Reactions of Diphosphine-Stabilized Tetracobalt Carbonyl Clusters with −Si(OR)3-Functionalized Alkynes

Mono- and polynuclear Ag(i) complexes of N-functionalized bis(diphenylphosphino)amine DPPA-type ligands: synthesis, solid-state structures and reactivity

DPPA-type ligands (Ph₂P)₂N(p-Z)C₆H₄ (Z = H, SMe, OMe) led to Ag(i) complexes of various nuclearities and an unexpected influence of the para-substituent Z is observed, including for CH₂Cl₂ activation.

Functional Short-Bite Ligands: Synthesis, Coordination Chemistry, and Applications of N-Functionalized Bis(diaryl/dialkylphosphino)amine-type Ligands

The aim of this review is to highlight how the diversity generated by N-substitution in the well-known short-bite ligand bis(diphenylphosphino)amine (DPPA) allows a fine-tuning of the ligand properties and offers a considerable scope for tailoring the properties and applications of their corresponding metal complexes. The various N-substituents include nitrogen-, oxygen-, phosphorus-, sulfur-, halogen-, and silicon-based functionalities and directly N-bound metals. Multiple DPPA-type ligands linked through an organic spacer and N-functionalized DRPA-type ligands, in which the PPh2 substituents are replaced by PR2 (R = alkyl, benzyl) groups, are also discussed. Owing to the considerable diversity of N-functionalized DPPA-type ligands available, the applications of their mono- and polynuclear metal complexes are very diverse and range from homogeneous catalysis with well-defined or in situ generated (pre)catalysts to heterogeneous catalysis and materials science. In particular, sustained interest for DPPA-type ligands has been motivated, at least in part, by their ability to promote selective ethylene tri- or tetramerization in combination with chromium. Ligands and metal complexes where the N-substituent is a pure hydrocarbon group (as opposed to N-functionalization) are outside the scope of this review. However, when possible, a comparison between the catalytic performances of N-functionalized systems with those of their N-substituted analogs will be provided.

Chelating versus bridging bonding modes of N-substituted bis(diphenylphosphanyl)amine ligands in Pt complexes and Co2Pt clusters

N-substituted dppa ligands Ph2P-NR-PPh2 [R = -CH2CH2SCH2C6H5 (1), -CH2CH2S(CH2)5CH3 (2), -(CH2)9CH3 (3), -C6H5 (4)] were used for the synthesis of cis-[PtCl2{Ph2PN(R)PPh2}] complexes [R = -CH2CH2SCH2C6H5 (5), -CH2CH2S(CH2)5CH3 (6), -(CH2)9CH3 (7), -C6H5 (8)] and heterotrinuclear clusters of formula [PtCo2(CO)7{Ph2PN(R)PPh2}] [R = -CH2CH2SCH2C6H5 (9), -CH2CH2S(CH2)5CH3 (10), -(CH2)9CH3 (11), -C6H5 (12)]. The presence of relatively bulky substituents on N resulted in a higher chelating power of the ligands. The thermodynamic study of the equilibrium between the chelate and the bridged forms of clusters 9-11 showed that the bridged form is favoured by enthalpic factors whereas entropic factors favour chelation. The structures of 5 and 9 were determined by single crystal X-ray diffraction.

Easy one-pot synthesis of new dppm-type linkers for immobilizations

New synthetic routes to symmetric and unsymmetric dppm-type chelate linkers containing the ethoxysilane group are described and the compounds were characterized also by solid-state NMR spectroscopy and X-ray structures.

Synthesis and transformations of 60-, 62-, and 64-electron Co4(CO)x(PNR2)2 (x = 8, 9, 10) clusters

A unique family of bis-(amino)phosphinidene Co4 clusters with electron counts in the 60–64 e regime is described. The 62-electron (5 Co–Co) butterfly compound [Co4(CO)8(µ-CO){µ3-P(TMP)}2] (TMP = 2,2,6,6-tetramethyl piperidyl) (1a) is obtained via condensation of the bridged (amino)phosphinidene complex [Co2(CO)6{µ-P(TMP)}]. Further heating and removal of CO gives the 60-electron (6 Co–Co) tetrahedral compound [Co4(CO)6(µ-CO)2{µ3-P(TMP)}2] (3a). The reaction of K[Co(CO)4] with PCl2(N-i-Pr2) gives the 64-electron (4 Co–Co) square-planar derivative [Co4(CO)8(µ-CO)2(µ4-PN-i-Pr2)2] (2), which loses one carbonyl ligand to form the 62-electron (5 Co–Co) butterfly compound [Co4(CO)8(µ-CO)(µ3-PN-i-Pr2)2] (1b). Complex 1b releases another carbonyl to form the 60-electron (6 Co–Co) tetrahedral compound [Co4(CO)6(µ-CO)2(µ3-PN-i-Pr2)2] (3b). X-ray structural analyses of compounds 1a, 1b, 2, and 3a have been carried out. The reversibility of the CO elimination reactions and the structural rearrangements accompanying changes in electron count in this series are discussed.Key words: cobalt, cluster compounds, phosphinidene, skeletal rearrangement.