The synthesis and characterization of bis-substituted derivatives of the [a{sup 2}-B{sub 20}H{sub 18}]{sup 4{minus}} anion and the interconversion of isomers
The apical-apical (a{sup 2}) isomer of [Et{sub 4}N]{sub 4}[B{sub 20H{sub 18}}] reacts with oxalyl chloride in dichloromethane to produce a protonated bis-substituted carbonyl species, [Et{sub 4}N][a{sup 2}-B{sub 20}H{sub 17}(CO){sub 2}] ([Et{sub 4}N][H1]), in 60% yield. Removal of the bridging hydrogen of the [H1]{sup {minus}} anion in aprotic media results in rearrangement to form the equatorial-equatorial [e{sup 2}-B{sub 20}H{sub 16}(CO){sub 2}]{sup 2{minus}} anion ([e{sup 2}-1]{sup 2{minus}}). The reaction of [Et{sub 4}N][H1] with sodium azide in acetonitrile produces [Et{sub 4}N]{sub 3}-[a{sup 2}-B{sub 20}H{sub 17}(NCO){sub 2}] ([Et{sub 4}N]{sub 3}[H2]) in 53% yield, which subsequently reacts with isopropylamine in acetonitrile to provide the urea derivative [a{sup 2}-B{sub 20}H{sub 16}(NH{sub 2}C(O)NH(i-Pr)){sub 2}]{sup 2{minus}} ([Et{sub 4}N]{sub 2}[4]) in 89% yield. The [H1]{sup {minus}} ion is hydrolyzed in aqueous acetonitrile to give a protonated [a{sup 2}-B{sub 20}H{sub 17}(CO{sub 2}H){sub 2}]{sup 3{minus}} ion ([H3]{sup 3{minus}}) in 61% yield. The a{sup 2} isomers of the bis-substituted species [B{sub 20}H{sub 16}(CO{sub 2}H){sub 2}]{sup 4{minus}} ([3]{sup 4{minus}}) ([2]{sup 4{minus}}), and [B{sub 20}H{sub 16}(NCO){sub 2}]{sup 4{minus}} ([2]{sup 4{minus}}), and [{sub 20}H{sub 16}(NH{sub 2}C(O)NH(i-Pr)){sub 2}]{sup 2{minus}}([4]{sup 2}), formed by the removal of the bridging proton from their protonated precursors, rearrange to form a mixture of ae isomers in solution.
- Research Organization:
- Univ. of California, Los Angeles, CA (US)
- Sponsoring Organization:
- USDOE; National Institutes of Health (NIH)
- DOE Contract Number:
- FG03-95ER61975
- OSTI ID:
- 20075878
- Journal Information:
- Inorganic Chemistry, Vol. 39, Issue 9; Other Information: PBD: 1 May 2000; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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