Iron-hydrogen and iron-cobalt metallocarboranes. Synthesis and chemistry of [(CH3)2C2B4H4]2FeIIH2 and a novel tetracarbon carborane system, (CH3)4C4B8H8

Chemistry ofC-Trimethylsilyl-Substituted Heterocarboranes. 26. Further Investigation of Oxidative Cage Closure, Cage Fusion, and Cage Isomerizations: Synthetic, Structural, and Bonding Studies on “Carbons Adjacent” and “Carbons Apart” Tetracarba-nido-dodecaborane(12) Derivatives

“…The cage structures of XI and XII are essentially those reported by Grimes for (CH 3 ) 4 C 4 B 8 H 8 and (C 2 H 5 ) 4 C 4 B 8 H 8 , respectively. , This is not too surprising, since the synthesis of XI is similar to that used by Grimes in that both involve the reaction of the monoanion of a nido -2,3-C 2 B 4 carborane with an easily reduced divalent transition-metal halide. In Grimes' syntheses FeCl 2 was used, followed by air oxidation, while for XI and XII , the more easily reduced NiCl 2 was used , and no additional oxidant was needed. Since an outside oxidant was required when FeCl 2 was used, the intermediate metallacarborane [2,3-(CH 3 ) 2 -2,3-C 2 B 4 H 4 ] 2 FeH 2 could be isolated and structurally characterized .…”

“…The syntheses of higher order borane and carborane cages are generally accomplished by atom insertion reactions or the fusion of smaller clusters . Over 20 years ago, Grimes and co-workers reported the first metal-promoted oxidative face-to-face fusion reaction in the C 2 B 4 carborane system . In these reactions a transition metal sandwiched metallacarborane hydride of the type (R 2 C 2 B 4 H 4 ) 2 MH x (M = Fe ( x = 2), Co ( x = 1); R = CH 3 , C 2 H 5 , n -C 3 H 7 , CH 2 C 6 H 5 ) underwent mild air oxidation to produce 12-vertex tetracarbon carborane clusters with the general formula, R 4 C 4 B 8 H 8 . − The structures of the solid-state fusion products were found to be functions of the nature of R. When R = CH 3 , the C 4 B 8 cage had an distorted-icosahedral geometry in which all four carbon atoms were localized on the same side of the cluster face and linked to one another in a Z-shaped pattern (isomer GA), while when R = C 2 H 5 the carbon face was more open such that the middle carbon−carbon bond was broken (isomer GB); when R = C 3 H 7 , mixtures of both GA and GB structures were found in the solid products .…”

Role of metals in borane clusters

“…On complexation with Fe2+ to form (R2C2B4H4)2FeH2 (Figure 9), the "extra" protons become partially associated with the metal (as revealed by NMR), probably tautomerizing over several FeB2 triangular faces. 27,28 It is possible, as has been speculated elsewhere,28 that these hydrogens are involved somehow in the oxidative fusion process.…”

Isomeric commo‐Ferracarboranes: meso‐, dd/ll‐[PPh3R][commo‐Fe(2,4‐closo‐C2B8H10)2] and Their Bimetal Ferra–Copper Zwitterion Derivatives

“…B. Sivaev and V. I. Bregadze . A series of C‐ and B‐substituted {C 2 B 4 } small‐carborane‐based commo ‐ferracomplexes H 2 Fe(R 2 C 2 B 4 H 3 R′) (R = Me, Et, Me 2 CH, PhCH; R′ = Et), as well as mixed‐ligand compounds (Me 2 C 2 B 4 H 4 )FeH 2 (Me 2 C 2 B 5 H 5 ) and (Me 2 C 2 B 4 H 4 )FeH 2 (Me 2 C 2 B 7 H 7 ), were synthesized and investigated by R. N. Grimes and co‐workers . Isomers of the C‐methyl‐substituted tricarbon sandwich ferracarboranes (X‐Me‐2,3,X‐C 3 B 7 H 9 ) 2 Fe, where X is the position of the carbon‐bonded CH 3 ‐group, was investigated by L. G. Sneddon's group .…”