Dialkyl ruthenium porphyrin

The first ruthenium porphyrin alkyls to be reported were prepared from the zerovalent dianion, [Ru(Por)] with iodomethane or iodocthane, giving the ruthe-nium(lV) dialkyl complexes Ru(Por)Me2 or Ru(Por)Et2 (Por = OEP, TTP). Alternatively, the Ru(lV) precursors Ru(Por)X2 react with MeLi or ArLi to produce Ru(Por)Mc2 or Ru(Por)Ar2 (Ar = / -C(,H4X where X = H, Me, OMe, F or Cl) 147-149 The osmium analogues can be prepared by both methods, and Os(Por)R2 where R = Me, Ph and CH2SiMe2 have been reported.Some representative structures are shown in Fig. 5, and the preparation and interconversion of ruthenium porphyrin alkyl and aryl complexes are shown in Scheme 10. 

Alkyl and aryl systems - As already mentioned in Sect. 3.2, dialkyl ruthenium and osmium porphyrins have been synthesized according to Eq. (22) by the reaction of metalloporphyrin dianions [M(P)]2 with alkyl iodides [223, 260, 261,307]. These dianions have been obtained by reduction of porphyrin dimers [M(P)]2. 

It was later demonstrated that decomposition of a dialkyl ruthenium(IV) porphyrin also yields the carbene species (TPP)Ru(CHCH3) due to a-abstrac-tion [127]. More recently [128], it was reported that addition of ethyl diazomethyl acetate to the 14 electron species, (TMP)Ru [129], also affords (TMP)Ru(CHC02CH2CH3) in a more classical route (Eq. 17). 

The ruthenium porphyrins, (TPP)RuCO and (TMP)RuCO catalyze carbene insertion into S - H bonds, leading to dialkyl and alkyl aryl sulfides using ethyl diazo acetate under mild conditions. The insertion process is regiospe-cific since dithiothreitol reacts to give the S - H insertion product without any trace of the ether compound (Scheme 18) [172]. With a homochiral porphyrin ruthenium complex, asymmetric insertions were obtained but with low enantioselectivities [191]. 

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