Heteromultimetallic Transition Metal Complexes Based on Unsymmetrical Platinum(II) Bis-Acetylides

Abstract

The synthesis of a unique series of heteromultinuclear transition metal complexes with up to seven different metal atoms is reported by using consecutive synthesis methodologies including metathesis, dehydrohalogenation, and carbon−carbon cross-coupling reactions. In these compounds the metals Ti, Fe, Ru, Os, Re, Pt, and Cu are connected via carbon-rich bridging units comprising 1,3,5-triethynylbenzene and 2,2′-bipyridyl-5-yl. These molecules have been characterized by elemental analysis, IR and NMR spectroscopy, and ESI-TOF mass spectrometry. The main structural feature of these compounds is an unsymmetrical trans-configurated platinum(II) bis-acetylide unit. The structure of 1-(FcCC)-3-[( t Bu2bpy)(CO)3ReCC]-5-[trans-(Ph3P)2(RcCC)PtCC]C6H3 (3) and 1,3-[(Ph3P)2(η5-C5H5)OsCC]2-5-[(CO)3(Cl)Re(bpyCC)]C6H3 (18) (Fc = (η5-C5H5)(η5-C5H4)Fe; Rc = (η5-C5H5)(η5-C5H4)Ru; t Bu2bpy = 4,4′-di-tert-butyl-2,2′-bipyridyl; bpy = 2,2′-bipyridyl-5-yl) in the solid state is reported. Both compounds are characterized by the central 1,3,5-triethynylbenzene core, bridging the individual transition metal building blocks. These organometallic fragments show thereby typical structural properties. The appropriate metal acetylide moieties are, as expected, found in a linear arrangement with representative M−C and CC bond distances.

Intermetallic communication through a 1,3,5-triethynylbenzene connector

“…The potential separation between the two oxidation processes (DE 0 = 0.195 V) allows a K c of 2Â10 3 to be calculated, which confirms that the mixed valence [Ru 2 (II,III)] monocation belongs to the slightly delocalized Robin-Day's Class II. The comproportionation constant is similar to that found in 1,3,5-triethynylbenzene-based 1,3-[(PPh 3 ) 2 (g 5 [6,7]. Table 1 Data from cyclic voltammograms (all values in V vs. E 0 of the ferrocene/ferrocenium redox couple [6,7], dE/dt = 0.10 V s À1 )…”

“…1, Table 2). The cyclic voltammogram of 4 with one [(Ph 3 P) 2 (g 5 (Table 2). However, the expected reduction of the bipyridyl group [11] is not observed in the electrochemical window of dichloromethane.…”

“…Fig. 5 (top) illustrates the cyclic voltammetric response given by the diosmium complex 1,3-[(Ph 3 P) 2 (g 5 -C 5 H 5 )Os-C"C] 2 -5-[bpy-C"C]C 6 H 3 (5) in dichloromethane solution. The two osmium(II) units result in two separated one-electron oxidation processes and therefore due interact with each other.…”

“…In this report we describe the use of 1,3,5-triethynylbenzene as bridging ligand for different transition metal building blocks including [(g 2 -dppf) (g 5 -C 5 H 5 )Ru], [(PPh 3 ) 2 (g 5 -C 5 H 5 )Os], [( t Bu 2 bpy)-(CO) 3 Re], and [(bpy)(CO) 3 ClRe], respectively, (dppf = 1,1 0 -bis-(diphenyl-phosphino)ferrocene; t Bu 2 bpy = 4,4'-di-tert-butyl-2, 2 0 -bipyridyl; bpy = 2,2 0 -bipyridyl-5-yl) [5]. The electrochemical behavior and spectroscopic characterization of these heterometallic complexes to investigate electronic communication between the metal centers is discussed.…”

Ultrafast charge transfer dynamics in supramolecular Pt(ii) donor–bridge–acceptor assemblies: the effect of vibronic coupling

“…These new systems add to the growing body of & [Donor$C≡C$Pt$ C≡C$Acceptor] motifs. 33,[40][41][42][43] with electron donating and accepting ligands coordinated to the metal centre through ethynyl functionality in a arrangement.…”