Organic Materials Research Group, Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States.
Inorg Chem. 2011 Mar 21;50(6):2654-60. doi: 10.1021/ic102557s. Epub 2011 Feb 22.
A comparative study of the reactivity of dinitrogen acids [closo-1-CB(9)H(8)-1-COOH-10-N(2)] (3[10]) and [closo-1-CB(9)H(8)-1-COOH-6-N(2)] (3[6]) was conducted by diazotization of a mixture of amino acids [closo-1-CB(9)H(8)-1-COOH-6-NH(3)] (1[6]) and [closo-1-CB(9)H(8)-1-COOH-10-NH(3)] (1[10]) with NO(+)BF(4)(-) in the presence of a heterocyclic base (pyridine, 4-methoxypyridine, 2-picoline, or quinoline). The 10-amino acid 1[10] formed an isolable stable 10-dinitrogen acid 3[10], while the 6-dinitrogen carboxylate 36 reacted in situ, giving products of N-substitution at the B6 position with the heterocyclic solvent (4[6]). The molecular and crystal structures for pyridinium acid 4[6]a were determined by X-ray crystallography. The electronic structures and reactivity of the 6-dinitrogen derivatives of the {1-CB(9)} cluster were assessed computationally at the B3LYP/6-31G(d,p) and MP2/6-31G(d,p) levels of theory and compared to those of the 10-dinitrogen, 2-dinitrogen, and 1-dinitrogen analogues.
对二氮杂羧酸[closo-1-CB(9)H(8)-1-COOH-10-N(2)] (3[10])和[closo-1-CB(9)H(8)-1-COOH-6-N(2)] (3[6])的反应性进行了比较研究，方法是在杂环碱（吡啶、4-甲氧基吡啶、2-吡啶或喹啉）存在下，用 NO(+)BF(4)(-)将氨基酸[closo-1-CB(9)H(8)-1-COOH-6-NH(3)] (1[6])和[closo-1-CB(9)H(8)-1-COOH-10-NH(3)] (1[10])的混合物进行重氮化。10-氨基 1[10]形成可分离稳定的 10-二氮杂羧酸 3[10]，而 6-二氮杂羧酸根 36就地反应，与杂环溶剂（4[6]）在 B6 位置发生 N-取代产物。通过 X 射线晶体学确定了吡啶翁酸 4[6]a 的分子和晶体结构。在 B3LYP/6-31G(d,p)和 MP2/6-31G(d,p)理论水平上计算了{1-CB(9)}簇的 6-二氮衍生物的电子结构和反应性，并与 10-二氮、2-二氮和 1-二氮类似物进行了比较。
