Bis(allenylidene) Complexes of Palladium and Platinum
نویسندگان
چکیده
trans-Bis(alkynyl)palladium complexes, trans-[(PEt3)2Pd(-CtCC{dO}NR2)2] (NR2 = NMe2 (2a), N(CH2)4 (2b)), were synthesized by two different methods: (a) by copper-catalyzed reaction of HCtCC(dO)NR2with [PdCl2(PEt3)2] under basic conditions and (b) by treatingHCtCC(dO)NR2 with AgNO3 followed by transmetalation of the alkynyl ligand from silver to [PdCl2(PEt3)2]. The reaction of AgCtCC(dO)NMe2 (3a) with trans-[Br(P Pr3)2PdCtCC(dO)N(CH2)4] (5) affords a complex containing two different alkynyl ligands, trans-[(PPr3)2Pd{-CtCC(dO)NMe2}{-CtCC(dO)N(CH2)4}] (6). Methylation of 2a,b and 6 with MeOTf or [Me3O]BF4 yields dicationic bisallenylidene complexes of palladium, trans-[(PEt3)2Pd{dCdCdC(OMe)NR2}2] 2þ 2X (X = OTf, BF4; NR2 = NMe2, N(CH2)4) and trans-[(PEt3)2Pd{dCdCdC(OMe)NMe2}{dCdCdC(OMe)N(CH2)4}] 2þ2OTf (7-OTf). In contrast to the reaction of 3a with [PdCl2(PEt3)2], that of 3a with the platinum complex [PtCl2(PPh3)2] gives cisand trans-[(PPh3)2Pt(-CtCC{dO}NMe2)2] (8a (cis) and 9a (trans)), depending on the reaction conditions and, upon subsequent alkylation with MeOTf, the cis and trans isomers of the first allenylidene platinum complexes, cisand trans[(PPh3)2Pt{dCdCdC(OMe)NMe2}2] 2þ2OTf .
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