borons).…”

“…Exo--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-C 2 …”

Preparative and structural studies on sulfur-linked carborane icosahedra: 2-Phenyl-ortho-carboranyl-sulfur systems (2-Ph-1,2-C2B10H10)2X (X=S, S2 or SO), and ortho-carboran-di-yl systems (1,2-C2B10H10Y)2 (Y=S or SO)

“…9,10,11 Our own published work so far has concentrated on one-cage systems and here we extend our investigation to the effect on of one π-donating atom of connecting it ed to two ortho-carborane cages. We prepared systems (PhCb o ) 2 X (X = S(1), S 2 (2) or SO (3)) in which the second cage carbon atom bore a phenyl substituent, 10,12 choosing 2-phenyl-ortho-carborane derivatives because they generally form suitable crystals for X-ray crystallographic studies (over fifty such compounds have been structurally characterised).…”

Trends in ortho-carboranes 1-X-2-R-1,2-C2B10H10 (R=Ph, Me) bearing an exo-CN-bonded substituent group (X=NO, NNR′ or NHR′′)

“…The remarkable capacity of -donor substituents, attached to carbon atoms of an ortho-carborane C 2 B 10 cage, to influence cage C1-C2 bond lengths was first detected some two decades ago [1] with the structural characterisation of the proton sponge salt of the anion PhCb o O  , (Cb o = 1,2-C 2 B 10 H 10 ; O  at cage carbon C1, Ph at C2)…”