Coordination chemistry of perhalogenated cyclopentadienes and alkynes, XXVII. Synthesis of bimetallic perchlorcymantrene derivatives [C5Cl4 − x(R)x (MLn)]Mn(CO)3 with Ni, Pd or Pt – Complex fragments as ring substituents. Structures of {C5Br4[Ni(PMe3)2(Cl

Treatment of [(C5Cl4Br)Mn(CO)3] (1a) with nBuLi and the halide complexes [Ni(PR3)2Cl2] (R = Me, Et, nPr, nBu; R3 = Me2Ph), [Pd(PPh3)2Cl2], [Pd(dppe)Cl2], and [Pt(PEt3)2Cl2] yields the bimetallic cyclopentadienyl-bridged complexes {[C5Cl4(MLn)]Mn(CO)3} with MLn = trans-Ni(PR3)2Cl (2a–e), cis Pd(PR3)2Cl (3a,b) and cis-Pt(PEt3)2Cl (4), while with [Pd(COD)Br2] a mixture of the neutral {[C5Cl4(Pd(COD)Br)]Mn(CO)3} (5a) and the anionic {(OC)3Mn[C5Cl4-Pd(Br)(μ-Br)2(Br)Pd-C5Cl4]Mn(CO)3}2− (5b) is formed. The reaction of 1a, {[C5Cl5 − n(SiMe3)n] Mn(CO)3} (n = 1: 1b; 2: 1c) or {[C5Cl5 − n(SMe)n]Mn(CO)3} (n = 1: 1d; 2: 1e) with a solution of in situ generated “Ni(PMe3)2(C2H4)” gives {[C5Cl4Ni(PMe3)2X]Mn(CO)3} (X = Cl/Br: 2a/2a′) or the corresponding ring-silyl or methylthio-substituted derivatives {[C5Cl4 − n(SiMe3)nNi(PMe3)2Cl]Mn(CO)3} (6a,b) or {[C5Cl4 − n(SMe)n Ni(PMe3)2Cl] Mn(CO)3} (7a,b), respectively. Similarly, the oxidative addition to [(C5Br5)Mn(CO)3] (1f) yields a mixture of compounds {[C5Br4Ni(PMe3)2X]Mn(CO)3} (X = Cl/Br: 8/8′). The molecular structures of 7b and 8/8′ have been determined by X-ray diffraction and show the trans configuration of the PMe3 ligands in both complexes and the 1,2,4-regiochemistry of the three non-chlorine substituents in 7b.

The bimetallic cyclopentadienyl bridged complexes {[C5X4 − n(R)n(MLm)]Mn(CO)3} (X = Cl, Br; R = Cl, SiMe3, SMe; M = Ni, Pd, Pt) are prepared from halogeno-cymantrenes either via lithium-halide exchange followed by treatment with [MCl2Lm] or via oxidative addition of in situ generated [Ni(PMe3)2(C2H4)].Figure optionsDownload as PowerPoint slideHighlights
► [C5X4Br]Mn(CO)3 (X = Cl, Br) react with BuLi and [MCl2Ln](M=Ni, Pd, Pt) to [C5X4(MLn)]Mn(CO)3.
► [C5X4Br]Mn(CO)3 oxidatively add to “Ni(PR3)2” to give bimetallic [C5X4(MLn)]Mn(CO)3.
► The structures of [C5Cl2(SMe)2Ni(PMe3)2Cl]Mn(CO)3 and [C5Br4Ni(PMe3)2(Cl,Br)]Mn(CO)3 have been determined by X-ray diffraction.