Substituted boat-shaped Co 6 carbonyl cluster derivatives containing a semi-interstitial P atom and both bridging dithiolate and heterocyclic phosphido ligands

Abstract

The reaction of Co 2(CO) 8 with Cl PSCH 2CH 2CH 2S gives the Co 6 cluster Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(CO) 12 ( 5). X-ray structural analysis of 5 revealed that six Co atoms form a boat-shaped array consisting of a basal square of four cobalt atoms with two opposite edges bridged by two apical Co atoms, a semi-interstitial P atom, a propanedithiolate ligand doubly bridging a basal side and a heterocyclic phosphido ligand bridging the opposite basal edge. Reaction of 5 with PPh 3 results in the formation of the mono-substituted products (Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(μ-CO)(CO) 10(PPh 3) ( 6) and (Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(μ-CO)(CO) 11(PPh 3) ( 7). Reaction of (Co 6(μ 6-P)(μ-SCH 2CH 2S)(μ- PSCH 2CH 2S )(CO) 12 ( 4) with PPh 3 at higher temperature results in the formation of the di-substituted cluster Co 6(μ 6-P)(μ-SCH 2CH 2S)(μ- PSCH 2CH 2S )(CO) 10·(PPh 3) 2 ( 8). Reactions of 5 with P(OEt) 3 result in the substitution of one or two carbonyl groups to give (Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(CO) 11P(OEt) 3)} ( 9) and {Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(CO) 11(P(OEt) 3)} ( 9′) with different spectral data from that of ( 9), and {Co 6(μ 6-P)(μ-SCH 2CH 2CH 2S)(μ- PSCH 2CH 2CH 2S )(μ-CO)(CO) 9(P(OEt) 3) 2} ( 10). X-ray structural analysis of 10 identified the sites of phosphite substitution as the two apical Co atoms. A semi-bridging CO group in 10 is located on a basal side. The IR ν(CO) solution spectrum of 10 does indicate the existence of the semi-bridging CO group in the solution as well.