Alkoxy,amido and thiolato complexes of tris (3, 5-dimethylpyrazolyl)borato(nitrosyl) molybdenum fluoride,chloride and bromide

The complexes Mo{HB(Me₂pyz)₃}(NO)XY {HB(Me₂pyz)₃  HB(3, 5-Me₂C₃HN₂)₃; X=Y=F, Cl or Br; X=F, Y=OEt, NHMe or SBuⁿ; X=Cl, Y=NHR (R=Me Et, Buⁿ, Ph, p-MeC₆H₄), NMe₂ and SR (R=Buⁿ, C₆H₁₁, CH₂Ph, Ph); X=Br, Y=NHMe, NMe₂ and SBuⁿ} have been prepared and characterised spectroscopically. Their properties are generally similar to those of their iodo-analogues.     

Cationic β-diketonato molybdenum nitrosyl complexes: redox and structural properties

Summary -Diketones react with [Mo(NO){HB(dmpz)₃}I₂] [HB (dmpz)₃ = tris (3,5-dimethylpyrazolyl)borate] giving the cationic complexes [Mo(NO) {HB(dmpz)₃}{OC(R)CRC-(R)O}]⁺ (R = R = Me, R = H, Me or n-Bu; R = R = Ph, R = H; R = Me, R = n-Bu, R = H), isolated as triiodide salts. Electrochemical studies show that these complexes exhibit three electrode processes: two associated with oxidation of I _inf3 ^sup– and one with reduction of the metal-containing cation. Reduction of the cation where R = R = R = Me with cobaltocene afforded the neutral paramagnetic [Mo(NO) {HB(dmpz)₃} {OC(Me)CMeC(Me)O}], which was characterized by i.r. and e.p.r. spectroscopy. In contrast, 3-chloropentane-2, 4-dione reacts efficiently with [Mo(NO){HB(dmpz)₃}I₂] giving the known chloro-analogue, [Mo(NO)-{HB(dmpz)₃}Cl₂], and no -diketonate complex was detected. The X-ray crystal structure determination of [Mo(NO){HB(dmpz)₃} {OC(Me)CMeC(Me)O}]I₃ confirms that the cation is six-coordinate and shows that the 559-01 (diketonate) bonds are slightly longer than in comparable compounds, implying that the -diketonate ligand is not such a strong -donor as alkoxide groups.     

Monometallic,homo- and hetero-bimetallic complexes based on redox active tris(3,5-dimethylpyrazolyl)boratomolybdenum and tungsten nitrosyls. Part V.Para-substituent effects on the reduction potentials of arylamide complexes

Summary Two series of complexes having the formula [M{HB(3,5-Me₂C₃N₂H)₃}(NO)Cl(NHC₆H₄Z-p)]; in which M=Mo and Z=F, Cl, Br, OMe, SMe, CN, CO₂Me or NO₂ and M=W and Z=Br, OMe, CN, CO₂Me or NO₂, have been prepared. The reduction potentials of these new complexes were measured by cyclic voltammetry and, in combination with previously reported data for related species and for [Mo{HB(3,5-Me₂C₃N₂H)₃} (NO)I-(NHC₆H₄Z-p], were used to determine reaction constants for the reduction of [M{HB(3,5-Me₂C₃N₂H)₃}(NO)X(NHC₆H₄Z)]M=Mo and X=I or Cl; M=W, X=Cl.Part IV. N. Al Obaidi, M. Chaudhury, D. Clague, C. J. Jones, J. C. Pearson, J. A. McCleverty and S. S. Salam, submitted toJ. Chem. Soc., Dalton Trans., Paper 6/869.     

The synthesis and structure of bis(acetonitrile)nitrosyl tris(3,5-dimethylpyrazolyl)borato molybdenum hexafluorophosphate

Summary Treatment of [Mo{HB(3,5-Me₂C₃HN₂)₃}(NO)I₂] with one or two moles of AgPF₆ in acetonitrile afforded the paramagnetic (one unpaired electron) complex [Mo{HB(3,5-Me₂C₃NH₂)₃}(NO)(NCMe)₂][PF₆]. The structure of this complex was determined crystallographically, and the six-coordinate geometry of the complex cation confirmed.     

Halogen oxidation and nitrosylation of some aldimine and ketimine carbonyl complexes of chromium and molybdenum

Summary The halogen oxidation and nitrosylation of cis-[(SB)M-(CO)₄] [M = Cr or Mo, SB = N,N-ethylenebis(p-tolualideneimine), N,N-ethylenebis(p-N,N-dimethylaminobenzalideneimine) or N,N-ethylenebis(methyl-p-methoxyphenylketimine); M = Mo, SB = N,N-ethylenebis-(cinnamylideneimine) or N,N-ethylenebis(methyl-p-methylphenylketimine)] have been studied. Halogenation of [(SB)Cr(CO)₄] yielded [(SB)CrX₂] (X = Cl, Br or I) where-as [(SB)Mo(CO)₄] gave [(SB)Mo(CO)₃X₂] (X = Br or I) and [(SB)MoX _x ] (X = I, n = 2; X = Cl or Br, n = 4). NOCl produced [(SB)Cr(NO)₂Cl₂] and [(SB)Mo(CO)₂(NO)Cl] when reacted with the corresponding [(SB)M(CO)₄]. The complexes were characterized by physico-chemical and spectroscopic measurements.     

Diastereoselectivity at chiral metal center of half-sandwich-type ruthenium complexes with planar-chiral cyclopentadienyl ligands in multiple ligand transfer reaction

The triple ligand transfer reaction between planar-chiral cyclopentadienyl-ruthenium complexes [Cp′Ru(NCMe)₃][PF₆] (1) (Cp′ = 1-(COOR²)-2-Me-4-R¹C₅H₂; R¹ = Me, Ph, t-Bu) and iron complexes CpFe(CO)(L)X (2) (L = PMe₃, PMe₂Ph, PMePh₂, PPh₃; X = I, Br) resulted in the formation of metal-centered chiral ruthenium complexes Cp′Ru(CO)(L)X (3) in moderate yields with diastereoselectivities of up to 68% de. The configurations of some major diastereomers were determined to be by X-ray crystallography. The diastereoselectivity of 3 was under kinetic control and not affected by the steric effect of the substituents on the Cp′ ring of 1 and the phosphine of 2. Although the double ligand transfer reaction between [Cp′Ru{P(OMe)₃}(NCMe)₂][PF₆] (7) and CpFe(CO)₂X (8) produced Cp′Ru{P(OMe)₃}(CO)X (9), the selectivity at the ruthenium center was low.     

Half-sandwich metal diselenolate complexes Cp#M(NO)(SePh)2 (M = Mo or W; Cp# = Cp or MeCp) as ligands. Synthesis of selenolate-bridged heterobimetallic compounds

The reactions of half-sandwich diselenolate Mo and W complexes Cp^#M(NO)(SePh)₂ (M = Mo; Cp^# = Cp (1a), MeCp (1b); M = W; Cp^# = Cp (1c)) with (Norb)Mo(CO)₄, Ni(COD)₂ and Fe(CO)₅ have been investigated. Treatment of (1a), (1b) and (1c) with (Norb)Mo(CO)₄ in PhMe gave the bimetallic complexes: CpMo(NO)(-SePh)₂Mo(CO)₄ (2a), MeCpMo(NO)(-SePh)₂Mo(CO)₄ (2b) and CpW(NO)(-SePh)₂Mo(CO)₄ (2c) in moderate yields. Irradiation of (1a) and (1c) in the presence of Fe(CO)₅ gave heterobimetallic complexes CpMo(CO)(-SePh)₂Fe(CO)₃ (3a) and CpW(NO)(-SePh)₂Fe(CO)₃ (3c). Ni(COD)₂ reacts with two equivalents of (1a), (1b) and (1c) to give [CpMo(NO)(-SePh)₂]₂Ni (4a), [MeCpMo(NO)(-SePh)₂]₂Ni (4b) and [CpW(NO)(-SePh)₂]₂Ni (4c) in good yields. The new heterobimetallic complexes were characterized by i.r., ¹H-n.m.r., ¹³C-n.m.r. and EI-MS spectroscopy.     

Ruthenium(II) carbonyl complexes containing tridentate Schiff bases

New ruthenium(II) complexes, [Ru(CO)(B)(LL)(PPh₃)] (where, LL = tridentate Schiff bases; B = PPh₃, pyridine, piperidine or morpholine) have been prepared by reacting [RuHCl(CO)(PPh₃)₃] or [RuHCl(CO)(PPh₃)₂(B)] with Schiff bases containing donor groups (O, N, X) viz., salicylaldehyde thiosemicarbazone (X = S), salicylaldehyde semicarbazone (X = O), o-hydroxyacetophenone thiosemicarbazone (X = S) and o-hydroxyacetophenone semicarbazone (X = O). The new complexes were characterised by elemental analysis, spectral (i.r., ¹H- and ³¹P-n.m.r.), data.     

Oxidative addition of asparagusic acid based disulfides to Pt

[Pt(PPh₃)₄] reacts smoothly and swiftly at room temperature with asparagusic acid and with selected amide and ester derivatives of this cyclic disulfide to afford Pt^II dithiolate chelates of the type cis-[Pt{CRR′(CH₂S)₂}(PPh₃)₂]. The crystal structures of three such products are reported.     

Tetraazaadamantane derivatives of group VI metal carbonyls

Summary Tetraazaadamantane (taad) reacts with group VI metal hexacarbonyls to give mononuclear (taad)M(CO)₅ (M=Cr, Mo and W) derivatives. Mixed ligand metal tricarbonyls,cis- (L-L)(taad)M(CO)₃ (L-L=o-phenanthroline or 2,2-bipyridine; M=Cr and Mo) have also been synthesised. Bromine or iodine reacts with (taad)M(CO)₅ (M=Cr and Mo) to give [(taad)M(CO)₅X]⁺X^– (X=Br or I). Nitrosyl chloride reacts with (taad)M(CO)₅ at room temperature to yieldmer- (taad)M(CO)₃NOCl while with the mixed (L-L)(taad)-Mo(CO)₃ complex, a mixture of (L-L)Mo(NO)₂Cl₂ and (L-L)Mo(CO)₂NOCl was obtained. An analogous reaction with (L-L)(taad)Cr(CO)₃, gave only (L-L)Cr(NO)₂Cl₂ derivatives. The products have been characterised by elemental analysis, i.r. spectra, conductivity data and magnetic measurements.     

The photo-induced decarbonylation of Cp′M(NO)(CO)2 (M = Cr,Mo, W) with diorgano dichalcogenides (R2E2; E = S,Se; R = Me,Ph)

The photo-induced decarbonylation of CpCr(NO)(CO)₂ (1a) in MeCN solution in the presence of R₂E₂ (E = S, Se; R = Me, Ph) leads to the formation of chalcogenolato-bridged binuclear complexes Cp₂Cr₂(NO)₂(-ER)₂ [E = S; R = Me (2a), Ph (3a); E = Se, R = Me (4a), Ph (5a)] while reactions between CpM(NO)(CO)₂ [M = Mo (1b), W (1c)] and Ph₂E₂ (E = S, Se) result in mononuclear complexes CpM(NO)(EPh)₂ [M = Mo; E = S (9b), Se (10b); M = W, E = S (11c), Se (12c)]. The corresponding reactions of (1b) with Me₂E₂ (E = S, Se) yielded both mono and binuclear complexes: CpMo(NO)(SeMe)₂ (8b), Cp₂Mo₂(NO)₂(-EMe)₂ [E = S (6b), Se (7b)]. The new complexes have been characterized by i.r., ¹H-, ¹³C-n.m.r. spectra and by electron-impact mass spectrometry.     

Synthesis and characterization of β-diketonato- and phenoxoderivatives of mono(dizirconium-ennea-isopropoxy)copper(II)

Summary -Diketonato- and phenoxo-derivatives of mono(dizirconium-ennea-isopropoxy) copper(II), [Cu{Zr₂(OPr-i)₉}-(RCOCHCOR)] and [Cu{Zr₂(OPr-i)₉}(-OAr)], have been prepared by the interaction of K(RCOCHCOR) or KOAr (1 mol) [R = R = Me (1a); R = R = CF₃ (1b); R = Me, R = CF₃ (1c); OAr = 2,6-Me₂C₆H₃O (2a), 3,5-Me₂C₆H₃O (2b), p-ClC₆H₄O (2c)] with [Cu{Zr₂-(OPr-i) ₉}(-Cl)] (1 mol) in PhH. Alcohol interchanges of the derivative [Cu{Zr₂(OPr-i)₉}(-Cl)] have also been studied. These new compounds have been characterized by elemental analyses, i.r., electronic and e.s.r. spectra, and magnetic susceptibility measurements. The studies indicate a distorted octahedral geometry around Cu^II.     

31P{1H}-n.m.r. as a tool for identification of ruthenium isomers containing PPh3 or 1,4-bis(diphenylphosphino)butane ligands. X-ray structures of the cis-{RuCl2(PPh3)2 [4,4′-(-X)2-2,2′-bipy]} complexes [X=-H, -Me, -SMe and (-Cl, -Me)]

A series of cis-{RuCl₂(PPh₃)₂[4,4-(X)₂-2,2-bipy]} [cis-chlorines; X=-H, -Me, -SMe, and (-Cl,-Me)] complexes have had their structures determined by single crystal X-ray diffraction. The geometry of these complexes, also determined in CH₂Cl₂ solution by ³¹P{¹H}-n.m.r. spectroscopy, showed that the chemical shifts for the phosphorus atoms are slightly dependent on the pKa of the 4,4-(-X)₂-2,2-bipy ligands.     

Novel P‐Stereogenic PCP Pincer‐Aryl Ruthenium(II) Complexes and Their Use in the Asymmetric Hydrogen Transfer Reaction of Acetophenone

Achiral P‐donor pincer‐aryl ruthenium complexes ([RuCl(PCP)(PPh₃)]) 4c , d were synthesized via transcyclometalation reactions by mixing equivalent amounts of [1,3‐phenylenebis(methylene)]bis[diisopropylphosphine] ( 2c ) or [1,3‐phenylenebis(methylene)]bis[diphenylphosphine] ( 2d ) and the N‐donor pincer‐aryl complex [RuCl{2,6‐(Me₂NCH₂)₂C₆H₃}(PPh₃)], ( 3 ; Scheme 2). The same synthetic procedure was successfully applied for the preparation of novel chiral P‐donor pincer‐aryl ruthenium complexes [RuCl(P*CP*)(PPh₃)] 4a , b by reacting P‐stereogenic pincer‐arenes (S,S)‐[1,3‐phenylenebis(methylene)]bis[(alkyl)(phenyl)phosphines] 2a , b (alkyl=ⁱPr or ^tBu, P*CHP*) and the complex [RuCl{2,6‐(Me₂NCH₂)₂C₆H₃}(PPh₃)], ( 3 ; Scheme 3). The crystal structures of achiral [RuCl(equation/tex2gif-sup-3.gifPCP)(PPh₃)] 4c and of chiral (S,S)‐[RuCl(equation/tex2gif-sup-6.gifPCP)(PPh₃)] 4a were determined by X‐ray diffraction (Fig. 3). Achiral [RuCl(PCP)(PPh₃)] complexes and chiral [RuCl(P*CP*)(PPh₃)] complexes were tested as catalyst in the H‐transfer reduction of acetophenone with propan‐2‐ol. With the chiral complexes, a modest enantioselectivity was obtained.     

Transition metal complexes of γ-mercaptoalkylpiperidines

Summary Complexes with 1-methyl-3-(mercaptomethyl)piperidine (LH) and 1-methyl-2-(2-mercaptoethyl)piperidine (LH) Ligands in their thiolato (R), andN-protonated (HR) orN-methylated (MeR) zwitterionic form, of stoichiometry MR₂ (M=Ni, R=L or L; M=Cd, R=L), MR (M=Cu or Ag, R=L and L), [Ni(MeR)₂]I₂ · nH₂O (R=L, n=1; R=L, n=2), [Ni(HR)₂]X₂ (R=L or L, X=ClO₄; R=L, X=Br), and [Ag(HR)] ClO₄ (R=L) have been prepared and characterized. According to i.r. and electronic spectra, and magnetic measurements the nickel complexes exhibit polymeric frameworks built up from mercapto-bridged metal atoms in square-planar environments. Complexes with copper, silver, and cadmium exhibit similar polymeric arrangements through bridging sulphur atoms but with a different geometry at the metal centers, the first two being mainly linear, as anticipated, and the latter tetrahedral. In no case does coordinationvia nitrogen take place and therefore these ligands behave simply as mercaptides.     

Synthesis of Boron–Nitrogen–Phosphorus Compounds from N-Silylphosphoranimines

Two modes of reactivity of N-silylphosphoranimines have been utilized to prepare the title compounds containing either B–N=P or Si–N=P–N–B linkages. First, silicon-nitrogen bond cleavage reactions of the N-silylphosphoranimines, Me₃SiN=PMe(R)OCH₂CF₃ (1: R=Me, 2: R=Ph), with various chloroboranes gave the new N-borylphosphoranimines, Ph(Me₂N)B–N=PMe₂OCH₂CF₃ (2) and [(Me₃Si)₂N](Cl)B–N=PMe₂OCH₂CF₃ (10). In other cases, however, the expected B–N=P products were unstable and cyclic phosphazenes [Me(R)P=N]_3,4 were obtained. Second, deprotonation-substitution reactions of the aminophosphoranimines, Me₃SiN=P(R)Me–N(R)H, were used to prepare a series of novel (borylamino)-phosphoranimines, Me₃SiN=P(R)(Me)–N(R)–B(NMe₂)₂ (18: R=Me, R=t-Bu; 19: R=R=Me; 20: R=Ph, R=t-Bu; 21: R=Ph, R=Me) and Me₃SiN=PMe₂–N(t-Bu)–B(Ph)X (22: X=NMe₂, 23: X=OCH₂CF₃). All of the new boron–nitrogen–phosphorus products were fully characterized by multinuclear NMR (¹H, ¹³C, and ³¹P) spectroscopy and elemental analysis.     

Tridentate Schiff base complexes of ruthenium(III) containing ONS/ONO donor atoms and their biocidal activities

New ruthenium(III) complexes of the [RuY(LL)(E)₂] type (Y = Cl or Br; LL = tridentate Schiff bases; E = PPh₃ or AsPh₃) have been synthesised by reacting [RuX₃(EPh₃)₃] (X = Cl, E = P; X = Cl or Br, E = As) or [RuBr₃(EPh₃)₂(MeOH)] with Schiff bases having the donor groups (O, N, X) viz., salicylaldehydethiosemicarbazone (X = S), salicylaldehydesemicarbazone (X = O), o-hydroxyacetophenonethiosemicarbazone (X = S) and o-hydroxyacetophenonesemicarbazone (X = O). The new complexes were characterised by elemental analysis, spectral (i.r., electronic spectra, e.p.r.), magnetic moment and cyclic voltammetry data. Biocidal activity studies were also carried out for the new complexes.     

Isocyanide complexes of molybdenum nitrosyl

Reaction of π-cyclopentadienylmolybdenum nitrosyl halide with CNR (R = alkyl) gives [(π-C₅H₅)Mo(NO)X₂(CNR)] (X = Br or I), [Mo(NO)(CNR)₅]X (X = I or PF₆) and [Mo(NO)(CNR)₄I]; treatment of [Mo(NO)(CNR)₅]I with R′NH₂ gives [Mo(NO)(CNR)₄ {C(NHR)(NHR′)}]I or [Mo(NO)(CNR)₄(NH₂R′)]I (R′ = alkyl) depending on temperature.     

Hydrido-silyl complexes,Part VIII. Photochemical reaction of [Fe(CO)3H(PR′3)SiR3] with silanes,HSiR3: Influence of PR′3 and SiR3 on formation and structures of bis-silyl complexes [Fe(CO)3(PR′3)(SiR3)2]

Summary Upon u.v. irradiation of [Fe(CO)₄(PR ₃ )] with HSiR₃ (HSiR₃ = HSiMePh₂, PR₃ = PPh₃; HSiR₃ = HSiMe₂Cl, PR₃ = PPh₃ or PMe₂Ph; HSiR₃ = HSiMeCl₂, PR₃ = PPh₃, PMePh₂, PMe₂Ph or PMe₃; HSiR₃ = HSiCl₃, PR₃ = PPh₃, PMePh₂, PMe₂Ph, PMe₃ or PBu ₃ ⁿ ) the corresponding hydridosilyl complexes [Fe(CO)₃H(PR₃)SiR₃] are formed. The complexes have themer configuration with acis disposition of the hydride and the silyl ligands. Prolonged irradiation with an excess of silane results in the formation of bis-silyl complexes [Fe(CO)₃(PR₃)(SiR₃)₂], if electron density at the metal is not too high. Thus, [Fe(CO)₃H(PPh₃)SiMePh₂] and [Fe(CO)₃-H(PMe₂Ph)SiMe₂Cl] can be obtained but not the corresponding bis-silyl complexes. Most bis-silyl complexes are obtained asmer-isomers with acis-arrangement of the silyl ligands. Only for [Fe(CO)₃(PR₃)(SiCl₃)₂] with small phosphine ligands (PR₃ = PMe₃ or PMe₂Ph) is thefac-isomer formed.Part VII of this series, ref. (1).     

The chemistry of cyclopentadienyl nitrosyl and related complexes of molybdenum,part 10(1). Cationic allyl complexes and attack thereon by nucleophiles

Summary The syntheses of [Mo(⁵-C₅H₅)(³-C₃H₄R)(CO)(NO)]⁺ (R=H, 1- or 2-Me) and [Mo(⁵-C₅H₅)(³-C₃H₅)(NCR)(NO)]⁺ (R=Me or Ph), by treatment of Mo(⁵-C₅H₅)(CO)₂(NO) with RC₃H₄Br and Ag⁺, and of Mo(⁵-C₅H₅)(³-C₃H₅)(NO)I with Ag⁺ in the presence of RCN, is described. Treatment of these cations with nucleophiles gives Mo(⁵-C₅H₅)(³-C₃H₅)(NO)X (X=halide, NCS or NCO), Mo(⁵-C₅H₅)(³-C₃H₅Q)(CO)(NO) (C₃H₅Q= propene ligand, Q= H, SCOMe, SEt, S₂CNMe₂, S₂CNEt₂, S₂CN(Bu-n)₂, C₅H₅, acac, OH, OMe or OAc), and [Mo(⁵-C₅H₅)(₂C₃H₅L)(CO)(NO)]⁺ (L=PEt₃, n-Bu₃P, PPh₃, PPh₂H, PMe₂Ph, C₅H₅N, 1-, 3- or 4-MeC₅H₄N and Me₂NNH₂). Reaction of [Mo(⁵-C₅H₅)(³-C₃H₅)(NCMe)(NO)⁺ with pyridine gave [Mo(⁵-C₅H₅)(³-C₃H₅)(pyr)(NO)]⁺, while treatment of [Mo(⁵-C₅H₅)(³-C₃H₅)(CO)(NO)]⁺ with PPh₃ in the presence of NaOEt afforded Mo(⁵-C₅H₅)(CO)(NO)(PPh₃). The¹H and¹³C n.m.r. spectra of these complexes are discussed particularly in relation to the occurrence ofexo andendo isomers of the allylic species. Comparison is made briefly between Mo(⁵-C₅H₅)(³-C₃H₅)(NO)I and Mo(C₅H₅)₂(NO)I.