Syntheses and X-ray crystallographic studies of {[Ni(en)2(pot)2]0.5CHCl3} and [Ni(en)2](3-pytol)2

Two novel Ni(II) complexes {[Ni(en)₂(pot)₂]0.5CHCl₃} (3) {pot = 5-phenyl-1,3,4-oxadiazole-2-thione} (1) and [Ni(en)₂](3-pytol)₂ (4) {3-pytol = 5-(3-pyridyl)-1,3,4-oxadiazole-2-thiol} (2) have been synthesized using en as coligand. The metal complexes have been characterized by physical and analytical techniques and also by single crystal X-ray studies. The complexes 3 and 4 crystallize in monoclinic system with space group P21/a and P121/c, respectively. The complex 3 has a slightly distorted octahedral geometry with trans (pot)⁻ ligands while 4 has a square planar geometry around the centrosymmetric Ni(II) center with ionically linked trans (3-pytol)⁻ ligands. The π?π (face to face) interaction plays an important role along with hydrogen bondings to form supramolecular architecture in both complexes.     

Syntheses and study on nickel and copper complexes with 1,3,5-benzenetricarboxylic acid. Crystal and molecular structure of [Cu3(mdpta)3(btc)](ClO4)3 · 4H2O

Nickel and copper complexes containing 1,3,5-benzenetricarboxylic acid, with a combination of selected N-donor ligands and Schiff bases, of the composition Ni₃(bimz)₆(btc)₂ · 12H₂O (1), Ni₃(btz)₉(btc)₂ · 12H₂O (2), Ni₂(L₁)(btc) · 7H₂O (3), Ni₃(L₂)₂(Hbtc) · 9H₂O (4), Ni₂(L₃)(btc) · 4H₂O (5), Cu₂(L₄)(btc) · 7H₂O (6), [Cu₃(pmdien)₃(btc)](ClO₄)₃ · 6H₂O (7) and [Cu₃(mdpta)₃(btc)](ClO₄)₃ · 4H₂O (8); H₃btc = 1,3,5-benzenetricarboxylic acid, bimz = benzimidazole, btz = 1,2,3-benztriazole, L₁ = 2-[(phenylimino)methyl]phenol, L₂ = N,N′-bis-(salicylidene)propylenediamine, L₃ = 2-{[(2-nitrophenyl)methylene]amino}phenol, L₄ = 2-[(4-methoxy-phenylimino)methyl]phenol, pmdien = N,N,N′,N″,N″-pentamethyldiethylenetriamine, mdpta = N,N-bis-(3-aminopropyl)methylamine, have been synthesized. The complexes have been studied by elemental analysis, IR, UV–Vis spectroscopies, magnetochemical and conductivity measurements and selected compounds also by thermal analysis. The crystal and molecular structure of complex 8 was solved. The complex is trinuclear with btc³⁻-bridge. The coordination polyhedron around each copper atom can be described as a distorted square with a CuON₃ chromophore formed by one oxygen atom of carboxylate and three nitrogen atoms of mdpta. The magnetic properties of 8 have been studied in the 1.8–300 K temperature range revealing a very weak antiferromagnetic exchange interaction with J = −0.56 cm⁻¹ for g = 2.13(9). The antimicrobial activities against selected strains of bacteria were evaluated. It was found that only complex 5 is able to inhibit the growth of Staphylococcus strains.     

Novel octahedral nickel(II) dithiocarbamates with bi- or tetradentate N-donor ligands: X-ray structures of [Ni(Bzppzdtc)(phen)2]ClO4 · CHCl3 and [Ni(Bz2dtc)2(cyclam)]

A series of novel octahedral nickel(II) dithiocarbamate complexes involving bidentate nitrogen-donor ligands (phen = 1,10-phenanthroline, bpy = 2,2′-bipyridine) or a tetradentate ligand (cyclam = 1,4,8,11-tetraazacycloteradecane) of the composition [Ni(BzMetdtc)(phen)₂]ClO₄ (1), [Ni(Pe₂dtc)(phen)₂]ClO₄ (2), [Ni(Bzppzdtc)(phen)₂]ClO₄ · CHCl₃ (3), [Ni(Bzppzdtc)(phen)₂](SCN) (4), [Ni(BzMetdtc)(bpy)₂]ClO₄ · 2H₂O (5), [Ni(Pe₂dtc)(cyclam)]ClO₄ (6), [Ni(BzMetdtc)₂(cyclam)] (7), [Ni(Bz₂dtc)₂(cyclam)] (8) and [Ni(Bz₂dtc)₂(phen)] (9) (BzMetdtc = N,N-benzyl-methyldithiocarbamate(1-) anion, Pe₂dtc = N,N-dipentyldithiocarbamate(1-) anion, Bz₂dtc = N,N-dibenzyldithiocarbamate(1-) anion, Bzppzdtc = 4-benzylpiperazinedithiocarbamate(1-) anion), have been synthesized. Spectroscopic (electronic and infrared), magnetic moment and molar conductivity data, and thermal behaviour of the complexes are discussed. Single crystal X-ray analysis of 3 and 8 confirmed a distorted octahedral arrangement in the vicinity of the nickel atom with a N₄S₂ donor set. They represent the first X-ray structures of such type complexes. The catalytic influence of complexes 2, 3, 6, and 7 on graphite oxidation was studied and discussed.     

Crystal structure and spectral characterization of hexanuclear oxo titanium(IV) clusters: [Ti6O6(OSi(CH3)3)6(OOCR)6] (R = Bu,CH2Bu,C(CH3)2Et)

Hexanuclear oxo titanium(IV) siloxo carboxylate complexes with the general formula [Ti₆O₆(OSi(CH₃)₃)₆(OOCR)₆] (R = Bu^t (1), CH₂Bu^t (2), C(CH₃)₂Et (3)) were synthesized in quantitative yield, by the reaction of Ti(OSiMe₃)₄ with the appropriate organic acid. Crystal structure determination revealed that molecules of 1–3 are composed of [Ti₆-(μ₃-O)₆] cores stabilized by six syn–syn carboxylato bridges and six terminal siloxide ligands. Each metal atom is surrounded by six oxo atoms, capping the triangular faces of the distorted octahedron. Spectral characterization (IR, NMR) of 1–3 revealed a significant non-equivalence of the carboxylate group interactions, resulting from the asymmetry of the Ti-μ-OOC bonds of the syn–syn bridges. The thermal stability of the studied compounds was determined from TGA/DTA analysis.     

Synthesis,characterization, DNA-binding and DNA-photocleavage studies of [Ru(bpy)2(BPIP)] and [Ru(phen)2(BPIP)] (BPIP = 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline)

New ligand 2-(4′-biphenyl)imidazo[4,5-f][1,10]phenanthroline (BPIP) and its complexes [Ru(bpy)₂(BPIP)]²⁺ (1) (bpy = 2,2′-bipyridine) and [Ru(phen)₂(BPIP)]²⁺ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by mass spectroscopy, ¹H NMR and cyclic voltammetry. The interaction of two Ru(II) complexes with calf thymus DNA (CT-DNA) was investigated by spectroscopic and viscosity measurements. Results indicate that both complexes bind to DNA via an intercalative mode and the DNA-binding affinity of complex 2 is much greater than that of complex 1. Furthermore, when irradiated at 365 nm, both complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA.     

Synthesis and characterization of palladium(II) complexes with chiral aminophosphine ligands: Catalytic behaviour in asymmetric hydrovinylation. Crystal structure of cis-[PdCl2(PPh((R)-NHCHCH3Ph)2)2]

Optically active ligands of type Ph₂PNHR (R = (R)-CHCH₃Ph, (a); (R)-CHCH₃Cy, (b); (R)-CHCH₃Naph, (c)) and PhP(NHR)₂ (R = (R)-CHCH₃Ph, (d); (R)-CHCH₃Cy, (e)) with a stereogenic carbon atom in the R substituent were synthesized. Reaction with [PdCl₂(COD)₂] produced [PdCl₂P₂] (1) (P = PhP(NHCHCH₃Ph)₂), whose molecular structure determined by X-ray diffraction showed cis disposition for the ligands. All nitrogen atoms of amino groups adopted S configuration. The new ligands reacted with allylic dimeric palladium compound [Pd(η³-2-methylallyl)Cl]₂ to gave neutral aminophosphine complexes [Pd(η³-2-methylallyl)ClP] (2a-2e) or cationic aminophosphine complexes [Pd(η³-2-methylallyl)P₂]BF₄ (3a-3e) in the presence of the stoichiometric amount of AgBF₄. Cationic complexes [Pd(η⁴3-2-methylallyl)(NCCH₃)P]BF₄ (4a-4e) were prepared in solution to be used as precursors in the catalytic hydrovinylation of styrene. ³¹P NMR spectroscopy showed the existence of an equilibrium between the expected cationic mixed complexes 4, the symmetrical cationic complexes [Pd(η³-2-methylallyl)P₂]BF₄ (3) and [Pd(η³-2-methylallyl)(NCCH₃)₂]BF₄ (5) coming from the symmetrization reaction. The extension of the process was studied with the aminophosphines (a-e) as well as with nonchiral monodentate phosphines (PCy₃ (f), PBn₃ (g), PPh₃ (h), PMe₂Ph (i)) showing a good match between the extension of the symmetrization and the size of the phosphine ligand. We studied the influence of such equilibria in the hydrovinylation of styrene because the behaviour of catalytic precursors can be modified substantially when prepared ‘in situ’. While compounds 3 and bisacetonitrile complex 5 were not active as catalysts, the [Pd(η³-2-methylallyl)(η²-styrene)₂]⁺ species formed in the absence of acetonitrile showed some activity in the formation of codimers and dimers. Hydrovinylation reaction between styrene and ethylene was tested using catalytic precursors solutions of [Pd(η³-2-methylallyl)LP]BF₄ ionic species (L = CH₃CN or styrene) showing moderate activity and good selectivity. Better activities but lower selectivities were found when L = styrene. Only in the case of the precursor containing Ph₂PNHCHCH₃Ph (a) ligand was some enantiodiscrimination (10%) found.     

Synthesis, characterization, and ethylene polymerization behavior of [(RR′-admpzp)2Ti(OPr)2] complexes (RR′-admpzp = 1-dialkylamino-3-(3,5-dimethyl-pyrazol-1-yl)-propan-2-olate)

[(RR′-admpzp)₂Ti(OPrⁱ)₂] complexes (2a-c), synthesized from reaction of Ti(OPrⁱ)₃Cl (0.5 equiv) with 1-dialkylamino-3-(3,5-dimethyl-pyrazol-1-yl)-propan-2-ol compounds in the presence of triethylamine (0.5 equiv), are pseudo-octahedral with each RR′-admpzp ligand κ²-O,N(pyrazolyl) coordinated to the titanium center. In solution, 2a-c adopt isomeric structures that are in dynamic equilibrium. At 23 °C, 2a-c/1000 MAO catalyst systems furnished high molecular weight polymers with narrow molecular weight distributions (M_w/M_n = 2.7-2.8). At 100 °C, 2a-c/MAO catalyst systems exhibited increased polymerization activity and 2c/1000 MAO system furnished high molecular weight polyethylene with a molecular weight distribution (M_w/M_n = 2.1) that is close to that found for single-site catalysts.     

Synthesis,crystal structure and magnetic properties of the helical oxalate-bridged copper(II) chain {[(CH3)4N]2[Cu(C2O4)2] · H2O}n

The preparation, crystal structure and magnetic properties of a new oxalate-containing copper(II) chain of formula {[(CH₃)₄N]₂[Cu(C₂O₄)₂] · H₂O}_n (1) [(CH₃)₄N⁺ = tetramethylammonium cation] are reported. The structure of 1 consists of anionic oxalate-bridged copper(II) chains, tetramethylammoniun cations and crystallization water molecules. Each copper(II) ion in 1 is surrounded by three oxalate ligands, one being bidentate and the other two exhibiting bis-bidenate coordination modes. Although all the tris-chelated copper(II) units from a given chain exhibit the same helicity, adjacent chains have opposite helicities and then an achiral structure results. Variable-temperature magnetic susceptibility measurements of 1 show the occurrence of a weak ferromagnetic interaction through the oxalate bridge [J = +1.14(1) cm⁻¹, the Hamiltonian being defined as H = –J ∑_nmS_i · S_j]. This value is analyzed and discussed in the light of available magneto-structural data for oxalate-bridged copper(II) complexes with the same out-of-plane exchange pathway.     

New stable germylenes, stannylenes, and related compounds: 6. Heteroleptic germanium(II) and tin(II) compounds [(SiMe3)2N-E-OCH2CH2NMe2]n (E = Ge, n = 1; Sn, n = 2): synthesis and structure

New stable heteroleptic germanium(II) and tin(II) compounds [(SiMe₃)₂N-E¹⁴-OCH₂CH₂NMe₂]_n (E¹⁴ = Ge, n = 1 (1), Sn, n = 2 (2)) have been synthesized and their crystal structures have been determined by X-ray diffraction analysis. While compound 1 is monomer stabilized by intramolecular Ge ← N coordination, compound 2 is associated to dimer via intermolecular dative Sn ← O interactions.     

Intra- and intermolecular hydrogen bonds in [Ag(PPh3)3(HL)] complexes [H2L: H2xspa = 3(aryl)-2-sulfanylpropenoic acids; H2cpa = 2-cyclopentylidene-2-sulfanylacetic acid]

Compounds of the type [Ag(PPh₃)₃(HL)] {H₂xspa=3(aryl)-2-sulfanylpropenoic acids: x = Clp [3-(2-chlorophenyl)-], -o-mp [3-(2-methoxyphenyl)-], -p-mp [3-(4-methoxyphenyl)-], -o-hp [3-(2-hydroxyphenyl)-], -p-hp [3-(4-hydroxyphenyl-); H₂cpa = 2-cyclopentylidene-2-sulfanylacetic acid} were synthesized and characterised by IR and NMR (¹H ¹³C and ³¹P) spectroscopy and by FAB mass spectrometry. The crystal structures of [Ag(PPh₃)₃(HClpspa)], [Ag(PPh₃)₃(H-o-mpspa)], [Ag(PPh₃)₃(H-p-mpspa)] and [Ag(PPh₃)₃(Hcpa)] reveal the presence of discrete molecular units containing an intramolecular O-H···S hydrogen bond between the S atom and one of the O atoms of the COOH group. This intramolecular hydrogen bond remains in [Ag(PPh₃)₃(H-o-hpspa)]·EtOH and [Ag(PPh₃)₃(H-p-hpspa)] but in both cases polymeric structures are built on the basis of O-H···O interactions that involve the -OH substituent of the phenyl group of the sulfanylpropenoate fragment.     

Bis(silylaminodiarylphosphoranylsilylmethyl-C,N)-tin(II) and -lead(II) complexes and their precursors; structures of H(LL′), H(LL″), Sn(LL″)2 and Pb(LL″)2; [LL′] = [CH(SiMe3)P(Ph)2NSiMe3],

We report a series (a)-(d) of tandem reactions involving the conversion of: (a) 2CH₂(SiMe₃)P(Ph)₂NSiMe₃ [2H(LL′)] (III) into successively [Li(LL′)]₂ (1a) and [Pb(LL′)₂] (3a); (b) 1a in turn into {[Li(LL″)]₂} (2) and [Pb(LL″)₂] (4); (c) 1a successively into Sn(LL′)Cl (5) and [Sn(LL″)₂] (6); (d) (1b) into (3b). Experimental details for the preparation and characterisation (including elemental analysis and multinuclear NMR spectra in C₆D₆ and EI mass spectra) of 1a, 2, 3a, 3b, 4, 6, III (a new synthesis) and IV are provided. The X-ray structures of crystalline 4, 6, III and IV are presented; those of 1a, 2 and 3a were previously published.     

Trifluoroacetylacetonate rhodium(III) methyl complexes, cis-[Rh(TFA)(PPh3)2(CH3)(L)][BPh4] and cis-[Rh(TFA)(PPh3)2(CH3)(I)] (L = CH3CN, NH3, pyridine), in comparison with their acetylacetonate analogs

The oxidative addition of CH₃I to planar rhodium(I) complex [Rh(TFA)(PPh₃)₂] in acetonitrile (TFA is trifluoroacetylacetonate) leads to the formation of cationic, cis-[Rh(TFA)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] (1), or neutral, cis-[Rh(TFA)(PPh₃)₂(CH₃)(I)] (4), rhodium(III) methyl complexes depending on the reaction conditions. 1 reacts readily with NH₃ and pyridine to form cationic complexes, cis-[Rh(TFA)(PPh₃)₂(CH₃)(NH₃)][BPh₄] (2) and cis-[Rh(TFA)(PPh₃)₂(CH₃)(Py)][BPh₄] (3), respectively. Acetylacetonate methyl complex of rhodium(III), cis-[Rh(Acac)(PPh₃)₂(CH₃)(I)] (5), was obtained by the action of NaI on cis-[Rh(Acac)(PPh₃)₂(CH₃)(CH₃CN)][BPh₄] in acetone at −15 °C. Complexes 1-5 were characterized by elemental analysis, ³¹P{¹H}, ¹H and ¹⁹F NMR. For complexes 2, 3, 4 conductivity data in acetone solutions are reported. The crystal structures of 2 and 3 were determined. NMR parameters of 1-5 and related complexes are discussed from the viewpoint of their isomerism.     

Transition metal complexes with thiosemicarbazide-based ligands. Part LIV. Nickel(II) complexes with pyridoxal semi- (PLSC) and thiosemicarbazone (PLTSC). Crystal and molecular structure of [Ni(PLSC)(H2O)3](NO3)2 and [Ni(PLTSC-H)py]NO3

This paper describes the synthesis of the first Ni(II) complexes with pyridoxal semicarbazone (PLSC), viz. Ni(PLSC)Cl₂ · 3.5H₂O (1), [Ni(PLSC)(H₂O)₃](NO₃)₂ (2), Ni(PLSC)(NCS)₂ · 4H₂O (3), [Ni(PLSC-2H)NH₃] · 1.5H₂O (4), as well as two new complexes with pyridoxal thiosemicarbazone (PLTSC), [Ni(PLTSC-H)py]NO₃ (5) and [Ni(PLTSC-H)NCS] (6). Complexes 1–3 are paramagnetic and have most probably an octahedral structure, for complex 2 this was proved by X-ray diffraction analysis. In contrast, complexes 4–6 are diamagnetic and have a square-planar structure, and in the case of complex 5 this was also confirmed by X-ray structural analysis. In all cases the Schiff bases are coordinated as tridentate ligands with an ONX (X = O, PLSC; X = S, PLTSC) set of donor atoms. With the complexes involving the neutral form of PLSC and the monoanionic form of PLTSC, the PL moiety is in the form of a zwitterion. In addition to the above-mentioned techniques, all the complexes were characterized by measuring their molar conductivities, UV–Vis and partial IR spectra.     

Synthesis and diphosphine ligand fluxionality in Os3(CO)10(bmi): Kinetic evidence for nondissociative diphosphine isomerization and X-ray crystal structure of 1,1-Os3(CO)10(bmi)

The triosmium cluster 1,2-Os₃(CO)₁₀(MeCN)₂ reacts rapidly with the diphosphine ligand 2,3-bis(diphenylphosphino)-N-p-tolylmaleimide (bmi) at room temperature to give bmi-bridged cluster 1,2-Os₃(CO)₁₀(bmi) (2b) as the major product, along with the chelating isomer 1,1-Os₃(CO)₁₀(bmi) (2c) and the hydride-bridged cluster HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) as minor by-products. All three cluster compounds have been isolated and fully characterized in solution by IR and NMR spectroscopies (¹H and ³¹P), and X-ray crystallography in the case of 2c. Cluster 2b is unstable and readily isomerizes to 2c in quantitative yield on mild heating. The kinetics for the conversion of 2b → 2c have been measured over the temperature range of 318-348 K in toluene solution, and based on the observed activation parameters a nondissociative isomerization process that proceeds via a transient μ₂-bridged phosphine moiety is presented. Near-UV photolysis of cluster 2c at room temperature affords HOs₃(CO)₉[μ-(PPh₂)CC{PPh(C₆H₄)}C(O)N(tolyl-p)C(O)] (3) with a quantum yield of 0.017. The reactivity of clusters 2b, 2c, and 3 is discussed with respect to related diphosphine-substituted Os₃(CO)₁₀(P-P) clusters prepared by our groups.     

Synthesis and characterisation of six Fe(II or III), Co(II) or Zr(IV) complexes containing the ligand [CH(SiMe2R)P(Ph)2NSiMe3] (R = Me, NEt2) and of [Co{N(SiMe3)C(Ph)C(H)P(Ph)2NSiMe3}2]

The C,N-(trimethylsilyliminodiphenylphosphoranyl)silylmethylmetal complexes [Fe(L)₂] (3), [Co(L)₂] (4), [ZrCl₃(L)]·0.83CH₂Cl₂ (5), [Fe(L)₃] (6), [Fe(L′)₂] (7) and [Co(L′)₂] (8) have been prepared from the lithium compound Li[CH(SiMe₂R)P(Ph)₂NSiMe₃] [1a, (R = Me) {≡ Li(L)}; 1b, (R = NEt₂) {≡ Li(L′)}] and the appropriate metal chloride (or for 7, FeCl₃). From Li[N(SiMe₃)C(Ph)C(H)P(Ph)₂NSiMe₃] [≡ Li(L″)] (2), prepared in situ from Li(L) (1a) and PhCN, and CoCl₂ there was obtained bis(3-trimethylsilylimino- diphenylphosphoranyl-2-phenyl-N-trimethylsilyl-1-azaallyl-N,N′)cobalt(II) (9). These crystalline complexes 3-9 were characterised by their mass spectra, microanalyses, high spin magnetic moments (not 5) and for 5 multinuclear NMR solution spectra. The X-ray structure of 3 showed it to be a pseudotetrahedral bis(chelate), the iron atom at the spiro junction.     

Chalcogen-capped ruthenium carbonyl clusters derived from diphosphazane mono- and dichalcogenides of the type X2P(E)N(R)PX2 and X2P(E)N(R)P(E)X2 (E = S or Se)

Reactions of Ru₃(CO)₁₂ with diphosphazane monoselenides Ph₂PN(R)P(Se)Ph₂ [R = (S)-∗CHMePh (L⁴), R = CHMe₂ (L⁵)] yield mainly the selenium bicapped tetraruthenium clusters [Ru₄(μ₄-Se)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] (1, 3). The selenium monocapped triruthenium cluster [Ru₃(μ₃-Se)(μ_sb-CO)(CO)₇{κ²-P,P-Ph₂PN((S)-∗CHMePh)PPh₂}] (2) is obtained only in the case of L⁴. An analogous reaction of the diphosphazane monosulfide (PhO)₂PN(Me)P(S)(OPh)₂ (L⁶) that bears a strong π-acceptor phosphorus shows a different reactivity pattern to yield the triruthenium clusters, [Ru₃(μ₃-S)(μ₃-CO)(CO)₇{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (9) (single sulfur transfer product) and [Ru₃(μ₃-S)₂(CO)₅{κ²-P,P-(PhO)₂PN(Me)P(OPh)₂}{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (10) (double sulfur transfer product). The reactions of diphosphazane dichalcogenides with Ru₃(CO)₁₂ yield the chalcogen bicapped tetraruthenium clusters [Ru₄(μ₄-E)₂(μ-CO)(CO)₈{μ-P,P-Ph₂PN(R)PPh₂}] [R = (S)-∗CHMePh, E = S (6); R = CHMe₂, E = S (7); R = CHMe₂, E = Se (3)]. Such a tetraruthenium cluster [Ru₄(μ₄-S)₂(μ- CO)(CO)₈{μ-P,P-(PhO)₂PN(Me)P(OPh)₂}] (11) is also obtained in small quantities during crystallization of cluster 9. The dynamic behavior of cluster 10 in solution is probed by NMR studies. The structural data for clusters 7, 9, 10 and 11 are compared and discussed.     

Synthesis and characterisation of [AlMen{Si(SiMe3)3}3−n(thf)] (n = 1 or 2)

The crystalline compounds [AlMe_n{Si(SiMe₃)₃}_3−n(thf)] [n = 2 (1) or 1 (2)] were prepared from the lithium sisyl [Li{Si(SiMe₃)₃}(thf)₃] (A) and the appropriate methylaluminium chloride [AlCl_3−nMe_n] in thf. The X-ray structure of 1 is reported. Unlike A or a magnesium sisyl [Mg{Si(SiMe₃)₃}₂(thf)₂] (B), neither 1 nor 2 underwent an insertion reaction with an α-H-free nitrile.