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The syntheses and characterisations of six new diaryl telluride complexes of palladium(II) and platinum(II) are reported. It is suggested that the streochemistry of platinum(II) telluride complexes is determined as much by kinetic factors as by any tendency of tellurium to accept d π electrons from platinum. The far infrared spectra of Pd(Ph 2 Te) 2 X 2 (X = Cl, Br) are discussed. The oxidative addition of two diorganoditellurides to Pd(PPh 3 ) 4 is demonstrated. Dimeric compounds are isolated containing both bridging and terminal RTe groups.

Thienylmercury(II)chloride reacts with [Pd(PPh3)2Cl2], [Pd(PPh3)4] and [Pt(PPh3)4] to afford new compounds containing a metal-2-thienyl linkage. The compound [Pd(PPh3)2(2-C4H3S)Cl] probably has trans stereochemistry. 2-Bromothiophen undergoes oxidative addition with [Pd(PPh3)4] and [Pt(PPh3)4], probably via a radical mechanism. With [Pd(CO)(PPh3)3], a carbonyl inserted product is obtained. The bromo-metal(II) complexes have trans stereochemistry. The course of the reaction between 3-methyl-2-bromothiophen and Pd(PPh3)4 is more complex. Thus, there is evidence of some cis bromopalladium(II) compounds amongst the products, also there is good evidence to support the view that some isomerisation of 3-methyl-2-thienyl to 4-methyl-2-thienyl occurs during the reaction, thus giving greater molar quantities of [Pd(PPh3)2(4-CH3-2-C4H2S)Br] than can be accounted for from any initial 4-methyl-2-bromothiophen impurity. The metallation of the thiophen ring, probably in the 4-position, with palladium(II) is described for 3-theylidene-4-methylaniline.

Palladium(II)chloride affords simple coordination compounds with C 5 H 5 N + N - COMe and C 5 H 5 N + N - COEt but the derivative of N-(1-pyridinio)proprionamidate decomposes with evolution of HCl at the melting point. Both C 5 H 5 N + N - SO 2 Ph (L) and C 5 H 5 N + N - COPh (L′) give coordination compounds with cobalt(II) and copper(II). The series [ML 4 ] (CLO 4 ) 2 (M = Co, Cu, Zn) is isomorphous and evidence is available from spectroscopic measurements (UV and ESR) to support the tetrahedral environment about the metal ions, although in the copper compound some distortion is present. [Co 2 L 4 X 2 ]X 2 (X = Cl, Br) and [Cu 2 L 4 Cl 2 ]Cl 2 are isomorphous, dimeric and have pseudo tetrahedral stereochemistry; [CuL 2 Br 2 ] and [ZnL 2 Cl 2 are isomorphous and tetrahedral. The spectroscopic data are discussed in such depth as the data derived from polycrystalline specimens permit. [CoL 4 ′] (ClO 4 ) 2 contains O-bonded C 5 H 5 N + N - COPh and exists in at least two polymorphic forms one of which is magnetically abnormal [Co 2 -L 4 ′Cl 2 ]Cl 2 is dimeric and contains both O- and N-bonded ylide, [Co 2 L 2 X 4 ] are also dimers but contain only the O-bonded ylide. [CuL 3·5 ′] (ClO 4 ) 2 , which contains copper(II) in a distorted 6-coordinate environment, is contrasted with the well defined [CuL 4 ] (ClO 4 ) 2 (above). N-(1-pyridinio)benzamidate undergoes NN bond rupture to give pyridine and phenylisocyanate at 190–200°C, but this decomposition temperature may be lowered by approx. 100°C in the presence of anhydrous copper(II) chloride which is shown to give an N-bonded complex with the ylide.