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New Approach to the Chemistry of Polysulfides Using Diphosphanylmethanide Complexes of Manganese(I)

2001; Wiley; Volume: 7; Issue: 20 Linguagem: Espanhol

10.1002/1521-3765(20011015)7

1521-3765

Javier Ruiz, Mario Ceroni, O.V. Quinzani, Vı́ctor Riera, Marilín Vivanco, Santiago García‐Granda, Juan F. Van der Maelen, Maurizio Lanfranchi, António Tiripicchio,

Organometallic Compounds Synthesis and Characterization

Unprecedented polysulfides with pendant carbonyl complexes of formula [(CO)4Mn{(PPh2)2C-Sn−C(PPh2)2}Mn(CO)4] have been prepared by nucleophilic degradation of S8 with the diphosphanylmethanide derivative [Mn(CO)4{(PPh2)2CH}]. Control can be established over the sulfur chain length as well as over the acid–base behavior of the C−Sn−C bridging unit, which can be reversibly protonated at the carbon atoms (structure of the doubly protonated form of S2 derivative shown). The study of the nucleophilic degradation of S8 by the methanide complex [Mn(CO)4{(PPh2)2CH}] (2) has led to the preparation of a unique class of polysulfide derivatives of formula [(CO)4Mn{(PPh2)2C−Sn−C(PPh2)2}Mn(CO)4]. The structures of 3 (n=6), 4 (n=2), and 7 (n=1) have been determined by X-ray crystallography, whereas those polysulfides with the sulfur chains S7, S5, S4, and S3 have been detected by spectroscopic methods. The polysulfides with n>2 lose sulfur spontaneously, a process that can be accelerated by treatment with PPh3 or Na/Hg. Complexes 3, 4, and 7 were protonated at the two methanide carbon atoms to give the cationic dinuclear derivatives [(CO)4Mn{(PPh2)2C(H)−Sn−C(H)(PPh2)2}Mn(CO)4]2+ (8, n=6; 9, n=2; 10, n=1). The 1H NMR spectrum of 9 suggests the existence of intramolecular C−H⋅⋅⋅S interactions, in agreement with the X-ray structural determination of this complex. By treatment of 4 and 7 with one equivalent of HBF4 it is possible to selectively protonate just one methanide carbon atom, which allows the isolation of the mixed cationic derivatives [(CO)4Mn{(PPh2)2C(H)−Sn−C(PPh2)2}Mn(CO)4]+ (11, n=2; 6, n=1). Additionally, heterometallic complexes containing a bridging disulfide unit, of general formula [(CO)4Mn{(PPh2)2C(AuPPh3)S−SC(AuPPh3)(PPh2)2}Mn(CO)4]2+ (12) and [(CO)4Mn{(PPh2)2C(H)S−SC(AuPPh3)(PPh2)2}Mn(CO)4]+ (13), were prepared by reaction of 4 and 11, respectively, with [AuCl(PPh3)] in the presence of TlPF6. El estudio de la degradación nucleofílica de S8 por el complejo metanuro [Mn(CO)4{(PPh2)2CH}] (2) ha conducido a la preparación de una clase única de derivados polisulfuro de fórmula [(CO)4Mn{(PPh2)2C−Sn−C(PPh2)2}Mn(CO)4]. Las estructuras de 3 (n=6), 4 (n=2) y 7 (n=1) han sido determinadas mediante cristalografía de rayos-X, mientras que los polisulfuros con cadenas de azufre S7, S5, S4 y S3 han sido detectados mediante métodos espectroscópicos. Para n>2 estos complejos son inestables y pierden azufre espontáneamente, un proceso que puede ser acelerado por tratamiento con PPh3 ó Na/Hg. Estos polisulfuros fueron protonados sobre los dos átomos de carbono metanuro dando los complejos catiónicos dinucleares [(CO)4Mn{(PPh2)2C(H)−Sn−C(H)(PPh2)2}Mn(CO)4]2+ (8: n=6, 9: n=2, 10: n=1). El espectro de 1H RMN de 9 es llamativo sugiriendo la existencia de interacciones intramoleculares C−H⋅⋅⋅S, en consonancia con la determinación estructural de rayos-X para este compuesto. Mediante tratamiento de 4 y 7 con un equivalente de HBF4 es posible protonar selectivamente un único átomo de carbono metanuro lo que permite aislar los derivados catiónicos mixtos [(CO)4Mn{(PPh2)2C(H)−Sn−C(PPh2)2}Mn(CO)4]+ (11, n=2; 6, n=1). Mediante reacción de 4 y 11 con [AuCl(PPh3)] en presencia de TlPF6 se han obtenido además complejos heterometálicos que contienen una unidad disulfuro puente, de fórmula general [(CO)4Mn{(PPh2)2C(AuPPh3)S−SC(AuPPh3)(PPh2)2}Mn(CO)4]2+ (12) y [(CO)4Mn{(PPh2)2C(H)S−SC(AuPPh3)(PPh2)2}Mn(CO)4]+ (13).