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Over the past few years there has been much interest in the photochemistry of (i/5-C5R5)ML2 and (r)5-C5R5)ML(H)2 ( = Rh, Ir; R = H, CH3; L = CO, PR3, olefin) complexes leading to intermolecular activation of hydrocarbon C-H bonds.1 Extensive matrix isolation, flash photolysis, and low-temperature solution studies have been performed on these systems, and they indicate that their C-H activation and photosubstitutional reactions proceed initially via ligand dissociation to yield a 16electron species.2 Recently, theoretical models of methane C-H

Two Pd-imidazole complexes have been synthesized following the reaction of PdCI2 and imidazole at 1:2 and 1:4 metal:ligand ratios. Elemental and thermogravimetdc analytical data obtained from these compounds illustrate that they have the formulae Pd(IMDAH)2C12-4H20 and Pd(IMDAH)3C12 (MDAH = imidazole), respectively. The mechanism of thermal decomposition for these complexes in air involves initial dissociation of I-I20 and IMDAH ligands in the 120--340 *C range, subsequent dissociation of the chloride atoms to form PdO in the 530--570 "C range, and finally formation of Pd metal at 820-840 *C.Heterocyclic iigands are used in several industrial and medical applications. For example, azoles have been used as corrosion inhibitors for metals and alloys [1] and complexes formed between azotes and Cu or Pd metals have been used to model biological structures and in anti-tumor drug therapy [2,3]. The nature of chemical bonding in Cu-azole complexes has been studied by several techniques including Xray photoelectron spectroscopy (XPS) [4,5], Fourier transform infrared spectroscopy (FTIR) [6], and X-ray diffraction [7]. However, at this time relatively little work has appeared on Pd-azole compounds.Pd-IMDAH (IMDAH = imidazole) complexes may be useful in industry as catalytic agents in epoxy curing reactions. For such applications the thermal stability of the complex could influence the curing mechanism of the resin and subsequently its physical properties. Previously, several Pd-IMDAH complexes have been prepared and characterized by FTIR spectroscopy [3]. This paper reports the synthesis and elemental characterization of two Pd-IMDAH complexes and describes their mechanism of thermal decomposition.