174585-24-1Relevant academic research and scientific papers
Synthesis and characterization of pentanuclear complexes composed of pairs of macrocyclic Ni2L and Zn2L complexes linked by cis-[PtCl2(dppba)2] and trans-[RhCl(CO)(dppba) 2] [dppba = (4-Diphenylphosphanyl)benzoate, L = macrocyclic ligand]
Golecki, Matthias,Kersting, Berthold
, p. 2473 - 2481 (2013)
The ability of the square-planar complexes cis-[PtCl2(Hdppba) 2] (4) and trans-[RhCl(CO)(Hdppba)2] (5), where Hdppba represents 4-(diphenylphosphanyl)benzoic acid to act as bridging metalloligand for dinuclear macrocyclic [Ni2L]2+ and [Zn 2L]2+ complexes is demonstrated (L2- is a 24-membered hexaazadithiophenolate macrocycle). Pentanuclear Ni4Pt and Zn4Pt complexes of composition [(M2L) 2(μ-dppba)2PtCl2]2+ [M = Ni (7a) or Zn (8a)] could be obtained either from substitution reactions between 4 and the corresponding [M2L(μ-Cl)]+ compounds (M = Ni, Zn) or by treatment of [PtCl2(NCMe)2] with the [M 2L(μ-dppba)]+ complexes (M = Ni, Zn). The pentanuclear Ni4Rh and Zn4Rh complexes of composition [(M 2L)2(μ-dppba)2RhCl(CO)]2+ [M = Ni (9a) or Zn (10a)] were obtained by treatment of [Rh2Cl 2(CO)4] with the [M2L(μ-dppba)]+ complexes. The new complexes were characterized by elemental analyses, ESI mass spectrometry, IR and UV/Vis spectroscopy, and by 1H, 13C, and 31P NMR (for Zn). The Pt and Rh dppba complexes in 7a-10a act in all cases as quadridentate bridging ligands linking two bioctahedral LNi 2 (or LZn2) units by μ1, 3-bridging carboxylate functions. The 31P chemical shifts and the 1J(P, Pt) and 1J(P, Rh) coupling constants further show that the cis and trans stereochemistry of the mononuclear starting materials 4 and 5 is maintained in the pentanuclear products. It is also demonstrated that the terminal Cl- ligands can be substituted by Br- and I- without affecting the pentanuclear nature of the complexes. Copyright
Zn(ii) Robson macrocycles as templates for chelating diphosphines
Ponsico, Sergio,Gulyas, Henrik,Martinez-Belmonte, Marta,Escudero-Adan, Eduardo C.,Freixa, Zoraida,Van Leeuwen, Piet W. N. M.
, p. 10686 - 10697 (2011/12/22)
Chelating diphosphines were constructed using dinuclear Zn(ii) complexes of Robson macrocycles (Zn-RMCs) as templates. The assembly process is driven by the interaction between the metal centers (Lewis acids) with anionic and neutral Lewis base-functionalized monophosphines. The stability of the final structure depends on the geometry and the affinity of the functional groups of the ditopic phosphines and on the structure of the RMC. In the free ligand the ditopic phosphines coordinate at opposite faces of the pseudo-planar macrocycle as is shown in the molecular structure of several of the assemblies, according to X-ray diffraction. Pre-organization of the system by coordinating the phosphorus atoms to a transition metal center enforced coordination of the functional groups at the same face of the RMC. For several templated diphosphines cis-PtCl2 complexes were identified by NMR. The in situ assembled diphosphines showed a chelating effect in the rhodium catalyzed hydroformylation of 1-octene. Combination of Zn-RMC 3 and phosphine A gave the highest l/b ratio (13) in acetonitrile.
