MeNC Insertion into Pd–C6F5 bonds: bis(µ-imidoyl-C,N)palladium complexes, a novel type of imidoyl co-ordination in palladium chemistry. Single-crystal X-ray structure of [Pd2{µ-C(C6F5)N(Me)}2Cl2(SC4H8)2]

Abstract

The complex cis- or trans-[Pd(C₆F₅)₂(CNMe)₂] reacts with PdCl₂ or [PdCl₂(NCPh)₂] to give [Pd₂(µ-Cl)₂(C₆F₅)₂(CNMe)₂] which in turn undergoes MeNC insertion to give cis-[{Pd₂(µ-Cl)₂[µ-C(C₆F₅)N(Me)]₂}_n]. The latter undergoes cleavage of the chloro-bridges by neutral ligands [L = CNMe, NMe₃, py, 4Me-py, 4Bu^t-py (py = pyridine), PPh₃, and SC₄H₈] affording dimeric complexes [LCl[graphic omitted]dClL]. {For L = CNMe the complex can also be obtained by heating trans-[Pd(C₆F₅)Cl(CNMe)₂].} The polymer also reacts with Tl(acac)(acac = acetylacetonate) or Ag(O₂CMe) affording the corresponding imidoyl-bridged dimers. The ¹H n.m.r. spectra show a mixture of two isomers for L = py, 4Me-py, and 4Bu^t-py; the four ¹⁹F n.m.r. spectra recorded reveal restricted rotation for the C₆F₅ group. The bridging location of the imidoyl groups has been ascertained by a single-crystal X-ray structure determination of the complex with L = SC₄H₈(tetrahydrothiophen), which crystallizes in the monoclinic space group P2₁/c, with unit-cell dimensions a= 9.304(2), b= 9.563(2), c= 34.979(5)Å, β= 95.76(2)°, and Z= 4. The structure was solved by the heavy-atom method and refined to R= 0.040 for 3 978 observed reflections.