Double deboronation and homometalation of 1,1'-bis(ortho-carborane)

作者：Thiripuranathar Gobika; Chan Antony P Y; Mandal Dipendu; Man Wing Y; Argentari Mario; Rosair Georgina M; Welch Alan J^*

来源：Dalton Transactions, 2017, 46(6): 1811-1821.

DOI：10.1039/c6dt04457c

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 alpha-[1-(8'-2'( p-cymene)-2',1',8'-closo-RuC2B9H10)-3-(p-cymene)-3,1,2-closo-RuC2B9H10] (3 alpha) and beta-[ 1-(8'-2'( p-cymene)-2', 1',8'-closo-RuC2B9H10)-3-(p-cymene)-3,1,2-closo-RuC2B9H10] (3 beta) in which the primed cage has undergone a spontaneous 3', 1', 2' to 2', 1', 8'-RuC2B9 isomerisation. Analogous cobaltacarboranes a-[1( 8'-2'-Cp-2', 1', 8'-closo-CoC2B9H10)-3-Cp-3,1,2-closo-CoC2B9H10] (4 alpha) and beta-[1-(8'-2'-Cp-2', 1',8'-closoCoC(2)B(9)H(10))- 3-Cp-3,1,2-closo-CoC2B9H10] (4 beta) 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)-2Cp- 2,1,8-closo-CoC2B9H10] (5) if the source of the tetraanion is [HNMe3] 2[7-(7'-7',8'-nido-C2B9H11)-7,8nido- C2B9H11]. Two-electron reduction and subsequent reoxidation of 4 alpha and 4 beta 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'-closoCoC(2)B(9)H(10))- 3-Cp-3,1,2-closo-CoC2B9H10] (6), which displays intramolecular dihydrogen bonding. Thermolysis of 6 yields 4 alpha, allowing a link to be established between the a and beta 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.

• 出版日期2017-2-14