ClCH CH Cl Research Articles

Synthesis and structure of a μ-( E)-vinylene-bis[dimethylglyoximato(1-)-dimethylglyoximato(2-)-(triphenylphosphine)rhodate] complex a vinylene-bridged dinuclear rhodium complex

[Rh(dmgH) 2(PPh 3)] (dmgH 2 = dimethylglyoxime), prepared by reduction of [Rh(dmgH) 2(PPh 3)Cl] with NaBH 4 in methanolic KOH, reacts with ( E)-1,2-dichloro ethylene to give the the ( E)-vinylene-bridged dinuclear rhodium complex [{K(MeOH) 2} 2-{(PPh 3)(dmg)(dmgH)RhCHCHRh(dmg)(dmgH)(PPh 3)}] ( 1). Furthermore, 1 is formed in a mixture with [Rh(dmgH) 2(PPh 3)(Z)-CHCHCl] ( 2) and [Rh(dmgH) 2(PPh 3)CHCH 2] ( 3) in the reaction of [Rh(dmgH) 2(PPh 3] − with ( Z)-ClCHCHCl and in a mixture with 3 in the reaction of [Rh(dmgH) 2(PPh 3)] − with acetylene. 1 crystallizes in the monoclinic space group C2/ c with: a = 22.711(5), b = 10.465(2), c = 27.910(6) A ̊ , β = 101.71(3)°, Z = 4 . The structure was refined up to R1 = 0.0373 for 4903 reflections. The molecule consists of two [Rh(dmg)(dmgH)(PPh 3)] subunits linked by an ( E)-CHCH bridge. The oxygen atoms of the dimethylglyoximato ligands and the solvent molecules (MeOH) are coordinated at the potassium ions. 1H, 13C and 31P NMR spectra of 1 agree definitely with the molecular structure in solid state, as was shown by comparison of the experimental spectra with the computer simulated spectra on the basis of AA′MM′XX′, AMM′XX′ and AA′XX′ spin systems for the vinylene protons, the carbon atoms and the phosphons atoms respectively. In CDCl 4/CD 3COOD the neutral complex [(PPh 1)(dmgH) 2RhCHCHRh(dmgH) 2(PPh 1)] ( 1′) is formed, as was shown by 1H, 13C and 31P NMR spectroscopy.

Highly Stereoselective Photochemical Oxidative Addition Reactions. Preliminary Communication

AbstractCyclometallated complexes of the type cis‐bis(2‐phenylpyridine)platinum(II) (C22H16N2Pt) and cis‐bis(2‐(2′‐thienyl)pyridine)platinum(II) (C18H12N2S2Pt) undergo thermal or photochemical oxidative addition (TOA or POA) reactions with a number of substrates. TOA (with CH3I, CH3CH2I etc.) yield mixtures of several isomers which rearrange slowly (within ca. one week at room temperature) to one of the possible cis‐isomers. CH2Cl2, CHCl3, or (E)ClCHCHCl, e.g., do not react thermally. POA yield directly complexes of Pt(IV) with the halide and a σ‐bonded C‐atom in cis‐position. The configuration, as assigned by extensive use of 1H‐NMR data, can be characterized for the two chelating ligands C …︁ N and C′ …︁ N′ by C,C′‐cis; N,N′‐cis and C(chelate), Cl‐trans.