The electrochemistry of some alkylidynetricobalt nonacarbonyl cluster complexes

Syntheses and molecular structures of some tricobaltcarbonylclusters containing 2,4,6-trimethyl-1,3,5-trithiane

“…Simple substitution of three CO ligands in Co 3 (m 3 -CH)(CO) 9 by 2,4,6-trimethyl-1,3,5-trithiane (S Me 3) occurred in refluxing benzene to give dark red Co 3 (m 3 -CH)(m 3 -S Me 3)(CO) 6 (1) in 86% yield. A similar reaction of Co 3 (m 3 -CC≡CSiMe 3 )(CO) 9 with S Me 3 gave Co 3 (m 3 -CC≡CSiMe 3 )(m 3 -S Me 3)(CO) 6 (2) in 90% yield, accompanied by a small amount of black crystals, identified by a single-crystal X-ray diffraction structure determination as the hexatriyne complex Me 3 SiC≡CC 2 [Co 2 (m-S Me 3)(CO) 4 ]C 2 [Co 2 (CO) 6 ]SiMe 3 (3).…”

“…In a manner analogous to that observed for 1, oxidation of 6 caused a shift in band intensities but no pronounced shift in energies of the n(CO) bands, whilst reduction results in the appearance of a bridging n(CO) band near 1750 cm -1 . The similarities in the general appearance of the spectra associated with 1 and 6 in their comparable redox states indicates that despite the small contribution from the carbon chain to the LUMO in 6, the cluster cores in [6] 2are largely independent. It is well worth…”

“…(acetone-hexane, 3/7). The major brown band (R f 0.55) afforded {(OC) 9 Co 3 }(m-C≡CC≡C){Co 3 (m 3 -S Me 3)(CO) 6 (ii) A solution of {(OC) 9 Co 3 }(m-C≡CC≡C){Co 3 (m 3 -S Me 3)(CO) 6 } 5 (45 mg, 0.05 mmol) and S Me 3 (18 mg, 0.1 mmol) in benzene (15 ml) was heated at reflux point for 3 h. The dark coloured precipitate which separated was filtered off, washed with benzene and extracted with acetone. The concentrated acetone extracts were purified by preparative t.l.c.…”

“…The phosphoniodithioformate S 2 CPCy 3 reacts with Co 3 (m 3 -CX)(CO) 9 (X = H, Cl) to give the heptacarbonyl Co 3 (m 3 -CX)(m 2 -S,S'-S 2 CPCy 3 ) (CO) 7 with the sulfur donors bound at axial sites. 27 In the complex Co 3 (m 3 -CPh)(m 3 -S H 3)(CO) 6 [S H 3 = trithiacyclohexane, (CH 2 S) 3 ], the sulfur ligand caps the basal face of the CCo 3 cluster. 28 Tris(thiomethyl)methane behaves similarly.…”

“…With a view to altering both the steric constraints about the carbon chain and the electronic properties of the CCo 3 cluster in {Co 3 (m 3 -C)(CO) 9-n L n } 2 {m- (C≡C) x } systems, we have commenced an investigation of the synthesis and properties of complexes containing carbon chains end-capped by one or two Co 3 clusters bearing 2,4,6-trimethyl-1,3,5-trithiane ligands (S Me 3). This paper presents the synthesis and spectroscopic characterization of several further examples of CCo 3 clusters containing the S Me 3 ligand, including {Co 3 (m 3 -S Me 3)(CO) 6 } 2 (m-C≡CC≡C) (6) and Co 3 {m 3 -C(C≡C) 2 [Ru(dppe)Cp*]}(m 3 -S Me 3)(CO) 6 (7). In the case of the bis(cluster) 6, electrochemical and IR spectroelectrochemical studies have also been carried out, supported by DFT calculations.…”