Building Blocks for Molecular Polygons Based on Platinum Vertices and Polyynediyl Edges.

Reactions of Cl 2 P(CH 2 ) 3 PCl 2 and p -MgBrC 6 H 4 X (X = a /OMe, b /O t Bu, c / t Bu, d /SiMe 3 ) give the diphosphines ( p -XC 6 H 4 ) 2 P(CH 2 ) 3 P( p -C 6 H 4 X) 2 ( 1a - d ; 47-66%). Additions of 1a , d to (COD)PtCl 2 yield (CH 2 (CH 2 P( p -C 6 H 4 X) 2 ) 2 )PtCl 2 ( 2a , d ; 62-88%), which upon reaction with butadiyne (2 equiv; HNEt 2 /cat. CuI) give (CH 2 (CH 2 P( p -C 6 H 4 X) 2 ) 2 )Pt((C≡C) 2 H) 2 ( 3a , d ; 34-76%). Alternatively, 3a - d can be accessed from trans -( p- tol 3 P) 2 Pt((C≡C) 2 H) 2 and 1a - d (30-87%). Reactions of ( p -tol 3 P) 2 PtCl 2 and H(C≡C) 2 SiR 3 (2 equiv, HNEt 2 /cat. CuI; R = Me/Et/ i Pr) give trans -( p -tol 3 P) 2 Pt((C≡C) 2 SiR 3 ) 2 (77-95%), and subsequent additions of 1a , b , d yield the corresponding adducts (CH 2 (CH 2 P( p -C 6 H 4 X) 2 ) 2 )Pt((C≡C) 2 SiR 3 ) 2 (R/X = Me/OMe, 5a ; i Pr/OMe, 6a ; i Pr/O t Bu, 6b ; i Pr/SiMe 3 , 6d ; 52-95%) and (for 5a ) a luminescent diplatinum byproduct with trans Pt((C≡C) 2 SiMe 3 ) 2 units. 5a and 6b hydrolyze in the presence of F - to 3a , b (92-93%). Reaction of 2a and 3a (HNEt 2 /cat. CuI) affords the Pt 4 C 16 polygon ([(CH 2 (CH 2 P( p -C 6 H 4 OMe) 2 ) 2 )Pt(C≡C) 2 ] 4 as an H 2 NEt 2 + Cl - adduct (66%). The 13 C{ 1 H} NMR spectra of 3a - d , 5a , and 6a , b , d feature complex AMXX' (CPtPP') spin systems, and simulations allow J values to be extracted. The crystal structures of 2a , 3a , b , d , 5a , and 6a are determined and analyzed.