476352-95-1Relevant academic research and scientific papers
Structures, bonding, and reaction chemistry of the neutral organogallium(I) compounds (GaAr)n (n = 1 or 2) (Ar = terphenyl or related ligand): An experimental investigation of Ga-Ga multiple bonding
Hardman, Ned J.,Wright, Robert J.,Phillips, Andrew D.,Power, Philip P.
, p. 2667 - 2679 (2003)
The synthesis, structure, and properties of several new organogallium(I) compounds are reported. The monovalent compounds GaAr* (Ar* = C6H3-2,6-Trip2, Trip = C6H2-2,4,6-Pr3i 1), GaAr# (Ar# = C6H3-2,6(ButDipp)2, ButDipp = C6H2-2,6- Pri2-4-But, 4), and the dimeric (GaAr′)2 (Ar′ = C6H3-2,6-Dipp2, Dipp = C6H3-2,6-Pri2, 6) were synthesized by the reaction of "Gal" with (Et2O)LiAr*, (Et2O)LiAr# (3), or (LiAr′)2. Compounds 1 and 4 were isolated as green crystals, whereas 6 was obtained as a brown-red crystalline solid. All three compounds dissolved in hydrocarbon solvents to give green solutions and almost identical UV/visible spectra. Cryoscopy of 1 and 6 showed that they were monomeric in cyclohexane. Crystals of 1 and 4 were unsuitable for X-ray crystal structure determinations, but an X-ray data set for 6 showed that it was weakly dimerized in the solid with a long Ga - Ga bond of 2.6268(7) A and a trans-bent CGaGaC core array. The 1,2-diiodo-1,2-diaryldigallane compounds {Ga(Ar*)I}2 (2), {Ga(Ar#)I}2 (5), and {Ga(Ar′)I}2 (7) were isolated as byproducts of the synthesis of 1, 4, and 6. The crystal structures of 2 and 7 showed that they had planar ICGaGaCl core arrays with Ga - Ga distances near 2.49 A, consistent with Ga - Ga single bonding. Treatment of 1, 4, and 6 with B(C6F5)3 immediately afforded the 1:1 donor-acceptor complexes ArGa{B(C6F5)3} (Ar = Ar*, 8; Ar#, 9; Ar′, 10) that featured almost linear gallium coordination, Ga - B distances near the sum of the covalent radii of gallium and boron, as well as some close Ga...F contacts. Compound 1 also reacted with Fe(CO)5 under ambient conditions to give Ar*GaFe(CO)4 (11), which had been previously synthesized by the reaction of GaAr*Cl2 with Na2Fe(CO)4. Reaction of 1 with 2,3-dimethyl-1,3-butadiene afforded the compound {Ar*GaCH2C(Me)C(Me)CH2}2 (12) that had a 10-membered 1,5-Ga2C8 ring with no Ga - Ga interaction. Stirring 1 or 6 with sodium readily gave Na2{Ar*GaGaAr*} (13) and Na2(Ar′GaGaAr′) (14). The former species 13 had been synthesized previously by reduction of GaAr*Cl2 with sodium and was described as having a Ga - Ga triple bond because of the short Ga - Ga distance and the electronic relationship between [Ar*GaGaAr*]2- and the corresponding neutral group 14 alkyne analogues. Compound 14 has a similar structure featuring a trans-bent CGaGaC core, bridged by sodiums which were also coordinated to the flanking aryl rings of the Ar′ ligands. The Ga - Ga bond length was found to be 2.347(1) A, which is slightly (ca. 0.02 A) longer than that reported for 13. Reaction of Ga{N(Dipp)C(Me)}2CH, 15 (i.e., GaN/NDipp2), which is sterically related to 1, 4, and 6, with Fe(CO)5 yielded Dipp2N/NGaFe(CO)4 (16), whose Ga - Fe bond is slightly longer than that observed in 11. Reaction of the less bulky LiAr″ (Ar″ = C6H3-2,6-Mes2) with "Gal" afforded the new paramagnetic cluster Ga11Ar4″ (17). The ready dissociation of 1, 4, and 6 in solution, the long Ga - Ga distance in 6, and the chemistry of these compounds showed that the Ga - Ga bonds are significantly weaker than single bonds. The reduction of 1 and 6 with sodium to give 13 and 14 supplies two electrons to the di-gallium unit to generate a single bond (in addition to the weak interaction in the neutral precursor) with retention of the trans-bent geometry. It was concluded that the stability of 13 and 14 depends on the matching size of the sodium ion, and the presence of Na - Ga and Na - Ar interactions that stabilize their Na2Ga2 core structures.
New Experimental Insight into the Nature of Metal?Metal Bonds in Digallium Compounds: J Coupling between Quadrupolar Nuclei
Kobera, Libor,Southern, Scott A.,Rao, Gyandshwar Kumar,Richeson, Darrin S.,Bryce, David L.
, p. 9565 - 9573 (2016/07/14)
Multiple bonding between atoms is of ongoing fundamental and applied interest. Here, we report a multinuclear (1H,13C, and71Ga) solid-state magnetic resonance spectroscopic study of digallium compounds which have been proposed, albeit somewhat controversially, to contain single, double, and triple Ga?Ga bonds. Of particular relevance to the nature of these bonds, we have carried out two-dimensional71Ga J/D-resolved NMR experiments which provide a direct measurement of J(71Ga,71Ga) spin–spin coupling constants across the gallium?gallium bonds. When placed in the context of clear-cut experimental data for analogous singly, doubly, and triply bonded carbon spin pairs or boron spin pairs, the71Ga NMR data clearly support the notion of a different bonding paradigm in the gallium systems. Our findings are consistent with an increasing role across the purported gallane–gallene–gallyne series for classical and/or slipped π-type bonding orbitals.
