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DOI: 10.1055/sos-SD-002-00214

Kündig, E. P.; Pache, S. H.Science of Synthesis, (20032162.

Milder complexation conditions and shorter reaction times are possible with suitable [M(CO)3L3] precursors (Scheme 5). For chromium, these include the complexes with L=acetonitrile, ammonia, or pyridine. [M(NCR)3(CO)3] and [M(CO)3(pyridine)3] are pre­pared by heating [M(CO)6] in the appropriate solvent under reflux. Reaction times increase from chromium to tungsten. With molybdenum, and particularly with tungsten, it is better to use the higher boiling propionitrile rather than acetonitrile. Tris(ammine)tricarbonylchromium(0) is best prepared by treating hexacarbonylchromium(0) with potassium hydroxide in ethanol, followed by addition of ammonium hydroxide (90% yield on a 10g scale).[‌62‌,‌63‌] (Arene)tricarbonylchromium complexes are obtained on heating at reflux the pyridine and ammonia precursor complexes in the presence of an arene in dioxane. Room temperature complexation of arenes is accomplished by reaction of tris(ammine)tri­carbon­ylchromium(0) or [M(CO)3(pyridine)3] with boron trifluoridediethyl ether complex in the presence of an arene[‌64‌] or hetero­arene (see Section 2.4.9). Other sources of [M(CO)3] fragments are [W(CO)3{MeN(CH2CH2NMe2)2}] with boron trifluoride-diethyl ether complex,[‌65‌] [Mo(CO)3(diglyme)],[‌66‌] and [Mo(CO)3(DMF)3].[‌67‌]

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Me(MM)8(eeeeeeee)8 + MM8MMe8 8 (M=Me; M8=M) 88 [‌88‌]
Me(MM)8(eeeeeeee)8 + MM8MMe8 8 (M=Me; M8=MMe) 88 [‌88‌]
M(MM)8(MeMMM8MM8MMe8)8 + MM8MMe8 8 (M=M; M8=M) 88 [‌88‌]
M(MM)8(MeMMM8MM8MMe8)8 + MM8MMe8 8 (M=M; M8=Me) 88 [‌88‌]
Me(MM)8(MM8)8 + MM8MMe8 88 88 [‌88‌]
Me(MM)8(MM8)8, eeeeeee, eeee 88 88 [‌88‌]
Me(MM)8(MM8)8, eeeeeee, eeee 88 88 [‌88‌]
Me(MM)8(MMMe)8 88 88 [‌88‌]
Me(MM)8(M88M8) (88) 88 88 [‌88‌]
Me(MM)8 88 88 [‌88‌]
[(eeee/eee) 88:88]
Me(MM)8(M88M8) (88) 88 88 [‌88‌]
[(eeee/eee) 88:88]
Me(MM)8(M88M8) (88) 88 88 [‌88‌]
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Meeeeeeeeee(η8-8,8-eeeeeeeeeeeeeeeeee)eeeeeeee(8) (88):[‌88‌]

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