An experimental and theoretical study of the coordination and donor properties of tris-2-pyridyl-phosphine ligands

Producción CientíficaThe coordination characteristics and donor/acceptor properties of a series of 2-pyridyl substituted phosphine ligands have been investigated using structural, spectroscopic and DFT calculational studies. A range of different coordination modes are observed in Mo and W carbonyl complexes of tris-2-pyridyl-phosphine ligands of the type P(2-py’) (2-py’ = substituted or unsubstituted 2-pyridyl group), including an unprecedented example exhibiting N,N′,μ2-π coordination. DFT calculations were used to assess the relative donor/acceptor properties of a range of related 2-pyridyl-phosphine ligands with respect to PPh3 and PtBu3.Ministerio de Ciencia, Innovación y Universidades (PGC2018-096880-A-I00. AEI / FEDER, UE

Deprotonation, insertion and isomerisation in the post-functionalisation of tris-pyridyl aluminates

Producción CientíficaPost-functionalisation of the aluminate anion [EtAl(6-R-2-py)3]− (6-R-2-py = 6-R-2-pyridyl, R = Me or Br) can be accomplished via nucleophilic addition of the pyridyl groups to the electrophilic C[double bond, length as m-dash]O group of aldehydes (RCH[double bond, length as m-dash]O) or by deprotonation of carboxylic acids (RCO2H). NMR spectroscopic and crystallographic studies show how 6-Me-2-py groups can detect chirality and reveal a new aspect of isomerism.Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - Fondo Social Europeo (Ramon y Cajal contract RG-R, RYC-2015-19035)

A Tris(3‐pyridyl)stannane as a Building Block for Heterobimetallic Coordination Polymers and Supramolecular Cages

Producción CientíficaThe systematic assembly of supramolecular arrangements is a persistent challenge in modern coordination chemistry, especially where further aspects of complexity are concerned, as in the case of large molecular mixed‐metal arrangements. One targeted approach to such heterometallic complexes is to engineer metal‐based donor ligands of the correct geometry to build 3D arrangements upon coordination to other metals. This simple idea has, however, only rarely been applied to main group metal‐based ligand systems. Here, we show that the new, bench‐stable tris(3‐pyridyl)stannane ligand PhSn(3‐Py)3 (3‐Py=3‐pyridyl) provides simple access to a range of heterometallic SnIV/transition metal complexes, and that the presence of weakly coordinating counter anions can be used to build discrete molecular arrangements involving anion encapsulation. This work therefore provides a building strategy in this area, which parallels that of supramolecular transition metal chemistry.Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - Fondo Social Europeo (Ramon y Cajal contract RG‐R, RYC‐2015‐19035)Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - FEDER - Unión Europea (project PGC2018‐096880‐A‐I00)

Highly adaptive nature of group 15 tris(quinolyl) ligands─studies with coinage metals

The substitution of heavier, more metallic atoms into classical organic ligand frameworks provides an important strategy for tuning ligand properties, such as ligand bite and donor character, and is the basis for the emerging area of main-group supramolecular chemistry. In this paper, we explore two new ligands [E(2-Me-8-qy)3] [E = Sb (1), Bi (2); qy = quinolyl], allowing a fundamental comparison of their coordination behavior with classical tris(2-pyridyl) ligands of the type [E′(2-py)3] (E = a range of bridgehead atoms and groups, py = pyridyl). A range of new coordination modes to Cu+, Ag+, and Au+ is seen for 1 and 2, in the absence of steric constraints at the bridgehead and with their more remote N-donor atoms. A particular feature is the adaptive nature of these new ligands, with the ability to adjust coordination mode in response to the hard–soft character of coordinated metal ions, influenced also by the character of the bridgehead atom (Sb or Bi). These features can be seen in a comparison between [Cu2{Sb(2-Me-8-qy)3}2](PF6)2 (1·CuPF6) and [Cu{Bi(2-Me-8-qy)3}](PF6) (2·CuPF6), the first containing a dimeric cation in which 1 adopts an unprecedented intramolecular N,N,Sb-coordination mode while in the second, 2 adopts an unusual N,N,(π-)C coordination mode. In contrast, the previously reported analogous ligands [E(6-Me-2-py)3] (E = Sb, Bi; 2-py = 2-pyridyl) show a tris-chelating mode in their complexes with CuPF6, which is typical for the extensive tris(2-pyridyl) family with a range of metals. The greater polarity of the Bi–C bond in 2 results in ligand transfer reactions with Au(I). Although this reactivity is not in itself unusual, the characterization of several products by single-crystal X-ray diffraction provides snapshots of the ligand transfer reaction involved, with one of the products (the bimetallic complex [(BiCl){ClAu2(2-Me-8-qy)3}] (8)) containing a Au2Bi core in which the shortest Au → Bi donor–acceptor bond to date is observed

Synthesis of tris(3-pyridyl)aluminate ligand and its unexpected stability against hydrolysis: revealing cooperativity effects in heterobimetallic pyridyl aluminates

Producción CientíficaWe report the elusive metallic anion [EtAl(3-py)3]− (3-py = 3-pyridyl) (1), the first member of the anionic tris(3-pyridyl) family. Unexpectedly, the lithium complex 1Li shows substantial protic stability against water and alcohols, unlike related tris(2-pyridyl)aluminate analogues. This stability appears to be related to the inability of the [EtAl(3-py)3]− anion to chelate Li+, which precludes a decomposition pathway involving Li/Al cooperativity.Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (projects PGC2018-096880-A-I00 and PGC2018-099470-B-I00)Ministerio de Economía, Industria y Competitividad - Agencia Estatal de Investigación - Fondo Social Europeo (contract RYC-2015-19035