Sulfato complexes, osmium

Athough sulfato complexes of osmium undoubtedly exist none have been definitely established or characterized. 

Osmium tetroxide was heated with phthalonitrile to form an osmium derivative which was crystallized from concentrated sulfuric acid as the diamagnetic sulfato-osmium(IV) phthalocyanine 25). A six-coordinate sulfato-bridged structure was proposed, but no infrared data were cited in support of this idea. The complex is extremely soluble in concentrated sulfuric acid. The diamagnetism is unexpected. Osmium(IY) has a d4 configuration, and a moment above 2.0 B.M. might have been predicted. The... 

The 0x0 (0 ) ligand is dominant in the coordination chemistry of osmium, participating in the VIII to IV oxidation states inclusive. The tetroxide OSO4 is the single most important compound of osmium OSO4 and the recently discovered [0s04] ion arc tetrahedral. The /ra 5-[0=0s —O] osmyl moiety displays an extensive chemistry, comparable with that of the uranyl 0=U=0 unit, and there is an extensive and unique cyclic oxo-ester chemistry (p. 584). There is surprisingly little information on hydroxo, aqua, sulfato, nitrato or phosphato complexes, but much recent work has been carried out on carboxylato species, and clearly much work remains to be done on the O-donor chemistry of the element. There are a reasonable number of sulfur-donor complexes but few with selenium or tellurium. 

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