Coordination of arenes and phosphines by charge separated alkaline earth cations
Coordination of arenes and phosphines by charge separated alkaline earth cations
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DOI：
10.1039/c8dt03124j
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发表时间：
2018-09-28
影响因子：
4
通讯作者：
Hill, Michael S.
中科院分区：
文献类型：
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作者：
Garcia, Lucia;Anker, Mathew D.;Hill, Michael S.
生成β -二酮胺酮2族阳离子[((BDI)-B-Me)Ae]（+）和[(t-BuBDI)Ae](+) ((BDI)-B-Me = HC{(Me) cn -2,6-i- pr2c6h3}(2)；t-BuBDI = HC{(t-Bu) cn -2,6-i- pr2c6h3}(2)；Ae = Mg或Ca)，与弱配位阴离子[Al{OC(CF3)(3)}(4)]（-）结合，可以表征从芳烃溶剂结晶成甲苯或苯的电荷分离碱土eta(6)-pi加合物。将1,4-二氟苯加入[(BDI)-B-Me)Mg]（+）中，分离得到[(BDI)-B-Me)Mg(1,4- f2c6h4)(3)](+)，其中氟苯分子通过kappa(1)-F-M相互作用进行配位。虽然DFT分析表明，聚hapto芳烃与Mg的结合是有效的静电起源，但与Ca （Sr和Ba）的相互作用引起了芳烃HOMOs与碱土价和轨道的小但显著的π重叠。三苯基膦与[((BDI)-B-Me)Mg]（+）和[(t-BuBDI)Mg]（+）在甲苯溶剂中反应，分离出末端配位的镁-膦加合物。所得到的Mg-P键长[2.5972(13),2.6805（12）埃]与之前在末端但形式上阴离子磷化体配体的镁衍生物中观察到的键长相当，而DFT计算支持键的有效静电性质。
Generation of beta-diketiminato group 2 cations, [((BDI)-B-Me)Ae](+) and [(t-BuBDI)Ae](+) ((BDI)-B-Me = HC{(Me)CN-2,6-i-Pr2C6H3}(2); t-BuBDI = HC{(t-Bu)CN-2,6-i-Pr2C6H3}(2); Ae = Mg or Ca), in conjunction with the weakly coordinating anion, [Al{OC(CF3)(3)}(4)](-), allows the characterisation of charge separated alkaline earth eta(6)-pi adducts to toluene or benzene when crystallised from the arene solvents. Addition of 1,4-difluorobenzene to [((BDI)-B-Me)Mg](+) results in the isolation of [((BDI)-B-Me)Mg(1,4-F2C6H4)(3)](+) in which the fluorobenzene molecules coordinate via kappa(1)-F-M interactions. Although DFT analysis indicates that the polyhapto arene binding to Mg is effectively electrostatic in origin, the interactions with Ca (Sr and Ba) are observed to invoke small but significant pi overlap of the arene HOMOs with the alkaline earth valence nd orbitals. Reaction of triphenylphosphine with [((BDI)-B-Me)Mg](+) and [(t-BuBDI)Mg](+) in toluene solvent allows the isolation of the respective terminally coordinated magnesium-phosphine adducts. The resultant Mg-P bond lengths [2.5972(13), 2.6805(12) angstrom] are comparable to those previously observed in magnesium derivatives of terminal but formally anionic phosphide ligands, while the effectively electrostatic nature of the bonding is supported by DFT calculations.