En Route to Bis‐Carbene Analogues of the Heavier Group 13 Elements: Consideration of Bridging Group and Metal(I) Source

Abstract

With the aim of exploring the effect of steric constraints imposed on the metal-metal interaction of bis-carbene analogues of thallium by the linking scaffold, seven dinuclear thallium diyls with a series of rigid, semirigid, and flexible bridging scaffolds were synthesized. The solid-state molecular structures were determined for four of these compounds by single-crystal XRD and compared with the results of DFT calculations, which were performed for all substances. These compounds serve as models to investigate the metal-metal distance in the absence of co-coordinated molecules (additional ligands, solvent molecules). In addition, the effect of the metal(I) precursor, and more specifically the counterion, on the synthetic access to bis-carbene analogues of indium and thallium was investigated. For indium, only InI yields the desired dinuclear indium diyl. With InBr no reaction was observed, and using InCl gave rise to a mononuclear indium(III) compound. For thallium, both TlI and TlBr allow access to the related bis-carbene analogue, although the yield with the latter is significantly lower. In contrast, no reactions were observed with TlCl and TlBF .

Group 13 Heavier Carbene Analogues Stabilized by the Bulky Bis(4-benzhydryl-benzoxazol-2-yl)methanide Ligand

“…The butterfly folding angle between both benzoxazolyl moieties declines from 1 to 3 (Table ). These findings are in good agreement with previously reported monomeric six-membered NacNac-based thallium, indium, and gallium heterocycles as [M 13 L 6 ] (M 13 = Tl, ,, In, ,, or Ga − ) or bis­(NacNac) complexes as [(M 13 L) 2 R] − [M 13 = Tl, In, or Ga; L = {DippNCMe}­HC­{MeCN}, where R = 1,2-alkylene, 1,3-xlylene, or (hetero)­arylene bridge].…”

Ligands with Two Monoanionic N,N‐Binding Sites: Synthesis and Coordination Chemistry

“…Since then, three methods have been successfully applied for the synthesis of N‐bridged bis(β‐diimine)s (Scheme ). Although two of them start from β‐aminoketones, a successful, neat reaction is only observed with 1,3‐bis(aminomethyl)benzene (route ii ) . In case of other diamines, pre‐activation of the β‐aminoketone using trialkyl oxonium tetrafluoroborate, also known as Meerwein's salt, is necessary .…”

“…Heteroleptic dinuclear complexes of type C are known for transition metals (Cu, Y, Zn) as well as for rare‐earth (Yb) and main‐group elements (Al, Ca, In, Mg, Na, Tl). Notably, calcium and magnesium complexes of type C show a dynamic behavior and undergo rapid ligand exchange in accordance with the Schlenk equilibrium yielding homoleptic complexes of type D .…”

“…Althought wo of them start from b-aminoketones, as uccessful, neat reactioni so nly observed with 1,3-bis(aminomethyl)benzene (route ii). [89] In case of other diamines, pre-activation of the b-aminoketone using trialkyl oxoniumt etrafluoroborate, also known as Meerwein's salt, [90] is necessary. [88,91] All derivatives reported so far contain terminal aryl groups,w hereas the opposite holds true for the first compartmental N-bridged bis(b-diimine), containing an additional amineg roup in the bridge,w hich was obtained through route iii)b yt reating a bis(b-aminocarbonyl)c ompound with primary alkyl amines.…”

“…[91a] With (almost) parallelo riented NacNac moieties, am ononuclear complex of type B has been isolated, in whichacalciumi sf ramed by both bis(b-diiminate) units and ac oordination number of five is reachedt hrough the complexation of an additional THF molecule. [99] Heterolepticd inuclear complexes of type C are knownf or transition metals (Cu, [91h] Y, [100] Zn [91b,e, j] )a sw ell as for rare-earth (Yb) [100] and main-group elements (Al, [101] Ca, [91b,e] In, [102] Mg, [103] Na, [100] Tl [89,102] ). Notably,c alcium and magnesium complexes of type C show ad ynamic behavior and undergo rapid ligand exchange in accordance with the Schlenke quilibrium yielding homoleptic complexes of type D. yields ah exanuclear copperc omplex, [104] or incorporates the pyridyl nitrogen atom into the coordination sphere of the two magnesium or zinc centers [91b, 103b] as illustrated for the dinuclear magnesium complex XVII (Figure 19).…”