Mark D. Spicer

The chemistry of copper and silver in their higher oxidation states

A. Introduction B. Copper(III) chemistry. (i) Fluorides and oxides (ii) Group VIB donor Iigands (iii) GroupVBdonorIigands (iv) Groups IIIB and IVB donor hgands (v) Biological role of copper(III) C. Copper chemistry D. Silver(II) chemistry (i) Fluorides and oxides (ii) Group VIB donor Iigands (iii)’ Group VB donor ligands (iv) Groups IIIB and IVB donor ligands E. Silver(II1) chemistry (i) Fluorides and oxides (ii) Group VIB donor ligands (iii) Group VB donor hgands F. Silver(IV) or (V) chemistry G. Gold chemistry, some comparisons Acknowledgements Note added in proof References 46 47 48 50 63 75 78 79 80 80 83 85 95 95 96 100 102 106 107 108 108 109

Reductions of Challenging Organic Substrates by a Nickel Complex of a Noninnocent Crown Carbene Ligand

The first crown-tetracarbene complex of Ni(II) has been prepared, and its crystal structure determined. The complex can be reduced by Na/Hg, with an uptake of two electrons. The reduced complex reductively cleaves arenesulfonamides, including those derived from secondary aliphatic amines, and effects Birch reduction of anthracenes as well as reductive cleavage of stilbene oxides. Computational studies show that the orbital that receives electrons upon reduction of the complex 2 is predominantly based on the crown carbene ligand and also that the HOMO of the parent complex 2 is based on the ligand.

The synthesis of soft tripodal ligands: restrictions on the preparation of hydrotris(thiazolyl)borate anions from borohydride melts

The syntheses of two new, soft, tripodal anions, hydrotris(mercaptothiazolyl)borate (Tz) and hydrotris(mercaptobenzothiazolyl)borate (Tbz), are reported. These species not only extend the series of thiazolylborate anions which call be generated using the protocol of Trofimenko, but analysis of the respective thione melting points and pK(a) values, enables the prediction of which thiazolylborate anions can be produced using borohydride melts. Both of the products are converted into their thallium complexes, which can be used as convenient ligand transfer reagents. The X-ray crystal structure of thaliium(I) hydrotris(2-mercapto-benzothiazolyl)borate, [Tl(Tbz)](infinity), is reported. The ligand complexes to Tl as a C-3 tridentate species, while a bridging thione links Tl(Tbz) units into zigzag one-dimensional polymeric chains.

The Preparation and Structures of Group 12 (Zn, Cd, Hg) Complexes of the Soft Tripodal Ligand Hydrotris(methimazolyl)borate (Tm)

Complexes of the hydrotris(methimazolyl)borate ligand (Tm) have been prepared with zinc, cadmium and mercury halides. Complexes of type [M(Tm)X] were obtained and characterised by NMR and mass spectrometry, X-ray crystallographic analysis of [Zn(Tm)X] (X = Cl, Br, I) reveals a symmetrical coordination mode of the ligand, but no significant change with different halides, which sit on the approximate C-3 axes of the complexes, The structures of [M(Tm)Br] (M = Cd, Hg) are isomorphous with one another, Again, the ligand is symmetrically coordinated to the metal, but the halide is now significantly displaced from the approximate C-3 axis of the M(Tm) unit, resulting in what approximates to a trigonal pyramidal geometry. Unlike in most distorted mercury structures, little bond length expansion (towards two- or three-coordinate geometries) occurs. This is ascribed to the strong affinity of the thione donors for Hg.

Hydrotris(methimazolyl)borate, a soft analogue of hydrotris(pyrazolyl)borate. Preparation and crystal structure of a novel zinc complex

The synthesis of a new ligand, hydrotris(methimazolyl)borate,† a soft analogue of hydrotris(pyrazolyl)borate, is reported; to demonstrate the coordination chemistry of this novel ligand, complexes of CuI and ZnII are prepared and characterised.

A coordination polymer strategy for anion encapsulation: anion–π interactions in (4,4) nets formed from Ag(I) salts and a flexible pyrimidine ligand

Anions encapsulated by a uniform mode of anion-pi binding in isomorphous (4,4) nets formed from Ag(I) salts and bis(4-pyrimidylmethyl)sulfide appear to be structurally directing.

Co-ordination chemistry of higher oxidation states. Part 26. Spectroscopic studies of tellurate complexes of the trivalent Group 1B metals. X-Ray structure of Na5[Cu{TeO4(OH)2}2]·16H2O

The structure of Na5[Cu{TeO4(OH)2}2]·16H2O has been determined by X-ray structure analysis. It crystallises in the triclinic space group P with a= 5.922(4), b= 8.939(2), c= 12.528(2)A, α= 98.45(1), β= 99.11(3), γ= 93.82(4)°, and Z= 1. The structure was refined to R= 0.040 for 2 131 observed reflections [F > 3σ(F)]. The composition of the crystal examined was deficient in sodium leading to a proposed formula Na5–xHx[Cu{TeO4(OH)2}2]·16H2O (x= 0.64). The discrete centrosymmetric anion contains CuIII with approximately square-planar CuO4 groups linked by trans edges to TeO4(OH)2 octahedra [Cu–O 1.833(4) and 1.839(4)A]. The [M{TeO4(OH)2}2]5– ions (M = Cu, Ag, or Au) have been studied by i.r., u.v.–visible, and n.m.r. (125Te, 109Ag, and 17O) spectroscopy. For [Ag{TeO4(OH)2}2]5– the 125Te n.m.r. signal (+774 p.p.m.) is a doublet [2J(107,109Ag–125Te)= 73 Hz]. For the silver(III) ions [Ag{TeO4(OH)2}2]5– and [Ag{IO5(OH)}2]5– the 109Ag n.m.r. signals occur at ca.+2 800 p.p.m. from Ag+(aq).

Sodium hydrotris(methimazolyl)borate, a novel soft, tridentate ligand: preparation, structure and comparisons with sodium hydrotris(pyrazolyl)borate†

The hydrotris(methimazolyl)borate anion (Tm), a soft analogue of the hydrotris(pyrazolyl)borate anion (Tp), has been synthesized. This novel ligand system has been designed to maintain the tripodal geometry around the boron while allowing the replacement of the three nitrogen donor atoms by three sulfur (thione) donor atoms, thus providing a complementary soft, tridentate, face capping ligand system. The two ions, Tm and Tp were compared by X-ray analysis and ab initio calculations in an attempt to explore the effects of exchanging the hard donor atoms for soft donor atoms in this type of ligand. The compound NaTm is essentially salt like with discrete anions and hydrated sodium cations. The structure of NaTp crystallised under identical conditions is observed to be an infinite ribbon containing monodentate, bridging and pendant pyrazolyl units. The co-ordination sphere of the sodium cation in NaTp is completed by two water molecules. Ab initio calculations at the Hartree–Fock level using a 6-31G* basis set on these anions and their sodium complexes suggested that while both ions are in general similar in nature, there are subtle differences which will influence their chemistry. Ab initio calculations were also used to provide a rational analysis of the formation of the two sodium salts obtained and on the analogous copper complexes further to clarify the hard and soft nature of the two ligand systems.

The first combined in situ FTIR and EXAFS study of a matrix isolated molecule

Abstract The results of a combined matrix isolation IR and EXAFS study on methylene bromide (CH 2 Br 2 ) isolated in argon are described and it is demonstrated that data of acceptable quality from both techniques may be obtained from the same sample. The IR data are in excellent agreement with literature values and confirm that matrix isolated samples may be routinely obtained with the novel window arrangement employed. The EXAFS data lead to intramolecular bonded and non-bonded distances ( d (BrC)=1.95(2) A, d (Br··Br)=3.19(3) A) in agreement with microwave and electron diffraction data and additionally an interaction with the argon matrix is observed with d (Br⋯Ar) ≈ 3.75 A consistent with the sum of the van der Waals radii of Br and Ar.

Structures of the potassium aluminate [{K2(Me3AlOBut)2·pmdeta}∞] and [{K(pmdeta)2}+(AlMe4)–]: how the nature of the alane reagent determines which of these products form from alkoxide-containing reaction mixtures

Equimolar mixtures of AlMe3, ButOK and pmdeta produce either title compound depending on whether solvent-free, dimeric [(AlMe3)2] or the amine-solvated monomer [Me3Al·(H)N(CH2Ph)2] is used as the source of the alane.