Howard M. Colquhoun

Carbaborane derivatives of the late- and post-transition elements. Part 2. Dicarbaundecaboranyl compounds of copper(I), gold(I), and mercury(II); the crystal and molecular structure of 3-triphenylphosphine-3-mercura-1,2-dicarbadodecaborane(II), a pseudo-σ-bonded metallacarbaborane

The novel d10 metallacarbaboranes B9C21,2[Hg(PPh3)]3H11(1), [AsPh4][B9C21,2(HgMe)3H11], B9C21,2[Au(PPh3)]3(NC5H5)4H10, B9C21,2[Cu(PPh3)]3(NC5H5)4H10, and [3.3′-{HgB9C21,2(NC5H5)4H10}2] have been prepared by reactions of [{HgCl2(PPh3)}2] with Tl[B9C21,2Tl3H11], [HgMe(O2CMe)] with aqueous K[B9C2H12]–K[OH], and Na[B9C27,8(NC5H5)9H10] with [AuCl(PPh3)], [{CuCl(PPh3)}4], and HgCl2 respectively. The molecular structure of compound(1), as the 0.5-dioxan solvate, has been determined at –60 °C, and shows the mercury atom to be co-ordinated almost linearly by PPh3 and the unique boron atom of the C2B3 face, implying a direct mercury–boron σ bond (Hg–B 2.20, Hg–P 2.39 A, P–Hg–B 172°). The crystals are triclinic, space group P with cell dimensions a= 10.913 5(17), b= 11.188 3(19), c= 12.007 1(18)A, α= 83.50(1), β= 86.98(1), γ= 61.55(1)°, and Z= 2, and the structure has been refined to R= 0.037 for 2 447 independent observed reflections.

The isolation and X-ray structure of a complex between lithium picrate and dibenzo-36-crown-12

Abstract The crystal structure of 2Li picrate.dibenzo-36-crown-12.2H2O was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystalli

Characterisation of degradation products in the oxidation of the dodecahydro-7,8-dicarba-nido-undecaborate(1–) ion: a new synthesis of 4,5-dicarba-nido-nonaborane(11)

Degradation of aqueous 1 mol dm–3 K[B9C27,8H12] by aqueous FeCl3(1.25 mol dm–3) yields B8C25,6H12(33%) as previously reported, together with B8C25,6H11(OH)(1.6%), B8C25,6ClH11(0.9%). and B7C24,5H11(4.2%). The yield of B7C24,5H11 may be increased substantially by using lower concentrations of reactants (0.1–0.2 mol dm–3), and this reaction thus provides a simple synthesis of this otherwise highly inaccessible carba-borane. The mass spectrum of B7C24,5H11 has been obtained. The 11B n.m.r. spectrum of B8C25,6ClH11, when compared with spectra of the four isomers of B10ClH13, suggests that substitution has occurred at the 10 position, but the position of substitution of the hydroxy-group in B8C25,6H11(OH) remains uncertain.

A comparison of the receptor stereochemistry in [Pt(bipy)(NH3)2·dinaphtho-30-crown-10][PF6]2 and [Diquat·dinaphtho-30-crown-10][PF6]2(bipy = 2,2′-bipyridine)

X-Ray crystallography and 1H n.m.r. spectroscopy have revealed dramatic differences in the binding of [Pt(bipy)(NH3)2]2+ and [Diquat]2+ dications by dinaphtho-30-crown-10 (DN30C10) with the platinum complex adopting a slewed position, apparently in order to maximise overlap between the π-arene systems in the receptor and in the complex, whereas the Diquat dication adopts a symmetrical position more consistent with maximisation of Coulombic interactions.

Synthesis and X-ray crystal structure of 3-diethyldithiocarbamato-3-aura-1,2-dicarbadodecaborane. A ‘slipped’ 18-electron metallacarborane

Reaction of Tl2(7,8-C2B9H11) with Et2NCS2AuBr2 affords the known ion (1,2-C2B9H11)2Au–, and also the novel 18-electron species (1,2-C2B9H11)Au(S2CNEt2) which is shown from X-ray data to have the ‘slipped’ structure previously found only in 20- or 21-electron systems; a similar structure is also deduced for the 18 electron compound (Ph3P)2Pt(1,2-C2B9H11).

Reactions of arylpalladium complexes with ammonia and chelating amines. Crystal and molecular structure of [Pd(o-C6H4CHNCH2CH2NH2)(NH2CH2CH2NH2)][PF6], a product of transamination and ligand substitution

Reaction of trans-[Pd(Ph)(PPh3)2Cl] with NH3, NH2CH2CH2NH2(en), and NH2(CH2)3NH2(pn) afforded trans-[Pd(Ph)(PPh3)2(NH3)]+ and [Pd(Ph)(PPh3)(N–N)]+ where N–N = en or pn. Treatment of [{Pd(o-C6H4CHNPh)X}2](X = Cl or O2CMe) with ammonia gave [Pd(o-C6H4CHNPh)(NH3)X], but with an excess of NH3, [Pd(o-C6H4CHNPh)(NH3)2]Cl and [Pd(o-C6H4CHNPh)(NH3)3][O2CMe] were formed. With 1,2-bis-(dimethylamino)ethane, [Pd(o-C6H4CHNPh)(Me2NCH2CH2NMe2)]+ was isolated whereas with en, a transamination reaction occurred giving [Pd(o-C6H4CHNCH2CH2NH2)(en)]+. The structure of this cation (as the PF6– salt) was determined crystallographically. Crystals are triclinic, space group P, a= 8.109(16), b= 11.027(27), c= 18.93(4)A, α= 88.30(19), β= 83.19(18). γ= 81.05(18)°, and Z= 4. The NH2 group of the o-C6H4CHNCH2CH2NH2 ligand is not co-ordinated to palladium.

The binding of neutral platinum complexes by crown ethers. X-Ray crystal structures of [trans-PtCl2(PMe3)NH3˙dibenzo-18-crown-6] and [{trans-PtCl2(PMe3)NH3}2·18-crown-6]

Complexes of the type trans-PtCl2(L)NH3 where L = PMe3(1), PEt3(2), and NH3(3) co-ordinate to 18-crown-6 (18C6) and dibenzo-18-crown-6 (DBI8C6) by hydrogen bonding of their NH3 ligands, forming the crystalline adducts [(1)–DBI8C6], [(2)–DBI8C6], [(1)2–18C6], [(2)2–18C6], and [(3)–18C6]n which also display considerable stability in solution.

The isolation and x-ray crystal structure of a complex between sodium hexafluorophosphate and dibenzo-36-crown-12

The crystal structure of 2NaPF 6 ·dibenzo-36-crown-12 was determined by X-ray diffraction methods. The 2:1 (metal:ligand) complex crystallises in the monoclinic system, space group P 2 1 / n with cell constants of a = 14.189(2), b = 9.372(1), c = 16.750(3) A, and β = 108.98(1)°. The two NaPF 6 units are each coordinated through five oxygen atoms to opposite faces of the macrocycle in a centrosymmetric manner.

Synthesis, structure, and chemistry of ligating dichlorodiazomethane. The crystal and molecular structures of [WBr(dppe)2N2CCl2]+[PF6]– and [WBr(dppe)2{N2C(Cl)C(CN)2}]·CH2Cl2

A complex of dichlorodiazomethane, [WBr(dppe)2N2CCl2]+[PF6]–, which is formed by reaction of [WBr(dppe)2N2H2]+Br– with CXCl3(X = Br or H) in the presence of a diphenyl iodonium salt and aqueous base, undergoes rapid reaction with nucleophiles to give a range of novel organodinitrogen complexes; the molecular structures of the parent dichlorodiazomethane complex, and its reaction product with dicyanomethanide ion (a vinyl diazenido complex), were determined by single-crystal X-ray analysis.

Crown ethers as second-sphere ligands. The interactions of transition-metal ammines with 18-crown-6 and dibenzo-18-crown-6

Neutral and cationic transition-metal ammines interact with crown ethers in aqueous and non-aqueous solution via(N–H ⋯ O) hydrogen-bond formation to give discrete or polymeric adducts which are readily isolated by crystallisation. Dibenzo-18-crown-6 generally yields discrete 1 : 1 (metal complex : crown) adducts in which only one face of the macrocycle interacts with an ammine ligand, whereas 18-crown-6 often binds two such ligands, one to each face of the crown ether. The resulting adducts are then either polymeric or of 2 : 1 (metal complex : crown) stoicheiometry. Ammines which yield isolable adducts include [W(CO)5(NH3)], trans-[PtCl2(PMe3)(NH3)], trans-[PtCl2(NH3)2], [Co(NH3)6][PF6]3, [Cu(NH3)4(H2O)][PF6]2, and [Pt(H2NCH2CH2NH2)2][PF6]2. Such adduct formation provides the basis for a novel method of separating different transition metals; for example, 18-crown-6 selectively precipitates the copper(II) complex (as a polymeric 1:1 adduct) in the presence of an equimolar amount of the cobalt(III) ammine.