Addressing the Chemical Sorcery of “GaI”: Benefits of Solid-State Analysis Aiding in the Synthesis of P→Ga Coordination Compounds

Abstract

The differing structures and reactivities of "GaI" samples prepared with different reaction times have been investigated in detail. Analysis by FT-Raman spectroscopy, powder X-ray diffraction, (71)Ga solid-state NMR spectroscopy, and (127)I nuclear quadrupole resonance (NQR) provides concrete evidence for the structure of each "GaI" sample prepared. These techniques are widely accessible and can be implemented quickly and easily to identify the nature of the "GaI" in hand. The "GaI" prepared from exhaustive reaction times (100 min) is shown to possess Ga2I3 and an overall formula of [Ga(0)]2[Ga(+)]2[Ga2I6(2-)], while the "GaI" prepared with the shortest reaction time (40 min) contains GaI2 and has the overall formula [Ga(0)]2[Ga(+)][GaI4(-)]. Intermediate "GaI" samples were consistently shown to be fractionally composed of each of these two preceding formulations and no other distinguishable phases. These "GaI" phases were then shown to give unique products upon reactions with the anionic bis(phosphino)borate ligand class. The reaction of the early-phase "GaI" gives rise to a unique phosphine Ga(II) dimeric coordination compound (3), which was isolated reproducibly in 48% yield and convincingly characterized. A base-stabilized GaI→GaI3 fragment (4) was also isolated using the late-phase "GaI" and characterized by multinuclear NMR spectroscopy and X-ray crystallography. These compounds can be considered unique examples of low-oxidation-state P→Ga coordination compounds and possess relatively long Ga-P bond lengths in the solid-state structures. The anionic borate backbone therefore results in interesting architectures about gallium that have not been observed with neutral phosphines.

A Comprehensive Investigation of a Zwitterionic GeI Dimer with a 1,2‐Dicationic Core

“…This dearth in examples could be attributed to the fact that more electron density is necessary to help soften the repulsive Coulombic force. Instead of oxidation to tetrel(III), a tetrel(I) species could be targeted using L‐type ligands, which has been a useful approach in accessing Ga II 1,2‐dications …”

“…Instead of oxidation to tetrel(III), at etrel(I) speciesc ould be targeted using L-type ligands, which has been au seful approach in accessing Ga II 1,2-dications. [17,18] There are ah andful of compounds containing heavy tetrel elements with an oxidation state of (I). Aside from some exceptions, [19][20][21] the field has been dominated by two main classes, the heavy alkyne analogues [22][23][24][25] and those supported by monoanionic chelating ligands (A-E in Figure 1).…”

Synthesis and Structures of Polyhedral Hexa‐ and Octagallium Cluster Compounds

“…[1b], The clusters isolated from corresponding reactions with Li(thf) 3 (R 1 ) depended on the “GaI” composition , . It was also demonstrated that the products resulting using “GaI“ vary with time of ultra‐sonification , . “GaI” is insoluble in organic solvents or decomposes under disproportionation into Ga 0 and GaI n · Do (n = 2,3) with donor solvents (Do), making the reactions poorly selective.…”

“…[8,24] It was also demonstrated that the products resulting using "GaI" vary with time of ultra-sonification. [15,25] "GaI" is insoluble in organic solvents or decomposes under disproportionation into Ga 0 and GaI n ·Do (n = 2,3) with donor solvents (Do), [26] making the reactions poorly selective. The isolation of Ga 3 I 5 (PEt 3 ) 3 by addition of P(Et) 3 to "GaI" demonstrates possible disproportionation pathways.…”

Cationic cluster formation versus disproportionation of low-valent indium and gallium complexes of 2,2’-bipyridine

“…Stabilizing gallium in its low oxidation states (<III) has been an objective since the 1,930 s. (ref. 13 ) Subvalent gallium halides Ga I [Ga III X 4 ] (X=Cl, Br and I) 14 , ‘GaI' (refs 15 , 16 ) and metastable, donor stabilized Ga I Cl solutions 9 are important milestones and to this day used as starting material for further Ga I chemistry: for example, arene- 17 , Cp x -complexes (Cp x : Cp=C 5 H 5 and Cp*=C 5 Me 5 ), (ref. 18 ) N-heterocyclic carbene (NHC) analogues 19 20 of Ga I , or metalloidal gallium clusters 7 .…”