Reactions of the cationic fragments [RuCP(PPh2N]HR)2]+ and [RuTp(PPh2NHR)2]+ (R = Ph, n-Pr) with alkynes:: Formation of four-membered azaphosphacarbenes

The synthesis of RuCp(PPh2NHR)(2)Cl (1a,b; R = Ph, n-Pr) and RuTp(PPh2NHR)(2)Cl (2a,b) is reported. Chloride abstraction from la with AgCF3SO3 affords RuCp(PPh2N-HPh)(2)(eta(1)-OSO2CF3) (3), whereas when AgSbF6 is used instead [RUCP(kappa(2)(P,P)-PPh2NHC6H4PPh2)(NH2+Ph)](+) (4) is formed. In the course of this reaction the P-N bond of one PPh2NHPh ligand is cleaved while a new P-C bond is formed, with concomitant formation of an aniline ligand. In the presence of Ag+ (CF3SO3- or SbF6-) complexes 1 and 2 react with terminal alkynes HC CR'(R'= Ph, P-C6H4Me, n-Bu) and propargylic alcohols to give novel azaphosphacarbene complexes of the types [RuCP(kappa(2)(C,P)=C(CH2R')N(R)PPh2)(kappa(1)(P)-PPh2NHR)](+) (5a-c, 6a-c), [RuTp(kappa(2)(C,P)=C(CH2R')N(R)PPh2)(kappa(1)(P)-PPh2NHR)](+) (14a,b, 15a-c), [RUCP(kappa(2)(C,p)= C(CH=CPh2)N(Pr-n)PPh2)(kappa(1)(P)-PPh2NHPrn)](+) (12), and [RuTp(kappa(2)(C,P)=C(CH=CPh2)N(Pr-n)-PPh2)(kappa(1)(P)-PPh2NHPrn)](+) and [RuTp(kappa(2)(C,P)=C(CH=CPh2)N(Pr-n)-PPh2)(kappa(1)(P)-PPh2NHPrn)](+) (17). These reactions proceed via vinylidene and allenylidene intermediates, respectively, which could be isolated in some cases: viz. [CpRu(PPh2NHPh)(2)(=C=C=CPh2)](+) (11) and [RuTp(PPh2NHR)(2)(=C=C=CPh2)](+) (16a,b). Furthermore, complexes 1a,b react with 3-butyn-1-ol to yield the oxacyclopentylidene complexes [CpRu(PPh2NHR)(2)(=C4H6O)](+) (7a,b). In sharp contrast to 6a-c (R = n-Bu), 5a-c (R = Ph) turned out to be quite sensitive toward traces of water, leading eventually to the formation of the aminocarbene complexes [RuCp(=C(CH2R)NHPh)(PPh2NHPh)(kappa(1)(P)-PPh2OH)](+) (8a,b) featuring a kappa(1)(P)-coordinated PPh2OH ligand. This ligand could be easily deprotonated to yield the neutral complex RuCp(=C(CH2Ph)NHR)(PPh2NHPh)(kappa(1)(P)-OPPh2) (10a,b). The formation of these complexes is reversible. Finally, representative structures have been determined by X-ray crystallography.