Cycloadditionsreaktionen von Molybdän- und Wolfram-Phospheniumkomplexen mit Diazoethylacetat: Synthese und strukturelle Charakterisierung von drei- und fünf-gliedrigen Phosphametallacyclen

Cycloaddition Reactions of the Phosphinidene-Bridged Complex [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HMes*)] with Diazoalkanes and Other Heterocumulenes

“…With regard to reactions involving phosphinidene complexes, we can only quote a phosphadiazadiene complex of type Q , [Fe 2 Cp 2 {μ-CyPNNCH­(CO 2 Me)}­(μ-CO)­(CO) 2 ], which rearranged into a derivative of type R , [Fe 2 Cp 2 {μ-CyPNHNC­(CO 2 Me)}­(μ-CO)­(CO) 2 ], upon chromatography on alumina . An analogous rearrangement occurred in the room-temperature reaction of the trigonal phosphanyl complexes [MCp­(P t Bu 2 )­(CO) 2 ] with N 2 CHR to give the chelate derivatives [MCp­(κ 2 N , C - t Bu 2 PNHNCR)­(CO) 2 ] (M = Mo, W; R = CO 2 Me) . We note that in both cases the diazoalkane molecule forms rings like that of 4 but containing P–N bonds rather than P–C bonds, because they follow from nucleophilic attack of P to the N atom of the diazoalkane molecule.…”

“…With regard to reactions involving phosphinidene complexes, we can only quote a phosphadiazadiene complex of type Q, temperature reaction of the trigonal phosphanyl complexes [MCp(P t Bu 2 )(CO) 2 ] with N 2 CHR to give the chelate derivatives [MCp(κ 2 N , C -t Bu 2 PNHNCR) (CO) 2 ] (M = Mo, W; R = CO 2 Me). 29 We note that in both cases the diazoalkane molecule forms rings like that of 4 but containing P−N bonds rather than P−C bonds, because they follow from nucleophilic attack of P to the N atom of the diazoalkane molecule. Very recently, an imine-stabilized carboranylphosphinidene has been reported to react with N 2 CH(CO 2 Me) to give a product requiring P−N bond formation and an 1,3-H shift in the diazoalkane fragment.…”

Reactions of the Phosphinidene-Bridged Complexes [Fe2(η5-C5H5)2(μ-PR)(μ-CO)(CO)2] (R = Cy, Ph, 2,4,6-C6H2tBu3) with Diazoalkanes. Formation and Rearrangements of Phosphadiazadiene-Bridged Derivatives

“…260 ppm), as expected. The observed chemical shifts, in fact, are comparable (if we allow for the change in metal) to that of the iminoacyl 13 C resonance in the mononuclear phosphine-iminoacyl complex [MoCp(CO) 2 { t Bu 2 PNHNC(CO 2 Et)}] (171.3 ppm) . Interestingly, the latter complex is formed by a route related to that leading to complexes 7 , a matter to be addressed later.…”

“…Although the 1,3-shift responsible for the formation of 7f is not a common rearrangement, there are some precedents of related SiMe 3 shifts involving two N atoms or C and N atoms, and even 1,4-shifts between O and N atoms . Besides this, we should note the parallelism between the formation of the phosphide-iminoacyl complex 7f (reaction of the phosphinidene 1a with a diazoalkane followed by photochemically induced decarbonylation and 1,3-SiMe 3 shift) and the thermal formation of the mononuclear phosphine-iminoacyl complex [MoCp(CO) 2 { t Bu 2 PNHNC(CO 2 Et)}] from a terminal phosphide complex with ethyldiazoacetate followed by decarbonylation and 1,3-H shift at the presumed (undetected) diazoalkane adduct initially formed . In the formation of compounds 7 , however, no 1,3-H shift seems to be feasible at the intermediate stages 6 / G without apparent reason, although it is clear that the observed SiMe 3 shift yields an isomer having the bulky silyl group pointing away from the dimetal center, therefore much more favored on steric grounds.…”

Syntheses and crystal structures of [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C′,P′}ClH]Cl·2.75CH2Cl2 and its derivatives, [IrIII{C(CHCO2Et)(dppm)2-κ4 P,C,C′,P′}(CH2CO2Et)Cl]Cl·CH3OH·0.5H2O, [IrIII{C(CHCO2Et)(dppm)2-κ4

“…By the use of this compound, a targeted synthesis of cyclopropanes or rather heterocyclopropanes, consisting of a transition metal, an electron-donor atom and a carbene carbon, is possible and has been reported several times in the literature (e.g. Nomura et al, 2011;Liu & Yan, 2015;Malisch et al, 1998;Strecker et al, 1991;Zhang et al, 2005, and references cited therein). An electrophilic reaction partner such as a transition metal establishes a nucleophilic attack of the diazo subunit and, according to the choice of the reaction conditions, the elimination of the nitrogen leaving group is supported.…”