Caridad Ruiz

Synthesis of dialkyl, diaryl and metallacyclic complexes of Ni and Pd containing pyridine, α-diimines and other nitrogen ligands: Crystal structures of the complexes cis-NiR2py2 (R=benzyl, mesityl)

Abstract The alkylation of NiCl 2 py 4 or PdCl 2 py 2 with organomagnesium or organolithium reagents affords dialkyl complexes cis -MR 2 py 2 (R=Me, CH 2 SiMe 3 , CH 2 Ph, CH 2 CMe 2 Ph, 2,4,6-C 6 H 2 Me 3 ). The methyl and trimethylsilyl derivatives undergo ligand exchange reactions with chelating nitrogen ligands (α-diimines or 2-imidoylpyridines), yielding the corresponding dialkyl derivatives in good to excellent yields. A catalytic amount of PMe 3 induces the transformation of the nickel complex Ni(CH 2 CMe 2 Ph) 2 py 2 into the metallacyclic derivative NiCH 2 CMe 2 -o- C 6 H 4 ( py ) 2 .The latter, and the related palladacycle Pd ( CH 2 CMe 2 -o- C 6 H 4 ) ( cod ) , also undergo facile ligand exchange reactions.

Synthesis and characterization of dioxocomplexes of molybdenum with (η-C5H5)Co{P(O)(OEt)2}3, C5H4(SiMe3) and 1,3-C5H3(SiMe3)2 ligands. X-ray crystal structure of [(η-C5H5)Co{P(O)(OEt)2}3]MoO2Cl

Abstract The interaction of (NH4)2Mo2O7 with Me3SiCl in 1,2-dimethoxyethane (dme) gives, in a one pot reaction, the known dioxo-compound MoCl2O2(dme) (1). Dioxo–molybdenum complexes of the type (L)MoO2Cl (L=monoanionic, formally tridentate, ancillary ligand like (η-C5H5)Co{P(O)(OEt)2}3, LOEt (2) C5H4(SiMe3), Cptms (3) and 1,3-C5H3(SiMe3)2, Cp2tms (4)) have been prepared using 1 as the starting material. Other known oxo complexes are also easily accessible from 1, for example, the reaction with CpTl, PMe3 and Li[(Me3SiN)2CPh].tmda affords CpMoO2Cl (5), MoOCl2(PMe3)3 (7) and Mo(O)2{(Me3SiN)2CPh}2 (8), respectively. Complex 4 acts as a good catalyst of the oxo-transfer model reaction from dimethylsulfoxide to PPh3 at room temperature. Complex (LOEt)MoO2Cl (2) has been structurally characterized by X-ray crystallography.

Organometallic derivatives of Ni(II) with poly(pyrazolyl)borate ligands

Abstract The reaction of the alkyl or aryl derivatives Ni(R)X(PMe 3 ) 2 (R=CH 2 SiMe 3 , CH 2 CMe 3 , C 6 H 5 ; X=Cl, Br) with the potassium salt of the Bp ligand (Bp=dihydrobis(pyrazolyl)borate anion) forms the corresponding compounds BpNi(R)(PMe 3 ). In contrast, the reaction of the aryl derivatives Ni(C 6 H 4 - p -X)Br(PMe 3 ) 2 (X=H, Me, OMe, NMe 2 ) with the Bp tBu anion (Bp tBu =dihydrobis(3- t -butylpyrazolyl)borate) proceeds with formation of complexes of composition Bp tBu Ni(C 6 H 4 - p -X)(PMe 3 ) 2 , in which the polydentate ligand is bound to the metal through only one pyrazolyl group. The Tp anion leads to only aryl derivatives; the phenyl complex TpNi(C 6 H 5 )(PMe 3 ) has been obtained, and the reaction of the alkyl complex Ni(CH 2 CMe 2 Ph)Cl(PMe 3 ) 2 with KTp furnishes the aryl TpNi(C 6 H 4 - o -Bu t )(PMe 3 ), by means of a rearrangement of the neophyl ligand. The Tp ligand in these complexes is bonded in the η 2 fashion, although an X-ray analysis carried out for TpNi(Ph)(PMe 3 ) reveals the existence of an important Ni…N interaction with the third pz ring. Upon reaction with the bulky hydrotris(3- t -butylpyrazolyl)borate anion, the aryl derivatives Ni(C 6 H 4 - p -X)Br(PMe 3 ) 2 (X=H, Me, OMe, NMe 2 ) form complexes of composition Tp tBu Ni(C 6 H 4 - p -X)(PMe 3 ) 2 , in which the polydentate ligand is once more bound to the metal through only one pyrazolyl group. These complexes represent the first examples of η 1 coordination of poly(pyrazolyl)borate-type ligands. The acyl and aroyl complexes BpNi(COR)(PMe 3 ) (R=CH 2 SiMe 3 , CH 2 CMe 3 ) and TpNi(COPh)(PMe 3 ) have been obtained by carbonylation of the parent compounds. The aroyls Tp tBu Ni(COC 6 H 4 - p -X)(PMe 3 ) 2 have also been obtained from the derivatives Ni(COC 6 H 4 - p -X)Br(PMe 3 ) 2 although they evolve CO slowly in solution. An X-ray analysis carried out with Tp tBu Ni(C 6 H 4 - p -Me)(PMe 3 ) 2 confirms the η 1 -coordination mode of the Tp tBu ligand, which was deduced from NMR studies.

Novel carbon dioxide and carbonyl carbonate complexes of molybdenum. The X-ray structures of trans-[Mo(CO2)2(HN(CH2CH2PMe2)2}(PMe3)] and [Mo3(μ2-CO3)(μ2-O)2(O)2(CO)2(H2O)(PMe3)6].H2O

A new bis(carbon dioxide) adduct of molybdenum containing the tridentate, bis(phosphine) ligand, HN(CH2CH2PMe2)2 (NP2), in a mer conformation has been synthesized and structurally characterized. Its carbonyl carbonate isomer [Mo(CO3)(CO)(NP2)(PMe3)] has also been prepared. In addition, the reactivity of the complex [Mo(CO3)(CO)(PMe3)4] toward CO has been studied, a transformation that has led to the formation of the dicarbonyl complex [Mo(CO3)(CO)2(PMe3)3]. This complex liberates CO2 upon heating under a carbon monoxide atmosphere by means of a CO–CO3 conproportionation reaction. The new trinuclear complex [Mo3(μ2-CO3)(μ2-O)2(O)2(CO)2(H2O)(PMe3)6]·H2O, resulting from the interaction of [Mo(CO3)(CO)(PMe3)4] and water, has been isolated and structurally characterized.

A comparative study of the use of triethylammonium salts of the [Fe2(CO)6(μ-CO)(μ-SR)]− anion in the synthesis of iron-gold clusters. Crystal structures of [Fe2(CO)6(μ-CO)(μ-SiPr)(μ-AuPPh3)] and [Fe2(CO)5(PPh3)(μ-SEt)2]

Abstract Salts of the type (NEt3H)[Fe2(CO)6(μ-CO)(μ-SR)] (R=1cr; iPr, tBu, Ph) react with [ClAuPPh3] in the presence of TIBF4 to produce the neutral iron-gold clusters [Fe2(CO)6(μ-CO)(μ-SR)(μ-AuPPh3)] (R=1cr; iPr, 1; R=1cr; tBu, 2; R=1cr; Ph, 3) in high yields. The structure of 1 has been determined by X-ray diffraction methods. Crystals are monoclinic, space group P21/c, with a = 11.373(1), b = 14.899(3), c = 17.997(8) A, β = 95.12(2)° and Z = 4, R = 0.030 and R′ = 0.035 for 3579 unique reflections with I ⩾ 2σ(I). The basic skeleton consists of an Fe2Au triangle where the FeFe bond is bridged by a carbonyl and a thiolate group. In contrast, the reaction of the salts (NEt3H)[Fe2(CO)6(μ-CO)(μ-SR)] (R = Et or C6F5) with [ClAuPPh3] does not afford the corresponding mixed iron-gold clusters, and the diiron mono- or di-substituted complexes [Fe2(CO)5 (PPh3)(μ-SR)2] (R=1cr; Et, 4; R=1cr; C6F5, 5) and [Fe2(CO)4(PPh3)2(μ-SEt)2] (6) are obtained instead. The structure of 4 has been established by single-crystal X-ray diffraction studies. Crystals are triclinic, space group, P 1 , with a = 10.472(4), b = 11.329(2), c = 13.437(2) A, α = 80.34(2), β = 92.62(3), γ = 114.46(2)°, and Z = 2, R = 0.027 and R′ = 0.030 for 3732 unique reflections with I ⩾ 2σ(I). The FeFe bond in 4 is almost symmetrically double-bridged by two thiolate ligands and the phosphine group attached to the Fe(1) is trans to the iron-iron bond.

Synthesis and reactivity of new palladium alkyl complexes containing PMe3 ligands: Insertion reactions and formation of bis(pyrazolyl)borate derivatives

Abstract The complex PdCl2(cod) (cod = 1,4-cyclooctadiene) reacts with one equivalent of R(Mg)Cl (R = CH2CMe2Ph, CH2SiMe3, CH2C6H4-o-Me) to yield monoalkyl derivatives of composition Pd(R)Cl(cod). The cyclooctadiene ligand is readily displaced by dmpe (dmpe = 1,2-bis(dimethylphosphino)ethane) and PMe3 to generate Pd(R)Cl(L2) (L2 = (PMe3)2, dmpe) of which, the complex Pd(CH2CMe2Ph)Cl(PMe3)2 thermally isomerizes to the palladium aryl Pd(C6H4-o-CMe3)Cl(PMe3)2 in the presence of catalytic amounts of NEt3. Carbonylation of the alkyl derivatives affords acyl complexes Pd(COR)Cl(L2) and related iminoacyl derivatives have also been obtained by the analogous reaction with tert-butyl-isocyanide. New alkyl and acyl species containing bis(pyrazolyl)borate ligands have been prepared by halide metathesis in the Pd(R/COR)Cl(PMe3)2 complexes. During the course of these reactions one equivalent of PMe3 is liberated. The complex Bp∗Pd(CH2SiMe3)(PMe3) has been structurally characterized by X-ray crystallography.

Binuclear σ- and η3-benzylic derivatives of nickel

The stepwise reaction of the dibromides m- and p-BrCH2C6H4Br with [Ni(cod)(PMe3)2](cod = cycloocta-1,5-diene) affords the σ-benzylic derivatives trans-[Ni(CH2C6H4Br)Br(PMe3)2]1a(meta) or 1b(para) and the binuclear species trans,trans-[(Me3P)2BrNi(µ-σ : σ-CH2C6H4)NiBr(PMe3)2]2a(meta) or 2b(para). If the second oxidative addition is carried out using equimolar amounts of [Ni(cod)2] and PMe3 the pseudo-allyl complexes trans-[(Me3P)BrNi(µ-η3 : σ-CH2C6H4)NiBr(PMe3)2]5a(meta) or 5b(para) are obtained instead. Carbonylation of the binuclear compounds 2 yields the stable bis(acyl) derivatives trans,trans-[(Me3P)2BrNi(µ-COCH2C6H4CO)NiBr(PMe3)2]3a(meta) or 3b(para) while excess of PMe3 induces a reductive elimination process that furnishes the bis(aryl) species trans,trans-[(Me3P)2BrNi(µ-C6H4CH2C6H4)NiBr(PMe3)2]4a(meta) or 4b(para). A crystal structure determination of complex 2b has been undertaken: monoclinic, space group P21/c, with cell dimensions a= 11.241(1), b= 8.866(2), c= 29.323(8)A, β= 90.22(1)° and Z= 4. The geometry around both nickel atoms is distorted square planar, with a dihedral angle between the two co-ordination planes of 103.77(9)°.

Zero valent molybdenum and tungsten ethylene isocyanide complexes: Synthesis and structural properties

Abstract Compounds of composition trans,mer-[M(C2H4)2(CNR)(PMe3)3] (1) and trans,trans,trans-[M(C2H4)2(CNR)2(PMe3)2] (2) for various combinations of M = Mo, W and R = CHMe2, CMe3 and C6H11, have been obtained by the stepwise reaction of trans-[M(C2H4)2(PMe3)4] with the corresponding isocyanide. Compounds 2 can also be obtained by treatment of 1 with CNR, a reaction that allows the synthesis of the mixed isocyanide trans,trans-[Mo(C2H4)2(CNCMe3)(CNC6H11)(PMe3)2] (2g). A similar reaction, starting with trans,mer-[M(C2H4)2(CO)(PMe3)3], produces the mixed isocyanide—carbonyl derivatives trans,trans-[M(C2H4)2(CNR)(CO)(PMe3)2] (3). X-ray structural studies on complexes 2b and 3b (M = Mo, R = CMe3) have been carried out. Both compounds are monoclinic, P21/n but while the structure of 3b has been refined to a conventional R value of 0.034 by using 2976 observed reflections (unit cell constants: a = 10.972(3), b = 18.923(4), c = 10.544(3) A; β = 98.89(2)°) extensive disorder problems have prevented anisotropic refinement of 2b, and a final isotropic R value of 0.097 has been obtained. For compound 3b, the MoC bond distances are 1.959(5) (MoCO), 2.137(4) (MoCNR) and 2.283(9) A (av. MOC2H4).

BIS- AND TRIS(PYRAZOLYL)BORATE COMPLEXES OF THE HEAVIER ALKALINE-EARTH ELEMENTS CA, SR, AND BA

Abstract Sandwich complexes of the composition MTp2* [Tp*hydrotris(3,5-dimethylpyrazolylborate ; MCa, 1 ; Sr, 2 ; Ba, 3] have been generated by the direct reaction of the iodides MI2 with KTp*. Attempts to prepare the half-sandwich compounds MTp*(I) have met with no success when MCa, Sr, but the reaction of BaI2 with 1 equiv. of KTp* in THF produced BaTp*(I)(THF)n (4a), which can be readily converted into the related adduct BaTp*(I)(HMPA)2 [4b, HMPAOP(NMe2)3]. The above compounds have been characterized by analytical and spectroscopic methods, and the structures proposed have been confirmed by X-ray studies carried out with the Ba derivatives 3 and 4b. Attempts to derivatize compounds 4 led mostly to undesired products, but treatment with KTp* and KBp* [Bp*dihydrobis(3,5-dimethylpyrazolyl)borate] resulted in the formation of 3 and BaTp*Bp*(THF), 6, respectively. Bis(pyrazolyl)borate derivatives of the composition M(Bp′)2(THF)n have also been obtained by the direct reaction of MI2 (MCa, Sr, Ba) with KBp* or TlBp† [Bp†dihydrobis(3-t-butyl-pyrazolyl)borate].

Formation of 2-thienyl derivatives during the thermal activation of thiophene by Tp∗Ir(C2H4)2

Abstract The reaction of thiophene with [Tp∗Ir(C2H4)2] (Tp∗ = hydrotris(3,5-dimethylpyrazolyl)borate ligand) at 60°C results in the incorporation of three molecules of the heterocycle, two in the form of 2-thienyl fragments and the third S-coordinated to the Ir atom in its intact form, e.g. [Tp∗Ir(2-thienyl)2(SC4H4)] 2. The reactions of 2 with PMe3, CO and H2 have been investigated. The molecular structure of the binuclear hydride [ Tp ∗ Ir(H) ] 2 (μ-H)(μ -S,C-SC4H3) 6 has been determined by X-ray studies.