Group 5 chemistry supported by β-diketiminate ligands

Abstract

β-Diketiminate (BDI) ligands are widely used supporting ligands in modern organometallic chemistry and are capable of stabilizing various metal complexes in multiple oxidation states and coordination environments. This review describes recent advances in the chemistry of group 5 metals, namely vanadium, niobium and tantalum supported by the BDI ligand framework. Special emphasis is put on the reactivity of low-valent complexes, as well as low-coordinate complexes containing reactive multiply bonded groups, such as alkylidene, imido and nitrido groups.

β-Diketiminate complexes of the first row transition metals: applications in catalysis

“…Catalytic reactions using vanadium β-diketiminate complexes are scarce, although the stoichiometric reactivity of group 5 complexes is covered in detail by a recent Perspective from Arnold and co-workers. 23 In what is a rare example of catalysis, the η 6 -coordinating ability of a series of V(I) complexes is exploited by Tsai for the catalytic cyclotrimerization of alkynes. 24 Complex 3 gives a modest yield of cyclotrimerized phenylacetylene in a ratio of 80 : 20 of 1,3,5-substituted : 1,2,4substituted product (Scheme 4a).…”

“…a metal chloride) and reduction to replace unreactive chloride co-ligands with hydride or methyl groups (or in the case of copper, replace MeCN with THF). These unusual forms of β-diketiminate pre-catalysts undertake C-H amination with an iron (22,Scheme 19a) or copper (23,Scheme 19b) centred MOF and hydrogenation with a cobaltcontaining MOF (24,Scheme 19c It could be argued that the conditions used to carry out these transformations are more forcing than the conditions needed when using a discrete mononuclear homogeneous catalyst. Taking the research of Chirik and co-workers as an example, an asymmetric cobalt bis(imino)pyridine catalyst can be used to enantioselectively hydrogenate disubstituted alkenes using 4 atm H 2 at RT in 24 h, 41 in comparison to the MOF catalyzed (racemic) process which requires 1.5 days and 40 bar H 2 .…”

Noninnocent β‐Diiminate Ligands: Redox Activity of a Bis(alkylimidazole)methane Ligand in Cobalt and Zinc Complexes

“…β‐Diketiminates (NacNac − ) represent a class of monoanionic N,N‐chelating ligands (Scheme ) that have been studied thoroughly for the synthesis of metal complexes . The tunable steric parameters and electronic properties of these ligands have been shown to exert a predictable control over the properties of the coordinated metal ion .…”

“…The tunable steric parameters and electronic properties of these ligands have been shown to exert a predictable control over the properties of the coordinated metal ion . For most of the complexes, the NacNac ligands are generally considered as stable scaffolds that do not participate in redox processes . Accordingly, attention was centered on the redox properties and reactivity of the coordinated metal center, whereas the redox non‐innocent properties of these ligands have been less explored .…”

Bis(benzoxazol‐2‐yl)methanes Hounding NacNac: Varieties and Applications in Main Group Metal Coordination

“…[1,2] The -diketiminate or NacNac ligand family represents a well-established compound class that combines most of these features. Hence, it finds widespread application in transition -as well as main-group metal mediated catalysis, [7][8][9][10][11][12][13] and the stabilization of low oxidation state main-group metals. [14][15][16][17][18][19] This paper focuses on the recent development of novel NacNac-like ligand platforms comprising additional donor sites and increasing steric demand.…”