Cooperativity in Transition Metal Tetrylene Complexes

Abstract

Cooperative reactivity between transition metals and ligands, or between two metals, has created significant opportunities for the development of new transformations that would be difficult to carry out with a single metal. Here we explore cooperativity between transition metals and divalent heavier group 14 elements (tetrylenes), a less‐explored facet of the field of cooperativity. Tetrylenes combine their strong σ‐donor properties with an empty p‐orbital that can accept electron density. This ambiphilicity has allowed them to form metal tetrylene and metallotetrylene complexes that place a reactive site adjacent to the metal. We have selected examples to demonstrate what has been achieved so far regarding cooperative reactivity, as this already spans metal‐, tetrylene‐ or multi‐site‐centred bond cleavage, cycloaddition, migration, metathesis, and insertion. We also highlight some challenges that need to be overcome for this cooperativity to make it to catalysis.

Dehydrogenative Double C−H Bond Activation in a Germylene‐Rhodium Complex**

“…[2] Moreover, they represent the prospects of new avenues for transition metal/P‐element cooperation. [ 3 , 4 ] However, the coordination chemistry of tetrylenes remains considerably less explored than their lighter carbene congeners, in no little part due to reduced stability. To overcome this limitation base‐stabilized tetrylenes have been explored and their complexes have found relevance in catalysis.…”

Calix[4]pyrrolato Stannate(II): A Tetraamido Tin(II) Dianion and Strong Metal‐Centered σ‐Donor

“…The coordinative properties of [2] 2− are exemplified in structurally diverse complexes with tungsten and ruthenium. The η 5 ‐coordination behavior suggests the possibility of placing a transition metal center near a nucleophilic tin(II) atom, expedient for cooperative activation modes [43] . Spontaneous hydride substitution reaction with benzaldehydes and the straightforward reaction of [2] 2− with acyl chlorides grants access to the yet underexplored class of acyl metalloids, e.g., of interest as visible‐light photoinitiators [44] .…”

Calix[4]pyrrolatostannat(II): Ein Tetraamidozinn(II)dianion als starker, metallzentrierter σ‐Donor

“…Das η 5 -Koordinationsverhalten deutet auf die Möglichkeit hin, ein Übergangsmetallzentrum in der Nähe eines nukleophilen Zinn(II)atoms zu platzieren, welches kooperative Aktivierungsmodi begünstigt. [42] Die spontane Hydrid-substitutionsreaktion mit Benzaldehyden und die Reaktion von [2] 2À mit Acylchloriden ermöglicht den Zugang zu der noch wenig erforschten Klasse der Acylmetalloide, welche z. B. als Photoinitiatoren im vis-Bereich von Interesse sind.…”