Department of Chemistry 6-331 , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.
Department of Chemistry, Merkert Chemistry Center , Boston College , Chestnut Hill , Massachusetts 02467 , United States.
J Am Chem Soc. 2018 Oct 24;140(42):13609-13613. doi: 10.1021/jacs.8b09616. Epub 2018 Oct 10.
The reaction between Mo(O)(CHAr)(OR)(PMe) (Ar = ortho-methoxyphenyl, OR = OCMe(CF)) and 2 equiv of LiOHMT (OHMT = O-2,6-(2,4,6-MeCH)CH) leads to Mo(O)(CHAr)(OHMT), an X-ray structure of which shows it to be a trigonal bipyramidal anti benzylidene complex in which the o-methoxy oxygen is coordinated to the metal trans to the apical oxo ligand. Addition of 1 equiv of water (in THF) to the benzylidyne complex, Mo(CAr)(OR)(THF) (Ar = para-methoxyphenyl, OR = OR or OC(CF) (OR)) leads to formation of {Mo(CAr)(OR)(μ-OH)(THF)}(μ-THF) complexes. Addition of 1 equiv of a phosphine (L) to Mo(CAr)(OR)(THF) in THF, followed by addition of 1 equiv of water, all at room temperature, yields Mo(O)(CHAr)(OR)(L) complexes in good yields for several phosphines (e.g., PMePh (69% by NMR), PMePh (59%), PEt (69%), or P( i-Pr) (65%)). The reaction between Mo(O)(CHAr)(OR)(PEt) and 2 equiv of LiOHMT proceeds smoothly at 90 °C in toluene to give Mo(O)(CHAr)(OHMT), a four-coordinate syn alkylidene complex. Mo(O)(CHAr)(OHMT) reacts with ethylene (1 atm in CD) to give (in solution) a mixture of Mo(O)(CHAr)(OHMT), Mo(O)(CH)(OHMT), and an unsubstituted square pyramidal metallacyclobutane complex, Mo(O)(CHCHCH)(OHMT), along with ethylene and ArCH═CH. Mo(O)(CHAr)(OHMT) also reacts with 2,3-dicarbomethoxynorbornadiene to yield syn and anti isomers of the "first-insertion" products that contain a cis C═C bond.
Mo(O)(CHAr)(OR)(PMe)（Ar=邻甲氧基苯基，OR=OCMe(CF))与 2 当量的 LiOHMT（OHMT=O-2,6-(2,4,6-MeCH)CH)反应生成 Mo(O)(CHAr)(OHMT)，其 X 射线结构表明它是一个反苄叉的三角双锥配合物，其中邻甲氧基氧原子与顶端的氧配体处于反位。将 1 当量的水（在 THF 中）加入到苄叉配合物 Mo(CAr)(OR)(THF)（Ar=对甲氧基苯基，OR=OR 或 OC(CF)(OR)）中，会生成{Mo(CAr)(OR)(μ-OH)(THF)}(μ-THF)配合物。在 THF 中，将 1 当量的膦（L）加入到 Mo(CAr)(OR)(THF)中，然后加入 1 当量的水，在室温下进行反应，得到几种膦（如 PMePh（69%通过 NMR）、PMePh（59%）、PEt（69%）或 P(i-Pr)（65%））的 Mo(O)(CHAr)(OR)(L)配合物，产率较高。Mo(O)(CHAr)(OR)(PEt)与 2 当量的 LiOHMT 在 90°C 的甲苯中反应顺利，生成 Mo(O)(CHAr)(OHMT)，这是一个四配位的顺式亚烷基配合物。Mo(O)(CHAr)(OHMT)与乙烯（在 CD 中的 1 个大气压）反应，得到（在溶液中）Mo(O)(CHAr)(OHMT)、Mo(O)(CH)(OHMT)和一个未取代的正方形三角面金属环丁烷配合物 Mo(O)(CHCHCH)(OHMT)，以及乙烯和 ArCH=CH。Mo(O)(CHAr)(OHMT)还与 2,3-二羧酸甲酯降冰片二烯反应，生成“第一次插入”产物的顺式和反式异构体，其中包含一个顺式 C=C 键。
