title: Double deboronation and homometalation of 1,1'-bis(ortho-carborane).
abstract: Double deboronation of 1,1'-bis(ortho-carborane) results in a mixture of racemic and meso diastereoisomers which are sources of the [7-(7'-7',8'-nido-C2B9H10)-7,8-nido-C2B9H10]4-tetraanion. Consistent with this, metalation of the mixture with {Ru(p-cymene)} affords the diastereoisomers α-[1-(8'-2'-(p-cymene)-2',1',8'-closo-RuC2B9H10)-3-(p-cymene)-3,1,2-closo-RuC2B9H10] (3α) and β-[1-(8'-2'-(p-cymene)-2',1',8'-closo-RuC2B9H10)-3-(p-cymene)-3,1,2-closo-RuC2B9H10] (3β) in which the primed cage has undergone a spontaneous 3',1',2' to 2',1',8'-RuC2B9isomerisation. Analogous cobaltacarboranes α-[1-(8'-2'-Cp-2',1',8'-closo-CoC2B9H10)-3-Cp-3,1,2-closo-CoC2B9H10] (4α) and β-[1-(8'-2'-Cp-2',1',8'-closo-CoC2B9H10)-3-Cp-3,1,2-closo-CoC2B9H10] (4β) are formed by metalation with CoCl2/NaCp followed by oxidation, along with a small amount of the unique species [8-(8'-2'-Cp-2',1',8'-closo-CoC2B9H10)-2-Cp-2,1,8-closo-CoC2B9H10] (5) if the source of the tetraanion is [HNMe3]2[7-(7'-7',8'-nido-C2B9H11)-7,8-nido-C2B9H11]. Two-electron reduction and subsequent reoxidation of 4α and 4β afford species indistinguishable from 5. The reaction between [Tl]2[1-(1'-3',1',2'-closo-TlC2B9H10)-3,1,2-closo-TlC2B9H10] and [CoCpI2(CO)] leads to the isolation of a further isomer of (CpCoC2B9H11)2, rac-[1-(1'-3'-Cp-3',1',2'-closo-CoC2B9H10)-3-Cp-3,1,2-closo-CoC2B9H10] (6), which displays intramolecular dihydrogen bonding. Thermolysis of 6 yields 4α, allowing a link to be established between the α and β forms of 3 and 4 and racemic and meso forms of the [7-(7'-7',8'-nido-C2B9H10)-7,8-nido-C2B9H10]4-tetraanion, whilst reduction-oxidation of 6 again results in a product indistinguishable from 5.
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Gobika
authors.initials: G
authors.lastname: Thiripuranathar
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Antony P Y
authors.initials: AP
authors.lastname: Chan
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Dipendu
authors.initials: D
authors.lastname: Mandal
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Wing Y
authors.initials: WY
authors.lastname: Man
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Mario
authors.initials: M
authors.lastname: Argentari
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Georgina M
authors.initials: GM
authors.lastname: Rosair
authors.affiliation: Institute of Chemical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS UK. a.j.welch@hw.ac.uk.
authors.forename: Alan J
authors.identifier: http://orcid.org/0000-0003-4236-2475
authors.initials: AJ
authors.lastname: Welch