The ligand H2C(PPh2BH3)2 (4-H2) reacted with one or a half equivalent of (para-tBu-C6H4CH2)2Ca·(THF)4 to form the calcium complexes Ca[HC(PPh2BH3)2]2 (4-H)2Ca and CaC(PPh2BH3)2 (4-Ca), respectively. The crystal structures of their THF adducts (4-H)2Ca·THF and [4-Ca·(THF)]2 follow the same trends as observed for the corresponding iminophosphorano substituted complexes Ca[HC(PPh2NR)2]2 and [CaC(PPh2NR)2]2. The P–C bonds shorten upon gradual deprotonation, whereas the P–B and P–N bonds elongate. The geometries of DFT-optimized model systems and complete molecular structures show similar trends. Also the charge distribution within the boranophosphorano complexes is similar to that in the iminophosphorano complexes. The high positive charges on Ca (1.74–1.75) indicate a predominantly ionic ligand–Ca bonding. High negative charges on the central carbon atom (−1.103 in Ca[HC(PH2BH3)2]2 and −1.775 in [CaC(PH2BH3)2]2) compare well to those calculated for analogous iminophosphorano complexes (−1.126 Ca[HC(PH2NH)2]2 and −1.847 [CaC(PH2NH)2]2, respectively). Thus, in both types of complexes delocalization of electron density over the boranophosphorano or iminophosphorano substituents does not play a major role. Complex [4-Ca·(THF)]2 does not react with adamantyl cyanide. Instead the adduct (4-Ca)2·(THF)·(adamantyl-CN) formed (a crystal structure has been determined).
                                    配体 H2C(PPh2BH3)2 (4-H2) 与一或半当量的 (para-tBu-C6H4CH2)2Ca·(THF)4 反应形成
钙络合物 Ca[HC(PPh2BH3)2]2 (4-分别为 H)2Ca 和 CaC(PPh2BH3)2 (4-Ca)。它们的 THF 加合物 (4-H)2Ca·THF 和 [4-Ca·(THF)]2 的晶体结构遵循与相应亚
氨基
磷取代配合物 Ca[HC(PPh2NR)2]2 和 [CaC] 相同的趋势(PPh2NR)2]2。 P-C 键随着逐渐去质子化而缩短,而 P-B 和 P-N 键则延长。 DFT 优化模型系统和完整分子结构的几何形状显示出相似的趋势。此外,
硼杂正膦配合物内的电荷分布与亚
氨基正膦配合物中的电荷分布相似。 Ca 上的高正电荷 (1.74–1.75) 表明主要是离子
配体-Ca 键合。中心碳原子上的高负电荷(Ca[HC(PH2BH3)2]2 中为 -1.103 和 [CaC(PH2BH3)2]2 中为 -1.775) 与类似亚
氨基
磷配合物的计算结果 (-1.126 Ca[HC( PH2NH)2]2 和 -1.847 [CaC(PH2NH)2]2 分别)。因此,在两种类型的配合物中,
硼烷正膦或亚
氨基正膦取代基上的电子密度离域并不起主要作用。络合物[4-Ca·(THF)]2 不与
金刚烷基
氰反应。相反,形成加合物(4-Ca)2·(THF)·(
金刚烷基-CN)(晶体结构已确定)。