Helen M. Dawes

Adducts of trimethylindium with amine and phosphine ligands; X-ray crystal structure of Me3InNHCMe2(CH2)3CMe2, Me3InN(CH2CH2)3N and Me3InNHMe(CH2)2NHMeInMe3

Abstract Treatment of trimethylindium diethyletherate separately with a number of amines and a phosphine has given the products Me3InL where L ue5fb NH(C6H11)2 (1), NHCHMe(CH 2 ) 3 C HMe (2), NHCMe 2 (CH 2 ) 3 C Me2 (3), N(CH2CH2)3CH (4), N(CH2CH2)3N (5), (CH2NEt)3 (6) and P(NMe2)3 (7). The complexes Me3In-NHMe(CH2)2NHMeInMe3 (8) and Me2InCl[MeNH C(CH) 4 N ] (9) have also been made by direct reaction of Lewis acid etherate and Lewis base. The X-ray crystal structure of 3 shows a longer Inue5f8N bond (2.50 A) than that found in the crystal structure of 8 (2.38 A); both possess distorted tetrahedral metal environments. The X-ray crystal structure of 5 shows a linear polymer of alternating Me3In and N(CH2CH2)3N units; the Me3In unit is planar and the indium is almost perfectly trigonal bipyramidal and the Inue5f8N bonds are very long (2.62 A) compared with 3 and 8. Variable temperature 1H NMR studies of 6 show the adduct bond is very labile: rapid exchange between adduct components is occurring even at −70°C.

Monodentate pyridine-2-thiol and chelating and bridging pyridine-2-thiolato complexes derived from rhodium(I) chloro-carbonyl dimer

Abstract Dicarbonyl- and monocarbonyl-rhodium(I) compounds formed from [Rh 2 Cl 2 (CO) 4 ] and pyridine-2-thiol (NC 5 H 4 SH) in chloroform slowly give blue-black crystals of the dinuclear rhodium(II) compound [Rh 2 Cl 2 (μ-NC 5 H 4 S) 2 (η 1 -NHC 5 H 4 S) 2 (CO) 2 ]·2CHCl 3 (Rhue5f8Rh distance 2.652(4) A) rather than the much more common tetra-bridged species. Oxidation by air and heat lead to the tris-chelate compound [Rh III NC 5 H 4 S) 3 ].

NMR studies of stereochemical non-rigidity in dinuclear thiolato-bridged complexes of platinum(IV) with platinum(II) and palladium(II): the structure of [Pt(dppe)(μ2-SMe)2PtClMe3]

Abstract The complexes [M(dppe)(μ2-SMe)2PtXMe3] [M = Pd or Pt; X = Cl, Br or I; dppe = 1,2-bis(diphenylphosphino)ethane] have been synthesized, and by means of 1H and 31P variable-temperature NMR studies are shown to have several different fluxional modes. Where possible, accurate activation parameters for the processes have been determined. The unexpected trends of these values demonstrate the consequences of the presence of the four-membered Pt(IV)ue5f8Sue5f8M(II)ue5f8S ring. The structure of a representative member of this novel range of complexes, [Pt(dppe)(μ2-SMe)2PtClMe3], has been determined by X-ray diffraction methods.

The preparation and crystal structure analysis of bis(L-Arginine)Cu(II)(acetate)2trihydrate

Abstract The crystal structure of bis(L-arginine)Cu(II)(acetate)2trihydrate has been determined by X-ray analysis. The complex crystallizes in the monoclinic space group P21, with cell dimensions a = 15.948(2), b = 16.878(2), c = 10.378(2) A, β = 108.47(1)°, Z = 4. There are two independent formula units in the asymmetric unit. The Cu atoms were located from a Patterson synthesis and the remaining atoms from difference Fourier syntheses. The structure was refined by least-squares to R = 0.079 and R = 0.11. Each copper atom has an essentially square planar coordination with the two arginine molecules chelated via the carboxy oxygens and the α-amino nitrogens, but with distorted six-fold coordinations completed by weak Cu…O (acetate) interactions. Electrostatic interactions between the acetates and the protonated ends of the amino acid residues link the two independent [Cu(L-arginine)2(acetate)2] units into dimers, which are then connected via hydrogen bonds, also involving the water molecules, into an infinite network.

Alkyl, hydrido, and tetrahydroaluminato complexes of manganese with 1,2-bis(dimethylphosphino)ethane (dmpe). X-Ray crystal structures of Mn2(µ-C6H11)2(C6H11)2(µ-dmpe), (dmpe)2Mn(µ-H)2AlH(µ-H)2AlH(µ-H)2-Mn(dmpe)2, and Li4{MnH(C2H4)[CH2(Me)PCH2CH2PMe2]2}2·2Et2O

Alkylation of MnBr2dmpe)2[dmpe = 1,2-bis(dimethylphosphino)ethane] with MgBut2 leads to the t-butyl complex MnBut2(dmpe); alkylation with Mg(C6H11)2 gives the cyclohexyl-bridged dimer Mn2(µ-C6H11)2(C6H11)2(µ-dmpe)(2). By contrast, alkylation with MgEt2 leads to the diamagnetic manganese(I) species, trans-MnH (C2H4)(dmpe)2. Interaction of the latter with LiBut leads to deprotonation of the dmpe ligand and formation of a complex, (4), of stoicheiometry Li2(MnH(C2H4)[CH2(Me)PCH2CH2PMe2]2}·Et2O. A reduction of MnII to MnI also occurs in the interaction of MnBr2(dmpe)2 with LiAlH4 when the tetrahydroaluminate complex [Mn(AlH4)(dmpe)2]2(5) is formed. Hydrolysis of (5) gives the volatile diamagnetic hydride MnH3(dmpe)2. The X-ray crystal structures of the complexes (2), (4), and (5) have been determined. In (2), the molecule, which has two-fold symmetry, has two manganese atoms each bound to one terminal related cyclohexyl group [Mn–C = 2.118(10)A] and bridged asymmetrically by two symmetry related cyclohexyls [Mn–C = 2.256(9), 2.327(9)A]. The Mn ⋯ Mn distance is quite short at 2.616(5)A and the manganese atoms have a distorted tetrahedral co-ordination. In complex (4), two MnH(C2H4)(dmpe)2 units [Mn–H 1.44(4),Mn–C (av.) 2.121(5), Mn–P 2.213(3)–2.274(3)A] have each lost two hydrogen atoms, one from each of two dmpe methyls, and the resulting four CH2 groups form multicentre alkyl bridges to a central Li4 tetrahedron [C ⋯ Li 2.20–2.36(I), Li ⋯ Li 2.46(1)–2.69(1)A]. Two of the lithiums are co-ordinated by diethyl ether [ Li–O 2.053(8)A]. The complex as a whole has C2 symmetry and the manganese(I) centre has a pseudo-octahedral geometry, although pentagonal bipyramidal is an alternative description if the ethylene is considered to occupy two co-ordination sites. Complex (5) is a centrosymmetric dimer in which two cis-octahedral MnH2(dmpe)2 units are bridged by a AlH-(µ-H)2AlH moiety via Al(µ-H)2Mn linkages. The two H atoms in the AlH2Mn bridge are closer to the Mn atoms [Mn–H = 1.61(3), 1.63(3)A] than to the Al atoms [Al–H = 1.81(3), 1.81(3)A]. The Al–H distances in the AlH2Al unit are 1.64(3) and 1.80(3)A, while the terminal Al–H distance is 1.51(3)A. The aluminium has trigonal bipyramidal co-ordination with one terminal hydrogen in an equatorial position.

Synthesis, structure and spectroscopy of heterometallic compounds containing linear AuCNM, AuNCM and MNCAuCNM chains of atoms (M = Rh OR Ir): Crystal structure of I{PMe2Ph)3Cl2Rh(μ-NC)}2Au][ClO4]·2CH2Cl2

Abstract The aqua-complexes [MCl2(H2O)(PMe2Ph)3] [ClO4] (M = Rh or Ir) react rapidly with [Au(CN)(PPh3)] to give the cyano-bridged compounds [(PPh3)Au(μ-CN)MCl2 (PMe2Ph)3] [ClO4]. These could not be isolated in a pure state because they readily disproportionate to a mixture also containing [Au(PPh3)2]+ and [{(PMe2Ph)3Cl2M(μ-NC)}2 Au] [ClO4]. The disproportionation is much more rapid when [Au(CN)(PPh3)] is in slight excess. The complexes were characterized by 1H, 13C and 31P NMR methods, and the single-crystal X-ray structure of [{(PMe2Ph)3Cl2Rh(μ-NC)}2Au][ClO4] is reported.

The preparation and crystal structure analysis of a 2:1 complex between L-lysine and copper(II) chloride

Abstract The crystal structure of bis(L-lysine)Cu(II) chloride dihydrate has been determined by X-ray analysis. The complex crystallizes in the monoclinic space group P 2 1 , with cell dimensions a = 5.189(1), b = 16.988(3), c = 11.482(2) A, β = 93.57(1)°. The position of the Cu atom was found from a Patterson synthesis, the remaining atoms were located with DIRDIF. The structure was refined by least-squares to R = 0.060 and R w = 0.065 for 2637 observed reflections. The copper(II) atom has an essentially square planar coordination with the two lysine molecules chelated via the carboxy oxygen and the α-amino nitrogen. However the two chlorine atoms form weak interactions with the metal to complete a strongly tetragonally elongated six-fold coordination. The two aliphatic chains have rather different geometries and are extended in a zig-zag mode. Extensive hydrogen bonding links the complex and the water molecules together.

Adducts of trimethylgallium and perdeuteriotrimethylgallium with amine ligands and some dimethylgallium organyl pnictides (N, P, As). X-ray crystal structures of [Me3Ga·NH(C6H11)2] and [Me3Ga·NH(CHMe)(CH2)3CHMe]

Abstract The adducts Me3Ga·L [where L = NH(C6H11)2 (1), NHCHMe(CH 2 ) 3 C HMe (2), N(CH2CH2)3CH (3) and 0.5 N(CH2CH2)3N (4)] have been prepared by displacement of either (a) ether from Me3Ga·Et2O or (b) diphos from (Me3Ga)2·diphos (diphos = bisdiphenyl phosphino ethane) and the X-ray crystal structures of 1 and 2 determined. (CD3)3Ga and the adducts (CD3)3Ga·L [L= NMe3, NH(C6H11)2, NHCHMe(CH 2 ) 3 C HMe and N(CH2CH2)3CH], were similarly prepared from [(CD3)3Ga]2·diphos. The covalently bonded dimethylgallium organyl pnictides (Me2GaL′)n [L′= NPri2, NCHMe(CH 2 ) 3 C HMe, PMe2 and AsMe2] were prepared by reactions of either (c) Me2GaCl and LiL′ or (d) Me3Ga·Et2O and HL′. All compounds were characterized by elemental analyses, IR, NMR and mass spectroscopy. The Ga geometry in both 1 and 2 is distorted tetrahedral.

Cis-1,4-cyclohexadienebisepisulphide complexes of chromium, molybdenum and tungsten carbonyls: the x-ray crystal structure of

Abstract The first metal carbonyl derivatives of a coordinated episulphide ring are reported. Two classes of complex have been obtained wherein the bisepisulphide behaves either as a bridging ligand between two metal pentacarbonyl moieties as in for example , or as a chelating ligand in a mononuclear metal pentacarbonyl complex such as , for which the X-ray crystal structure is reported.

The preparation and X-ray crystal structure of W3(μCN)3(NO)3(CO)9

Abstract The nitrosation of Na[W(CO)5CN] using amyl nitrite and sulphuric acid in a two phase water— diethyl ether system gives the trinuclear compound W3(μCN)3(NO)3(CO)9. A single crystal X-ray diffraction study showed that the compound contains a nine-membered ring of three tungsten atoms and three bridging cyanide groups. The terminal carbonyl and nitrosyl ligands were not distinguishable.