Coordination and fragmentation of 1,4-dithiacyclohexane by a triosmium cluster

Abstract

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 °C yielded Os 3(CO) 11( SCH 2CH 2SCH 2C H 2) ( 1 in 46% yield. The reaction of 1,4-DTCH with Os 3(CO) 10(NCMe) 2 at 25 °C yielded Os 3(CO) 10 SCH 2CH 2SCH 2C H 2) ( 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(μ 3-ν 2- CCH 2(μ- H) 2 ( 3), Os 2( CO) 6(μ- SCH 2 CH 2 S)( 4), Os 3( CO) 10 (μ- SCH 2 CH 2 S)( 5), Os 3( CO) 8(μ 30-ν 2- C CH 2)( SCH 2CH 2SCH 2C H 2)(μ- 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 °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 °C. Compounds 4 and 5 were characterized by single crystal X-ray diffraction analysis. Both compounds contain a bridging, chelating ethanedithiolato, SCH 2CH 2S, ligand. Compound 4 can be obtained from 5 in good yield by heating to 125 °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: Os 3S 2O 10C 14H 8, space group, P2 1/n, a=8.641(2), b=25.108(4), c=10.533(1) A ̊ , β=113.35(1)°, Z=4,2064 reflections, R=0.037. For 4: Os 2S 2O 6C 8H 4, space group P2 1/n, a=8.612(2), b=16.062(8), c=9.988(4) A ̊ , β=98.37(1)°, Z=4, 1295 reflections, R=0.044. For 5 Os 3S 2O 10C 12H 4, space group P2 1/c, a=14.079(2), b=9.383(1), c=15.153(2) A ̊ , β=108.20(8)°, Z=4 , 1893 reflections, R=0.030.