Platinum complexes imidazole

Co-condensation reaction of the vapors of l,3-di-rcrt-butylimidazol-2-ylidene and nickel, palladium, or platinum gives the coordinatively unsaturated 14-electron sandwiches [L M] (M=Ni, Pd, Pt) of the carbene type (990M3228). Palladium(O) carbene complexes can also be prepared by the direct interaction of l,3-R2-imidazol-2-ylidenes (R=/-Pr, r-Bu, Cy, Mes) (L) with the palladium(O) compound [Pd(P(o-Tol)3)2] (OOJOM(595)186), and the product at the first stage is [(L)PdP(o-Tol)3l, and then in excess free carbene [PdL ]. 

A series of mixed-ligand thiosalicylato complexes of the type PtL(PPh3)Y2] (Y2 = thiosalicylate L = pyridine, 4-methylpyridine, picolinic acid hydrazide, imidazole) have been prepared by the reaction of [PtCl2(COD)] with PPh3, thiosalicylic acid, and A-donor ligand in MeOH solution.375 The X-ray structure of the pyridine derivative (162) was determined, the first example of where a platinum atom is coordinated to a N, O, P, and S donor atom set. 

A variation of the thermal elimination of an alcohol from the neutral 2-alkoxy-1,2-dihydro-l//-imidazole is the preformation of a chelate vic-bisamine complex which is subsequently attacked by an ort/io-ester to form the desired NHC complex. This principle has been shown with nickel and platinum [Eq. 

We recently succeeded in synthesizing platinum-NHC complexes which are stable under the reaction conditions [57]. Introduction of aromatic substituents (Scheme 24, R= NO2, Cl, Br, OCH3, COOEt) in the imidazole changed the properties of the complexes quite significantly. 

Under alkaline conditions, sixteen Pb(II) ions link the secondary hydroxyl side of y-CyD to form a metal-ion-mediated head-to-head dimer [217]. All the secondary hydroxyl groups are deprotonated and coordinated to bind Pb(II) ions forming a hexadecanuclear lead(II) alkoxide. Introduction of ionic substituents on CyDs enhances their metal-binding ability. Two amino groups introduced on the primary hydroxyl side of jS-CyD can chelate a platinum ion [64]. Imidazole-appended yS-CyD forms a ternary complex with a Cu(II) ion and L-tryptophanate [61]. The 6-amino and imidazolyl groups of the host molecule and the carboxyl and amino groups of L-tryptophanate are coordinated to the Cu(II) ion. 

An elegant study by Cavell and co-workers pointed towards abnormal imida-zolylidenes being more prone to reductive elimination than normal imidazo-lylidenes. " In the presence of an alkene ligand the mixed bis-carbene complex 11 underwent reductive elimination of the 4-imidazolylidene exclusively, thus yielding platinum(0) diolefin complex 12 and imidazolium salt 13 (Equation (5.1)). No reductive elimination of the normally bound imidazol-2-ylidene ligand was observed under these conditions. 

Solid-state reactions of palladium(II) and platinum(II) chloride complexes with imidazole and pyrazole or their hydrochloride salts are shown to produce metal complex salts and coordination compounds (10DT3714). Ball milling was performed in a Retsch MM200 ball mill (mixer mill) for... 

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