Three-coordinate iron(II) expanded ring N-heterocyclic carbene complexes

A sterically demanding seven-membered expanded ring N-heterocyclic carbene (NHC) ligand allows access to rare examples of three-coordinate iron(II)-NHC complexes incorporating only halide coligands of the general formula [Fe(NHC)X 2 ] (NHC = 7-DiPP; X = Br (1) Cl (2)). Reducing the steric influence of the ancillary NHC ligand through modulation of the N-aryl substituents leads to either four- or three-coordinate complexes of the general formula [Fe(NHC)Br 2 (THF)] (3) or [Fe(NHC)Br 2 ] (4) (NHC = 7-Mes), dependent upon the solvent of recrystallization. The further reduction of NHC steric influence results in four-coordinate geometries at iron in the form of the dimeric species [Fe(NHC)Br(μ-Br)] 2 (5) or [Fe(NHC)Br 2 (THF)] (6) (NHC = SDiPP), again dependent upon the solvent of recrystallization. Compounds 1-6 have been analyzed by 1 H NMR spectroscopy, X-ray crystallography, elemental microanalysis, Mössbauer spectroscopy (for 1 and 3-5), and Evans method magnetic susceptibility. In addition to these measurements the three-coordinate species 1 and 4 have been further analyzed by SQUID magnetometry and CASSCF calculations, which show significant magnetic anisotropy that is extremely sensitive to the coordination geometry

Water soluble, cyclometalated Pt(II)–Ln(III) conjugates towards novel bimodal imaging agents

Facile conjugation of a luminescent cyclometalated PtII complex with a DO3A-derived GdIII moiety yields a hybrid species with visible luminescence and enhanced relaxivity

Platinum-catalyzed synthesis of trichloroamidines.

A mild platinum-catalyzed method for the formation of free amidines from the reaction of amines and trichloroacetonitrile in nonpolar solvents has been developed. This protocol provides access to novel amidines that in some cases (4b-d) cannot be synthesized via the direct reaction of amines and halogenated nitriles. [on SciFinder(R)

Expanded ring N-heterocyclic carbenes: A comparative study of ring size in palladium (0) catalysed Mizoroki-Heck coupling

The synthesis and characterisation of a range of new 6- and 7-membered expanded ring N-heterocyclic carbene (NHC) complexes of zero valent palladium dvtms (divinyltetramethyldisiloxane) 8–14 is reported, with the first comparative catalytic study probing the effects of large ring N-heterocyclic carbene ligands (6-Mes and 7-Mes) with their analogous 5-membered derivative (IMes) on catalytic performance. The catalytic performances of the [Pd(NHC)(dvtms)] complexes are evaluated in the Mizoroki–Heck coupling of 4-bromoacetophenone and n-butyl acrylate, providing a ready and effective comparison into the influence of ring size and steric congestion on catalytic activity in carbon–carbon cross coupling reactions

Multifaceted catalysis approach to nitrile activation: direct synthesis of halogenated allyl amides from allylic alcohols.

Allyl amides were synthesized from the reaction of allyl alcs. and halogenated nitriles using a platinum multifaceted catalysis approach in which both the nucleophilic addn. and subsequent [3,3]-sigmatropic rearrangement steps of the process were catalyzed by the same complex. Addnl., 1H/13C{1H} NMR and GC studies provided the first insights into the mechanism of this transformation. [on SciFinder(R)

Expanded ring N-heterocyclic carbene complexes of zero valent platinum dvtms (divinyltetramethyldisiloxane): Highly efficient hydrosilylation catalysts

The synthesis and characterisation of a series of new 6- and 7-membered NHC (N-heterocyclic carbene) complexes 7–12 of zero valent platinum dvtms (divinyltetramethyldisiloxane), [Pt(NHC)(dvtms)] are reported. A number of the complexes were investigated as catalyst precursors in the hydrosilylation of a range of unsaturated substrates, including alkynes, alkenes and a ketone with triethylsilane and bis(trimethylsiloxy)methylsilane (MD’M), at low catalyst loading (0.005 mol %); in general, the activity, and the selectivity for 1-functionalised product was found to be high

Gold(I) complexes bearing sterically imposing, saturated six- and seven-membered expanded ring N-heterocyclic carbene ligands

The synthesis and characterization of novel six- and seven-membered expanded ring N-heterocyclic carbene (NHC) complexes of the general formula [Au(NHC)Cl] are described. The key structural parameters of complexes 1, 2, and 4 have been evaluated by solid-state analysis and by means of the percent buried volume (%Vbur) analysis. Complex 4 is found to demonstrate the largest %Vbur value of any gold(I) NHC complex reported to date, with a value of 52.6. All complexes 1–4 have been evaluated in a preliminary catalytic survey of the hydration of internal alkynes

Pd–PEPPSI-Type Expanded Ring N‑Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Activity in Suzuki–Miyaura Cross Coupling

The synthesis and characterization of the new six- and seven-membered Pd–PEPPSI-type N-heterocyclic carbene (NHC) complexes <b>3</b> and <b>4</b> is described. Complexes of the general formula [Pd­(NHC)­(3ClPy)­Cl₂] (NHC = 6- or 7-Mes, 3ClPy = 3-chloropyridine) are accessed via the oxidation of the well-defined parent palladium(0) complexes <b>1</b> and <b>2</b>. Complexes <b>3</b> and <b>4</b> have been employed in Suzuki–Miyaura cross-coupling and catalytic dehalogenation of a range of aryl halide substrates

CCDC 1010526: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures