Spectral,Structural,and Electrochemical Properties of Ruthenium Porphyrin Diaryl and Aryl(alkoxycarbonyl) Carbene Complexes:Influence of Carbene Substituents,Porphyrin Substituents,and trans-Axial Ligands

摘要

A wide variety of ruthenium porphyrin carbene complexes,including [Ru(tpfpp)(CR~1R~2)] (CR~1R~2=C(p-C_6H_4Cl)_2 1b,C(p-C_6H_4Me)_2 lc,C(p-C_6H_4OMe)_2 1d,C(CO_2Me)_2 1e,C(p-C_6H_4NO_2)CO_2Me 1f,C(p-C_6H_4OMe)CO_2Me 1g,C(CH= CHPh)CO_2CH_2(CH=CH)_2CH_3 1h),[Ru(por)(CPh_2)] (por=tdcpp 2a,4-Br-tpp 2b,4-Cl-tpp 2c,4-F-tpp 2d,tpp 2e,ttp 2f,4-MeO-tpp 2g,tmp 2h,3,4,5-MeO-tpp 2i),[Ru(por){C(Ph)CO2Et|] (por=tdcpp 2j,tmp 2k),[Ru(tpfpp)(CPh_2)(L)] (L=MeOH 3a,EtSH 3b,Et_2S 3c,Melm 3d,OPPh_3 3e,py 3f),and [Ru(tpfpp){C(Ph)-CO_2R}(MeOH)] (R=CH_2CH=CH_2 4a,Me 4b,Et 4c),were prepared from the reactions of [Ru(por)(CO)] with diazo compounds N_2CR~1R~2 in dichloro-meihane and,for 3 and 4,by furthertreatment with reagents L.A similar reaction of [Os(tpfpp)(CO)] with N_2CPh_2 in dichloromethane followed by treatment with MeIm gave [Os(tpfpp)(CPh_2)(MeIm)] (3d-Os).All these complexes were characterized by ~1H NMR,~(13)C NMR,and UV/Vis spec-troscopy,mass spectrometry,and elemental analyses.X-ray crystal structure determinations of 1d,2a,i,3a,b,d,e,4a-c,and 3d-Os revealed Ru=C distances of 1.806(3)-1.876(3) A and an Os=C distance of 1.902(3) A.The structure of 1d in the solid state features a unique "bridging" carbene ligand,which results in the formation of a one-dimensional coordination polymer.Cyclic voltammograms of la-c,g,2a-d,g-k,3b-d,4a,b,and 3d-Os show a reversible oxidation couple with E_(1/2) values in the range of 0.06-0.65 V (vs Cp_2Fe~(+/0)) that is attributable to a metal-centered oxidation.The influence of carbene Substituents,porphyrin Substituents,and trans-ligands on the Ru=C bond was examined through comparison of the chemical shifts of the pyrrolic protons in the porphyrin macrocycles (~1H NMR) and the M=C carbon atoms (~(13)C NMR),the potentials of the metal-centered oxidation couples,and the Ru=C distances among the various ruthenium porphyrin carbene complexes.A direct comparison among iron,ruthenium,and osmium porphyrin carbene complexes is made.