Dinuclear Cationic Zirconium Hydrides Stabilized by the <i>N</i>,<i>N</i>-Dibenzylcyclam Ancillary Ligand

Munhá, Rui F.; Ballmann, Joachim; Veiros, Luı́s F.; Patrick, Brian O.; Fryzuk, Michael D.; Martins, Ana M.

doi:10.1021/om300504q

Cited by 15 publications

(13 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Zr−N distances (Zr− N(amido) Zr1−N1: 2.1027 (12), Zr1−N3: 2.0981(12) Å, Zr− N(amine) Zr1−N2: 2.4238 (12), Zr1−N4: 2.4324(13) Å) are in the expected range of corresponding Zr−N distances (2.038(4)−2.242(4) Å for Zr−N(amido) 9 and 2.377(4)− 2.977(1) Å for Zr−N(amine) 9 ) for polydentate ligands with amine and amido donors. The angle at α-carbon atoms C11 and C15 of 113.96 (7)°and 114.53 (7)°do not indicate any distortion, as expected for the 16-electron zirconium center. The structure of 1 compares well with that of the cationic Me 3 TACD complex [Zr(Me 3 TACD)(CH 2 SiMe 3 ) 2 ][B(3,5-C 6 H 3 Cl 2 ) 4 ] 6 and the isoelectronic neutral rare-earth metal dialkyl complex [M(Me 3 TACD)(CH 2 SiMe 3 ) 2 ] (M = Sc, 8d Y 8e ).…”

Section: ■ Introductionsupporting

confidence: 56%

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

2014

View full text Add to dashboard Cite

Hydrogenation of bis(trimethylsilylmethyl) zirconium complex [Zr(Me 2 TACD)(CH 2 SiMe 3 ) 2 ] (1), prepared by reacting [Zr(CH 2 SiMe 3 ) 4 ] with 1,7-dimethyl-1,4,7,10-tetraazacyclododecane (Me 2 TACD)H 2 , gave dinuclear alkyl hydride complex [Zr(Me 2 TACD)(CH 2 SiMe 3 ) 2 (μ-H) 2 Zr-(Me 2 TACD)] (2). According to NMR spectroscopic and single-crystal X-ray diffraction studies, 2 exhibits a C s -symmetrical structure with two distinct zirconium centers, one eight-and the other seven-coordinate, bridged by an amido donor and two hydrides. Abstraction of the trimethylsilylmethyl groups by the weak Brønsted acid [NEt 3 H][B(3,5-C 6 H 3 Cl 2 ) 4 ] gave the monocationic mono(alkyl) dihydride [Zr(Me 2 TACD)(CH 2 SiMe 3 )(μ-H) 2 Zr(Me 2 TACD)][B(3,5-C 6 H 3 Cl 2 ) 4 ] (3) and the dicationic hydride complex [Zr(Me 2 TACD)(THF) 2 (μ-H) 2 Zr(Me 2 TACD)][B(3,5-C 6 H 3 Cl 2 ) 4 ] 2 (4). X-ray crystallography of the cationic complexes 3 and 4 revealed a C s -symmetrical dinuclear structure derived from that of 2. ■ INTRODUCTIONZirconium hydride complexes are important reagents in organic synthesis, 1 reduce small molecules such as carbon monoxide, 2 and activate dinitrogen. 3 They exhibit a polarized metal hydride bond at a relatively strong Lewis acidic and oxophilic metal center that can be modulated by the ancillary ligand set. Whereas zirconocene hydrides 4 and their derivatives have been extensively used, 2a,i,3a,5 zirconium hydrides supported by hard donor ligand sets still remain relatively unexplored. They could be expected to exhibit reactivity patterns distinct from those reported for zirconocene hydrides. 6 Recently, Fryzuk, Martins, et al. have introduced dianionic macrocyclic ligands based on cyclam 7 as supporting ligands for neutral hydride complexes. 3a We have reported (di)cationic zirconium hydride complexes that contain formally monoanionic (NNNN)-type macrocyclic ligands based on cyclen. 6 Here we report the synthesis and characterization of a neutral dinuclear zirconium hydride complex stabilized by the dianionic macrocycle (Me 2 TACD) 2− derived from 1,7-dimethyl-1,4,7,10-tetraazacyclododecane, (Me 2 TACD)H 2 . This L 4 X 2 -type or 12-electron-donor ligand has previously been shown to effectively support Lewis base free rare-earth metal alkyl and hydride compounds. 8a−c ■ RESULTS AND DISCUSSION Solvent-free bis(trimethylsilylmethyl) complex 1 was prepared in good yield by reacting light-and temperature-sensitive [Zr(CH 2 SiMe 3 ) 4 ] with (Me 2 TACD)H 2 at room temperature in benzene and crystallized from pentane as relatively robust yellow crystals (Scheme 1). 1 was characterized by NMR spectroscopy and by single-crystal X-ray diffraction. The NMR spectra in benzene-d 6 are consistent with C 2v -symmetry. Both methyl groups of the Me 2 TACD ligand appear as a sharp singlet at δ 2.29 ppm, and the CH 2 CH 2 protons as multiplets of an ABCD spin pattern centered at δ 3.47, 2.41, and 2.23 ppm. The resonance for ZrCH 2 was recorded at δ 0.16 and 41.6 ppm in the 1 H and 13 C NMR spectrum, respectively.Ac...

show abstract

Section: ■ Introductionsupporting

confidence: 56%

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

2014

View full text Add to dashboard Cite

show abstract

“…Two sodium atoms bind to two aryloxide oxygen atoms and one hydride, while the other binds to one aryloxide oxygen atom and one hydride. The Zr···Zr separation of 3.2766(6) Å is significantly longer than those reported for dizirconium complexes with three μ 2 -bridging hydride ligands (3.1050(6)–3.1630(10) Å). , This elongation may be due to association of sodium cations at hydrides. The solid-state structure of 2 is not consistent with an averaged 3-fold symmetry observed in solution by NMR spectroscopy.…”

Section: Resultsmentioning

confidence: 69%

Zirconium Hydride Complex Supported by a Tetradentate Carbon-Centered Tripodal Tris(aryloxide) Ligand: Synthesis, Structure, and Reactivity

2016

View full text Add to dashboard Cite

A dizirconium trihydride complex supported by a tetradentate carbon-centered tris(aryloxide) ligand [{Na(dme)}3{(O3C)Zr}2(μ-H)3] (2; [O3C] = [(3,5-(t)Bu2-2-O-C6H2)3C](4-)) was prepared by reacting [(O3C)Zr(thf)3] (1) with NaBHEt3 in toluene. Exposure of 2 in THF to CO2 (1 atm) resulted in facile insertion of CO2 into Zr-H bonds, yielding a formate complex [{Na(thf)2}3{(O3C)Zr}2(μ-O2CH)3] (3). Treatment of 2 with P4 in toluene led to formation of [Na(thf)5][{Na(thf)2}2{(O3C)Zr}2(μ-P3)] (4) and PH3, in which hydrogenation of P4 took place. Complex 2 reacted with Me3SiN3 to afford an azide-bridged cyclotrimer [{Na(thf)2}{(O3C)ZrN3(thf)}]3 (5) with concomitant liberation of Me3SiH. The molecular structures of these complexes 2-5 have been determined by X-ray diffraction analyses.

show abstract

“…The metal is located above the macrocycle at 1.098(2) Å from the defined by the four nitrogen atoms. The Zr-Namido and the Zr-Namine bond len the expected ranges for similar bonds in hexa-coordinated Zr(IV) co 16,18,19,27,[35][36][37][38]. The Zr-Cl and Zr-O bond lengths of 2.528(3) an respectively, and the O(1)-Zr(1)-Cl(1) angle at 87.0(1)° are comparable wi complexes based on Bn2Cyclam ligands [13,14,16,18,19,27,38].…”

Section: Resultsmentioning

confidence: 65%

“…The four nitrogen atoms of the macrocycle define one rec commonly reported for other cyclam based complexes [13-16,18,19,27,3 is located above the macrocycle at 1.222(2) Å from the average plane defin In complex 12, the zirconium is coordinated to the four nitrogen atoms of the macrocycle, and to the oxygen atoms of the isopropoxido ligands in a trigonal prismatic geometry. The four nitrogen atoms of the macrocycle define one rectangular face, as commonly reported for other cyclam based complexes [13][14][15][16]18,19,27,[35][36][37][38]. The metal is located above the macrocycle at 1.222(2) Å from the average plane defined by the cyclam nitrogen atoms.…”

Section: Resultsmentioning

confidence: 74%

Synthesis and Characterization of New Cyclam-Based Zr(IV) Alkoxido Derivatives

Alves¹,

Martins

2021

Reactions

Self Cite

View full text Add to dashboard Cite

In this study, new mono- and di-alkoxido zirconium(IV) complexes supported by tetradentate dianionic cyclam ligands were synthesized and characterized. These compounds were obtained by reaction of the parent Zr(IV) dichlorido species with one or two equivalents of the corresponding lithium alkoxido, whereas (3,5-Me2Bn2Cyclam)Zr(OPh)2 was prepared by protonolysis of the orthometallated species (3,5-Me-C6H4CH2)2Cyclam)Zr with phenol. The solid-state molecular structures of (Bn2Cyclam)ZrCl(OtBu) and (4-tBuBn2Cyclam)Zr(OiPr)2 show a trigonal prismatic geometry around the metal centers. (Bn2Cyclam)Zr(SPh)(OtBu) and (Bn2Cyclam)ZrMe(OiPr) were prepared by reaction of (Bn2Cyclam)ZrCl(OR) (R = iPr, tBu) with one equivalent of LiSPh or MeMgCl, respectively. The reactions of (Bn2Cyclam)Zr(OiPr)2 and (4-tBuBn2Cyclam)Zr(OiPr)2 with carbon dioxide suggested the formation of species that correspond to the addition of four CO2 molecules.

show abstract

Dinuclear Cationic Zirconium Hydrides Stabilized by the N,N-Dibenzylcyclam Ancillary Ligand

Cited by 15 publications

References 62 publications

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

Neutral and Cationic Zirconium Hydrides Supported by a Dianionic (NNNN)-Type Macrocycle Ligand

Zirconium Hydride Complex Supported by a Tetradentate Carbon-Centered Tripodal Tris(aryloxide) Ligand: Synthesis, Structure, and Reactivity

Synthesis and Characterization of New Cyclam-Based Zr(IV) Alkoxido Derivatives

Contact Info

Product

Resources

About