The M3(μ3-Se)(μ-Se)34+ clusters (written also as M3Se44+) show a strong tendency to add sulfur to the μ-Se bridges giving new chalcogen-rich clusters with M3(μ3-Se)(μ-SeS)34+ cores i.e. Mo3Se4S34+. They are isolated as dithiophosphate complexes [M3(μ3-Se)(μ-SeS)3((RO)2PS2)3]Cl (1a, M = Mo, R = Et; 1b, R =
i-Pr; 2a, M = W, R = Et, 2b, R =
i-Pr) upon treatment of solutions of [M3Se4(H2O)9]4+ in 2 M HCl with a large
excess of P4S10/ROH reagent. The structures of 1a and 2a have been determined by single crystal X-ray analysis. The sulfur atom forms a part of the μ-SeS ligand, which is asymmetrically coordinated to two metal atoms, so that the sulfurs are almost coplanar with the M3 triangle (equatorial positions) and the Se atoms are strongly out of the plane (axial positions). This represents a rare kind of linkage isomerism since the opposite bridging mode is observed for the SeS ligand in the clusters M3(μ3-S)(μ-SeS)34+ in which the Se is equatorial and the S occupies the axial positions. As an alternative the pure dithiophosphate salts KS2P(OR)2 (R = Et, i-Pr) do not lead to sulfur addition and allow isolation of [Mo3Se4((RO)2PS2)3(μ-CH3COO)(C5H5N)]
(3) upon recrystallyzation from a CH3CNâCH3COOHâpyridine mixture. Both 3 and its sulfur analogue abstract sulfur from propylene sulfide at room temperature to give Mo3Se4S34+ and Mo3S74+ clusters, respectively.
M3(µ3-Se)(µ-Se)34+ 簇(也可写作 M3Se44+)显示出强烈倾向,向 µ-Se 桥中添加
硫,生成新的富
金属簇,具有 M3(µ3-Se)(µ-SeS)34+ 核心,例如 Mo3Se4S34+。这些簇通过在 2M HCl 溶液中用过量
P4S10/ROH 试剂处理 [M3Se4(
H2O)9]4+,以
二硫代磷酸酯络合物 [M3(µ3-Se)(µ-SeS)3((RO)2PS2)3]Cl(1a,M = Mo,R = Et;1b,R = i-Pr;2a,M = W,R = Et,2b,R = i-Pr)的形式被分离出来。通过单晶 X 射线分析已经确定了 1a 和 2a 的结构。
硫原子是 µ-SeS
配体的一部分,该
配体不对称地配位于两个
金属原子,使得
硫原子几乎与 M3 三角形(赤道位置)共面,而 Se 原子强烈地偏离平面(轴向位置)。这代表了一种罕见的连接异构现象,因为在 M3(µ3-S)(µ-SeS)34+ 簇中,Se 位于赤道位置,S 占据轴向位置,观察到了相反的桥接模式。另一种选择是,纯
二硫代磷酸酯盐 KS2P(OR)2(R = Et,i-Pr)不会导致
硫的添加,并允许在从 CH3CN-CH3COOH-
吡啶混合物中重结晶后分离出 [Mo3Se4((RO)2PS2)3(µ-CH3COO)(
C5H5N)](3)。无论是 3 还是其
硫类似物都能在室温下从
丙烯硫醚中提取
硫,分别得到 Mo3Se4S34+ 和 Mo3S74+ 簇。