Homolytic Cleavage and Aggregation Processes in Cyclopentadienylchromium Chemistry

Abstract

The reactivity of the cyclopentadienylchromium tricarbonyl dimer [CpCr(CO) 3] 2 (Cp = C 5H 5, 1) toward several classes of organo-P-, -S- and -N-compounds will be described. The organic substrates include the following: (i) bis(diphenylthiophosphinyl)disulfane, R 2P(S)SSP(S)R 2; (ii) bis(thiophosphoryl)disulfane, (RO) 2P(S)SSP(S)(OR) 2; (iii) tetraalkylthiuram disulfides, R 2NC(S)SSC(S)NR 2; (iv) tetraalkyldiphosphine disulfides, R 2P(S)P(S)R 2; (v) dibenzothiazolyl disulfide, (C 6H 4NSC) 2; and (vi) Lawesson's reagent, (CH 3OC 6H 4) 2P 2S 4. The primary products, namely, the complexes CpCr(CO) 2(SPR 2), CpCr(CO) 2(S 2CNR 2), CpCr(CO) 2(SCSN(C 6H 4)), and CpCr(CO) 2(SPC 6H 4OCH 3), containing the thiophosphinito, dithiocarbamate, 2-mercaptobenzothiazole, and dithiophosphorane ligands, respectively, arise from facile cleavage of the S-S, P-P, and P-S bonds in the organic substrates. Further treatment of these complexes with 1 under thermal activation results in cleavage of C-X (X = N, S), P-S, and Cr-E (E = C, N, P, S) bonds, accompanied by C-C and P-P bond formation in some cases, generating a variety of organometallic compounds belonging to the phosphido, phosphinidene, thiocarbenoid, dithiooxamide, aminocarbyne, aminoalkenylacyl, and cuboidal types.