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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-t...

Water-soluble gold(III/I) N-heterocylic carbene complexes behave as efficient catalysts for the hydration of terminal alkynes in neat water. The transformation proceeds in the absence of Bronsted acids or halide scavengers and is suitable for sensitive substrates. Kinetic profiles and DFT studies provide a clear picture of intermediates present during catalysis.

This article reviews the surface adsorption of p-benzoquinonemonoimine zwitterions from the class of N-alkyldiaminoresorcinones (or 4,6-bis-dialkylaminobenzene-1,3-diones, i.e. C6H2(···NHR)2(···O)2), where R = H, R = C2H5, n-C4H9), on a variety of conducting surfaces. These small molecules with a large electrical dipole exhibit molecular orientation and packing on surfaces depending on the deposition methodology (from solution or from the vapor) as well as the substrate. What is very clear from the investigations of this class of molecules is that inter-molecular interaction is not simply driven by dipolar interactions alone, but frontier orbital symmetry as well. This is illustrated by the reversible adsorption of di-iodobenzene on molecular films of (6Z)-4-(butylamino)-6-(butyliminio)-3-oxocyclohexa-1,4-dien-1-olate C6H2(···NHR)2(···O)2 where R = n-C4H9, where it is clear that absorption is isomer specific.

[Bi(OAc)2(thf)4]3 [Bi7I24]·4H2O is synthesized by reaction of a 2:1 mixture of BiI3 and Pd(OAc)2 in THF (25 °C, 1 h, 43% yield).

The reactivity of molecules containing a metal-silicon bond is currently attracting considerable attention owing to its relevance to a number of important stoichiometric and catalytic transformations. The focus of this review concerns those stoichiometric reactions involving the metal-silicon bond which result in isolable Si-containing metal complex(es). Catalytic reactions are therefore only considered when strong evidence for MSi intermediate complexes is provided. Reactions in which the silicon atom leaves the metal complex are not examined. For convenience, the reactions will be classified into insertion and migration reactions, although this terminology does not necessarily have a mechanistic implication and is somewhat arbitrary since many reaction products could belong to one or the other section.

Oxidation of a THF solution of Li[HC(PPh 2 ) 2 ] with iodine affords the isomeric products Ph 2 P-CH=PPh 2 -PPh 2 =CH-PPh 2 2, (Ph 2 P) 2 C=PPh 2 -CH 2 -PPh 2 4 and (Ph 2 P) 2 CH-CH(PPh 2 ) 2 1, which result from P-P, P-C and C-C coupling, respectively. The latter pathway has now been established for the first time and the crystal structure of the resulting new chiral tetraphosphine 1 has been determined by X-ray diffraction.

Alkyl, silyl, and phosphane ligands are amongst the most familiar and ubiquitous ligands in organometallic and coordination chemistry. The C, Si, and P donor atoms of these ligands are sp(3)-hybridized and the ligands are related to each other by the isolobal analogy: (CR(3))(-)h(SiR(3))(-)hPR(3). Herein, we demonstrate that although a number of unusual observations concerning the reactivity and bonding of these ligands appears unrelated at first sight, they in fact provide offer an exiting and consistent picture that may form the basis for new paradigms. The characterization of stable complexes in which alkyl, silyl, and phosphane ligands behave as symmetrical bridges confirms that there is no inherent thermodynamic instability associated with these bonding situations, and, in fact, reactivity studies suggest that these ligands should be able to bridge between metal centers in reaction intermediates or transition states.

The first 12π-electron zwitterionic structure in quinonoid chemistry is described with the N,N,O,O -molecule 6 in which the positive charge is π-delocalized between the nitrogen atoms and the negative charge between the oxygen atoms; depending on the crystallization solvent, a 1D-tape-like H-bonded network can be generated in the solid-state.

A straightforwardly synthesised complex, [Pd(μ-Cl)Cl(NHC)]2 (NHC = bis(2,6-diisopropylphenyl)imidazol-2-ylidene, IPr), has been employed to mediate Suzuki–Miyaura reactions involving aryl chlorides at very low catalyst loadings and at room temperature.

Catalytic ethylene oligomerization represents a topic of considerable current academic and industrial interest, in particular for the production of linear alpha-olefins in the C4-C10 range, whose demand is growing fast. Identifying and fine-tuning the parameters that influence the activity and selectivity of metal catalysts constitute major challenges at the interface between ligand design, coordination/organometallic chemistry, and homogeneous catalysis. In this Account, we show how comparative studies aiming at modulating the coordinating properties of functional ligands for a metal, such as nickel, which is used in industrial processes, lead to beneficial effects in catalytic ethylene oligomerization.

In this account, we focus on results from our laboratory to illustrate recent developments in various fields of organometallic chemistry. Studies on hemilabile P,N donor ligands and on the ion-pair behaviour of cationic Pd(II) complexes have led to the full characterization of complexes with η 1 -allyl ligands. This still rare bonding mode for the allyl ligand in palladium chemistry allows facile insertion of CO into the Pd–C σ-bond, in contrast to the situation in related η 3 -allyl Pd(II) complexes. In order to develop new homogeneous catalysts for the selective dimerization and oligomerization of ethylene, a range of Ni(II) complexes have been prepared with new chelating P,N ligands where P represents a phosphine, phosphinite or phosphonite donor group and N a pyridine or oxazoline moiety. Finally, we shall examine bottom-up approaches to the formation of new nanomaterials of magnetic or catalytic interest by covalent anchoring of metal complexes and clusters into mesoporous materials using functional phosphine or alkyne ligands containing an alkoxysilyl group.

The bimetallic complex trans-[(OC)3Fe(μ-LP,N)2Cu]BF4 (2), which contains two bridging phosphinooxazoline ligands, is the first metal–metal bonded six-membered ring system with P,N donors and its crystal structure shows a unique bimetallic cradle conformation. This complex is an efficient catalyst for the cyclopropanation of styrene by ethyl diazoacetate and for the Diels–Alder reaction between cyclopentadiene and methacrolein, these reactions being catalyzed for the first time by heterometallic complexes.

The reactions of carbonylmetalate anions e.g. (Co(CO)4)- (II), (Fe(CO)3NO)-, (Mn(CO)5)-, (Mo(CO)3Cp)-, and (W(CO)3Cp)- with trinuclear clusters of the type (I), (IV) and (VI) occur by substitution of the Pd-bound halide by the carbonylmetalate anions to produce the clusters (III), (V), and (VII).

The synthesis and spectroscopic properties (1H and 31P n.m.r., i.r.) of complexes containing the β-ketophosphine Ph2PCH2C(O)Ph (HL) are described. In [NiX2(HL)2][X = Cl (1), Br, or I (3)], [PdCl2(HL)2](4), [PtCl2(HL)2](5), and [{PdCl(µ-Cl)(HL)}2](6), HL behaves as a P-bonded monodentate ligand whereas in the cationic complexes [Pd(HL)2][BF4]2 and [{Pd(µ-Cl)(HL)}2][CF3SO3]2 it acts as a P,O chelate. The crystal structures of (1) and (3) have been determined using single-crystal X-ray diffraction methods. Compounds (1) crystallises in space group P21/n, with a= 10.079(3), b= 11.510(3), c= 15.411(3)A, β= 93.42(2)°, and Z= 2. Compound (3) crystallises in space group P21/c, with a= 9.283(1), b= 10.261(1), c= 19.318(1)A, β= 96.20(1)°, and Z= 2. The structures have been refined to R 0.050 (R′ 0.060) for (1) and to R 0.032 (R′ 0.041) for (3). The geometries of these complexes are essentially identical although the ν(CO) frequencies of these complexes are significantly different [1 662 cm–1 for (1) and 1 620 cm–1 for (3)]; the nickel atom occupies a centre of symmetry and has thus a square-planar environment. Although the ketone group is bent towards the nickel atom, no significant Ni–O bonding interaction occurs, as deduced from the Ni–O distances [3.230(4)A in (1) and 3.231(1)A in (3)]. In refluxing toluene (1), (4), or (5) lead to the phosphine–phosphinite complexes cis-[[graphic omitted]Ph2}](M = Ni, Pd, or Pt). Treatment of (1), (4), or (5) with base gives the enolato-complexes cis-[[graphic omitted]Ph}2](M = Ni, Pd, or Pt). Reaction of (6) with NaH affords the binuclear complex [{P[graphic omitted]Ph]}2]. The latter reacts with PPh3 to give cis-[P[graphic omitted]Ph}(PPh3)], and with Ph2PCH2CH2PPh2–TlPF6 to give [P[graphic omitted]Ph}(Ph2PCH2CH2PPh2)]PF6. The P–O coupling products [N[graphic omitted]R}](R = Cl or Ph) are obtained by reaction of the complex [N[graphic omitted]Ph}2] with PCl3 and PPhCl2 respectively, and shown to have a five-co-ordinate structure. The square-planar P,P,P complex [N[graphic omitted]Ph}]PF6 results from reaction of [N[graphic omitted]Ph}] with TIPF6.

Coupling of acetylferrocene (I) with diphenylchlorophosphine (II) gives the ketophosphine (III).

The reaction of Na2(Fe(CO)4) with cis-PtCl2(PEt3)2 in THF yields cluster complexes of nuclearities 3, 5 and 6, and the new hexanuclear heterometallic cluster (I).

Heterotrimetallic complexes cis-[m–Pt(PPh3)2–Hg(C6Cl5)][m = Mo(CO)3(η-C5H5), W(CO)3(η-C5H5), Fe(CO)2(η-C5H5), Mn(CO)5, or Co(CO)4] have been prepared by the reaction of trans-[(C6Cl5) Hg–PtCl( PPh3)2] with the appropriate carbonylmetalate anions. The scope of this reaction is discussed. All the compounds have been characterised by 31P n.m.r. spectroscopy. Linear correlations are obtained for plots of the coupling constant ratios 1J(PaPt)/2J( PaHg) or 2J(PaHg)/2J(PbHg) against either the nucleophilicity or the oxidation potential of the carbonylmetalate anions.