Dinuclear Pyridine-4-thiolate-Bridged Rhodium and Iridium Complexes as Ditopic Building Blocks in Molecular Architecture

Abstract

A series of dinuclear pyridine-4-thiolate (4-Spy)-bridged rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 [diolef = 1,5-cyclooctadiene (cod), M = Rh (1), Ir (2); diolef = 2,5-norbornadiene (nbd), M = Rh (3)] were prepared by the reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) was obtained by the reaction of [Rh(acac)(CO)(PPh3)] (acac = acetylacetonate) with 4-pySH. Compounds 1-4 were assessed as metalloligands in self-assembly reactions with the cis-blocked acceptors [M(cod)(NCCH3)2](BF4) [M = Rh (a), Ir (b)] and [M(H2O)2(dppp)](OTf)2 [M = Pd (c), Pt (d); dppp = 1,3-bis(diphenylphosphino)propane]. The homometallic hexanuclear metallomacrocycles [{M2(μ-4-Spy)2(cod)2}2{M(cod)}2](BF4)2 (M = Rh [(1a)2], Ir [(2b)2]) and the heterometallic hexanuclear metallomacrocycles [{Rh2(μ-4-Spy)2(cod)2}2{Ir(cod)}2](BF4)2 [(1b)2], [{Rh2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(1c)2], Pt [(1d)2]), and [{Ir2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 (M' = Pd [(2c)2], Pt [(2d)2]) were obtained. NMR spectroscopy in combination with electrospray ionization mass spectrometry was used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of the synthesized species were found to be nonrigid in solution, and their fluxional behavior was studied by variable-temperature (1)H NMR spectroscopy. An X-ray diffraction study of the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 Å × 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moieties to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners.

Pyridinethiolate Titanocene Metalloligands and Their Self-Assembly Reactions To Yield Early–Late Metallamacrocycles

“…11 hexanuclear heterometallomacrocycles from dinuclear rhodium or iridium organometallic ditopic metalloligands bridged by the ambidentate pyridine-4-thiolato ligand. 15 It is important to remark the versatility of the pyridine-4-thiolato ligand, since it contains two different basic atoms and therefore is a good candidate for establishing a stable connection between early and late transition metal building blocks. Thus, we envisage the potential of titanocene thiolato complexes 16 having dangling pyridine groups as metalloligands for late transition metal fragments.…”

“…Figures S14 and S15 in Supporting Information), can not be ruled out accordingly with our previous observations in closely related systems. 15,22 Figure 4. Low-field region of the 1 H-1 H COSY NMR spectrum (nitromethane-…”

“…We have recently described the self-assembly of [Rh 4 (Pd or Pt) 2 ] and [Ir 4 (Pd or Pt) 2 ] hexanuclear heterometallamacrocycles from dinuclear rhodium or iridium organometallic ditopic metalloligands bridged by the ambidentate pyridine-4-thiolato ligand . It is important to note the versatility of the pyridine-4-thiolato ligand, since it contains two different basic atoms and therefore is a good candidate for establishing a stable connection between early- and late-transition-metal building blocks.…”

Rhodium(I) macrocyclic and cage-like structures containing diphosphine bridging 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- [9][10][11][12][13][14] and three-dimensional compounds [15][16][17][18], and they are of great interest due to their luminescent behaviour [19], their potential catalytic activity [20][21][22][23][24][25] and they could also be very useful in molecular recognition studies [26,27], among others.…”

Heterometallic AgI–IrIII Hydride Coordination Polymers Bridged by IrIII Metalloligands

“…To date, however, the use of metalloligands containing Ir complexes for the construction of functional heterometallic Ag I coordination polymers remains quite limited. To the best of our knowledge, only a few heterometallic coordination polymers of Ni II , Ag I , and Rh II supported by [M(Cp*)(CN) 3 ] – (M = Rh III and Ir III , Cp* = pentamethylcyclopentadienyl) metalloligands can be found in the literature,54 together with heterometallic metallomacrocycles of Pd II and Pt II supported by the [M(4‐Spy)(cod)] 2 (M = Rh I and Ir I , Spy = pyridine‐4‐thiolate, cod = 1,5‐cyclooctadiene) metalloligands 55…”