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MONO-DINITROGEN COMPLEXES OF MOLYBDENUM THAT PRODUCE AMMONIA AND HYDRAZINE. ISOLATION AND CHARACTERIZATION OF INTERMEDIATES (DIAZENIDO, HYDRIDE, HYDRAZIDO (2-))
Abstract
A new, extensive series of mono-dinitrogen complexes was reported. These were the first reported mono-N(,2) complexes to afford, upon treatment with excess acid in solution, more than a trace of ammonia and/or hydrazine. The sodium amalgam reduction of MoCl(,3) (Triphos), where Triphos = PhP(Ch(,2)CH(,2)PPh(,2))(,2), in tetrahydrofuran solution in the presence of 2L or L(,2) where L = PMe(,2)Ph, 1A; Me(,2)PCH(,2)PMe(,2), 2B; 1,2-(Me(,2)As)(,2)C(,6)H(,4), 4C; Ph(,2)PCH(,2)PPh(,2); 5D; Ph(,2)PCH(,2)CH(,2)PPh(,2), 6E; and 1,1'-(Ph(,2)PC(,5)H(,4))(,2)Fe), 7F with a stoichiometric amount of dinitrogen led to the formation of Mo(N(,2))(Triphos)(L(,2)) in high yields. The complexes were assayed with respect to their ability to form ammonia and/or hydrazine by reaction with acid in solution. All reacted with HBr in dichloromethane to afford varying amounts of ammonia, hydrazine, and dinitrogen (and some H(,2)). The highest yield of ammonia was obtained from 7F (20 mol/mol HBr in CH(,2)Cl(,2) @ 25(DEGREES)C), and the highest yield of ammonia was obtained from 1A (40 mol/mol HCl in toluene @ 70(DEGREES)C). Reaction with excess acid, in the solid state, or with a limited amount of acid, in solution, afforded six novel hydrazido(2-) compounds. Four of these complexes were found to possess the unique structural feature of a bidentate Triphos ligand. Six additional hydrazido(2-) derivatives were produced as a consequence of anion exchange or heating. A systematic study was conducted relative to the ability of selected hydrazido(2-) species to form ammonia and/or hydrazine upon treatment with anhydrous acid in solution. The other members of the new series of mono-N(,2) complexes were found to exhibit a substantially different chemistry, compared to complex 1A, with respect to reactivity with acids. Complexes 2B, 4C, and 5D were shown to react in the "solid state" with gaseous HBr to afford the corresponding hydrazido(2-) complexes. When this type of reaction was repeated with 2B, 5D, or 6E using HCl(,(g)), the products were always hydride-halide derivatives of the starting material. However, complex 2B was shown to react with two equivalents of triflic acid, without ligand loss, to afford a stable hydrazido(2-) complex of molybdenum, fac- Mo(N(,2)H(,2))(Triphos)(DMPM) (CF(,3)SO(,3))(,2). Reaction of 2B with one equivalent of HBr produced a rare molybdenum(1) complex, fac-MoBr(Triphos)(DMPM), which was characterized by a X-ray diffraction study.
Subject Area
Chemistry
Recommended Citation
TISDALE, ROBERT CLAYTON, "MONO-DINITROGEN COMPLEXES OF MOLYBDENUM THAT PRODUCE AMMONIA AND HYDRAZINE. ISOLATION AND CHARACTERIZATION OF INTERMEDIATES (DIAZENIDO, HYDRIDE, HYDRAZIDO (2-))" (1986). ETD collection for University of Nebraska-Lincoln. AAI8620822.
https://digitalcommons.unl.edu/dissertations/AAI8620822