The First Structurally Characterized Metal (κ~2 N,P)-Phosphinohydrazides: The Key to Understanding the Intramolecular Rearrangement R_2P-NR'-NR'-M PR_2-NR'-M. Metalloderivatives of Diisopropylphosphinohydrazines: Synthesis and Properties

摘要

A number of novel phosphinohydrazines, iPr_2P-NPh-NPh-H (1), iPr_2P-NH-NH-PiPr_2 (2), IPr_2P-NMe-NH_PiPr_2 (3), and H-NMe-NH-PiPr_2 (4), were prepared and characterized. The interaction of 1 with 1 equiv of n-BuLi afforded a complex compound [Li(DME)_3][Li{(NPh-NPh-PiPr_2)-κN}2] (5). The reaction of 5 with NiBr_2 resulted in the formation of the first stable transition metal phosphinohydrazide [Ni{(NPh-NPh-PiPr_2)-κ~2N,P}_2] (6). Similarly, the cobalt(II) derivative [Co{(NPh-NPh-PiPr_2)-κ~2N,P}_2] (7) was prepared by the reaction of 1 with Co[N(SiMe_3)_2]_2. An X-ray study reveals formation of the complexes containing elongated N-N bonds.(1.443(1), 1.466(2), and 1.470(2) _ for 5, 6, and 7, respectively) as compared with the starting material 1 (1.407(1) A). Nickel phosphinohydrazide 6 has a square-planar cis configuration; the cobalt complex 7 possesses a square-planar centrosymmetric trans configuration. The half-sandwich nickel(11) complex [CpNi{(NPh-NPh-PiPr_2)-κ~2N,P}] (8) was prepared by prolonged heating of phosphinohydrazine 1 with NiCp_2 in toluene. The lithiation of 3 with n-BuLi resulted in the formation of an iminophosphoranate [LiN=PiPr_2_NMe_PiPr_2] (13) (in situ), which is the product of insertion of a PIPr_2 group into the nitrogen-nitrogen bond. The hydrolysis of 13 followed by the addition of CoCl_2 gave the phosphino_iminophosphoranato complex [CoC1_2{(HN=PPr_2_NMe-PiPr_2)-κ~2N,P}] (15) according to X-ray investigation. The phosphinohydrazine 3 reacted with FeX_2 in toluene to form adducts (1:1) [FeX_2{(PiPr_2-NMe-NH-PiPr_2)-κ~2P,F}] (X = CI (9), Br (10)), while CoCl_2 gave the complex salt [(Co(PiPr_2-NMe-NH-PiPr_2)-κ~2P,P'}_2(μ-C1)_3][CoC1_3(THF)] (11). A THE solution of complex 11 shows thermochromic behavior.