Polyyn-diyls Capped by Diruthenium Termini:  A New Family of Carbon-Rich Organometallic Compounds and Distance-Dependent Electronic Coupling Therein

Abstract

Polyyn-diyls capped by Ru(2)(ap)(4) termini (ap = 2-anilinopyridinate), that is, [Ru2(ap)4](mu-C,C'-C2m)[Ru2(ap)4] (compounds 1-5 with m = 1-4 and 6), were synthesized through either a metathesis reaction between Ru2(ap)4Cl and LiC(2m)Li or a Glaser homocoupling reaction of Ru2(ap)4(CmH) under Eglinton/Hay conditions. X-ray diffraction studies of compounds 2 and 4 revealed both the linear rigid rod topology of these compounds and the fine structural details about the Ru2 cores and polyyn-diyl chains. Cyclic and differential pulse voltammetric (CV and DPV) measurements and spectroelectrochemical studies show that reduced and oxidized forms of 1, 2, 4, and 5 are donor-acceptor systems in which the Ru2 termini are coupled to varying degrees depending upon the length of the polyyn-diyl bridge.

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

“…[11a] However, when similar sequences were conducted with PtC 12 Si at À25 8C or À45 8C, no tractable products could be isolated. Under these conditions, the rate of decomposition of the intermediate PtC 12 H is presumably too fast. Importantly, a ClSiMe 3 treatment step must be survived before any oxidizing agent is encountered.…”

“…In this paper, we describe the most extensive series of C x complexes isolated to date (x = 6, 8, 10, 12,16,20,24,28) and their detailed physical characterization. These feature the p-tolyl-substituted platinum endgroup {PtA C H T U N G T R E N N U N G (p-tol){PA C H T U N G T R E N N U N G (ptol) 3 } 2 }, which is more electron-rich than the pentafluorophenyl analogue mentioned above.…”

“…[23] Also, desilylation somehow occurs under the conditions of Scheme 3 (top), in which fluoride ion is absent. We therefore wondered whether PtC 12 Si might undergo protodesilylation under the Hay homocoupling conditions.…”

“…As shown in Scheme 4, PtC 12 Si was treated under such conditions at 10 8C. Indeed, chromatography gave the deep red tetracosadodecaynediyl complex PtC 24 Pt in 36 % yield, along with 38 % of recovered PtC 12 Si.…”

“…Species with cumulenic bridges are much less stable. [8] Of the polyynediyl complexes, only those with {FeA C H T U N G T R E N N U N G (h 5 -C 5 Me 5 )(CO) 2 }, [9] {RuA C H T U N G T R E N N U N G (h 5 -C 5 R 5 )(L) 2 } or {Ru(L')(L) 4 } n + , [10] {ReA C H T U N G T R E N N U N G (h 5 -C 5 Me 5 )(NO)A C H T U N G T R E N N U N G (PPh 3 )}, [11] {Ru 2 (2-anilinopyridinate) 4 }, [12] {PtA C H T U N G T R E N N U N G (C 6 F 5 ){PA C H T U N G T R E N N U N G (p-tol) 3 } 2 }, [13] and {PtA C H T U N G T R E N N U N G (C 6 F 5 )A C H T U N G T R E N N U N G (RAr 2 P) 2 } [14] endgroups have been extended to long chain lengths, beyond four triple bonds (! C 10 ).…”