Joyce M. Waters

Metallacyclohexatrienes or ‘metallabenzenes.’ Synthesis of osmabenzene derivatives and X-ray crystal structure of [Os(CSCHCHCHCH)(CO)(PPh3)2]

The first metallabenzene,[O[graphic omitted]H)(CO)(PPh3)2] has been prepared from [Os(Co)(CS)(PPh3)3] and ethyen; X- ray crystal structure determination reveals a planar six-membered ring with no significant alternation of C–C bond lengths thus supporting the idea of electron delocalization within the ring.

The crystal and molecular structure of dichloro-1,2-bis (diphenylphosphino)-ethanedigold (I)

Abstract The structure of Au 2 (Ph 2 PCH 2 CH 2 PPh 2 )Cl 2 has been determined by single crystal X-ray methods. The compound crystallizes with four formula units in a cell of dimensions a = 12.815(2), b = 11.160(2), c = 19.054(4) A, β = 109.33(1)°, V = 2571 A 3 , space group P 2 1 / n . The structure has been refined by full-matrix least-squares methods to a final R index of 0.035 for the 127 variables and 1360 observed data. The coordination about the Au atoms is linear with mean AuP and AuCl bond lengths of 2.239 and 2.315 A respectively. Pairs of molecules are held together by weak intermolecular Au⋯Au interactions of 3.189 A.

The structure of a compound of unexpected conformation involved in the xylose-lyxose epimerization

The structure of a molybdenum(VI) complex of the sugar, lyzose, has been established by the X-ray method.

A tetrahedral complex of gold(I): the crystal and molecular structure of Au(Ph2PCH2CH2PPh2)2Cl.2H2O

Abstract The structure of Au(Ph2PCH2CH2PPh2)2Cl·2H2O has been determined by single crystal X-ray methods. The compound crystallizes with four formula units in a cell of dimensions a = 10.057(1), b = 21.074(2), c = 21.724(1) A, β = 94.06(3)°, V = 4730 A3, space group P21/n. The structure has been refined by full-matrix least-squares methods to a final R index of 0.038 for the 217 variables and 4263 observed data. The coordination about the Au atom is found to be tetrahedral with AuP bond lengths varying from 2.384(2) to 2.412(2) A.

Some observations on the structures of pyridoxal-aminoacid schiff base complexes

Abstract Structures are reported for (pyridoxylidene-DL-valinato)copper(II), a = 25.640(2), c = 13.326(2) A, γ = 120°, space group R 3 , Z = 8 and (3-methoxysalicylidene-DL-valinato)copper(II), a = 23.515(8), b = 9.194(4), c = 17.034(6) A, β = 126.41(7)°, space group C2/c, Z = 8. The former compound is polymeric with square-pyramidal co-ordination to copper involving five donor atoms of the ligand; the latter is monomeric with planar co-ordination geometry which includes a donor oxygen from water. Attention is drawn to bond length changes in the pyridoxylidene compound which, it is suggested, can be associated with reactivity.

Coordinatively unsaturated σ-aryl complexes of ruthenium(II) and osmium(II)

Abstract The hydrido complexes MHCl(CO)(PPh3)3 (M = Ru, Os) react with the organomercury compounds R2Hg (R = phenyl, p-tolyl, o-tolyl, trans-β-styryl) to give the five-coordinate, σ aryl and alkenyl complexes MRCl(CO)(PPh3)2 in high yield. Bromide and iodide analogues of these compounds can be prepared through reaction with silver perchlorate followed by addition of excess bromide or iodide ions. The X-ray crystal structures of two of the complexes, Ru(p-tolyl)Cl(CO)(PPh3)2 and Ru(o-tolyl)Cl(CO)(PPh3)2, have been determined.

Preparation of niobium and tantalum organoimido complexes from reactions of the pentahalides with amines: The crystal and molecular structure of bis(t-butylamine)bis(t-butylimido)bis(μ-ethoxy)tetrachloroditantalum

Abstract MCl5 (M = Nb, Ta) reacts with 2 equivalents of Me3SiNHCMe3 to give [M(NCMe3)Cl3(NH2CMe3)] from which [M(NCMe3)Cl3(PMe3)2] is obtained on addition of PMe3. One equivalent of Me3SiNHCMe3 reacts with MCl5 in the presence of 3 equivalents of PMe3 to give [M(NCMe3)Cl3(PMe3)2] and PMe3HCl. MCl5 reacts with excess RNH2 (R = CMe3, CHMe2, CH2Me) to give [M(NR)(NHR)Cl2(NH2R)] and 3 equivalents of RNH3Cl. One equivalent of alcohol replaces the amido ligand in [M(NCMe3)(NHCMe3)Cl2(NH2CMe3)] to give [M(NCMe3)(OR)Cl2(NH2CMe3)]2 (M = Nb, R = OCMe3; M = Ta, R = OEt). The structure of [Ta(NCMe3)(μ-OEt)Cl2(NH2CMe3)]2 was determined by single-crystal X-ray diffraction methods. Crystals are triclinic, space group P 1 with a = 9.900(5), b = 10. 161(17), c = 9.017(6) A and α = 103.91(8), β = 97.77(4), γ = 64.40(7)°. The structure was solved by Patterson and Fourier methods and refined to an R value of 0.062 for 1319 observed data. The TaNimido and TaNamino bond lengths are 1.70(2) A and 2.28(2) A, respectively; the bridging TaO bond lengths are 2.01(2) A and 2.32(2) A, the longer one lying trans to the imido function.

Dihapto-acyl derivatives of ruthenium(II). Preparation and structure of Ru[η2-C(O)CH3] I(CO)(PPh3)2 and Ru[η2-C(O)p-tolyl]I(C0) (PPh3) 2

Abstract Reaction between Ru(CO)2(PPh3)3 and MeHgI yields Ru[η2-C(O)CH3]I(CO)(PPh3)2 which in solution exists mainly as RuCH3I(CO)2(PPh3)2 and crystal structure determination of Ru[η2-C(O)CH3]I(CO)(PPh3)2 and previously described Ru[η2-C(O)p-tolyl]I(CO) (PPh3)2 confirms that in the solid state both molecules contain dihapto-acyl ligands.

Organo-imido alkoxides of tungsten(VI). The crystal and molecular structures of [W(NPh)(μ-OMe)(OMe)3]2 and [W(NPh)(OCMe3)3Cl(NH2CMe3)]

Abstract Reaction of phenylimido tungsten tetrachloride with MeOH and t -butylamine gave the dimeric complexes [W(NPh)(μ-OMe)(OMe) 3 ] 2 and [W(NPh)(μ-OMe)(OMe) 2 Cl] 2 . With ethanol [W(NPh)(μ-OEt)(OEt) 2 Cl] 2 was formed whereas iso propyl and neo pentyl alcohols gave the monomeric complexes [W(NPh)(OR) 4 (NH 2 CMe 3 )](R = CHMe 2 , CH 2 CMe 3 ); t -butanol gave [W(NPh)(OCMe 3 )3Cl(NH 2 CMe 3 )] which could not be converted to [W(NPh) (OCMe 3 ) 4 ]. Further reaction of [W(NPh)(μ-OMe)(OMe) 3 ] 2 with o -HOC 6 H 4 CH = NC 6 H 3 Me 2 (salim-H) gave the salicylaldimine complex [W(NPh)(OMC) 3 (salim)]. The products were characterised by analytical data, IR, 1 H NMR, 13 C NMR and mass spectroscopy. The crystal and molecular structures of the title complexes have been determined from single crystal X-ray diffractometer data. Crystals of [W(NPh)(μ-OMe)(OMe) 3 ] 2 are triclinic with a = 8.473(7), b = 10.776(5), c = 7.683(A, α = 102.26(3), β = 102.68(4), γ = 71.13(6)°, space group P 1 Crystals of 3) [W(NPh)(OCMe 3 ) 3 Cl(NH 2 CMe 3 ) are monoclinic with a = 9.341(2), b = 29.608(7), c = 10.257(2) A, β = 106.28(2)°, space group, P 2 1 / c . Both structures were solved by Patterson and Fourier methods and refined to R = 0.075 for the 1022 observed data of [W(NPh) (μ-OMe)(OMe) 3 ] 2 and to R = 0.074. For the 2033 observed data of [W(NPh)(OCMe 3 ) 3 Cl(NH 2 CMe 3 ). The former molecule is shown to be a dimer, the two halves of the molecule being related by a centre of symmetry. Both W atoms adopt a distorted octahedral coordination geometry and they are linked by two methoxy bridges. Trans to one of the bridging donors is the phenyl imido group with a WN bond length of 1.61(4) A; the remaining coordination sites are filled with methoxy groups. The structure of W(NPh)(OCMe 3 ) 3 Cl(NH 2 CMe 3 ) is monomeric with the phenylimido group trans to the NH 2 CMe 3 ligand in a distorted octahedral coordination geometry. Remaining sites are filled with the chloride and 3 OCMe 3 ligands. The WN (imido) bond length is 1.71(2) A, whilst WN(amine) is 2.40(2) A

Polymorphism in Schiff base complexes of copper(II): the crystal and molecular structure of a second brown form of bis(N-methyl-2-hydroxy-1-naphthaldiminato)copper(II)

Abstract A third polymorph of the title compound has been grown by careful choice of solvent and an X-ray analysis has allowed comparison with the structure of the two forms already known. The space group is P2 1 c , a = 10.525, b = 14.740, c = 12.605 A , β = 104.8° . The molecule is dimeric with a tetragonal pyramidal coordination arrangement about copper atoms. The three isomers so far investigated thus show 4-, 5- and 6-fold stereochemistry. Details of bond lengths and angles are compared within the isomers.