Reactivity of silyl-substituted heterobimetallic iron–platinum hydride complexes towards unsaturated molecules: Part II. Insertion of trifluoropropyne and hexafluorobutyne into the platinum–hydride bond

Abstract

Insertion of hexafluorobutyne into the Pt–H bond of the heterobimetallic complexes [(OC) 3Fe{Si(OMe) 3}(μ-Ph 2PXPPh 2)Pt(H)(PPh 3)] ( 1a X = CH 2; 1b X = NH) yields the σ-alkenyl complexes [(OC) 3Fe{μ-Si(OMe) 2(OMe)}(μ-Ph 2PXPPh 2)Pt{C(CF 3) C(H)CF 3}] ( 3a X = CH 2; 3b X = NH). This insertion reaction is accompanied by dissociation of the platinum bound PPh 3 ligand and saturation of the vacant coordination site by a dative μ−η 2-Si–O → Pt interaction. Addition of the Pt–H bond of 1a across the triple bond of 3,3,3-trifluoropropyne affords in a regiospecific manner [(OC) 3Fe{μ-Si(OMe) 2(OMe)}(μ-dppm)Pt{C(CF 3) CH 2}] ( 2) having the trifluoromethyl substituent on the α-carbon. Addition of RN C to 3 affords the isocyanide adducts [(OC) 3Fe{Si(OMe) 3}(μ-Ph 2PXPPh 2)Pt(CNR){C(CF 3) C(H)CF 3}] ( 4a R = t-Bu, X = CH 2; 4b R = 2,6-xylyl, X = CH 2; 4c R = 2,6-xylyl, X = NH). In dichloromethane solution 3a is gradually transformed into the C 4F 6-bridged compound [(OC) 3Fe(μ-dppm)(μ-CF 3C CCF 3)Pt(CO)] 5. The Pt-bound carbonyl ligand of 5 is displaced by xylylisocyanide or trimethylphosphite affording the derivatives [(OC) 3Fe(μ-dppm)(μ-CF 3C CCF 3)Pt(CNxylyl)] 6 and [(OC) 3Fe(μ-dppm)(μ-CF 3C CCF 3)Pt{P(OMe) 3}] 7. The molecular structures of 4a, 5 and 6 have been determined by X-ray diffraction studies.