Synthesis and Characterization of Three-Coordinate and Related β-Diketiminate Derivatives of Manganese, Iron, and Cobalt

Abstract

Treatment of M[N(SiMe(3))(2)](2) (M = Mn, Fe, Co) with various bulky beta-diketimines afforded a variety of new three-coordinate complexes which were characterized by UV-vis, (1)H NMR and IR spectroscopy, magnetic measurements, and X-ray crystallography. Reaction of the beta-diketimine H(Dipp)NC(Me)CHC(Me)N(Dipp) (Dipp(2)N(wedge)NH; Dipp = C(6)H(3)-2,6-Pr(i)(2)) with M[N(SiMe(3))(2)](2) (M = Mn or Co) gave Dipp(2)N(wedge)NMN(SiMe(3))(2) (M = Mn, 1; Co, 3) while the reaction of Fe[N(SiMe(3))(2)](2) with Ar(2)N(wedge)NH (Ar = Dipp, C(6)F(5), Mes, C(6)H(3)-2,6-Me(2), or C(6)H(3)-2,6-Cl(2)) afforded the series of iron complexes Ar(2)N(wedge)NFe[N(SiMe(3))(2)] (Ar = Dipp, 2a; C(6)F(5), 2b; Mes, 2c; C(6)H(3)-2,6-Me(2), 2d; C(6)H(3)-2,6-Cl(2), 2e). This represents a new synthetic route to beta-diketiminate complexes of these metals. The four-coordinate bis-beta-diketiminate complex Fe[N(wedge)N(C(6)F(5))(2)](2), 4, was also isolated as a byproduct from the synthesis of 2b. Direct reaction of the Dipp(2)N(wedge)NLi with CoCl(2) gave the "ate" salt Dipp(2)N(wedge)NCoCl(2)Li(THF)(2), 5, in which the lithium chloride has formed a complex with Dipp(2)N(wedge)NCoCl through chloride bridging. The Fe(III) species Dipp(2)N(wedge)NFeCl(2), 6, was obtained cleanly from the reaction of FeCl(3) with Dipp(2)N(wedge)NLi. Magnetic measurements showed that all the complexes have a high spin configuration. The different substituents in the series of iron complexes 2a-e allowed assignment of their paramagnetically shifted (1)H NMR spectra. The X-ray crystal structures 1-2d and 3 showed that they have a distorted three-coordinate planar configuration at the metals whereas complexes 4-6 have highly distorted four-coordinate geometries.

Neutral and cationic Fe(II) β-diketiminate complexes

“…[35], and B(C 6 F 5 ) 3 [36] were prepared by the literature procedures. [(BDK)FeCl 2 ] was prepared according to a modification of a published procedure [13] using THF as reaction solvent and diethyl ether for extraction and crystallisation. were commercial products and were used without further purification.…”

“…Both have a magnetic moment in benzene solution of 5.6 l B , consistent with a high-spin d 6 -configuration (4 unpaired electrons). This is commonly observed in the family of (b-diketiminate)Fe II X complexes [7,8,10,11,13,14]. The presence of unpaired electrons in 1 and 2 results in 1 H NMR spectra consisting of paramagnetically shifted, broad resonances in the frequency window from +150 to À150 ppm.…”

“…Me BDK] À [10][11][12][13][14]. Despite the formal electron deficiency of the threecoordinate iron benzyl complex, no interaction between the arene part of the benzyl group and the iron atom is present in 1.…”

Platinum(II)‐Mediated Double Coupling of 2,3‐Diphenylmaleimidine with Nitrile Functionalities To Give Annulated Pentaazanonatetraenate (PANT) Systems

“…Five complexes (10, 11·1/8nC 6 H 14 , 15, 16·CCl 4 , and 17·CHCl 3 ) were characterized by X-ray crystallography ( Figure 2). They exhibit square planar geometries: three positions are occupied with the newly formed N N N tridentate ligand, whereas the fourth position is filled with the chloride.…”

“…-Diketonates [1,2] (A, Figure 1) and -diketiminates [3,4] (B), as dinitrogen analogues of diketonates, exhibit a broad spectrum of useful applications that is reflected in a great amount of publications on synthetic approaches to these systems and their usage in practically significant areas. By contrast, studies on relevant trinitrogen ligand systems, namely 1,3,5-triazapenta-1,4-dienes (TAPD; C), were by far more scarce until the past decade when studies on TAPD complexes experienced a rapid growth, and currently these species are gradually becoming one of the most useful groups of nitrogen-based ligands in coordination chemistry (for a review on TAPD systems see ref.…”