www.simplex-academic-publishers.com Global Journal of Inorganic Chemistry Volume 1, Issue 1, August 2010, pp. 1-8 ISSN 0976  9110 | EISSN 0976  9129 Ligand effect transfer in triad complexes: Allyl palladium(II) and dicarbonyl rhodium(I) moieties linked by ruthenium(II) trans-dicyanide central unit Yu. S. Varshavsky a* , T.G. Cherkasova a , M.R. Galding a , V.N. Khrustalev b , I.S. Podkorytov a , V.A. Gindin a , S.N. Smirnov a , A.B. Nikolskii a a St. Petersburg State University, Universitetskii pr. 26, Petrodvorets, St. Petersburg, 198504 Russia b Nesmeyanov Iinstitute of Organoelement Compounds, Vavilov Str., 28, Moscow, 119991 Russia *Author for correspondence: Yu. S. Varshavsky, e-mail: yurelv@gmail.com Received 29 Apr 2010; Accepted 24 May 2010; Available Online 31 Aug 2010 Abstract Trans-[RuPy 4 (CN) 2 ] cleaves chloride bridges in [Pd(η 3 C 3 H 5 )Cl] 2 to form heterometallic triad complex [(η 3 C 3 H 5 )ClPd(NC)Ru(Py) 4 (CN)PdCl(η 3 C 3 H 5 )] (I). Action of trans-[RuPy 4 (CN) 2 ] on the mixed (1:1) solution [Rh(CO) 2 Cl] 2 + [Pd(η 3 C 3 H 5 )Cl] 2 yields non-symmetric triad [(CO) 2 ClRh(NC)Ru(Py) 4 (CN)PdCl(η 3 C 3 H 5 )] (II) which coexists, in solutions, with related symmetric triads, I and [(CO) 2 ClRh(NC)Ru(Py) 4 (CN)RhCl(CO) 2 ] (III) in binomial 1:2:1 proportions. Under action of [Rh(CO) 2 Cl] 2 , II transforms into III with parallel formation of [Pd(η 3 C 3 H 5 )Cl] 2 . 13 C chemical shifts of the Rh-bound CO, 13 C and 1 H chemical shifts of Pd-bound C 3 H 5 , and Ru- bound Py ligands are sensitive to the nature of the ligands at a remote metal center. X-Ray structure data for the 1:1 co-crystal of I and II are presented. Keywords: Rhodium; Ruthenium; Palladium; Heterometallic triads; NMR; X-Ray 1. Introduction Cyanide bridged triad complexes M′- NC-M-CN-M′′ αM→ M′→ M′′ - transition metal atoms) were investigated extensively within the last two decades [1-8]. Most of the studies on this relatively new class of compounds were focused on the phenomena of long-range electronic interactions between metal atoms; therewith experimental techniques most suitable for the description of the electronic state of the metal centers, such as magnetochemistry, UV- Vis spectrometry, cyclic voltammetry, etc., were applied. In this case, the transfer of ligand effects through metal centers appeared out of explicit attention, though it is one of the leading lines of traditional transition metal organometallic chemistry. In our previous paper [9] we checked the sensitivity of NMR parameters to these effects and determined 1 H and 13 C chemical shifts for heterometallic triads containing Rh(CO) 2 and Rh(η 4 -C 8 H 12 ) terminal units connected together by the trans [Ru(C 5 H 5 N) 4 (CN) 2 ] central unit (abbreviation Py is used further for pyridine, C 5 H 5 N). The study has revealed slight but distinct remote ligand effects transferred along the L-Rh-NC-Ru-CN- Rh-L′ chainа In the present work we extend this approach to the triads containing the terminal palladium(II) π-allyl unit, Pd(η 3 C 3 H 5 ), which also belongs to the classical examples of platinum metals organometallic derivatives. Preliminary results of this study were reported recently [10]. 2. Experimental 2.1 General All operations were carried out in a dry argon atmosphere using the orthodox version of Schlenk techniques. All solvents were purified according to the standard procedures [11]. Trans- [RuPy 4 (CN) 2 ] [7, 12], [Rh(CO) 2 Cl] 2 [13], and [Pd(η 3 C 3 H 5 )Cl] 2 [14] were prepared by the published procedures. The 13 C-enriched samples of [Rh(CO) 2 Cl] 2 were prepared by the action of 40% enriched 13 CO on a solution of [Rh(C 2 H 4 ) 2 Cl] 2 [15] in benzene. The 1 H and 13 C{ 1 H} NMR spectra were measured on a Bruker spectrometer DPX-300 at 300.13 MHz for 1 H and 75.47 MHz for 13 C, respectively, using CDCl 3 as a solvent. The 1 H and 13 C chemical shifts were measured with the solvent as an internal standard (δ 1 H 7.28 ppm; δ 13 C 77.65 ppm) and referenced to TMS. The IR