A Synthetic Breakthrough into an Unanticipated Stability Regime: A Series of Isolable Complexes in which C₆, C₈, C₁₀, C₁₂, C₁₆, C₂₀, C₂₄, and C₂₈ Polyynediyl Chains Span Two Platinum Atoms

Abstract

The reaction of trans-[PtCl(p-tol){P(p-tol)3}2] (PtCl) and H(C[triple chemical bond]C)2H (cat. CuI, HNEt2) gives PtC4H (82 %), which can be cross-coupled with excess HC[triple chemical bond]CSiEt3 (acetone, O2, CuCl/TMEDA; Hay conditions) to yield PtC6Si (77 %). The addition of nBu4N+F- in wet acetone gives PtC6H (84 %), and further addition of ClSiMe3 (F- scavenger) and excess HC[triple chemical bond]CSiEt3 (Hay conditions) yields PtC(8)Si (23 %). Similar cross-coupling reactions of PtCxH (generated in situ for x>6) and excess H(C[triple chemical bond]C)2SiEt3 give a) x=4, PtC8Si (29 %), PtC12Si (30 %), and PtC16Si (1 %); b) x=6, PtC10Si (59 %) and PtC14Si (7 %); c) x=8, PtC12Si (42 %); and d) x=10, PtC14Si (20 %). Hay homocoupling reactions of PtC4H, PtC6H, PtC8H, and PtC10H give PtC8Pt, PtC12Pt, PtC16Pt, and PtC20Pt (88-70 %), but PtC12H decomposes too rapidly. However, when PtC12Si and PtC14Si are subjected to Hay conditions, protodesilylation occurs in the presence of the oxidizing agent and PtC24Pt (36 %) and PtC28Pt (51 %) are isolated. Reactions of PtC6H and PtC10H with PtCl (CuI, HNEt2) give PtC6Pt (56 %) and PtC10Pt (84 %). The effect of the chain lengths in PtCxPt upon thermal stabilities (>200 degrees C for x< or =20), IR nu(C[triple chemical bond]C) patterns (progressively more bands), colors (yellow to orange to deep red), UV/Vis spectra (progressively red-shifted and more intense bands with epsilon>400,000 M(-1) cm(-1)), redox properties (progressively more difficult oxidations), and NMR spectra (many monotonic trends) are analyzed, including implications for the sp carbon allotrope carbyne. Whereas all other dodecaynes and tetradecaynes rapidly decompose at room temperature, PtC24Pt and PtC28Pt remain stable at >140 degrees C. Crystal structures of PtCxSi (x=6, 8, 10) and PtCxPt (x=6, 8, 10, 12) have been determined.

Coordination‐Driven Self‐Assembly, Structures, and Dynamic Properties of Diplatinum Hexatriynediyl and Butadiynediyl Complexes in which the sp Carbon Chains are Shielded by sp3 Carbon Chains: Towards Endgroup–Endgroup Interactions

“…[2] They are much more effective than most other types of unsaturated bridging ligands, which usually can be twisted out of conjugation. [2] The C x linkages also appear to be extend-A C H T U N G T R E N N U N G able to greater lengths [4][5][6] than in analogs with carbon-or silicon-based endgroups.…”

“…[6] As this field grows and evolves, attention is increasingly being directed at "second generation" families of complexes with special architectural features. One example would be polygons; squares with Pt 4 C 16 cores have been reported by Youngs, Bruce, and Anderson.…”

“…[5,6,9,10] These have been covalently linked in lateral arrays ("bundles") [11] and longitudinal arrays (e.g., [PtA C H T U N G T R E N N U N G (CC) 4 ] n' Pt oligomers). [12] As summarized in Scheme 1, we have also developed two complementary routes to complexes of the formula trans,trans-[(C 6 F 5 …”

“…[8] Among our own efforts, we have described extensive series of diplatinum polyynediyl or [PtA C H T U N G T R E N N U N G (CC) n Pt] complexes (n = 2, 3, 4,5,6,8,10,12,14). [5,6,9,10] These have been covalently linked in lateral arrays ("bundles") [11] and longitudinal arrays (e.g., [PtA C H T U N G T R E N N U N G (CC) 4 ] n' Pt oligomers).…”

Polyine mit tert‐Butyl‐Endgruppen: kristallographischer Nachweis einer reduzierten Bindungslängenalternanz

“…[3d,g, 4,5] Die vorliegenden Daten zeigen, dass dieser Trend bei den momentan mit organisch-chemischen Methoden zugänglichen Polyinlängen noch keinen Grenzwert erreicht hat.…”