Is 2.07 Å a Record for the Shortest Pt−S Distance? Revision of Two Reported X-ray Structures

The comparison of the very similar compounds (Ph3P)2Pt(μ-S)2Pt(PPh3)2 (1) and (Ph2PyP)2Pt(μ-S)2Pt(PPh2Py)2 (2) raises intriguing questions about the reliability of the reported Pt2S2 core in 1, where the Pt−S bonds are the shortest ever reported. Also, the trans-annular S···S separation of 2.69 Å is surprisingly shorter in 1 than in 2 (3.01 Å), but no incipient coupling between two S2− bridges seems reasonable in this case. Various considerations lead to reformulate 1 as [(Ph3P)2Pt(μ-OH)2Pt(PPh3)2](BF4)2, 3. The sets of cell parameters for 1 and 3 are not equal but two axes match, and the volume of 1 is exactly double. Simple matrices may be constructed to interconvert the direct and reciprocal crystalline cells, thus corroborating their identity of the compounds. It is concluded that, in the structure solution of 1, some atoms were either neglected (BF4− counterions) or ill identified (sulfido in place of hydroxo bridges), while the structure of 3 was solved by collecting only one-half of the possible reflections (hence, also the different space groups). A new preparation, crystallization and X-ray structure of 3 confirms the above points and dismisses any other theoretical conjecture about two electronically different Pt2S2 cores in 1 and 2.