Reactions of [Nb2(µ-S2)2(dtc)4] 1 (dtc = diethyldithiocarbamate, S2CNEt2) with chalcogen-transfer reagents PEt3Y (Y = Se or Te) were investigated. With PEt3Se, fully substituted [Nb2(µ-Se2)2(dtc)4] 2 forms if a catalytic amount of free PEt3 is present. However PEt3Te gives [Nb2(S)(Te2)(dtc)4] 3 which has a new core with two different chalcogens acting as bridges. The structures of both 2 and 3 were determined by X-ray analysis [2: Nb–Nb 2.974(2), Se–Se 2.303(2). 3: Nb–Nb 2.920(4), Te–Te 2.648(3) Å]. Electrochemistry of 2 and 3 was studied and a reversible one-electron oxidation was found for 2, giving a blue ESR-active (19-plet, g = 2.0489, A = 52.5 G) species [Nb2(µ-Se2)2(dtc)4]+ at 638 mV vs. NHE. By contrast in the reaction of [Nb2(µ-S2)2(acac)4] 4 (Hacac = acetylacetone) with PEt3Te only the sulfur abstraction product [Nb2(µ-S)2(acac)4] 5 formed, which could be more directly prepared from 4 and PEt3. Crystal structures of 4 and 5 were determined.
[Nb2(µ-S2)2(dtc)4] 1 (dtc =
二乙基二
硫代
氨基甲酸酯, S2CNEt2) 与 chalcogen-transfer 试剂 PEt3Y (Y = Se 或 Te) 的反应进行了研究。使用 PEt3Se,如果存在催化量的自由 PEt3,则会形成全取代的 [Nb2(µ-Se2)2(dtc)4] 2。然而,使用 PEt3Te,则生成 [Nb2(S)(Te2)(dtc)4] 3,其具有以两种不同
硫属元素作为桥的新型核心结构。2 和 3 的结构通过 X 射线分析确定 [2: Nb–Nb 2.974(2), Se–Se 2.303(2). 3: Nb–Nb 2.920(4), Te–Te 2.648(3) Å]。对 2 和 3 进行了电
化学研究,发现 2 可以发生可逆的单电子氧化反应,形成蓝色 ESR 活性 (19-plet, g = 2.0489, A = 52.5 G) 物种 [Nb2(µ-Se2)2(dtc)4]+,相对于 NHE 在 638 mV 处。相反,[Nb2(µ-S2)2(acac)4] 4 (Hacac =
乙酰丙酮) 与 PEt3Te 的反应仅形成了
硫提取产物 [Nb2(µ-S)2(acac)4] 5,该产物可以直接通过 4 和 PEt3 制备。4 和 5 的晶体结构被确定。