Group VIIB

The known rhenium chalcogenides are of the composition ReYX2 and Re3Se2Xs (Y = S, Se X = Cl, Br), including Re3Te2Brs (140, 263, 264,353,393). Additionally, the compounds Re2S3Cl4 (140) and ReS2Br 

All of the known rhenium chalcogenide halides are stable in air. With the exception of ReaSaCh, they are insoluble in water, acids, and the common organic solvents. They dissolve readily in hot, 50% KOH (263, 264). ReaS3Cl4 is soluble in water, and ethanol, but insoluble in nonpolar organic solvents. With acids, alkalis, or hot water, hydrolytic decomposition takes place. Alkaline solutions can be oxidized to produce perrhenate compounds. 

Preparative Routes and Experimental Conditions for the Formation OF Rhenium Chalcogenide Halides 

Educts Temperature range (°C) Specific conditions Products Ref. 

Treatment of the rhenium sulfide chlorides with an excess of chlorine at temperatures above 450°C results in formation of ReClj (140). Reduction between 350 and 500°C gives binary rhenium chalcogenides (139,262). Action of water vapor on rhenium sulfide chlorides at 350-500°C produces oxysulfides (139). 

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Table Group VIIB (the halogens), is the earth s rarest naturally occurring element. All its isotopes are radioactive (Table I), hence the Greek name aoTaTCoC, meaning unstable 44, 45). The possibility of their existence was predicted from the -decay of polonium (55). Its three naturally occurring isotopes, At, At, and At, are the extremely short-lived natural daughters of AcA (77), RaA (76,173), and AcK (72), respectively.

Symbol Mn atomic number 25 atomic weight 54.938 a Group VIIB (Group 7) transition metal electron configuration [Ar]4s23d atomic radius 1.27A valence 0, -i-l, +2, -i-3, +A, +5, +6, +7 most common oxidation states +2, +A and +1] stable natural isotope Mn-55 (100%)... 

Cycloheptene complexes with gold, 12 348 Cyclohexadiene complexes with cobalt, 12 286 with group VIB metals, 12 225-227 with group VIIB metals, 12 240, 241 with iron, 12 264 with palladium, 12 313 with ruthenium, 12 278 with silver, 12 340... 

Disilyl selenide, 3 240 Disodium ethylenedithiolate complexes with group VIIB metals, 12 242 Disodium phthalocyanine, preparation and properties of, 7 39... 

Pentadentate 2,2 6, 2"-terpyridine, 30 107 Pentadiene complexes with iron, 12 255-257 with rhodium, 12 295 with silver, 12 340 Pentadienyl complexes with group VIB metals, 12 224, 225 with group VIIB metals, 12 240 JV,Af,/V,lV",N"-Pentaethyldiethylenetriamine, 42 76... 

The last class of carbamoyl complexes with which we have been concerned has been that with NO+ ligands. For preparative and structural studies in this area, besides the cationic cyclopentadienylnitrosylcarbonyl complexes of Group VIIB 121), the nitrosylcarbonyl metal cations of Mo and W offer interesting starting materials 121). 

Group VB Group VIB Group VIIB Group VIII ... 

For the Group VIB elements, there is a decrease in the reaction rate by a factor of 50-200 (see also Table VII) and for the group VIIB elements, a decrease by a factor of about 6300 upon going from the second- to the third-row element. This suggests that the metal-aqua bond is stronger in the third-row elements than in the second-row... 

Another interesting and significant feature about the results in Table VIII is the decrease in the reaction rate upon going from a group VIB metal ion with a formal charge of -1-4 to a group VIIB metal ion with a formal charge of 5 -l- = 10 and = 820. This indicates... 

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