Synthesis and structural characterisation of group 10 metal(ii) gallyl complexes: analogies with platinum diboration catalysts?

Abstract

Reactions of the anionic gallium(i) heterocycle, [:Ga{[N(Ar)C(H)](2)}](-) (Ar = C(6)H(3)Pr(i)(2)-2,6), with a variety of mono- and bidentate phosphine, tmeda and 1,5-cyclooctadiene (COD) complexes of group 10 metal dichlorides are reported. In most cases, salt elimination occurs, affording either mono(gallyl) complexes, trans-[MCl{Ga{[N(Ar)C(H)](2)}}(PEt(3))(2)] (M = Ni or Pd) and cis-[PtCl{Ga{[N(Ar)C(H)](2)}}(L)] (L = R(2)PCH(2)CH(2)PR(2), R = Ph (dppe) or cyclohexyl (dcpe)), or bis(gallyl) complexes, trans-[M{Ga{[N(Ar)C(H)](2)}}(2)(PEt(3))(2)] (M = Ni, Pd or Pt), cis-[Pt{Ga{[N(Ar)C(H)](2)}}(2)(PEt(3))(2)], cis-[M{Ga{[N(Ar)C(H)](2)}}(2)(L)] (M = Ni, Pd or Pt; L = dppe, Ph(2)CH(2)PPh(2) (dppm), tmeda or COD). The crystallographic and spectroscopic data for the complexes show that the trans-influence of the gallium(i) heterocycle lies in the series, B(OR)(2) > H(-) > PR(3) approximately [:Ga{[N(Ar)C(H)](2)}](-) > Cl(-). Comparisons between the reactivity of one complex, [Pt{Ga{[N(Ar)C(H)](2)}}(2)(dppe)], with that of closely related platinum bis(boryl) complexes indicate that the gallyl complex is not effective for the catalytic or stoichiometric gallylation of alkenes or alkynes. The phosphaalkyne, Bu(t)C[triple bond, length as m-dash]P, does, however, insert into one gallyl ligand of the complex, leading to the novel, crystallographically characterised P,N-gallyl complex, [Pt{Ga{[N(Ar)C(H)](2)}}{Ga{PC(Bu(t))C(H)[N(Ar)]C(H)N(Ar)}}(dppe)]. An investigation into the mechanism of this insertion reaction has been undertaken.

Synthesis of the Sterically Related Nickel Gallanediyl Complexes [Ni(CO)3(GaAr′)] (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) and [Ni(CO)3(GaL)] (L = HC[C(CH3)N(C6H3-2,6-iPr2)]2): Thermal Decomposition of [Ni(CO)3(GaAr′)] to give the Cluster [Ni4(CO)7(GaAr′)3]

“…The Ni-Ni distances are between 2.361(10) and 2.628(11) Å . A similar range of Ni-Ni distances was reported for Ni 4 (CO) 6 (GaCp*) 4 [13,17,[39][40][41]. Two of the six edges of the Ni 4 tetrahedron are bridged by a l-GaAr 0 fragment.…”

Reactions of Digallanes with p‐ and d‐Block Lewis Bases: Adducts, Bis(gallyl) Complexes, and Naked Ga+ as Ligand

“…Thus, we were interested in testing the reactivity of related tetrahalodigallanes(4) with similar TM Lewis bases. This was also motivated by a previous report of Ga−Ga bond oxidative addition to Pt 0 by Jones et al., as well as the unpredictable reactivity of tetrahalodiboranes(4) with Pt 0 complexes, which was shown by Norman et al. to lead to B−B oxidative addition in the case of B 2 F 4 and an unusual diplatinum complex of [B 2 I 4 ] 2− in the case of B 2 I 4 …”

Synthesis and structure of new compounds with Pt–Ga bonds: Insertion of the bulky gallium (I) bisimidinate Ga(DDP) into Pt–Cl bond

“…Very recently the first homoleptic platinum(0) complex, [Pt{Ga(Giso)} 3 ] with the neutral four-membered guanidinato gallium(I) heterocycle [:Ga(Giso)] (Giso ¼ {(2,6-i Pr 2 C 6 H 3 )NC(NCy 2 )N(C 6 H 3 -2,6-i Pr 2 )}, Cy ¼ cylohexyl) was reported by C. Jones and his coworkers, where they described particularly short PteGa (3-coordinate) bonds [10]. Likewise, few structurally interesting platinum complexes have also been reported with the anionic gallium (I) heterocyle by the salt elimination process [11].…”

“…These data match with the analytical and spectroscopic characterization of 4. [11]. This elongation is expected because of the tetra-coordinated Ga centre of 2 (also in 3), as compared with lower coordinate Ga centres in the cited reference compounds.…”