Synthesis and Spectroscopic Characterisation of a New Class of Heterobimetallic Zirconocene(IV) Compounds

Reactions of Cp₂ZrCl₂ with homometallic complexes of aluminium containing one residual hydroxy group Al(OGO)(OGOH) and Al(L)(OGOH) [where G=G¹=CMe₂CMe₂ (1a); G=G²=CMe₂CH₂CHMe (1b); G= G³=CMe₂CH₂CH₂CMe₂ (1c) and L=L¹=OC₆H₄CH=NCH₂CH₂O, G=G¹ (2a); L=L¹, G=G² (2b); L=L¹, G=G³ (2c); L=L²=OC₁₀H₆CH=NCH₂CH₂O, G=G¹ (2d); L=L², G=G² (2e); L=L², G=G³ (2f)] in THF using Et₃N as HCl acceptor affords novel heterobimetallic compounds of the types Al(OGO)₂Zr(Cl)Cp₂ and Al(L)(OGO)Zr(Cl)Cp₂, respectively. All of these derivatives have been characterised by elemental analyses, molecular weight measurements, and spectroscopic [IR, NMR (¹H and ²⁷Al)] studies.     

Homometallic glycolates containing hydroxyl functionality for anchoring another metal: synthesis and characterization of heterometallic alkoxide–glycolates of Ti and Zr incorporating Al and Nb

Reaction of Ti(OPrⁱ)₄ with 2-methyl-2,4-pentanediol [HOGOH, where G = CMe₂CH₂CH(Me)] in 1?:?3 M ratio under reflux afforded the monomeric [Ti(OGO)(OGOH)₂] (1), which on further reactions with [Al(OPrⁱ)₃] or [Nb(OPrⁱ)₅] in 1?:?1 and 1?:?2 M ratios afforded heterometallic derivatives, [Ti(OGO)₃{M(OPrⁱ)_n?2}] and [Ti(OGO)₃{M(OPrⁱ)_n?1}₂] [where M = Al (n = 3), Nb (n = 5)], respectively. Similar reactions of Zr(OPrⁱ)₄?PrⁱOH with a number of glycols [HOGOH, where G = CH(Me)CH(Me), CMe₂CMe₂, CMe₂CH₂CH(Me)] yielded dimeric [Zr₂(OGO)₂(OGOH)₄]. [Zr₂(OGO)₆{M(OPrⁱ)_n?2}₂] and [Zr₂(OGO)₄(OGOH)₂M(OPrⁱ)_n?2] [M = Al (n = 3), Ti (n = 4), Nb (n = 5)] were prepared by 1?:?2 and 1?:?1 reactions, respectively, of [Zr₂(OGO)₂(OGOH)₄] with Al(OPrⁱ)₃, Ti(OPrⁱ)₄, or Nb(OPrⁱ)₅. Surprisingly, a 1?:?2 reaction of [VO(OPrⁱ)₃] with 2,2-diethyl-1,3-propanediol in benzene followed a different reaction and produced a neutral tetranuclear derivative [V₄(O)₄(μ-OCH₂CEt₂CH₂O)₂(OCH₂CEt₂CH₂O)₄] (18). All of these derivatives were characterized by elemental analysis, molecular weight measurements, FT-IR, and ¹H NMR (and wherever possible, by ²⁷Al or ⁵¹V NMR) spectroscopic studies. The derivatives [Zr₂(OCMe₂CH₂CH(Me)O)₂(OCMe₂CH₂CH(Me)OH)₄] (9 and 18) were additionally characterized by single-crystal X-ray structure analysis.     

Synthesis and characterization of heterobimetallic mixed-ligand complexes containing Zr(μ-OPri)2Al bridging units

Interesting varieties of heterobimetallic mixed-ligand complexes [Zr{M(OPrⁱ) _n }₂ (L)] (where M = Al, n = 4, L = OC₆H₄CH = NCH₂CH₂O (1); M = Nb, n = 6, L = OC₆H₄CH = NCH₂CH₂O (2); M = Al, n = 4, L = OC₁₀H₆CH = NCH₂CH₂O (3); M = Nb, n = 6, L = OC₁₀H₆CH = NCH₂CH₂O (4)), [Zr{Al(OPrⁱ)₄}₂Cl(OAr)] (where Ar = C₆H₃Me₂-2,5 (5); Ar = C₆H₂Me-4-Bu₂-2,6 (6), [Zr{Al(OPrⁱ)₄}₂(OAr)₂] (where Ar = C₆H₃Me₂-2,5 (7); Ar = C₆H₂Me-4-Bu₂-2,6 (8), [Zr{Al(OPrⁱ)₄}₃(OAr)] (where Ar = C₆H₃Me₂-2,5 (9); Ar = C₆H₃Me₂-2,6 (10), [ZrAl(OPrⁱ)_7-n (ON=CMe₂) _n ] (where n = 4 (11); n = 7 (12), [ZrAl₂(OPrⁱ)_10-n (ON=CMe₂) _n ] (where n = 4 (13); n = 6 (14); n = 10 (15) and [Zr{Al(OPrⁱ)₄}₂{ON=CMe(R)} _n Cl_2–n] [where n = 1, R = Me (16); n = 2, R = Me (17); n = 1, R = Et (18); n = 2, R = Et (19)] have been prepared either by the salt elimination method or by alkoxide-ligand exchange. All of these heterobimetallic complexes have been characterized by elemental analyses, molecular weight measurements, and spectroscopic (I.r., ¹H-, and ²⁷Al- n.m.r.) studies.     

Synthesis and Spectroscopic Characterisation of Six-Coordinate Complexes of Oxovanadium(V)

Complexes of the types VO(L)(R-deaH), VO(R-dea)(LH), and VO(L)(OGOH)[L = deprotonated form of N-(1-hydroxyethyl) naphthaldimine; R-dea = deprotonated form of a N-substituted diethanolamine, with R = H or Ph; G = CH₂CH₂, CHMeCHMe, CMe₂CMe₂, CHMeCH₂CMe₂, CMe₂CH₂CH₂CMe₂] have been prepared by the equimolar reactions of VO(OPr ⁱ )₃, LH₂, and an appropriate diethanolamine or glycol in benzene. All of these coloured solid complexes have been characterised by elemental (C, H, N, and V) analyses and by spectroscopic (i.r., electronic, ¹H-, ⁵¹V-n.m.r) studies. The relative lability of the hydroxy group(s) of N-(1-hydroxyethyl)naphthaldiamine, diethanolamine, and glycol has also been investigated.     

O,O′-dialkyl and alkylene dithiophosphate derivatives of silver(I). X-ray crystal structure of [Ag{S2POCH2CMe2CH2O} PPh3]2 · 2H2O

Silver(I) dialkyl/alkylene dithiophosphates of the types [Ag{S₂P(OR)₂}] and [Ag{S₂P(OGO)}] (where R = –Pr ⁿ ; G = –CMe₂CH₂CHMe–, –CH₂CMe₂CH₂–, –CMe₂CMe₂– or –CH₂CH₂CHMe–) have been prepared by treating an aqueous solution of AgNO₃ with ammonia salts of the respective dithiophosphoric acid. The derivatives form 1:1 adducts readily with 2,2-bipyridine or Ph₃P in CH₂Cl₂ solution. These novel complexes have been characterized by elemental analyses, molecular weight measurements and spectral (i.r., ¹H- and ³¹P-n.m.r.) studies. The crystal structure of [Ag{S₂POCH₂CMe₂CH₂O · PPh₃]₂ · 2H₂O exhibits an unsymmetrical attachment of the silver(I) to the ligand moiety.     

Further studies on organonickel compounds: the synthesis of some new alkyl-, acyl- and cyclopentadienyl-derivatives and the crystal structure of trans-[Ni(CH2SiMe3)2(PMe3)2]

The complex [NiCl₂(PMe₃)₂] reacts with one equivalent of mg(CH₂CMe₃)Cl to yield the monoalkyl derivative trans-[Ni(CH₂CMe₃)Cl(PMe₃)₂], which can be carbonylated at room temperature and pressure to afford the acyl [Ni(COCH₂CMe₃)Cl(PMe₃)₂]. Other related alkyl and acyl complexes of composition [Ni(R)(NCS)(PMe₃)₂] (R = CH₂CMe₃, COCH₂CMe₃) and [Ni(R)(η-C₅H₅)L] (L = PMe₃, R = CH₂CMe₃, COCH₂CMe₃; L = PPh₃, R = CH₂CMe₂Ph) have been similarly prepared. Dialkyl derivatives [NiR₂(dmpe)] (R = CH₂SiMe₃, CH₂CMe₂Ph; dmpe = 1,2-bis(dimethylphosphine)ethane, Me₂PCH₂ CH₂PMe₂) have been obtained by phosphine replacement of the labile pyridine and NNN′N′-tetramethylethylenediamine ligands in the corresponding [Ni(CH₂SiMe₃)₂(py)₂] and [Ni(CH₂CMe₂Ph)₂(tmen)] complexes. A single-crystal X-ray determination carried out on the previously reported trimethylphosphine derivative [Ni(CH₂SiMe₃)₂(PMe₃)₂] shows the complex belongs to the orthorhombic space group Pbcn, with a = 14.345(4), b = 12.656(3), c = 12.815(3) Å, Z = 4 and R 0.077 for 535 independent observed reflections. The phosphine ligands occupy mutually trans positions P-Ni-P 146.9(3)° in a distorted square-planar arrangement.     

Heterotri- and -tetrametallic alkoxides of chromium(III) containing aluminium(III), gallium(III) and niobium(V)

CrCl₃ · 3THF reacts with two equivalents of potassium alkoxometallates K{M(OPr ⁱ ) _x } [M = Al(A), Ga(B), x = 4; M = Nb(C), x = 6] to give heterobimetallic chloride isopropoxides [Cr{M(OPr ⁱ ) _x }₂Cl(THF)] [M = Al(A – 1), Ga(B – 1), and Nb(C – 1)], in which the replacement of the chloride with an appropriate alkoxometallate (tetraisopropoxoaluminate, tetraisopropoxogallate, or hexaisopropoxoniobate) results in the formation of novel heterotrimetallic derivatives. The 'single pot synthesis of an heterotetrametallic isopropoxide [Cr{Nb(OPr ⁱ )₆}{Al(OPr ⁱ )₄}{Ga(OPr ⁱ )₄}] (7) has been carried out by the sequential addition of (A), (B), and (C) to a benzene suspension of CrCl₃ · 3THF. Alcoholysis of [Cr{Al(OPr ⁱ )₄}₂{Nb(OPr ⁱ )₆}] (1) and [Cr{Al(OPr ⁱ )₄}₂{Ga(OPr ⁱ )₄}] (5) with t-BuOH has also been studied and the derivatives characterized by elemental analyses, molecular weight determinations, spectroscopic [Electronic, i.r., ²⁷Al-n.m.r.] and magnetic susceptibility studies.     

Darstellung und Struktur der Zweikernigen tert-Butyliminovanadium(IV)-Komplexe [(μ?NtC4H9)2V2(CH2CMe3)2X2] (X = OtC4H9, CH2CMe3)

Synthesis and Molecular Structure of the Binuclear tert-Butyliminovanadium(IV) Complexes [(μ-N^tC₄H₉)₂V₂(CH₂CMe₃)₂X₂] (X = O^tC₄H₉, CH₂CMe₃) Syntheses of the neopentylvanadium(V) compounds ^tC₄H₉N?V(CH₂CMe₃)_3?n(O^tC₄H₉)_n (n = 0 ( 7 ), 1 ( 6 ), 2) are described. 6 and 7 decompose by irradiation splitting off neopentane and yielding the binuclear diamagnetic neopentylvanadium(IV) complexes [(μ-N^tC₄H₉)₂V₂(CH₂CMe₃)₂X₂] [X = O^tC₄H₉ ( 8 ), CH₂CMe₃ ( 11 )]. All compounds obtained are characterized by ¹H and ⁵¹V NMR spectroscopy. 8 has been found by X-ray diffraction analysis to be a binuclear complex with bridging tert-butylimino ligands and a vanadium—vanadium single bond. The complexes ^tC₄H₉N?V(CH₂C₆H₅)(O^tC₄H₉)₂ and [(μ-N^tC₄H₉)₂V₂(CH₂SiMe₃)₂(O^tC₄H₉)₂] ( 10 ) have been also prepared; the crystal structure of 8 and 10 are nearly identical.     

Synthesis, characterization and reactivity of the molybdenum(VI) complex [MoCl(NAr)2(CH2CMe2Ph)] (Ar=2,6-Pr2C6H3)

The compounds [MoCl(NAr)₂R] (R=CH₂CMe₂Ph (1) or CH₂CMe₃(2); Ar=2,6-Prⁱ₂C₆H₃) have been prepared from [MoCl₂(NAr)₂(dme)] (dme=1,2-dimethoxyethane) and one equivalent of the respective Grignard reagent RMgCl in diethyl ether. Similarly, the mixed-imido complex [MoCl₂(NAr)(NBu^t)(dme)] affords [MoCl(NAr)(NBu^t)(CH₂CMe₂Ph)] (3). Chloride substitution reactions of 1 with the appropriate lithium reagents afford the compounds [MoCp(NAr)₂(CH₂CMe₂Ph)] (4) (Cp=cyclopentadienyl), [MoInd(NAr)₂(CH₂CMe₂Ph)] (5) (Ind=Indenyl), [Mo(OBu^t)(NAr)₂(CH₂CMe ₂Ph)] (6), [MoMe(NAr)₂(CH₂CMe₂Ph)] (7), [MoMe(PMe₃)(NAr)₂(CH₂CMe ₂Ph)] (8) (formed in the presence of PMe₃) and [Mo(NHAr)(NAr)₂(CH₂CMe₂P h)](9). In the latter case, a by-product {[Mo(NAr)₂(CH₂CMe₂Ph) ]₂(μ-O)}(10) has also been isolated. The crystal structures of 1, 4, 5 and 10 have been determined. All possess distorted tetrahedral metal centres with cis near-linear arylimido ligands; in each case (except 5, for which the evidence is unclear) there are α-agostic interactions present.     

CO2 Fixation and Transformation by a Dinuclear Copper Cryptate under Acidic Conditions

CO₂ fixation and transformation by metal complexes continuously receive attention from the viewpoint of carbon resources and environmental concerns. We found that the dinuclear copper(II) cryptate [Cu₂L¹](ClO₄)₄ ( 1 ; L¹=N[(CH₂)₂NHCH₂(m‐C₆H₄)CH₂NH‐(CH₂)₂]₃N) can easily take up atmospheric CO₂ even under weakly acidic conditions at room temperature and convert it from bicarbonate into carbonate monoesters in alcohol solution. The compounds [Cu₂L¹(μ‐O₂COH)](ClO₄)₃ ( 2 ), [Cu₂L¹(μ‐O₂COR)](ClO₄)₃ ( 3 : R=CH₃; 4 : R=C₂H₅; 5 : R=C₃H₇; 6 : R=C₄H₉; 7 : R=C₅H₁₁; 8 : R=CH₂CH₂OH), [Cu₂L¹(μ‐O₂CCH₃)](ClO₄)₃ ( 9 ), and [Cu₂L¹(OH₂)(NO₃)](NO₃)₃ ( 10 ) were characterized by IR spectroscopy and ESI‐MS. The crystal structures of 2 – 6 and 10 were studied by single‐crystal X‐ray diffraction analysis. On the basis of the crystal structures, solution studies, and DFT calculations, a possible mechanism for CO₂ fixation and transformation is given.     

η4‐HBCC‐σ,π‐Borataallyl Complexes of Ruthenium Comprising an Agostic Interaction

Thermolysis of [Cp*Ru(PPh₂(CH₂)PPh₂)BH₂(L₂)] 1 (Cp*=η⁵‐C₅Me₅; L=C₇H₄NS₂), with terminal alkynes led to the formation of η⁴‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)B{R‐C=CH₂}(L)₂] ( 2 a – c ) and η²‐vinylborane complexes [Cp*Ru(R‐C=CH₂)BH(L)₂] ( 3 a – c ) ( 2 a , 3 a : R=Ph; 2 b , 3 b : R=COOCH₃; 2 c , 3 c : R=p‐CH₃‐C₆H₄; L=C₇H₄NS₂) through hydroboration reaction. Ruthenium and the HBCC unit of the vinylborane moiety in 2 a – c are linked by a unique η⁴‐interaction. Conversions of 1 into 3 a – c proceed through the formation of intermediates 2 a – c . Furthermore, in an attempt to expand the library of these novel complexes, chemistry of σ‐borane complex [Cp*RuCO(μ‐H)BH₂L] 4 (L=C₇H₄NS₂) was investigated with both internal and terminal alkynes. Interestingly, under photolytic conditions, 4 reacts with methyl propiolate to generate the η⁴‐σ,π‐borataallyl complexes [Cp*Ru(μ‐H)BH{R‐C=CH₂}(L)] 5 and [Cp*Ru(μ‐H)BH{HC=CH‐R}(L)] 6 (R=COOCH₃; L=C₇H₄NS₂) by Markovnikov and anti‐Markovnikov hydroboration. In an extension, photolysis of 4 in the presence of dimethyl acetylenedicarboxylate yielded η⁴‐σ,π‐borataallyl complex [Cp*Ru(μ‐H)BH{R‐C=CH‐R}(L)] 7 (R=COOCH₃; L=C₇H₄NS₂). An agostic interaction was also found to be present in 2 a – c and 5 – 7 , which is rare among the borataallyl complexes. All the new compounds have been characterized in solution by IR, ¹H, ¹¹B, ¹³C NMR spectroscopy, mass spectrometry and the structural types were unequivocally established by crystallographic analysis of 2 b , 3 a – c and 5 – 7 . DFT calculations were performed to evaluate possible bonding and electronic structures of the new compounds.     

Gemischtligandkomplexe des Rheniums. V. Die Bildung von Nitrenkomplexen durch Kondensation von Aceton an koordinierten Nitridoliganden. Darstellung und Strukturen von fac-[Re{NC(CH3)2CH2C(O)CH3}X3(Me2PhP)2]-Komplexen (X = Cl,Br)

Mixed-ligand Complexes of Rhenium. V. The Formation of Nitrene Complexes by Condensation of Acetone at Coordinated Nitrido Ligands. Syntheses and Structures of fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}X₃(Me₂PhP)₂] Complexes (X = Cl, Br) The reaction of rhenium(V)-mixed-ligand complexes of the general formula [ReN(Cl)(Me₂PhP)₂(R₂tcb)] (HR₂tcb = N? (N,N-dialkylthiocarbamoyl)benzamidine) with HCl or HBr in acetone initializes a condensation of the solvent and results in nitrene-like compounds as a consequence of a nucleophilic attack of the coordinated nitrido ligand on the condensed acetone. The chelate ligands are removed during this reaction and complexes of the type fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}X₃(Me₂PhP)₂] (X = Cl, Br) are formed. fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Cl₃(Me₂PhP)₂] crystallizes triclinic in the space group P1, a = 8.575(4); b = 9.088(3); c = 18.389(9) Å; α = 75.67(3)°, β = 85.30(3)°, γ = 70.58(4)°; Z = 2. A final R value of 0.031 was obtained on the basis of 6011 independent reflections with I ≥ 2σ(I). Rhenium is coordinated in a distorted octahedral environment with the three chloro ligands in facial positions. The rhenium-nitrogen bond (1,68(1) Å) is only slightly longer than typical Re? N bonding distances in nitrido complexes. fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Br₃(Me₂PhP)₂] is isomorphous with the chloro complex. Triclinic cell with a = 8.625(4); b = 9.198(3); c = 18.581(5) Å; α = 75.62(3)°, β = 85.40(3)°, γ = 70.91(3)°; Z = 2. The R value converged at 0.049 on the basis of 3644 independent reflections with I ≥ 2σ(I). fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Cl₃(Me₂PhP)₂] as well as fac-[Re{NC(CH₃)₂CH₂C(O)CH₃}Br₃(Me₂PhP)₂] crystallizes in the noncentrosymmetric space group P1.     

O,O′-Alkylene dithiophosphate derivatives of iron(II) and iron(III) and their reactions with nitrogen- and phosphorus-donor bases

Summary Solids of the stoichiometric formulae [Fe{S₂P(OPr-n)₂}₃] and [Fe{S₂PO₂G}₃] (G = —CH₂CMe₂CH₂—, CMe_2–CMe₂— or —CH₂CH₂CHMe—) are precipitated from the reactions of FeCl₃ with ammonium dithiophosphates in water. Soluble complexes of the type [Fe{S₂PO₂G}₂], formed by the reactions of FeCl₂ with NH₄[{S₂PO₂G}] in MeOH, can be extracted with benzene. Adducts of the types [Fe{S₂PO₂G}₂L] and [Fe{S₂PO₂G}₂(PPh₃)₂] are formed by the reaction of [Fe{S₂PO₂G}₂] with L (L = 2,2-bipyridyl or 1,10-phenanthroline) and PPh₃, respectively. All the compounds have been characterized by i.r. and u.v.-vis. spectroscopy and magnetic studies.This paper is dedicated to the late Dr. G. Srivastava, Associate Professor, Department of Chemistry, Rajasthan University, Jaipur.     

Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk‐Ox): Synthesis,Scope and Copolymerization with Styrene

The design of a synthetic route to a class of enantiomerically pure phosphaalkene–oxazolines (PhAk‐Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha‐Peterson reaction) was used as the P?C bond‐forming step. Attempted condensation of PhC(?O)Ox (Ox=CNOCH(iPr)C H₂) and MesP(SiMe₃)Li gave the unusual heterocycle (MesP)₂C(Ph)?CN‐(S)‐CH(iPr)CH₂O ( 3 ). However, PhAk‐Ox (S,E)‐MesP?C(Ph)CMe₂Ox ( 1 a ) was successfully prepared by treating MesP(SiMe₃)Li with PhC(?O)CMe₂Ox (52 %). To demonstrate the modularity and tunability of the phospha‐Peterson synthesis several other phosphaalkene–oxazolines were prepared in an analogous manner to 1 a : TripP?C(Ph)CMe₂Ox ( 1 b ; Trip=2,4,6‐triisopropylphenyl), 2‐iPrC₆H₄P?C(Ph)CMe₂Ox ( 1 c ), 2‐tBuC₆H₄P?C(Ph)CMe₂Ox ( 1 d ), MesP?C(4‐MeOC₆H₄)CMe₂Ox ( 1 e ), MesP?C(Ph)C(CH₂)₄Ox ( 1 f ), and MesP?C(3,5‐(CF₃)₂C₆H₃)C(CH₂)₄Ox ( 1 g ). To evaluate the PhAk‐Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical‐initiated copolymerization conditions to afford [{MesPC(Ph)(CMe₂Ox)}_x{CH₂CHPh}_y]_n ( 9 a : x=0.13n, y=0.87n; GPC: M_w=7400 g mol^?1, PDI=1.15).     

Synthetic,spectral as well as in vitro antimicrobial studies on some bismuth(III) bis(N,N‐dialkyldithiocarbamato) alkylenedithiophosphates

Mixed sulfur donor ligand complexes of the type bismuth(III) bis(N,N‐dialkyldithiocarbamato) alkylenedithiophosphate, [R₂NCS₂]₂BiS₂POGO [where R = CH₃ and C₂H₅; G = ‐CH₂‐C(C₂H₅)₂‐CH₂‐, ‐CH₂‐C(CH₃)₂‐CH₂‐, ‐CH(CH₃)‐CH(CH₃)‐ and ‐C(CH₃)₂‐C(CH₃)₂‐] were synthesized in 1:1 molar ratio of bismuth(III) bis(N,N‐dialkyldithiocarbamate) chloride and ammonium alkylenedithiophosphate in refluxing benzene and characterized by melting point, molecular weight determinations, elemental analysis (C, H, N, Bi and S) and spectral [UV, IR,NMR (¹H,¹³C and ³¹P) and powder X ray diffraction] studies; all these studies were in good agreement with the synthesized complexes. These newly synthesized derivatives are yellow and brown colored solids and are soluble in common organic solvents like benzene, chloroform, dichloromethane and DMF. Based on the physicochemical and spectral studies, a tentative structure of these newly synthesized complexes was assigned and the average particle size of the synthesized complexes determined by powder XRD, showing that nano range polycrystalline particles were formed with a monoclinic crystal system. These complexes were also screened for their antimicrobial activities using the well diffusion method. The free ligands as well as their mixed metal complexes were tested in vitro against four bacterial strains: two Gram‐positive, Staphylococcus aureus (ATCC 9144) (G⁺) and Bacillus subtilis (ATCC 6051), (G⁺) and two Gram‐negative, Escherichia coli (ATCC 9637) (G^?) and Pseudomonas aeruginosa (ATCC 25619) (G^?) to assess their antimicrobial properties. The results were indeed positive and exhibited good antibacterial effects. Chloroamphenicol used as a standard for comparison and synthesized complexes showed good antibacterial effects over chloroamphenicol. On the basis of these studies, the synthesized complexes help to understand the different structural and biological properties of main group elements with sulfur donor ligands. Copyright © 2010 John Wiley & Sons, Ltd.     

Trialkylhydridoalanate RxR′3-xAlH⊖ [R = CMe3; R′ = CH(SiMe3)2]

Trialkylhydridoalanates R_xR′_3?xAlH^? [R = CMe₃; R′ = CH(SiMe₃)₂] The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe₃)₂]₂CMe₃ 1 and Al[CH(SiMe₃)₂](CMe₃)₂ 2 not under proton abstraction from the C? H acidic elementorganic substituent, but under β-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates — [Hal{CH(SiMe₃)₂}₂CMe₃]^? 3 and [HAl{CH(SiMe₃)₂}(CMe₃)₂]^? 4 each with Li(TMEDA)₂^⊕ as counterion — were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3 . In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.     

Alkyl- und arylkomplexe des iridiums und rhodiums: XXI. Chelatphosphan-stabilisiertepentakoordinierte organoiridium(I)-komplexe Ir(R)(CO)( chel-P33)

Novel five-coordinate organoiridium(I) complexes of the type Ir(R)(CO)(chel-P₃) (chel-P₃=PhP(CH₂CH₂CH₂PPh₂)₂: R = CH₂CMe₃, CH₂SiMe₃; chel-P₃ = MeP-(CH₂CH₂CH₂PPh₂)₂: R = CH₂SiMe₃; chel-P₃PhP(CH₂CH₂PPh₂)₂; R = CH₂SiMe₃, 4-MeC₆H₄) have been prepared from Ir(R)(CO)(PPh₃)₂ and the respective triphosphine. According to ³¹P NMR, these compounds are stereochemically rigid at normal temperatures. The reaction of Rh(R)(CO)(PPh₃)₂, where R = CH₂CMe₃ or 2-MeC₆H₄, with PhP(CH₂CH₂CH₂PPh₂)₂ yielded the four-coordinate derivatives Rh(CH₂CMe₃)[PhP(CH₂CH₂CH₂PPh₂)₂] and Rh(2-MeC₆H₄)[PhP(CH₂CH₂CH₂PPh₂)₂]), which arealready known from the literature.     

Bildung und struktur der Cyclophosphane P4(CMe3)2[P(CMe3)2]2 und P4(SiMe3)2[P(CMe3)2]2

Formation and Structure of the Cyclophosphanes P₄(CMe₃)₂[P(CMe₃)₂]₂ and P₄(SiMe₃)₂[P(CMe₃)₂]₂ n-Triphosphanes showing a SiMe₃ and a Cl substituent at the atoms P¹ and P², like (Me₃C)₂P? P(SiMe₃)? P(CMe₃)Cl 3 or (Me₃C)₂P? P(Cl)? P(SiMe₃)₂ 4 are stable only at temperatures below ?30°C. Above this temperature these compounds lose Me₃SiCl, thus forming cyclotetraphosphanes, P₄(CMe₃)₂[P(CMe₃)₂]₂ 1 out of 3 , P₄(SiMe₃)₂[P(SiMe₃)₂]₂ 2a (cis) and 2b (trans) out of 4 . The formation of 1 proceeds via (Me₃C)₂P? P?PCMe₃ 5 as intermediate compound, which after addition to cyclopentadiene to give the Diels-Alder-adduct 6 (exo and endo isomers) was isolated. 6 generates 5 , which then forms the dimer compound 1 . Likewise (Me₃C)₂P? P?P-SiMe₃ 8 (as proven by the adduct 7 ) is formed out of 4 , leading to 2a (cis) and 2b (trans). Compound 1 is also formed out of the iso-tetraphosphane P[P(CMe₃)₂]₂[P(CMe₃)Cl] 9 , which loses P(CMe₃)₂Cl when warmed to a temperature of 20°C. 1 crystallizes monoclinically in the space group P2₁/a (no. 14); a = 1762.0(15) pm; b = 1687.2(18) pm; c = 1170.5(9) pm; β = 109.18(5)° and Z = 4 formula units in the elementary cell. The molecule possesses E conformation. The central four-membered ring is puckered (approx. symmetry 4 2m; dihedral angle 47.4°), thus bringing the substituents into a quasi equatorial position and the nonbonding electron pairs into a quasi axial position. The bond lengths in the four-membered ring of 1 (d (P? P) = 222.9 pm) are only slightly longer than the exocyclic bonds (221.8 pm). The endocyclic bond angles \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \beta $\end{document}(P/P/P) are 85.0°, the torsion angles are ±33° and d (P? C) = 189.7 pm.     

Homo- and hetero-bimetallic glycolates and triethanolaminates of niobium

[Nb(OⁱPr)₅] reacts with 2,5-dimethylhexane-2,5-diol (LH₂), 2,3-dimethylbutane-2,3-diol (L¹H₂) and triethanolamine (teaH₃) in different stoichiometric ratios to yield complexes of the types: [Nb(OⁱPr)₃(L)] (1), [Nb(OⁱPr)(L)₂] (2), [Nb(L)₂(LH)] (3), [Nb(L¹)₂(L¹H)] (4) and [Nb(tea)(teaH)] (5). Equimolar reactions of (3), (4) and (5) with Al(OⁱPr)₃, Ti(OⁱPr)₄ and [Ta(OⁱPr)₅] yield novel heterobimetallic isopropoxide-glycolate (6)–(9) and -triethanolaminate (10)–(12) derivatives. Reactions in appropriate molar ratios of (1), (2) and (10) with alkoxyethanols [ROC₂H₄OH; R = Me, Et] and acetylacetone [acacH] give derivatives [(MeOC₂H₄O)₃Nb(L)] (13), [(acac)Nb(L)₂] (14), [Nb(tea)₂{Al(OC₂H₄OMe)₂}] (15), [Nb(tea)₂{Al(OC₂H₄OEt)₂}] (16) and [Nb(tea)₂{Al(acac)₂}] (17). The complexes (6), (8) and (10) on reaction with an excess of t-BuOH give the tert-butoxo analogues (18), (19) and (20), respectively. These new derivatives have been characterized by elemental analyses, spectroscopic studies and molecular weight measurements.