The pentameric array of canted porphyrins (3‘TPyP)[Ru(TPP)(CO)]4 (1) (3‘TPyP = 5,10,15,20-tetra(3‘-pyridyl)porphyrin, TPP = meso-tetraphenylporphyrin) was synthesized by axial coordination of the 3‘N pyridyl groups of 3‘TPyP to the ruthenium core of four Ru(TPP)(CO) units; a thorough spectroscopic characterization of 1 in solution, together with a well-defined X-ray structure of the corresponding zinc derivative (Zn·3‘TPyP)[Ru(TPP)(CO)]4 (1Zn), is reported.

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The coordination chemistry of meso-pyridyl/phenyl porphyrins (PyPs) toward metallo-porphyrins with substitutionally labile axial ligands has been exploited for the self-assembling of ordered arrays of pigments. PyPs are particularly versatile bulding blocks: the peripheral N atom can be either in the 4'-position (4'PyPs) or in the 3'-position (3'PyPs), and they can provide connections to as many as four metal centers by coordination of the pyridyl groups. While 4'PyPs lead to arrays of perpendicularly linked, side-to-face, porphyrins, 3'PyPs yield the corresponding canted analogues. Even though several perpendicular arrays have been described, the examples of canted adducts are few and all very recent. We report here a detailed X-ray structure of the new adduct of two axially ligated canted porphyrins [Ru(TPP)(CO)(3'MPyP)] (1) (TPP = tetraphenylporphyrin, 3'MPyP = 5-(3'-pyridyl)-10,15,20-triphenylporphyrin) as well as its thorough spectroscopic characterization in solution, including the dynamic (1)H NMR investigation of the NH tautomeric exchange process. 1 crystallizes in the monoclinic space group P2(1)/a, Z = 4, with a = 13.508(1) Å, b = 29.972(1) Å, c = 19.084(1) Å, and beta = 96.03(1) degrees. The structural and spectroscopic data of 1 assume a strategic importance among axially ligated pyridylporphyrin systems, since they can be fruitfully compared to those of perpendicular analogues. The importance of a comparative investigation of the canted and perpendicular arrays of porphyrins is readily understood: it might help understanding how relevant physicochemical properties, such as photoinduced long-range electron or energy transfer processes, depend on the mutual orientation of the pigments in the 3-dimensional architecture while the other parameters in the supramolecular array (number of macrocycles, distance between them) are maintained substantially unchanged.

The diruthenium(II) complex [Ru 2 (µ-Cl)(µ-Me 2 SO-S,O)Cl 3 -(Me 2 SO-S) 3 (CO) 2 ] has been synthesized from cis,fac-[RuCl 2 -(Me 2 SO) 3 (CO)] in refluxing acetone and characterized by X-ray crystallography; unusual solution ( 1 H and 13 C NMR) and solidstate (IR) spectral features were found for the bridging sulfoxide, besides a remarkable inertness towards substitution reactions.Following earlier studies on chloro(dimethyl sulfoxide)ruthenium species, 1 we recently described a series of carbonyl derivatives. 2 We found that co-ordination of CO trans to a Me 2 SO-S molecule always involved its isomerization from the S-to Obonded (Me 2 SO-O). The new carbonyl-Me 2 SO complexes proved to be very useful precursors for the selective synthesis of substituted derivatives by replacement of the labile Me 2 SO-O ligand(s) trans to CO. In particular, the reactivity of cis,fac-[RuCl 2 (Me 2 SO) 3 (CO)] 1 with pyridylporphyrins allowed us to prepare several supramolecular adducts. 3 The further investigation of the solution chemistry and reactivity of 1 led us to the synthesis and structural characterization of the novel double bridged dimer [Ru 2 (µ-Cl)(µ-Me 2 SO-S,O)Cl 3 (Me 2 SO-S) 3 (CO) 2 ] 2 ( Fig. 1), which contains the rare µ-Me 2 SO-S,O moiety that bridges the two ruthenium centers via the S-and O-atoms. † The dinuclear complex consists of a cis-[RuCl 2 (Me 2 SO-S)(CO)] unit linked to cis-[Ru(Me 2 SO-S) 2 Cl(CO)] by Cl and Me 2 SO bridges, so that both metal atoms achieve a nearly octahedral environment [Ru(1) ؒ ؒ ؒ Ru(2) 2.9794(9) Å]. The dimer thus defines the Ru᎐Cl᎐Ru᎐S᎐O five membered ring. It is interesting to observe that in the Me 2 SO-S,O bridge the oxygen atom is trans to CO, while the sulfur atom is trans to Cl. In fact, O-bonding in ruthenium complexes is favoured only in the presence of trans π acceptor ligands (e.g. Me 2 SO-S, CO or NO). 2,5 * E-Mail: alessi@uts.univ. triests.it † Heating cis,fac-[RuCl 2 (Me 2 SO) 3 (CO)] (0.15 g, 0.34 mmol) in refluxing acetone (20 mL) for 4 h yielded a pale yellow solution whose volume was then reduced to ca. 10 mL. Crystals of 2 (50% yield) grew within 3 d from the solution stored at 4 ЊC (Found: C, 17.01; H, 3.36. C 10 H 24 -Cl 4 O 6 Ru 2 S 4 requires C, 16.85; H, 3.39%). IR (KBr): ν(CO) 2008, 1997 cm Ϫ1 (vs); ν(SO) 1141, 1107 cm Ϫ1 (vs, Me 2 SO-S), 1010 cm Ϫ1 (vs, µ-Me 2 SO-S,O); ν(Ru᎐O) 480 cm Ϫ1 (m); ν(Ru᎐S) 425 cm Ϫ1 (s); ν(Ru᎐Cl) 380 cm Ϫ1 (m). 1 H NMR (400 MHz, CD 3 NO 2 , vs. CH 3 NO 2 at δ 4.30) 3.). 1 H and 13 C resonances marked with a-g are correlated in the 2-D 1 H-13 C HETCOR spectrum. Pairs of methyls marked Me a,c , Me b,d , Me e,f and Me g,h belong to the same Me 2 SO according to the 2-D NOESY spectrum. The structure of 2 was determined by an X-ray crystallographic analysis. Crystal data: C 10 H 24 Cl 4 O 6 Ru 2 S 4 , M = 712.47, monoclinic, space group P2 1 /n (no. 14), a = 9.506(1), b = 13.447(1), c = 19.208(3) Å, β = 91.19(1)Њ, U = 2458(5) Å 3 , Z = 4, µ = 2.03 mm Ϫ1 , T = 293 K, R1 = 0.047 for 3183 unique reflections. CCDC reference number 1...

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