Synthesis and Structures of Gallium‐β‐Diketiminate Complexes: Isolation of a Dinuclear Gallium(II) Complex

Abstract

The sterically demanding β‐diketiminate ligand Ldmp [Ldmp = HC{(CMe)N(dmp)}2, dmp = C6H3‐2,6‐Me2] was used to stabilize various gallium complexes in the formal oxidation states +II and +III. The reaction of in situ generated [LdmpLi] with gallium chloride affords [LdmpGaCl2] (1), which was used as starting complex to synthesize a variety of gallium(III) compounds [LdmpGaX2] [X = F (2), I (3), H (4), and Me (5)]. Synthesis of the dinuclear complex [LdmpGaI]2 (6), with gallium in the formal oxidation state +II was accomplished by converting “GaI” with in situ generated [LdmpLi] in toluene. All compounds were characterized by elemental analyses, NMR spectroscopy, LIFDI‐TOF‐MS, and single‐crystal X‐ray diffraction. Additionally DFT calculations were performed for analysis of the bonding in 6.

Synthesis of Homo‐ and Heteroleptic Al, Ga and Zn Complexes Containing (Per)fluorinated β‐Diketiminate Ligands

“…[19a] The Zn-N bond length steadily increases and the N-Zn-N' bond angle steadily decreases with decreasing σ-donor capacity of the [23] and Mesnac 2 AlMe 2 [1.960(3), 1.966( 4) Å], [24] respectively. As was observed in the zinc complexes, the Al-N bond length also increases and the N-Al-N bond angles decrease with decreasing σ-donor capacity of the [25] and 10 Fnac 2 GaMe 2 . [23] The most electron rich complex Ar *nac 2 GaMe 2 shows the shortest N-Ga bonds [1.988( 2 [26] and (Mesnac 2 ) 2 Zn [Zn-N1 2.017(2) Å, Zn-N2 2.039(2) Å].…”

“…Comparable trends were observed when comparing complex 16 Fnac 2 GaMe 2 ( 3 ) with Ar *nac 2 GaMe 2 ( Ar *nac 2 = HC[C(Me)N‐ 2,6 ‐Me 2 –C 6 H 3 ) [ 25 ] and 10 Fnac 2 GaMe 2 . [ 23 ] The most electron rich complex Ar *nac 2 GaMe 2 shows the shortest N–Ga bonds [1.988(2)/1.999(2) Å], which steadily increases with increasing degree of fluorination to 1.988(3)/2.007(3) Å ( 10 Fnac 2 GaMe 2 ) and finally 2.027(10)/2.021(10) Å ( 3 ), whereas the N–Ga–N bond angles decrease with increase fluorine content [ Ar *nac 2 GaMe 2 93.34(9)°/93.41(8)°; 10 Fnac 2 GaMe 2 92.51(13)°; 3 91.54(6)°].…”

Molecular Main Group Metal Hydrides

“…β-Diketiminate (“Nacnac”) ligands offer an alternative LX (amido/imine) donor set based on a six-membered chelate ring for the stabilization of gallium hydrides, including examples of systems, such as ( Dipp Nacnac)­AlH 2 ( 485 ), that have been exploited in catalytic processes. , A number of different synthetic methods are available to access these compounds, including protonolysis routes similar to that used for the generation of a wide range of “simple” amidogallium linkages (e.g., ( Ph Nacnac)­GaH 2 ( 652 ) [ Ph Nacnac = {HC­(MeCNPh) 2 } − ] (eq ). Metathesis routes utilizing a β-diketiminate-stabilized gallium halide precursor and a reactive hydride source, such as a borohydride, offer a versatile route to both gallium­(III) dihydrides, of the type ( Ar Nacnac)­GaH 2 , and to halo­(X)/hydrido complexes of the type [( Ar Nacnac)­GaH­(X)]. − Precursors of the type ( Ar Nacnac)­GaX 2 are readily accessed from the corresponding gallium trihalides via metathesis, while unsymmetrical systems of the type [( Ar Nacnac)­GaR­(X)] (R = alkyl) can be accessed from either RGaX 2 via metathesis, or via oxidative addition of the C–Br bond in R-Br precursor at the Ga­(I) center of ( Dipp Nacnac)Ga ( 653 ). − …”

Cooperative Bond Activation by a Bimetallic Main-Group Complex

“…In each of the three cases, a bimetallic gallium­(II) complex possessing a gallium–gallium bond was obtained, in which one gallium ion carries the fluoride while the aryl group is bound to the other gallium ion. The gallium–gallium bond lengths of 2.4196(5) to 2.4520(8) Å are in good agreement with values of previously reported dinuclear gallium­(II) complexes based on β-diketiminate ligands . The Ga–N bonds are shorter and the N–Ga–N bite angles are more obtuse as compared to 2 , consistent with a less electron-rich gallium ion in the oxidation state +2.…”