674. Cycloheptatriene– and tropylium–metal complexes. Part I. The “normal” reaction of tricarbonyltropyliumchromium salts with anions

Formal chromium–chromium triple bonds and bent rings in the binuclear cycloheptatrienylchromium carbonyls (C7H7)2Cr2(CO)n (n=6,5,4,3,2,1,0): A density functional theory study

“…This cation is also historically significant in providing the first example of a cycloheptatrienylmetal complex of any type. Subsequent work led to the discovery of the chromium and tungsten analogues [(g 7 -C 7 H 7 )M(CO) 3 ] + (M = Cr [3] and W [4]). Furthermore, the other early examples of cycloheptatrienylmetal complexes (Fig.…”

“…This observation is a critical one since it indicates that a C 7 H 7 ring is more likely than a C 5 H 5 ring to bond only partially to a transition metal leaving some uncomplexed carbon atoms. The next g 3 -C 7 H 7 derivative to be discovered was the cobalt carbonyl derivative [11] (g 3 -C 7 H 7 )Co(CO) 3 (Fig. 2), obtained simply from the photolysis of Co 2 (CO) 8 with cycloheptatriene.…”

“…Shortly after its discovery, the molybdenum derivative [(g 7 -C 7 H 7 )Mo(CO) 3 ] + was found to be a useful source of other cycloheptatrienyl derivatives, particularly through the iodide (g 7 -C 7 H 7 )Mo(CO) 2 I, which is readily obtained in good yield from the reaction of [(g 7 -C 7 H 7 )Mo(CO) 3 ] + with iodide ion [8]. Exploration of the chemical reactivity of (g 7 -C 7 H 7 )Mo(CO) 2 I soon uncovered another feature of cycloheptatrienylmetal chemistry, namely the ability of the cycloheptatrienyl ring to form stable metal complexes in which not all seven carbon atoms of the C 7 H 7 ring are within bonding distance of the metal atom.…”

Syntheses of thiopyrylium-tungsten complexes

“…In these reactions, two new cationic compounds were obtained with a different structure type contrary to what was expected and identified as (2,4,6-triphenylthiopyrylium)tricarbonyltungsten perchlorate and (2,6-dianisyl-4-phenylthiopyrylium) tricarbonyltungsten perchlorate (2).…”

“…, tropyliumtricarbonylmolybdenum, [(g 7 -C 7 H 7 )Mo(CO) 3 ] ? have long been reported in the literature [1][2][3]. A dicationic salt, bis(2,4,6-triphenylthiopyrylium)dicarbonylmolybdenum perchlorate, {[(g 5 -2,4,6-H 2 (C 6 H 5 ) 3 C 5 S] 2 Mo(CO) 2 }(ClO 4 ) 2 (1) was reported in 1999 [4].…”