Tetranuclear [Rh₄(μ-PyS₂)₂(diolefin)₄] Complexes as Building Blocks for New Inorganic Architectures:  Synthesis of Coordination Polymers and Heteropolynuclear Complexes with Electrophilic d⁸and d¹⁰Metal Fragments

Abstract

The reaction of [Rh4(mu-PyS2)2(cod)4] (PyS2 = 2,6-pyridinedithiolate, cod = 1,5-cyclooctadiene) with CF3SO3Me gave the cationic complex [Rh(4)(mu-PyS(2)Me)(2)(cod)4][CF3SO3]2 (1) with two 6-(thiomethyl)pyridine-2-thiolate bridging ligands from the attack of Me+ at the terminal sulfur atoms of the starting material. Under identical conditions [Rh4(mu-PyS2)2(tfbb)4] (tfbb = tetrafluorobenzobarrelene) reacted with CF3SO3Me to give the mixed-ligand complex [Rh(4)(mu-PyS2)(mu-PyS2Me)(tfbb)4][CF3SO3] 2. The nucleophilicity of the bridging ligands in the complexes [Rh4(mu-PyS2)2(diolefin)4] was exploited to prepare heteropolynuclear species. Reactions with [Au(PPh3)(Me2CO)][ClO4] gave the hexanuclear complexes [(PPh3)2Au2Rh4(mu-PyS2)2(diolefin)4][ClO4]2 (diolefin = cod (3), tfbb (4)). The structure of 4, solved by X-ray diffraction methods, showed the coordination of the [Au(PPh3)]+ fragments to the peripheral sulfur atoms in [Rh4(mu-PyS2)2(diolefin)4] along with their interaction with the neighbor rhodium atoms. Neutral coordination polymers of formula [ClMRh4(mu-PyS2)2(diolefin)4]n (M = Cu (5, 6), Au (7)) result from the self-assembly of alternating [Rh4(mu-PyS2)2(diolefin)4] ([Rh4]) blocks and MCl linkers. The formation of the infinite polymetallic chains was found to be chiroselective for M = Cu; one particular chain contains exclusively homochiral [Rh4] complexes. Cationic heterometallic coordination polymers of formula [MRh4(mu-PyS2)2(diolefin)4]n[BF4]n (M = Ag (8, 9), Cu (10, 11)) and [Rh5(mu-PyS2)2(diolefin)5]n[BF4]n (12, 13) result from the reactions of [Rh4] with [Cu(CH2CN)4]BF4, AgBF4, and [Rh(diolefin)(Me2CO)2]BF4, respectively. The heterometallic coordination polymers exhibit a weak electric conductivity in the solid state in the range (1.2-2.8) x 10(-7) S cm(-1).

Synthesis of Tetranuclear Rhodium and Iridium Complexes Directed by 6-Mercaptopyridin-2-ol: Electrochemical Behavior, Chemical Oxidation, and Coordination Chemistry

“…The exocyclic C(5)−S distance, 1.777(4) Å, comparable to those observed for the μ 2 - S atoms in [Rh 4 (μ-PyS 2 ) 2 (cod) 4 ], 1.789(4) Å, and in the hexanuclear structurally related [(PPh 3 ) 2 Au 2 )Rh 4 (μ-PyS 2 ) 2 (tfbb) 4 ] complex, 1.757(10) and 1.790(10) Å, is slightly shorter than typical C−S single bonds (1.83(3) Å in alkanethiolates, for instance) and indicative of the thiolate character of these sulfur atoms. On the other hand, the exocyclic C−O distances of 1.299(5) Å suggest weak electron delocalization of the oxygen lone pairs into the aromatic ring.…”

“…The ability of these tetranuclear complexes to act as S , S coordination entities have been demonstrated by the assembly of coordination polymers using the complexes [Rh 4 (μ-pyS 2 ) 4 (diolefin) 4 ] (diolefin = cod, tfbb) as building blocks. Thus, cationic one-dimensional coordination polymers such as [AgRh 4 (μ-PyS 2 ) 2 (diolefin) 4 ] n [BF 4 ] n and [Rh 5 (μ-PyS 2 ) 2 (diolefin) 5 ] n [BF 4 ] n resulted from the zigzag chain arrangement of alternating [Rh 4 ] tetranuclear units and Ag + (d 10 ) and [Rh(diolefin)] + (d 8 ) metal fragments . In addition, the determination of the structure of the polymer [ClCuRh 4 (μ-PyS 2 ) 4 (cod) 4 ] n has revealed that the self-assembly process of coordination polymers containing trigonal-planar metal fragments as linkers is chiroselective since the one-dimensional chains are formed exclusively by homochiral [Rh 4 ] building blocks …”

New rhodium(I) supramolecular structures containing pyridyl and bipyridyl ligands

“…However, other metals have also been used in these reactions. In particular, Rh(I) and Ir(I) units have been explored in the synthesis of bi- [23][24][25][26][27] and three-dimensional compounds [28,29] and they are of great interest due to their potential catalytic activity and luminescent behaviour, that could be very useful in host-guest studies [30][31][32][33][34][35].…”

Heterometallic AgI–IrIII Hydride Coordination Polymers Bridged by IrIII Metalloligands

“…Metalloligands are classified based on the primary chelating functional group that coordinates to the primary metal ion, for example:15,22 β‐diketonate‐based, acetylacetonate‐based, dipyrrin‐based, mixed acetylacetonate–salen–dipyrrin‐based, porphyrin‐based, those based on Schiff bases, pyridine/pyrazine–2‐carboxylate‐based, oxamide‐ and oxamate‐based, tris(triazolyl)borate‐based, pyridine–amide‐based, dipyridyl‐based, chiral, and miscellaneous metalloligands. In particular, metalloligands containing Mn II ,24 Fe III ,24–27 Co III ,24,25,28–30 Ni II ,31 Cu II ,29,30,32 Zn II ,24 Mo V ,33 Rh I ,34 Rh II ,35 Cd II ,24 Re I ,36 and Au I[37] have been applied in the preparation of 4d–3d, 4d–4d, and 4d–5d heterometallic Ag I coordination polymers, which have been characterized structurally, magnetically, and photochemically, along with 3d–4d heterometallic coordination polymers of Mn II ,38 Ni II ,39 Cu II ,39,40 and Zn II[40] supported by Ag I metalloligands. In addition, the lanthanide metalloligands have been extensively employed in the preparations of 4d–4f heterometallic Ag I coordination polymers 41–53.…”