Synthesis of ferrocenyl and 1-methylpyrrolyl bisphophines via electrophilic addition and substitution reactions of tungsten-coordinated phosphenium ions and phosphine triflates
New symmetrical and unsymmetrical bisphosphine complexes were synthesized using electrophilic substitution reactions of tungsten pentcarbonyl-coordinated phosphenium ions [W(CO)5(PRRʹ)]+, phosphine triflates [W(CO)5{PRRʹ(OSO2CF3)}], [W(CO)5{PRCl(OSO2CF3)}] and protonated amino phosphine [W(CO)5{PCl2NH(Et)2}]+ (38) with N-methylpyrrole and ferrocene. Chloride abstractions from [W(CO)5{PPh2Cl}] (1) and [W(CO)5{PPhCl2}] (2) were carried out using aluminum chloride or silver trifluormethanesulfonate (AgOTf) to form [W(CO)5(PPh2)]+ (4), [W(CO)5{PPh2(OSO2CF3)}] (5), and [W(CO)5{PPhCl(OSO2CF3)}] (6). Trifilic acid (HOTf) was added to [W(CO)5{P(NEt)2Cl2}] (3) to form compound 38. Reactions of 4 or 5 with N-methylpyrrole led to regioisomers [W(CO)5{PPh2(2-C5H6N)}] (7) and [W(CO)5{PPh2(3-C5H6N)}] (8). Compound 6 reacted with N-methylpyrrole to form regioisomers [W(CO)5{PPhCl(2-C5H6N)}] (9) and [W(CO)5{PPhCl(3-C5H6N)}] (10). Electrophilic substitution of 4, 5, or 6 with the monosubstituted phosphine complexes 8 and 10 led to installation of another phosphino group onto the pyrrole ring to form 2,4-bis(phosphino)N-methylpyrrole complexes [(CO)10W2{μ-2,4-C5H5N)(PPh2)2}] (11), [W2(CO)10{μ-2,4-C5H5N(PPhCl)(PPh2)}] (12), and [W2(CO)10{μ-2,4-(PClPh)2C5H5N}] (26). Chloride abstractions from 12 and 26 using AgOTf led to [W2(CO)10{μ-C5H5N(PPh2)(PPhOSO2CF3)}] (13) and [W2(CO)10{μ-C5H5N(P(Ph)OTf)2}] (27). Electrophilic substitutions of 13 and 27 with H-R led to bisphosphines [W2(CO)10{μ-2-(PPh2)-4-(PPhR)C5H5N}] and [W2(CO)10{μ-C5H5N(PPhR)2}] (R = allyl, phenylalkynyl). Compound 26 was converted to the monotriflate complex [W2(CO)10{μ-2-(PPh(OSO2CF3)-4-(PClPh)C5H5N}] (28) using one equivalent of AgOTf. Addition of H-R to 28 led to monosubstituted products [W2(CO)10{μ-2-(PPhR)-4-(PClPh)C5H5N}] (R = allyl or phenylalkynyl). Chloride abstraction from monosubstituted bisphosphines with AgOTf led to [W2(CO)10{μ-2-(PPhR)-4-(PPh(OSO2CF3))C5H5N}] (R = allyl or phenylalkynyl). Addition of H-R led to [W2(CO)10{μ-2- (PPhR)-4-(PPhRʹ)C5H5N}] (R = allyl; Rʹ = phenylalkynyl or R = phenylalkynyl; Rʹ = allyl). Electrophilic addition reactions were used to install two diphenylphosphino groups onto ferrocene. Addition of 4 or 5 to [W(CO)5(PPh2(C10H9Fe)] (39) led to the known complex [(CO)10W2{μ-C10H8Fe(PPh2)2}] (40). Alternately, 2 equivalents of compound 5 or 4 were added to ferrocene to form 40. Electrophilic addition of 6 to 39 led to the unsymmetrical bisphosphine complex [W2(OC)10{μ-C10H8Fe(PPhCl)(PPh2)}] (41). Addition of 2 equivalents of 6 to ferrocene led to [W2(CO)10{μ-C10H8Fe(PPhCl)2}] (46). Chloride abstraction from 41 and 46 using silver triflate led to [W2(OC)10{μ-C10H8Fe(PPh(OSO2CF3))(PPh2)}] (42) and [W2(CO)10{μ-C10H8Fe(PPh(OSO2CF3))2}] (47). Reactions of 42 and 47 with nucleophiles H-R led to mono and disubstituted bisphosphine complexes [W2(OC)10{μ-C10H8Fe(PPhR)(PPh2)}] and [W2(OC)10{μ-C10H8Fe(PPh(R))2}] (R = allyl, phenylalkynyl, ferrocenyl). Sequential addition of two different groups to phosphorus was done by abstracting chloride from 46 using AgOTf to form [W2(CO)10{μ-C10H8Fe(PPhCl)(PPh(OSO2CF3f)}] (48). Reaction of 48 with H-R led to monosubstituted bisphosphine complex [W2(CO)10{μ-C10H8Fe(PPhCl)(PPh(R)}] (R = allyl, phenylalkynyl, ferrocenyl). Chloride abstraction from monosubstituted bisphosphines using AgOTf formed triflate complexes [W2(CO)10{μ-C10H8Fe(PPh(OSO2CF3))(PPh(R)}] (R = allyl, phenylalkynyl, ferrocenyl). Addition of H-R led to [W2(CO)10{μ-C10H8Fe(PPh(Rʹ))(PPh(R)}] (R = allyl; Rʹ = phenylalkynyl). Addition of 1/2 an equivalent of ferrocene to 38 led to [W2(CO)10{μ-C10H8Fe(PCl2)2}] (55). Compound 55 was converted into [W2(CO)10{μ-C10H8Fe(P(OTf)2(PCl(OTf))}] (56) by addition of AgOTf. Addition of H-R led to tetra-substituted products [W2(CO)10{μ-C10H8Fe(P(R)2)2}] (R = allyl, phenylakynyl, and indolyl).
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Faculty of Graduate Studies and Research, University of Regina