Site-differentiated clusters of the general formula [Re6(μ3-Se)8(PEt3)nL6ân](SbF6)2
[L = nicotinamide: 1
(n
= 5), 2
(n
= 4, trans-), and 3
(n
= 4, cis-)] have been made by ligand substitution reactions of the corresponding acetonitrile solvates [Re6(μ3-Se)8(PEt3)n(MeCN)6ân](SbF6)2
(n
= 5; n
= 4, cis- and trans-) with nicotinamide. De-iodination of [Re6(μ3-Se)8(PEt3)nI6ân]Inâ4
[n
= 4 (cis- and trans-), 5] with AgSbF6 in the presence of 3,5-pyridinedicarboxylic acid (PDCA) produced a related series of cluster complexes [Re6(μ3-Se)8(PEt3)nL6ân](SbF6)2
[L = PDCA: 4
(n
= 5), 5
(n
= 4, trans-), and 6
(n
= 4, cis-)]. Retention of stereochemistry in each case was confirmed by 1H and 31P NMR and these new cluster derivatives were further characterized by satisfactory microanalyses (CHN). In addition, the solid-state structure of trans-[Re6(μ3-Se)8(PEt3)4(PDCA)2](SbF6)2
(5) was established crystallographically, which revealed zigzag arrays of clusters mediated by complementary hydrogen-bonding interactions involving only one of the acid groups per PDCA ligand; the second acid group extends into a small space between the chains and appears to be in close contact with a Se atom on a neighboring cluster, as well as a hydrogen atom of that cluster's triethylphosphine ligands. Each polymer chain is skewed with respect to its neighbors, forming a pronounced lamellar structure.
通式为[Re6(δ3-Se)8(PEt3)nL6ân](SbF6)2 [L =烟酰胺]的位点差异化簇合物:1 (n = 5)、2 (n = 4,反式-)和 3 (n = 4,顺式-)]是通过相应的
乙腈溶物[Re6(δ3-Se)8(PEt3)n(MeCN)6ân](SbF6)2 (n = 5; n = 4,顺式和反式-)与烟酰胺的
配体取代反应制成的。在 3,5-
吡啶二
羧酸(
PDCA)存在下,用 AgSbF6 对[Re6(δ3-Se)8(PEt3)nI6ân]Inâ4 [n = 4(顺式和反式),5] 进行脱
碘反应,产生了一系列相关的簇合物[Re6(δ3-Se)8(PEt3)nL6ân](SbF6)2 [L =
PDCA:4(n = 5)、5(n = 4,反式-)和 6(n = 4,顺式-)]。1H 和 31P NMR 证实了每种情况下立体
化学的保留,并通过令人满意的显微分析(CHN)进一步确定了这些新簇衍
生物的特征。此外,反式-[Re6(δ3-Se)8(PEt3)4(
PDCA)2](SbF6)2 (5)的固态结构已通过晶体学方法确定,该结构显示了由互补氢键相互作用介导的之字形簇阵列,每个
PDCA
配体只涉及一个酸基;第二个酸基延伸到链之间的一个小空间,似乎与相邻簇上的一个
硒原子以及该簇的三乙
膦配体的一个氢原子密切接触。每条聚合物链相对于相邻的聚合物链都是倾斜的,形成了明显的层状结构。