Albuerne Isabel G, Alvarez M Angeles, García M Esther, García-Vivó Daniel, Ruiz Miguel A
Departamento de Química Orgánica e Inorgánica/IUQOEM, Universidad de Oviedo , E-33071 Oviedo, Spain.
Inorg Chem. 2015 Oct 19;54(20):9810-20. doi: 10.1021/acs.inorgchem.5b01527. Epub 2015 Oct 8.
The title phosphinidene complex could be sequentially protonated with HBF4·OEt2 or H(OEt2)2 to give the phosphido-bridged derivatives [Mo2Cp(μ-κ(1):κ(1),η(5)-HPC5H4)(η(6)-HMes*)(CO)2(PMe3)]X and then the hydrides [Mo2Cp(H)(μ-κ(1):κ(1),η(5)-HPC5H4)(η(6)-HMes*)(CO)2(PMe3)]X2 (X = BF4, BAr'4; Ar' = 3,5-C6H3(CF3)2; Mes* = 2,4,6-C6H2(t)Bu3). Density functional theory (DFT) calculations revealed that the most favored site for initial electrophilic attack is the metallocene Mo atom, but attachment of the electrophile to the phosphinidene P atom gives more stable products. This was in agreement with all other reactions investigated, which invariably involved the attachment of the added electrophile at the P site. Thus, the title compound reacted with S8 at 223 K to give the thiophosphinidene-bridged complex [Mo2Cp{μ-κ(1):κ(1),η(5)-P(S)C5H4}(η(6)-HMes*)(CO)2(PMe3)], a poorly stable molecule which reacted with MeI at room temperature to give the corresponding thiolatophosphido derivative, isolated as Mo2Cp{μ-κ(1):κ(1),η(5)-P(SMe)C5H4}(η(6)-HMes*)(CO)2(PMe3) (P-S = 2.128(4) Å) after anion exchange with Na(BAr'4). Reaction of the title compound with MeI proceeded smoothly to give the corresponding methylphosphido derivative, isolated analogously as Mo2Cp{μ-κ(1):κ(1),η(5)-P(Me)C5H4}(η(6)-HMes*)(CO)2(PMe3). The related complex Mo2Cp{μ-κ(1):κ(1),η(5)-P(Me)C5H4}(η(6)-HMes*)(CO)2(PMe2Ph) (P-C(Me) = 1.841(5) Å) could be prepared analogously from the neutral precursor [Mo2Cp{μ-κ(1):κ(1),η(5)-PC5H4}(η(6)-HMes*)(CO)2(PMe2Ph)]. In contrast, reaction of the title complex with ethylene sulfide involved opening of the C2S ring and formation of new P-C and Mo-S bonds (1.886(7) and 2.493(2) Å, respectively), with displacement of the PMe3 ligand, to give the phosphido-thiolato complex [Mo2Cp{μ-κ(2)(P,S):κ(1)P,η(5)-P(C2H4S)C5H4}(η(6)-HMes*)(CO)2]. All these derivatives of the title complex displayed an unusual trigonal pyramidal-like environment around the bridging P atom, with the added electrophile placed in the Mo2P plane as a result of the directionality of the relevant frontier orbital of the phosphinidene complex, according to DFT calculations.
标题膦亚基配合物可以依次用HBF₄·OEt₂或H(OEt₂)₂进行质子化，得到磷桥联衍生物[Mo₂Cp(μ-κ(1):κ(1),η⁵-HPC₅H₄)(η⁶-HMes*)(CO)₂(PMe₃)]X，然后得到氢化物[Mo₂Cp(H)(μ-κ(1):κ(1),η⁵-HPC₅H₄)(η⁶-HMes*)(CO)₂(PMe₃)]X₂（X = BF₄，BAr'₄；Ar' = 3,5-C₆H₃(CF₃)₂；Mes* = 2,4,6-C₆H₂(t)Bu₃）。密度泛函理论（DFT）计算表明，初始亲电攻击最有利的位点是茂金属Mo原子，但亲电试剂与膦亚基P原子的结合会产生更稳定的产物。这与所研究的所有其他反应一致，这些反应总是涉及添加的亲电试剂在P位点的结合。因此，标题化合物在223 K下与S₈反应，得到硫代膦亚基桥联配合物[Mo₂Cp{μ-κ(1):κ(1),η⁵-P(S)C₅H₄}(η⁶-HMes*)(CO)₂(PMe₃)]，这是一个稳定性较差的分子，在室温下与MeI反应，得到相应的硫醇基磷化物衍生物，在用Na(BAr'₄)进行阴离子交换后分离为Mo₂Cp{μ-κ(1):κ(1),η⁵-P(SMe)C₅H₄}(η⁶-HMes*)(CO)₂(PMe₃)（P-S = 2.128(4) Å）。标题化合物与MeI的反应顺利进行，得到相应的甲基磷化物衍生物，类似地分离为Mo₂Cp{μ-κ(1):κ(1),η⁵-P(Me)C₅H₄}(η⁶-HMes*)(CO)₂(PMe₃)。相关配合物Mo₂Cp{μ-κ(1):κ(1),η⁵-P(Me)C₅H₄}(η⁶-HMes*)(CO)₂(PMe₂Ph)（P-C(Me) = 1.841(5) Å）可以类似地从中性前体[Mo₂Cp{μ-κ(1):κ(1),η⁵-PC₅H₄}(η⁶-HMes*)(CO)₂(PMe₂Ph)]制备。相比之下，标题配合物与乙撑硫醚的反应涉及C₂S环的开环和新的P-C和Mo-S键（分别为1.886(7) Å和2.493(2) Å）的形成，同时PMe₃配体被取代，得到磷化物-硫醇盐配合物[Mo₂Cp{μ-κ(2)(P,S):κ(1)P,η⁵-P(C₂H₄S)C₅H₄}(η⁶-HMes*)(CO)₂]。根据DFT计算，标题配合物的所有这些衍生物在桥连P原子周围都显示出异常的三角锥状环境，由于膦亚基配合物相关前沿轨道的方向性，添加的亲电试剂位于Mo₂P平面内。
