Germanium(II) and Tin(II) Complexes of a Sterically Demanding Phosphanide Ligand

The reaction between PhPCl2 and 1 equiv of RLi, followed by in situ reduction with LiAlH4 and an aqueous workup yields the secondary phosphane PhRPH [R = (Me3Si)2CH]. Treatment of PhRPH with n-BuLi in diethyl ether generates the lithium phosphanide (RPhP)Li(Et2O)n [15(Et2O)], which may be crystallized as the tetrahydrofuran (THF) adduct (RPhP)Li(THF)3 [15(THF)]. Compound 15(Et2O) reacts with 1 equiv of either NaO-tBu or KO-tBu to give the corresponding sodium and potassium phosphanides (RPhP)Na(Et2O)n (16) and (RPhP)K(Et2O)n (17), which may be crystallized as the amine adducts [(RPhP)Na(tmeda)]2 [16(tmeda)] and [(RPhP)K(pmdeta)]2 [17(pmdeta)], respectively. The reaction between 2 equiv of 17 and GeCl2(1,4-dioxane) gives the dimeric compound [(RPhP)2Ge]2·Et2O (18·Et2O). In contrast, the reaction between 2 equiv of 15 and SnCl2 preferentially gives the ate complex (RPhP)3SnLi(THF) (19) in low yield; 19 is obtained in quantitative yield from the reaction between SnCl2 and 3 equiv of 15. Crystallization of 19 from n-hexane/THF yields the separated ion pair complex [(RPhP)3Sn][Li(THF)4] (19a); exposure of 19a to vacuum for short periods leads to complete conversion to 19. Treatment of GeCl2(1,4-dioxane) with 3 equiv of 15 yields the contact ion pair (RPhP)3GeLi(THF) (20), after crystallization from n-hexane/THF. Compounds 15(THF), 16(tmeda), 17(pmdeta), 18·Et2O, 19a, and 20 have been characterized by elemental analyses, multielement NMR spectroscopy, and X-ray crystallography. While 15(THF) is monomeric, both 16(tmeda) and 17(pmdeta) are dimeric in the solid state. The diphosphagermylene 18·Et2O adopts a dimeric structure in the solid state with a syn,syn-arrangement of the phosphanide ligands, and this structure appears to be preserved in solution. The ate complex 19a crystallizes as a separated ion pair, whereas the analogous ate complex 20 crystallizes as a discrete molecular species. The structures of 19 and 20 are retained in non-donor solvents, while dissolution in THF yields the separated ion pairs 19a and [(RPhP)3Ge][Li(THF)4] (20a).

PhPCl2 与 1 当量的 RLi 发生反应，随后通过 LiAlH4 的原位还原和水的处理，得到二级磷化氢 PhRPH [R = (Me3Si)2CH]。将 PhRPH 在二乙醚中与 n-BuLi 处理，生成锂磷化物 (RPhP)Li(Et2O)n [15(Et2O)]，该物质可结晶为四氢呋喃 (THF) 加合物 (RPhP)Li(THF)3 [15(THF)]。化合物 15(Et2O) 与 1 当量的 NaO-tBu 或 KO-tBu 反应，分别得到相应的钠磷化物 (RPhP)Na(Et2O)n (16) 和钾磷化物 (RPhP)K(Et2O)n (17)，它们可以结晶为胺加合物 [(RPhP)Na(tmeda)]2 [16(tmeda)] 和 [(RPhP)K(pmdeta)]2 [17(pmdeta)]。17 与 GeCl2(1,4-二氧六环)的 2 当量反应生成二聚体化合物 [(RPhP)2Ge]2·Et2O (18·Et2O)。相反，15 与 2 当量 SnCl2 的反应优先生成低产率的 ate 配合物 (RPhP)3SnLi(THF) (19)；19 可通过 SnCl2 与 15 的 3 当量反应以定量产率获得。从正己烷/THF 中结晶 19 可得到分离的离子对复合物 [(RPhP)3Sn][Li(THF)4] (19a)；将 19a 短期暴露于真空下会导致其完全转化为 19。GeCl2(1,4-二氧六环)与 15 的 3 当量反应生成接触离子对 (RPhP)3GeLi(THF) (20)，之后从正己烷/THF 中结晶。化合物 15(THF)、16(tmeda)、17(pmdeta)、18·Et2O、19a 和 20 已通过元素分析、多元素 NMR 光谱学和 X 射线晶体学进行了表征。虽然 15(THF) 为单聚体，但 16(tmeda) 和 17(pmdeta) 在固态中均为二聚体。二磷锗化物 18·Et2O 在固态中呈二聚体结构，磷化氢配体呈顺式，顺式排列，这种结构似乎在溶液中也得以保留。ate 配合物 19a 结晶为分离的离子对，而类似的 ate 配合物 20 结晶为独立的分子物种。在非供体溶剂中，19 和 20 的结构得以保留，而溶解在 THF 中则产生分离的离子对 19a 和 [(RPhP)3Ge][Li(THF)4] (20a)。