Cyclic oxacarbene complexes of the cycloheptatrienylmolybdenum auxiliary MoL₂(η-C₇H₇), L = CO or P-donor ligand: isolation and subsequent cyclisation of a hydroxyvinylidene intermediate

Synthesis, redox properties, EPR and ENDOR spectroscopy of the 17-electron cycloheptatrienylmolybdenum complexes [MoX(Ph2PCH2CH2PPh2)(η-C7H7)]z+ (z = 1, X = I, Br, Cl, F, NCO, NCS, CN, 13CN, Me, CCPh; z = 2, X = NCMe, CNMe, 13CNMe, oxacyclopentylidene)

“…in refluxing acetone has been described previously. 13 Cyclic voltammetric studies revealed that 12a undergoes a reversible one-electron oxidation and chemical oxidation with [Fe(η-…”

Molybdenum-Mediated Vinylidene Rearrangement of Internal Acylalkynes and Sulfonylalkynes

“…The 31 P­{ 1 H} NMR spectrum of the dark purple solution displays a singlet at δ 59.3, but this intermediate species was too unstable to be isolated. We consider that the initial step is the formation of a complex in which the O atom of the acyl group coordinates to the Mo atom, because similar treatment of 1 with acetone in toluene in the presence of NaBAr F 4 gave rise to the formation of a dark brown solution showing a 31 P­{ 1 H} NMR signal at δ 61.9, where [(η 7 -C 7 H 7 )­Mo­(dppe)­(acetone)] + is expected to be formed . After purification of the reaction mixture by column chromatography followed by recrystallization from Et 2 O/hexane, the desired vinylidene complex [(η 7 -C 7 H 7 )­Mo­[CCPh­(COPh)]­(dppe)]­[BAr F 4 ] 2a was isolated as orange crystals in 45% yield.…”

Synthesis and structure of the diynyl complexes [Mo(CCCCR)L2(η-C7H7)], L2=chelate N- or P-donor ligand, R=SiMe3 or H: X-ray crystal structures of [Mo(CCCCSiMe3)(2,2′-bipyridine)(η-C7H7)] and [Mo(CCCCH)(Ph2PCH2CH2PPh2)(η-C7H7)]

“…We have demonstrated that complexes of the Mo(dppe)(g-C 7 H 7 ) auxiliary not only exhibit reactivity patterns analogous to those of M(dppe)Cp * (M = Fe or Ru) [13,14] systems but also possess very electron-rich metal centres and, as 17-electron radicals, highly resolved epr spectra [15]. These properties render the MoL 2 (g-C 7 H 7 ) auxiliary as a potential novel end-cap group in investigations into all-carbon bridged organometallics, delivering the unique combination of a second row metal with the electron-donor capacity of the Fe(dppe)Cp * auxiliary and the application of a highly resolved epr probe previously only possible with the Re(NO)(PPh 3 )Cp * end-cap.…”