Reactions of 2-Butyne with Group 6-Group 10 Heterobimetallics. New Mixed-Metal Metallacycle Chemistry

Reactions of Terminal Alkynes with Group 6−Group 10 Heterobimetallics

“…The acyl ν(CO) stretch seen in 4a is 30−50 cm -1 higher in energy than acyl stretches seen in four-membered nickelacyclic species such as NiCp{μ-η 2 (1,3- Ni ),η 2 (1,2- Mo )C(Me)C(Me)C(O)}Mo(CO) 2 Cp (Figure , R = R‘ = Me), whose core geometries adopt structure A (Figure ). Furthermore the acyl carbon resonance of 4a appears at 173 ppm in its 13 C NMR spectrum, a value ∼10 ppm upfield from the acyl carbon resonances observed for 2-butyne and 1-phenylpropyne type A metallacycles . These data suggest that 4a is not isostructural to type A metallacycles.…”

“…The resultant NiC(R)C(R‘)C(O) metallacycle is π-complexed to the group 6 metal. Further reactions on these species lead to “ring-flip” reactions and to the formation of molybdenacycle or tungstenacycle species which are π-bonded to the nickel atom 1 Summary of the Reactions of Complexes 1 , 2 , and 2 ‘ with Disubstituted Alkynes …”

Reactions of nickel-group 6 complexes with a bulky terminal alkyne to afford alkyne–carbonyl coupled products: X-ray structure of the heterobimetallic nickelacyclobutenone complex [(η5-C5Me5)Mo(CO)2(η5-C5H4Me)] (Ni–Mo)

“…We share these interests and have been studying the reactions of [Cp aNi(CO)-M(CO) 3 Cp b ] (M = Cr, Mo, W; Cp a = Cp, Cp * ; Cp b = Cp, Cp 0 ) 1 and, more recently, of the unsaturated tricarbonyl complexes 1 [Cp * Ni@M(CO) 3 Cp ] (Cp = Cp, Cp 0 ; M = Mo, W) [7] with alkynes [8][9][10][11][12][13][14][15][16]. (Complexes 1 are represented with Ni@M double bonds but the real situation is more complex; a better representation is shown in Scheme 1.…”

“…The metal-metal bond is partially dative). The major products isolated from reactions of nickel-(group 6 metal) complexes with alkynes are nickelacyclobutenone species, in which the alkyne has coupled with a carbonyl group ligand, and this unit is bonded to the group 6 metal [8,9,13,14].…”

The formation and transformation of metallacycles containing phosphorus or sulfur on molybdenum– or tungsten–cobalt mixed-metal backbones ‡

“…The chemistry of heterobimetallic transition metal carbonyl complexes remains an area of continued interest. [1][2][3][4][5] The presence of two distinct metal centres within the same complex presents possibilities for the study of the relative reactivities of two different metal sites while cooperative interactions between the two metal centres may lead to complexes possessing unique reactivity properties.…”