Platinum Complexes Containing Pyramidalized Germanium and Tin Dihalide Ligands Bound through σ,σ ME Multiple Bonds

We present the isolation of the first mononuclear dihalogermylene, and mono‐ and dinuclear stannylene complexes of transition metals. These exhibit exceptionally pyramidalized Group 14 centers. Additionally, removal of the halide substituents from the Ge/Sn atom was successfully performed in two ways, halide abstraction and reduction, leading to a variety of unusual structural motifs.     

Cooperative Effects in π-Ligand Bridged Dinuclear Complexes. XII [1]. Heterodinuclear Electron Poor μ-Cyclooctatetraene Complexes with CrFe-and CrCo-Combinations

The synfacial heterodinuclear μ-Cot complexes (Cot = cyclooctatetraene) [(CpCr) (CpM)]μ-Cot (Cp = cyclopentadienyl; M ? Fe, 3 ; M ? Co, 4 ) are formed in a thermal reaction of the mononuclear mixed sandwich compound CpCr(n⁶-Cot) and CpML_n [M ? Fe, L_n = benzene (Bz); M ? Co, L_n = (C₂H₄)₂]. 3 possesses two unpaired electrons whereas 4 has only one unpaired electron and is ESR active. From the molecular structure of 3 and from the ESR data of 4 it can be deduced that the unpaired electrons are localized at the Cr centers predominantly forcing a close electronical relation between the heterodinuclear compounds 3 and 4 and the mononuclear sandwich complexes chromocene and CpCrBz, respectively.     

Synthesis,Characterization and Magnetic Studies of μ‐Oxamido Copper (II) ‐ Chromium (III) Heterodinuclear Complexes

Three new μ‐oxamido‐bridged heterodinuclear copper (II)‐chromium (III) complexes formulated [Cu(Me₂oxpn)Cr‐(L)₂](NO₃)₃, where Me₂oxpn denotes N,N'‐bis(3‐amino‐2, 2‐dimethylpropyl)oxamido dianion and L represents 5‐methyl‐1,10‐phenanthroline (Mephen), 4,7‐diphenyl‐1,10‐phenanthroline (Ph₂phen) or 2,2′‐bipyridine (bpy), have been synthesized and characterized by elemental analyses, IR and electronic spectral studies, magnetic moments of room‐temperature and molar conductivity measurements. It is proposed that these complexes have oxamido‐bridged structures consisting of planar copper (II) and octahedral chromium (III) ions. The variable temperature magnetic susceptibilities (4.2–300 K) of complexes [Cu(Me₂oxpn)Cr(Ph₂phen)₂](NO₃)₃ (1) and [Cu(Me₂oxpn)Cr(Mephen)₂] (NO₃)₃ (2) were further measured and studied, demonstrating the ferromagnetic interaction between the adjacent chromium (III) and copper (II) ions through the oxamido‐bridge in both complexes 1 and 2. Based on the spin Hamiltonian, ? = ‐ 2J?₁ · ?₂, the exchange integrals J were evaluated as + 21.5 an^?1 for 1 and + 22.8 cm^?1 for 2.     

Mechanisms in the Reaction of Palladium(II)–π‐Allyl Complexes with Aryl Halides: Evidence for NHC Exchange Between Two Palladium Complexes

A detailed experimental and DFT study (PBE level) of the reaction of [Pd(η³‐C₃H₅)(tmiy)(PR₃)]BF₄ (tmiy=tetramethylimidazolin‐2‐ylidene, PR₃=phosphane), precursors to monoligated Pd⁰ species, with aryl electrophiles yielding 2‐arylimidazolium salt is reported. Experiments establish that an autocatalytic ligand transfer mechanism is preferred over Pd^IV and σ‐bond metathesis pathways, and that transmetalation is the rate‐determining step. Calculations indicate that the key step involves the concerted exchange of NHC and iodo ligands between two different Pd^II complexes. This is corroborated by experimental results showing the slower reaction of complexes containing the bulkier dipdmiy (dipdmiy = diisopropyldimethylimidazolin‐2‐ylidene).     

Crystal Structures of the (−)-DIOP Complexes of Nickel,Palladium and Platinum Dichloride

The crystal structures of PdCl₂[(?)-DIOP], PtCl₂[(?)-DIOP] and of NiCl₂-[(?)-DIOP] have been determined by X-ray analysis and refined by least-squares methods [(?)-DIOP=(?)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-1,3-dioxolane]. The coordination around the nickel atom is tetrahedral, the coordination around palladium and platinum is square planar. The unit cell of the palladium complex contains two non-equivalent molecules with different conformations of the seven-membered chelate ring involving the metal and the two phosphorus atoms. PtCl₂[(?)-DIOP] is isostructural with the corresponding palladium complex.