Chemistry of (RC5H4)2TiS5: New Information on Its Reactions with Nucleophiles, Syntheses and Reactions of 1,4-[ (RC5H4)2Ti]2S4, and a Second Isomer of (RC5H4)2TiS2C2(C02Me)2

Dean M. Giolando, Thomas B. Rauchfuss, Arnold L. Rheingold, Scott R. Wilson

Research output: Contribution to journalArticlepeer-review

Abstract

Described are a series of reactions of [(RC5H4)2TiSx]n (R = H, CH3, i-Pr; x = 5 (1, n = 1), 3 (2, n = 2), 2 (3, n = 2)). The reactions of 1 with organophosphines in the presence of acetylenes gives the dithiolenes (RC5H4)2TiS2C2R 2. In the absence of acetylenes desulfurization of 1 gives the dimers [(RC5H4)2Ti]2Sx (x = 4, 6). These dimers could not be prepared from (RC5H4)2TiCl2 and Li2Sx; however, reaction of (RC5H4)2TiCl2 and Li2S2 in the presence of CS2 gives high yields of 3. The oxidation of (RC5H4)2Ti(SH)2 also gives 3. The mechanisms of these reactions are discussed in light of corresponding work on 1,2-C6H4(SR)2 (R = H, Sx). The structure of 1,4-[(i-PrC5H4)2Ti]2S4 (3c) was determined by X-ray crystallography. It crystallizes in the monoclinic space group C2/c with a = 35.481 (10) Å, b = 10.976 (3) Å, c = 23.553 (6) Å, β = 130.74 (3)°, V = 6950 (3) Å3, and Z = 4 and refined to R = 0.052 and R(w) = 0.074. The analysis confirms the structure as an 1,4-M2S4 ring in the chair conformation. Whereas 1 reacts with electrophilic acetylenes to give dithiolenes, the corresponding ambient temperature reaction of 3 with dialkyl acetylenedicarboxylates (DEAD or DMAD) gives vinyl disulfides. The structure of the vinyl disulfide complex (CH3C5H4)2TiS2C 2(CO2CH2CH3)2 (4) was confirmed by X-ray diffraction (monoclinic, P21/n; a = 9.772 (2) Å, b = 14.573 (2) Å, c = 11.756 (2) Å, β = 100.25 (1)°, V = 1647.4 (5) Å3, and Z = 4; refinement to R = 0.0387 and R(w) = 0.0411). The TiSSCC ring adopts an envelope conformation. The formation of 4 from 3 occurs via a bimolecular pathway according to the following equation d[4]/dt = (4.2 × 10-3 M-1 s-1)[3][DMAD]. Compound 4 easily rearranges to give the dithiolene. Labeling studies (C5H5 vs. CH3C5H4; DMAD vs. DEAD; 32S vs. 34S) demonstrate the intramolecularity of this rearrangement. These findings suggest that other acetylene-metal sulfide reactions may proceed via this unexpected pathway.

Original languageEnglish (US)
Pages (from-to)667-675
Number of pages9
JournalOrganometallics
Volume6
Issue number3
DOIs
StatePublished - Mar 1 1987

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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