Wire like diplatinum, triplatinum, and tetraplatinum complexes featuring X[PtCCCCCCCC]mPtX segments; iterative syntheses and functionalization for measurements of single molecule properties

Abstract

Reaction of (p-tol₃P)₂PtCl₂ and Me₃Sn(CC)₂SiMe₃ (1 : 1/THF/reflux) gives monosubstituted trans-Cl(p-tol₃P)₂Pt(CC)₂SiMe₃ (63%), which with wet n-Bu₄N⁺ F⁻ yields trans-Cl(p-tol₃P)₂Pt(CC)₂H (2, 96%). Hay oxidative homocoupling (O₂/CuCl/TMEDA) gives all-trans-Cl(p-tol₃P)₂Pt(CC)₄Pt(Pp-tol₃)₂Cl (3, 68%). Reaction of 3 and Me₃Sn(CC)₂SiMe₃ (1 : 1/rt) affords monosubstituted all-trans-Cl(p-tol₃P)₂Pt(CC)₄Pt(Pp-tol₃)₂(CC)₂SiMe₃ (46%), which is converted by a similar desilylation/homocoupling sequence to all-trans-Cl[(p-tol₃P)₂Pt(CC)₄]₃Pt(Pp-tol₃)₂Cl (7; 79%). Reaction of (p-tol₃P)₂PtCl₂ and excess H(CC)₂SiMe₃ (HNEt₂/cat. CuI) gives trans-Me₃Si(CC)₂Pt(Pp-tol₃)₂(CC)₂SiMe₃ (78%), which with wet n-Bu₄N⁺ F⁻ affords trans-H(CC)₂Pt(Pp-tol₃)₂(CC)₂H (96%). Hay oxidative cross coupling with 2 (1 : 4) gives all-trans-Cl[(p-tol₃P)₂Pt(CC)₄]₂Pt(Pp-tol₃)₂Cl (10, 36%) along with homocoupling product 3 (33%). Reaction of 3 and Me₃Sn(CC)₂SiMe₃ (1 : 2/rt) yields all-trans-Me₃Si(CC)₂(p-tol₃P)₂Pt(CC)₄Pt(Pp-tol₃)₂(CC)₂SiMe₃ (17, 77%), which with wet n-Bu₄N⁺ F⁻ gives all-trans-H(CC)₂(p-tol₃P)₂Pt(CC)₄Pt(Pp-tol₃)₂(CC)₂H (96%). Reaction of 3 and excess Me₃P gives all-trans-Cl(Me₃P)₂Pt(CC)₄Pt(PMe₃)₂Cl (4, 86%). A model reaction of trans-(p-tol)(p-tol₃P)₂PtCl and KSAc yields trans-(p-tol)(p-tol₃P)₂PtSAc (12, 75%). Similar reactions of 3, 7, 10, and 4 give all-trans-AcS[(R₃P)₂Pt(CC)₄]_nPt(PR₃)₂SAc (76–91%). The crystal structures of 3, 17, and 12 are determined. The first exhibits a chlorine–chlorine distance of 17.42 Å; those in 10 and 7 are estimated as 30.3 Å and 43.1 Å.