Mononuclear Rh(II) PNP-Type Complexes. Structure and Reactivity

The Rh(II) mononuclear complexes [(PNPtBu)RhCl][BF4] (2), [(PNPtBu)Rh(OC(O)CF3)][OC(O)CF3] (4), and [(PNPtBu)Rh(acetone)][BF4]2 (6) were synthesized by oxidation of the corresponding Rh(I) analogs with silver salts. On
the other hand, treatment of (PNPtBu)RhCl with AgOC(O)CF3 led only to chloride abstraction, with no oxidation. 2
and 6 were characterized by X-ray diffraction, EPR, cyclic voltammetry, and dipole moment measurements. 2 and
6 react with NO gas to give the diamagnetic complexes [(PNPtBu)Rh(NO)Cl][BF4] (7) and [(PNPtBu)Rh(NO)(acetone)][BF4]2 (8) respectively. 6 is reduced to Rh(I) in the presence of phosphines, CO, or isonitriles to give the Rh(I)
complexes [(PNPtBu)Rh(PR3)][BF4] (11, 12) (R = Et, Ph), [(PNPtBu)Rh(CO)][BF4] (13) and [(PNPtBu)Rh(L)][BF4]
(15, 16) (L = tert-butyl isonitrile or 2,6-dimethylphenyl isonitrile), respectively. On the other hand, 2 disproportionates
to Rh(I) and Rh(III) complexes in the presence of acetonitrile, isonitriles, or CO. 2 is also reduced by triethylphosphine
and water to Rh(I) complexes [(PNPtBu)RhCl] (1) and [(PNPtBu)Rh(PEt3)][BF4] (11). When triphenylphosphine and
water are used, the reduced Rh(I) complex reacts with a proton, which is formed in the redox reaction, to give a
Rh(III) complex with a coordinated BF4, [(PNPtBu)Rh(Cl)(H)(BF4)] (9).

通过银盐氧化相应的 Rh(I) 类似物，合成了 Rh(II) 单核配位化合物 [(PNPtBu)RhCl][BF4] (2), [(PNPtBu)Rh(OC(O)CF3)][OC(O)CF3] (4), 以及 [(PNPtBu)Rh(acetone)][BF4]2 (6)。另一方面，(PNPtBu)RhCl 与 AgOC(O)CF3 的处理仅导致氯离子提取，未发生氧化。化合物 2 和 6 通过 X射线衍射、电子顺磁共振、循环伏安法和偶极矩测量进行了表征。2 和 6 分别与 NO 气体反应，生成抗磁性配位化合物 [(PNPtBu)Rh(NO)Cl][BF4] (7) 和 [(PNPtBu)Rh(NO)(acetone)][BF4]2 (8)。在膦、CO 或异腈的存在下，6 被还原为 Rh(I)，分别生成 Rh(I) 配位化合物 [(PNPtBu)Rh(PR3)][BF4] (11, 12)（R = Et, Ph）、[(PNPtBu)Rh(CO)][BF4] (13) 和 [(PNPtBu)Rh(L)][BF4] (15, 16)（L = 伯丁基异腈或 2,6-二甲基苯基异腈）。另一方面，2 在乙腈、异腈或 CO 的存在下发生歧化，生成 Rh(I) 和 Rh(III) 配位化合物。2 还可通过三乙基膦和水还原为 Rh(I) 配位化合物 [(PNPtBu)RhCl] (1) 和 [(PNPtBu)Rh(PEt3)][BF4] (11)。当使用三苯基膦和水时，还原的 Rh(I) 配位化合物与在氧化还原反应中形成的质子反应，生成配位有 BF4 的 Rh(III) 配位化合物 [(PNPtBu)Rh(Cl)(H)(BF4)] (9)。