Chemistry of the Phosphinidene Oxide Ligand

Reaction of [Mo2Cp2(μ-H)(μ-PHR*)(CO)4] with DBU followed by O2 gives the first anionic phosphinidene oxide complex (H-DBU)[MoCp{P(O)R*}(CO)2] (1) (DBU = 1,8-diazabicyclo [5.4.0] undec-7-ene; R* = 2,4,6-C6H2tBu3). This anion displays three different nucleophilic sites located at the O, P, and Mo atoms, as illustrated by the reactions reported. Thus, reaction of 1 with excess HBF4·OEt2 gave the fluorophosphide complex [MoCp(PFR*)(CO)2] via the hidroxophosphide intermediate [MoCp{PR*(OH)}(CO)2]. Related alkoxyphosphide compounds [MoCp{P(OR)R*}(CO)2] (R = Me, C(O)Ph) were prepared by reaction of 1 with [Me3O]BF4 and PhC(O)Cl, respectively, whereas reaction of 1 with MeI or C3H5Br gave the P,O-bound phosphinite complexes [MoCp(κ2-OPRR*)(CO)2] (R = Me, C3H5). Metal-based electrophiles were found to bind at either O or Mo positions. Thus, reaction of 1 with [ZrCl2Cp2] gave the phosphinidene oxide bridged [MoCp{P(OZrClCp2)R*}(CO)2], whereas reaction with SnPh3Cl gave trans-[MoCp{P(O)R*}(CO)2(SnPh3)], an heterometallic complex having an intact terminal P(O)R* ligand.

将配合物[Mo₂(Cp)₂(μ-H)(μ-PHR*)(CO)₄]（其中Cp为环戊二烯基（Cyclopentadienyl））与1,8-二氮杂双环[5.4.0]十一碳-7-烯（1,8-diazabicyclo[5.4.0]undec-7-ene，缩写DBU）反应后再通入氧气，可得到首例阴离子型亚膦烯氧化物配合物(H-DBU)[MoCp{P(O)R*}(CO)₂]（1），其中R*=2,4,6-三(叔丁基)苯基（2,4,6-C₆H₂tBu₃）。该阴离子的O、P、Mo原子共存在三种不同的亲核位点，这一点可通过已报道的相关反应得到印证。具体而言，将配合物1与过量氟硼酸二乙醚络合物（HBF₄·OEt₂）反应，经由羟基膦化物中间体[MoCp{PR*(OH)}(CO)₂]，最终得到氟代膦化物配合物[MoCp(PFR*)(CO)₂]。通过类似的合成策略，分别以配合物1与[Me₃O]BF₄、苯甲酰氯（PhC(O)Cl）反应，可制备得到相应的烷氧基膦化物配合物[MoCp{P(OR)R*}(CO)₂]（R=Me, C(O)Ph）；而配合物1与碘甲烷（MeI）或烯丙基溴（C₃H₅Br）反应，则生成P、O双齿配位的配合物[MoCp(κ²-OPRR*)(CO)₂]（R=Me, C₃H₅）。研究发现，金属亲电试剂可结合在该阴离子的O或Mo位点上：例如，配合物1与二氯二茂锆（[ZrCl₂Cp₂]）反应，得到桥联亚膦烯氧化物的配合物[MoCp{P(OZrClCp₂)R*}(CO)₂]；而与三苯基氯化锡（SnPh₃Cl）反应则得到反式构型配合物trans-[MoCp{P(O)R*}(CO)₂(SnPh₃)]，这是一种保留完整末端P(O)R*配体的异金属配合物。