Photochemical reaction of [Re 2 (CO) 1 0 ] with tetramethylthiourea [S C{(NMe 2 ) 2 }] has led to the cleavage of the S C bond yielding two novel rhenium carbonyl compounds [Re 5 (CO) 1 7 (μ-R)(μ 4 -S){C(NMe 2 ) 2 } 2 ] (R=SH 8 or OH 9). The complexes have been characterised by spectroscopic methods and X-ray crystallography. The structure of 8 is based on a distorted Re 3 S 3 octahedral cluster with meridonal arrangement of the three Re and three S atoms. Two of the S atoms are each bound to three Re atoms at the centre and also bonded to a terminally placed Re(CO) 4 {C(NMe 2 ) 2 } moiety; the third S atom belongs to a SH group and bridges a pair of the meridonal Re atoms. Only two of the meridonal Re atoms lie within Re-Re bonding distance indicating that Re-Re bonds in [Re 2 (CO) 1 0 ] have also been cleaved during the reactions. Compound 9 is isostructural with 8, with the OH group replacing the SH group.