Synthesis and Structure of Neutral and Cationic Gallium Complexes Incorporating Bis(oxazolinato) Ligands

Abstract

+ and 3b + , respectively, which are either three-coordinate methylgallium cations or four-coordinate Ga solvent adducts, as their MeB(C 6 F 5 ) 3 -salts. These cationic species exhibit a limited stability and decompose in solution within several hours at room temperature. However, stable four-coor-

Gallium and indium complexes for ring-opening polymerization of cyclic ethers, esters and carbonates

“…As depicted in Fig. 3, the solid state molecular structure of 6 features a central fourcoordinate Ga(III) center effectively  2 -N,N'-chelated by the BOX-Me 2  bidentate ligand, which results into the formation of a distorted six-membered ring C 3 N 2 Ga metallacycle with the Ga center being displaced by 0.33(2) Å from the N(2)C(6)N(1)C(9) average plane [13]. The potential utility of five-coordinate (salen)GaX species for the CO 2 /CHO copolymerization was also assessed by Darensbourg et al Albeit inactive as co-polymerization initiators, the (salen)GaCl compounds 7a and 7b (Scheme 6) effectively homopolymerize CHO in the absence of any co-catalyst to yield PCHO, as deduced from NMR data [14].…”

“…min.) to afford low molecular weight PPO oligomers (M n = 339 g•mol 1 , M w /M n = 1.25)[13]. Yet, the oligomerization process is clearly multimodal (as deduced from SEC data), with the probable involvement of several active species.…”

Synthesis of alternating metallocopolymers by chiral recognition

“…All manipulations were performed under an inert atmosphere of argon or nitrogen using standard Schlenk line techniques. Valinol was obtained by reduction of valine; 1,1‐bis[(4 S )‐4‐isopropyl‐4,5‐dihydrooxazol‐2‐yl]ethane ( 1 ) was synthesized according to previous report . Solvents were purified and degassed by standard procedures.…”

CH Bond Activation with Triel Metals: Indium and Gallium Zwitterions through Internal Hydride Abstraction in Rigid Salan Ligands

“…To our knowledge, such Ga-/In-mediated intramolecular C sp 3ÀH activation is not documented. [12,13] Beyond sheer acid-base Lewis adducts, heavier triel (Ga, In) zwitterions can form through bimolecular addition processes, [14] but intramolecular activation is limited to the use of phosphine-gallanes and -indanes for the formation of M À -Au I + species (M = Ga, In) following chloride transfer from gold to the triel metal. [15] We have verified that the treatment of Al(CH 2 SiMe 3 ) 3 (instead of Al 2 Me 6 ) with {ON^(CH 2 )^NO}H 2 equally failed to return zwitterionic complexes.…”

“…[25] Finally, the proteo-ligand {Me^M e ON^-(CH 2 )^NO Me }H (obtained following a seven-step synthesis) [16] gave {Me^M e ON^(CH 2 )^NO Me }In-(CH 2 SiMe 3 ) 2 (8-Me) upon reaction with In(CH 2 SiMe 3 ) 3 (1.0 equiv). This complex did not evolve further upon heating to 130-150 8C for [12][13][14][15][16][17][18][19][20][21][22][23][24] h, and in particular the abstraction of hydride resulting in the formation of a hydropyrimidinium moiety was not detected. Yet, formation of an indium zwitterion is thermodynamically favored with a bisphenol, as the equimolar reaction of 8-Me with {ON^(CH 2 )^NO}H 2 returned 3 through ligand exchange and release of {Me^M e ON^-(CH 2 )^NO Me }H (Scheme 4).…”