Bilquis Hussain-Bates

Some reactions of tetrakis(tert-butylimido)osmium(VIII). X-Ray crystal structures of Os(NBut)O(O2CBut)2(NH2But)2·ButCO2H, (ButN)2 Os(µ-NBut)2Os(µ-NBut)X2(X = Cl or I) and [Os2(NBut)4(µ-NBut)2]I3

Reaction of Os(NBut)4 with carboxylic acids and halogens have been studied. Acetic and pivalic acids give different oxo carboxylate complexes, the acetate being Os(NBut)O(O2CMe-O)(O2CMe-OO′)(NH2But)1 and the pivalate Os(NBut)O(O2CBut-O)2(NH2But)22. The osmium(VI) compounds (ButN)2Os(µ-NBut)2Os(NBut)X2(X = 1, 3; or Cl, 5) have been obtained by interaction of Os(NBut)4 with, respectively, I2 and PPh4I in 1,2-C2H4Cl2; the iodine reaction also produces the paramagnetic mixed-valence diosmium(VI, VII) compound [Os2(NBut)4(µ-NBut)2]I34. The X-ray crystal structures of compounds 2–5 have been determined: 2 is octahedral with trans-NH2But and trans-carboxylate groups; 3 and 5 are isomorphous with tetrahedral and trigonal-bipyramidal osmium atoms, the latter having trans-halogens, a linear NBut and two NBut bridging groups. Compound 4 is similar to the dimeric compounds previously described and completes the series [Os(NBut)2(µ-NBut)]20,+,2+.

t-Butylimido and t-butylimido oxo aryls of rhenium. X-ray crystal structures of Re(NBut)2(2,6-Me2C6H3)2, Re(NBut)(2,4,6-Me3C6H2)(C27H32), Re(NBut)3(2,4,6-Me3C6H2), [(ButN)Br(2,4,6-Me3C6H2)Re(μ-NBut)(μ-O)(OC6H2Me2CH2)(NBut)], [Re(NBut)(O)Ar(μ-O)]2, Ar = 2,6-C6H3 and 2,4,6-C6H2

Abstract The interaction of Re(NBu t ) 2 Cl 3 with 2,6-xylyl magnesium bromide gives rise to the paramagnetic rhenium(VI) compound, Re(NBu t ) 2 (xyl) 2 , which is readily oxidized to the cation [Re(NBu t ) 2 (xyl) 2 ] + , isolated as its PF 6 − salt; the latter with Bu t NC gives the iminoacyl cation [Re(NBu t ) 2 (xyl)(Bu t NCxyl)] + . An unstable rhenium(V) anion, [Re(NBu t ) 2 (xyl) 2 ] − , has been characterized. Interaction of Re(NBu t ) 2 Cl 3 with excess mesityl Grignard gives a compound of stoichiometry Re(NBu t )(mes)(C 27 H 32 ) in which three aromatic rings are coupled, the central one comprising a η 5 -cyclohexadienyl ring bearing an exo -mesityl group in the 1-position and in the 3-position linked by a CH 2 group to an aryl group σ-bonded to the metal, which is formally in the V oxidation state. The compound Re(NBu t ) 2 Cl( o -tol) 2 has been synthesized; treatment with AgPF 6 produces the salt [Re(NBu t ) 2 ( o -tol) 2 ]PF 6 . Hydrolysis of Re(NBu t ) 2 ReCl 3 with LiOH gives Re(NBu t ) 2 Cl(OH) 2 , which on arylation, gives the oxo imido species Re(NBu t ) 2 (O)mes and [(Bu t N)Br(mes)Re(μ-NBu t )(μ-O)Re(OC 6 H 2 Me 2 CH 2 )(NBu t ) 2 ]. Interaction of excess NO with Re(NBu t ) 2 Ar 2 , Ar = 2,6-xylyl and mesityl, gives the compounds [Re(NBu t )(O) (μ-O)Ar] 2 ; the reaction involves a unique NN bond formation to give Bu t NNAr. Stoichiometric reactions of Re(NBu t ) 2 (xyl) 2 and NO lead to the complexes Re(NBu t )2 (xyl) 2 NO and Re(NBu t ) 2 (O)(xyl). Mechanisms for the NO reactions are proposed. X-ray structures of the compounds listed in the title have been determined; the compounds [Re (NBu t )(O)(μ-O)Ar] 2 have asymmetric oxo bridges.

t-Butylimido complexes of chromium. X-ray crystal structures of Cr(NBut) 2(PMe2Ph)Cl2 and [Cr(NBut)2(C5H4N)2(η1- O3SCF3)]O3SCF3

Abstract The compound Cr(NBut)2Cl2 has been synthesized and converted to Cr(NBut)2(NHBut)Cl, Cr(NBut)2(NHBut)2 and Li2 Cr(NBut)4, the latter completing the series of Group 6 compounds, Li2 M(NBut)4, M = Cr, Mo, W. The five-coordinate adducts, Cr(NBut)2Cl 2L, L = PMe3, PMe2Ph and ButNC, have been characterized as well as [Cr(NBut)2Cl2]2(μ-Ph2PCH2CH2PPh2) and the six-coordinate Cr(NBut)2Cl2(2,2′-bipyridyl). Chloride substitution reactions of Cr(NBut)2Cl2 lead to the compounds, Cr(NBut)2(η1-O 2CMe)2, [Cr(NBut)2(PMe3)2](O3SCF3)2·0.5MeCN, [Cr(NBut) 2py2(η1-O3SCF3)]SO3CF3 and [Cr(NBut)2(bpy)2](PF6) 2. The isocyanide, [Cr(NBut)2Cl2(ButNC)], with MeLi gives the η2-iminoacyl Cr(NBut)2[η2-(ButNCMe)]Cl. Interaction of Cr(NBut)2Cl2 with alkylating agents at low temperatures gives the chromium(V) dimer [Cl(ButN)Cr(μ-NBut)] 2 in a one-electron per chromium reduction and the same product is obtained by reduction of the dihalide with (η5-C5H5)2Co. X-ray structures of compounds listed in the title have been determined.

Reactions of dimesityldioxo-osmium(VI) with donor ligands; reactions of MO2(2,4,6-Me3C6H2)2, M = Os or Re, with nitrogen oxides. X-Ray crystal structures of [2,4,6-Me3C6H2N2]+[OsO2(ONO2)2(2,4,6-Me3C6H2)]–, OsO(NBut)(2,4,6-Me3C6H2)2, OsO3(NBut), and ReO3[N(2,4,6-Me3C6H2)2]

The interaction of OsO2(mes)2(mes = 2,4,6-Me3C6H2), with pyridines, an isocyanide, and tertiary phosphines gives rise to complexes such as trans-OsO2(bipy)(mes)2(bipy = 2,2′-bipyridyl), cis-OsO2(2,6-Me2C6H3NC)(mes)2, and cis-OsO2(PR3)2(mes)2. The oxoimido compound, OsO(NBut)(mes)2, has been synthesised. The reactions of MO2(mes)2, M = Os or Re, with oxides of nitrogen, which involve oxygen transfer to the metal atom, have been studied. With NO, ReO2(mes)2 gives the dimesitylamido compound, ReO3[N(mes)2], but OsO2(mes)2 is unreactive. The compound ReO2(mes)2 reacts with NO2(N2O4) quantitatively to give ReO3(mes), nitromesitylene, and 2,4,6-trimethylbenzenediazonium nitrate, OsO2(mes)2 gives the salt [(mes)N2]+[OsO2(ONO2)2(mes)] together with nitromesitylene and NO. The X-ray crystal structures of four compounds have been determined. In [(mes)N2][OsO2(ONO2)2(mes)] the anion has a distorted trigonal-bipyramidal structure with equatorial oxo functions and the unidentate O-bonded nitrates axial. The compounds OsO(NBut)(mes)2 and OsO3(NBut) are distorted tetrahedral with essentially linear, 4e imido ligands. The compound ReO3[N(mes)2] is also distorted tetrahedral and in the solid state shows evidence of ReO ⋯ Me(mes) interactions.

Dilithium tetra(t-butylimido)-molybdate(VI) and -tungstate(VI) and some reactions thereof. X-Ray crystal structures of W[(µ-NBut)2AlX2]2(X = Cl or Me), [W(NBut)2(NH2But)Cl(µ-Cl)]2, and [W2Cu5(NBut)2(µ-NBut)6(NHBut)2]BF4

The compounds Li2M(NBut)4(M = Mo or W) have been made by deprotonation of M(NBut)2(NHBut)2 in diethyl ether by methyl-lithium. Interaction of Li2M(NBut)4 with AlCl3, GaCl3, and AlMe3 gives rise to compounds of the type M[(µ-NBut)2M′X2]2 and the crystal structures of compounds where M = W, M′= Al, X = Cl and Me have been determined. The Li2M(NBut)4 compounds are readily protonated by weak acids such as water or MeOH. Interaction with strong acids gives initially M(NBut)2(NHBut)2 and further protonation of the amido compound by CF3SO3H or CF3CO2H gives octahedral neutral species such as M(NBut)2(NH2But)2(OSO2CF3)2; W(NBut)2(NHBut)2 with HBF4 gives only monoprotonation forming two species, [W(NBut)2(NHBut)(NH2But)]BF4 and W(NBut)2(NHBut)(NH2But)(F2BF2), depending on the conditions; HCl gives [W(NBut)2(NH2But)Cl(µ-Cl)]2. Interaction of Li2W(NBut)4 with [Cu(MeCN)4]BF4 gives a remarkable cation of stoicheiometry [WVI2CuI5(NBut)2(µ-NBut)6(NHBut)2]+ in which each W has one linear terminal NBut group and three NBut groups bridging to three copper(I) atoms in a triangle; two of these NBut groups are also bound to a CuI(NHBut) unit thus being µ3.

Synthesis and x-ray crystal structure of tetrakis[bis(1,2-dimethylphosphino)ethane] disilver(i)bis(tetraphenylborate)

Abstract The interaction of silver trifluoromethanesulphonate and 1,2-bis(dimethyl- phosphino)ethane (DMPE) in acetonitrile in the presence of sodium tetraphenylborate gives the dimeric complex [Ag2(DMPE)4](BPh4)2. In the cation, each silver atom is four-coordinate with one chelating diphosphine and two phosphorus atoms from the two bridging DMPE ligands. The Ag—P distances are 2.465-2.557(6) A and the AgP4 unit has distorted tetrahedral geometry.

tert-Butylimido complexes of osmium-(VIII), -(VII) and -(VI). X-Ray crystal structures of [(ButN)2Os(µ-NBut)2Os(NBut)(µ-O)]2, [Os(NBut)2(µ-NBut)]2 and [Os(NBut)2(µ-NBut)]2[BF4]2

The interaction of OsO4 with neat NHBut(SiMe3) gives the first homoleptic osmium(VIII) imido compound, Os(NBut)41, together with the tetranuclear osmium(VI) oxo-imido complex [(ButN)2Os(µ-NBut)2Os(NBut)(µ-O)]22. Complex 1 can be reduced to the osmium(VI) dimer, [Os(NBut)2(µ-NBut)]23, by triphenylphosphine or by sodium amalgam in tetrahydrofuran; with trimethyloxonium tetrafluoroborate an unusual reduction reaction leads to the osmium(VII) dimeric cationic complex [Os(NBut)2(µ-NBut)]2[BF4]24. The syntheses of Os(NR)3, R = 2,6-Me2C6H35, or 2,6-Pri2C6H36, by interaction of OsO4 with NHR(SiMe3) are reported. The X-ray crystal structures of 2, 3 and 4 have been determined. Compound 2 has a chain tetrameric structure with two (ButN)2Os(µ-NBut)2Os(NBut)(µ-O) units linked by a dioxo bridge. The outer Os atoms are four-co-ordinate, distorted tetrahedral, the inner Os atoms five-co-ordinate, square pyramidal. The bridging Os–N distances to the inner, five-co-ordinate osmiums are shorter than those to the outer osmiums; the terminal Os–N distances are essentially the same for both types of osmium. Compound 3 and the cation in 4 are dimers with imido bridges. The main difference between them is a significant shortening in the Os…Os distance in the osmium(VIII) compound as a result of Os–Os single bond formation. This also results in a slight shortening of the Os–N bridge distances in 4 as compared to the neutral molecule 3.

SYNTHESIS AND STRUCTURE OF IRIDIUM TETRAMESITYL

Interaction of anhydrous iridium trichloride and 2,4,6-trimethylphenyl (mesityl)lithium in diethyl ether forms the tetrahedral iridium(IV) tetramesityl that has been characterized by electron paramagnetic resonance spectroscopy and by X-ray diffraction.

Bis[1,2-bis(dimethylphosphino)ethane]dichlorotungsten(II) and its reactions. X-ray crystal structures of bis[1,2-bis(dimethylphosphino)ethane]tetrachlorotungsten(V) hexachloroantimonate(V) and bis{bis]1,2-bis(dimethylphosphino)ethane]tetrahydroaluminatohydridomolybdenum(II)}

Abstract The reduction of WCl4(THF)2 by sodium naphthalenide in the presence of 1,2-bis(dimethylphosphino)ethane (DMPE) in tetrahydrofuran affords trans-WCl2(DMPE)2. Interaction of this complex with NaBPh4 in MeCN gives [WCl(η2-MeCN)(DMPE)2]BPh4 and with SbCl5 the tungsten(V) complex [WCl4(DMPE)2]SbCl6. The X-ray crystal structure of the latter shows the cation to have dodecahedral geometry with equatorial chlorine atoms. Interaction of trans-MCl2(DMPE)2 (M = Mo and W) with LiAlH4 gives the hydrido aluminohydrides, [MH(AlH4)(DMPE)2]2, and the X-ray crystal structure of the molybdenum compound has been determined. Methanolysis of the tungsten compound gives WH4(DMPE)2.

Synthesis and reactions of tris(tetramethylethylenediaminelithium)hexamethylmetallates of rhodium, iridium and ruthenium(III) and of hexakis(neopentyl)(μ-oxo)dirhodium(IV). X-ray crystal structures of fac-RhMe3(CO)(Me2NCH2CH2NMe2), fac-RhMe3(C4H8S)(Me2NCH2CH2NMe2), fac-RhMe3(PMe3)3 and [(Me3CCH2)3Rh]2O

Abstract The interaction of methyllithium and the tetrahydrothiophen (THT) complexes, MCl3(THT)3 (M = Ru, Rh and Ir), in diethyl ether in the presence of tetramethylethylenediamine (TMED) gives the air- and thermally-sensitive compounds [Li(TMED)]3 [MMe6]. The rhodium compound is the starting material for the synthesis of the fac-trimethyl compounds, RhMe3(THT)(TMED), RhMe3(CO)(TMED) and RhMe3(PMe3)3; the iridium compound fac-IrMe3(CO)(TMED) is also described. Interaction of neopentyllithium or neopentylmagnesium bromide with RhCl3(THT)3 in the presence of a source of oxygen atoms (O2 or Me3NO) gives the diamagnetic compound, [(Me3CCH2)3Rh]2μ-O, which contains rhodium in the IV oxidation state and a linear RhORh bond. X-ray structures of the compounds listed in the title have been determined.