COORDINATION AND FRAGMENTATION OF 1,4-DITHIACYCLOHEXANE BY A TRIOSMIUM CLUSTER

The reactions of 1,4-dithiacyclohexane (1,4-DTCH) with Os-3(CO)(10)(NCMe)(2), Os-3(CO)(11)(NCMe) and Os-3(CO)(12) have been investigated. The reaction of 1,4-DTCH with Os-3(CO)(11)(NCMe) at 25 degrees C yielded Os-3(CO)(11)(SCH2CH2-CH2SCH2CH2) (1) in 46% yield. The reaction of 1,4-DTCH with Os-3(CO)(10)(NCMe)(2) at 25 degrees C yielded Os-3(CO)(10)(SCH2CH2SCH2CH2) (2) in 75% yield. Compound 2 was characterized by a single crystal X-ray diffraction analysis. The molecule consists of a triangular triosmium cluster with ten linear terminal carbonyl ligands, and a 1,4-DTCH ligand coordinated as a chelate to only one of the metal atoms. When compound 2 was heated to reflux in cyclohexane solvent four compounds were obtained: Os-3(CO)(9)(mu(3)-eta(2)C= CH2)(mu H)(2) (3), Os-2(CO)(6)(mu-SCH2CH2S) (4), Os-3(CO)(10)(mu-SCH2CH2S) (5), Os-3(CO)(8)(mu(3)-eta(2)-C=CH2)(SCH2CH2SCH2)(mu-H)(2) (6). The formation of ethylene as a coproduct was observed spectroscopically when the reaction was performed in toluene d(8) solvent in an NMR tube at 100 degrees C. The same cluster complexes were obtained from the pyrolysis of 1, and from the direct reaction of 1,4-DTCH with Os-3(CO)(12) at 125 degrees C. Compounds 4 and 5 were characterized by single crystal X-ray diffraction analysis. Both compounds contain a bridging, chelating ethanedithiolato, SCH2CH2S, ligand. Compound 4 can be obtained from 5 in good yield by heating to 125 degrees C in octane solvent. Compound 3 has been reported previously. Compound 6 is a simple 1,4-DTCH derivative of 3. Crystallographic data for 2: Os3S2O10C14H8, space group, P2(1)/n, a=8.641(2), b=25.108(4), c=10.533(1) Angstrom, beta=113.35(1)degrees, Z=4, 2054 reflections, R=0.037. For 4: Os2S2O6C8H4, space group P2(1)/n, a=8.612(2), b=16.062(8), c=9.988(4) Angstrom, beta=98.37(1)degrees, Z=4, 1295 reflections, R=0.044. For 5: Os3S2O10C12H4, space group P2(1)/c, a=14.079(2), b=9.383(1), c=15.153(2) Angstrom, beta=108.20(8)degrees, Z=4, 1893 reflections, R=0.030.