Bilquis Hussain

Dimethylindium dialkylamides and organylphosphides, X-ray crystal structure of (Me2InNR2)2 (R = Et, Pri, SiMe3) and (Me2InPBut2)2

The compounds (Me2InNR2)2 (R = Et, Pri, SiMe3 and (Me2InPR2 (R = But, have been prepared. the X-ray crystal structures of all but the diphenylphosphide have been determined, and show them to be pnictido-bridged dimers; the mass spectra of all the compounds indicate that they are dimeric in the vapour phase. The stability of the dialkylamide dimers in the vapour as determined from the mass spectra appears to be in the order NMe2 > NEt2 > NPr2i > N(SiMe3)2, in line with steric effects; the crystal structures showed a slight lengthening of the IN bond in the same order, but the most marked structural variation was shown to be the CC angle which had values of 131, 126, 119 and 109°, respectively. The corresponding value for (Me2InPBu2t)2 was 109°.

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  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 InN 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 InN 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.

t-Butylimido compounds of rhenium. X-ray crystal structures of [(ButN)2Re(μ-NBut)]2, (ButN)2ReCl3, (ButN)2ReCl2C6H5, (ButN)3Re(OSiMe3) and (ButN)3ReCl ☆

Abstract Previous studies on t-butylimido aryls of rhenium have been extended and the compounds (ButN)2RevVII(o-tol)3, (ButN)2ReVIICl2Ph and (BUtN)2ReVI(mes)2 synthesized. Electrochemical studies of the latter show reversible one-electron oxidation and reduction, and chemical oxidation leads to the cation [(ButN)2RevVII(mes)2]+ isolated as PF6− and CF3SO3− salts. Although the neutral complex does not undergo insertion with isocyanides, the cation does so to give η2-iminoacyls, {(ButN)2Re(mes)[η2-RNC(mes)]}+, R = 2,6-xylyl, t-Bu. Reduction of (ButN)3Re(OSiMe3) in hexane by sodium gives the bridged homoleptic compound (ButN)2Re(μ-NBut)2Re(NBut)2. The homoleptic anion [Re(NBut)4]− as the Li(tmed)+ complex has been synthesized via the new intermediates (ButN)3ReCl and (ButN)3Re(NHBut). X-ray crystal structures of the compounds listed in the title have been determined. The homoleptic rhenium(VI) t-butylimide is dimeric with four-coordinate rhenium and almost symmetrical imido bridges; the terminal imido groups have near linear geometry. The diamagnetism is consistent with a ReRe bond, although the ReRe distance of ca 2.7 A indicates this to be weak. The rhenium(VII) siloxide is also four-coordinate distorted tetrahedral; and the geometries of the Re-imido and Re-siloxide units indicate involvement of all ligands in π-interactions. The (ButN)3ReCl is also tetrahedral. The two bis-imido chloro compounds are five-coordinate with a geometry that can be conveniently described as trigonal bipyramidal where the imido groups occupy equatorial sites with unusually small inter-ligand angles of ca 110°.

1,2-bis(dimethyl)phosphinoethane complexes of molybdenum and vanadium. X-ray crystal structure of trans-[MoCl(η2-NCMe)(DMPE)2]BPh4, trans-[Mo(SPh)2(DMPE)2], trans-[V(NCMe)2 (DMPE)2]BPh4)2, trans-[V(CNBut)2(DMPE)2](PF6)2

Abstract The replacement of chloride in the complexes, trans -[MCl 2 (dmpe) 2 ] M = Mo and V, dmpe = 1,2-bis(dimethyl)phosphinoethane, by various other ligands has been studied. For Mo, acetonitrile gives the species trans -[MoCl(NCMe)(dmpe) 2 ] + , which has isomers with either η 1 - or η 2 -MeCN; these react with methanol to give the molybdenum(IV) ethylimido complex [MoCl(NEt)(dmpe) 2 ] + . Both Mo and V give [M(NCMe) 2 (dmpe) 2 ] 2+ cations. Other complexes synthesized are trans -[MoL 2 (dmpe) 2 ], L = NEt 2 , SPh; trans -[VL 2 (dmpe) 2 ], L = CN, SCN, CS 2 ; [VL 2 (dmpe) 2 ] + , L = EtCN, t BuNC; [VCl( t BuNC) (dmpe) 2 ] + and [V(NCMe) 6 ] 2+ . Nuclear magnetic and electron spin resonance spectra of the compounds are reported and the X-ray crystal structure of four of the compounds listed in the title are described.

Preparation of the bis(trimethylsilyl)amido lanthanide chlorides [{Ln[N(SiMe3)2]2(µ-Cl)(thf)}2](thf = tetrahydrofuran), and the crystal and molecular structures of the gadolinium and ytterbium complexes

Reaction of LnCl3 with 2 equivalents of LiL [L = N(SiMe3)2] in tetrahydrofuran (thf) at –5 °C yields [{LnL2Cl(thf)}2] for Ln = Eu, Gd, or Yb or [YL2Cl(thf)2] for Ln = Y. X-Ray crystal structure analysis of the compounds of Gd and Yb confirms the formation of halide-bridged dimers. In the M2Cl2 bridging unit the M–Cl bond lengths differ slightly and the angle at the metal (ca. 74°) is much smaller than at chlorine (ca. 106°). The metal co-ordination geometries are irregular but can be best described as distorted trigonal bipyramidal with the bridging chlorines spanning one axial and one equatorial site. The bond lengths M–Cl and M–N indicate a Gd–Yb radius difference of ca. 0.07 A, but the M–O distances differ by 0.093 A. Variable-temperature n.m.r. studies of [{EuL2Cl(thf)}2] and [{YbL2Cl(thf)}2] show that there is free rotation about Ln–N and Ln–O bonds at room temperature. These rotations are frozen out at low temperatures to give a solution structure having higher symmetry (C2h) than that found in the crystal.

Alkylimido and oxo aryls of rhenium. X-ray structures of (BuittN)2ReCl2(o-MeC6H4) and MO2(2,6-Me2C6H3)2, M = Re and Os

Abstract The compounds (ButN)3Re(aryl), (aryl = o-tol, xylyl and mes†), have been prepared from (ButN)3Re(OSiMe3) and the appropriate Grignard reagents. The aryls have been converted to the corresponding dichloride compounds, (ButN)2ReCl2(aryl) by treatment with HCl. The X-ray crystal structure of (ButN)2ReCl2(o-tol) has been determined. The compound has square pyramidal geometry with one linear (basal site) and one bent (axial site) imido group, which formally suggests a 16e configuration. The interaction of xylyl magnesium bromide with [Me3NH] [ReO4] or Re2O7 gives the diamagnetic rhenium(V) complex [(xylyl)2ReO2]2Mg(THF)2, which can be oxidized to the paramagnetic rhenium compound, ReO2(xylyl)2. Interaction of ReO3(OSiMe3) with either xylyl or mesityl Grignard yields ReO2(aryl)2 directly in higher yield. The molecule is tetrahedral. The interaction of OsO4 with xylyl magnesium bromide yields OsO2(xylyl)2. The geometries of the O2MC2 units in MO2(xylyl)2, M = Re and Os, are analogous to those found in the corresponding mesityl derivatives, with the OOsO angle much larger than the OReO angle (139° vs 121°).

Imido complexes of molybdenum and tungsten(VI); X-ray crystal structure of cis-(η1-CF3SO3)2 W(NBut)2(NH2But)2

Abstract The synthesis of the homoleptic molybdenum imido compound Li2Mo(NBut)4 is reported. The complexes M (NBut)2(NHBut)2 (M = Mo, W) can be protonated with various strong acids giving neutral species. The X-ray crystal structure of the tungsten complex W (NBut)2(NH2But)2 (SO3CF3)2 confirms the presence of O-coordinated cis- CF3SO3 groups.

Alkyl complexes of cobalt(II). X-ray crystal structures of (Me2NCH2CH2NMe2)CoR2, R = CH2SiMe3, CH2CMe3, [(Me2NCH2CH2NMe2)Li]2[Co(CH2SiMe3)4] and [(Me2NCH2CH2NMe2)2Li][CoCl{CH(SiMe3)2}2]

Abstract The interaction of lithium alkyls in diethyl ether in the presence of tetramethylethylenediamine (TMED, Me2NCH2CH2NMe2) with cobalt(II) chloride has led to the isolation of four complexes whose crystal structures have been determined. The complexes (TMED)CoR2, R = CH2SiMe3 and CH2CMe3, have tetrahedral geometry about cobalt; in [(TMED)Li]2[Co(CH2SiMe3)4] there are CH2SiMe3 groups bridging the lithium and cobalt atoms; in the ionic complex [(TMED)2Li][CoCl{CH(SiMe3)2}2] the geometry about cobalt is trigonal planar. Electron paramagnetic resonance spectra of the complexes and of the products of the reaction with oxygen are reported.

Triangulotrirhenium(III) alkoxides. X-ray crystal structures of Re3(μ-Cl)3(OBut)6 and Re3(μ-Cl)Cl(μ-menthoxo)2(menthoxo)5 and of Re2(μ-Cl)2(CO)6(THF)2

Abstract The syntheses of triangulotrirhenium cluster alkoxides from t -butanol, (−)-menthol and i -propanol are reported and the structures of Re 3 (μ-Cl) 3 (OBu t ) 6 and Re 3 (μ-Cl)Cl(μ-menthoxo) 2 (menthoxo) 5 determined by X-ray crystallography. Interactions with carbon monoxide and the X-ray structure of Re 2 (μ-Cl) 2 (CO) 6 (THF) 2 are reported.

Carbonylation of osmium and ruthenium oxo complexes. X-ray crystal structures of [Me4N]2[Os(O)2(COOMe)2(μ-OMe)]2 and [nPr4N][fac-Ru(O2CMe)3(CO)3]

Abstract Insertion of CO into the OsOMe bonds in [Os(O)2(OMe)4]2− leads to the formation of methoxide bridged dimers, [OS(O)2(COOMe)2(μ-OMe)]22−2, as their K+, Me4N+ and nBu4N+ salts. The X-ray structure of the nBu4N+ derivative is reported. Reduction of RuO4− in acetic acid by CO gives the anion [fac-Ru(O2CMe)3(CO)3]−, which has been structurally characterized as the nPr4N+ salt. IR, NMR and conductivity data are also reported.