Tripodal Amido Ligands Containing an "Active" Ligand Periphery

Memmler, Harald; Walsh, K. J.; Gade, Lutz H.; Lauher, Joseph W.

doi:10.1021/ic00120a009

Cited by 74 publications

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“…No cross-over products indicating the exchange of complex fragments were detected. 2.560(7) in 9 a is very similar to that of 2.535(5) previously found in the dichloro starting material 2 a, [13] and although in 12 this distance is rather longer [Zr´´´F(3) 2.70(1) ], being closer to that in 2 b [2.647 ], the interaction appears bonding in both insertion compounds. As in 2 b (vide supra), the coordinating fluorophenyl ring is apparently being forced over to facilitate chelation [N(3)-C(31)-C(32) 125.1(8) and 124(1)8, and N(3)-C(31-C(36) 114.8(8) and 116(1)8 in 9 a and 12, respectively].…”

Section: Resultssupporting

confidence: 81%

“…Insertion of polar unsaturated organic substrates into the polar metal ± metal bonds. reaction products are supported by the analytical data as well as the 1 H, 13 C, 29 Si, 19 F NMR and infrared spectrocopic data. Their most remarkable spectroscopic feature is the .…”

Section: Resultsmentioning

confidence: 55%

“…As in the monofluorophenyl analogue 2 a, the coordination at the central zirconium atom may be described as highly distorted octahedral with three amido-nitrogen atoms in facial sites [ZrÀN 2.052(6) ± 2.119(6) ], two bridging chloro ligands [Zr-Cl(1) 2.575(2) and ZrÀCl(2) 2.529(2) ] and with the sixth site being occupied by the ortho-fluorine atom of one of the phenyl groups. The Zr´´´F(3) bond lengths of 2.647(5) is slightly longer than the corresponding bond length of 2.535(5) observed in 2 a and that of 2.511(2) in the related compound [MeSi{SiMe 2 N(2-FC 6 H 4 )} 3 Zr(mCl) 2 Li(OEt 2 ) 2 ]; [13,14,16] however, considerable bonding character is indicated by the extent to which the phenyl ring is forced over to allow this chelate ring formation, giving a N(3)-C(31)-C(36) intra-chelate angle of 114.6(4)8 compared with 125.3(4)8 for N(3)-C(31)-C(32).…”

Section: Resultsmentioning

confidence: 71%

“…[13,14] Whether this is due to the influence which the substituents have on the electronic properties of the amido Ndonor functions or a consequence of the participation of the fluorophenyl groups in the coordination to the metal cannot be generally distinguished. In the heterodinuclear complexes described in this work the previously reported ligand system derived from HC{SiMe 2 N(2-FC 6 H 4 )} 3 (1 a) [13] has been employed as well as the novel trifluorinated compound HC{Si-Me 2 N(2,3,4-F 3 C 6 H 2 )} 3 (1 b), which was synthesized by an analogous route. Stabilization of early transition metal amido complexes by fluorinated aryl substituents has also been reported by Schrock and co-workers, who synthesized a series of pentafluorophenyl-substituted amido compounds.…”

Section: Resultsmentioning

confidence: 99%

“…[8] Reaction of 3 and 6 with methyl isonitrile leads to similar types of products, [HC{SiMe 2 N(2-FC 6 H 4 )} 3 Zr(h 2 -C(NMe)-FeCp(CO) 2 ] (7 a) and [HC{SiMe 2 N(2,3,4-F 3 C 6 H 2 )} 3 Zr(h 2 -C-(NMe)RuCp(CO) 2 ] (7 b) (see Scheme 3 later). However, these are thermally unstable and could only be characterized NMR spectrocopically in solution below 260 K. The characteristic 13 C NMR chemical shift of the resonance attributable to the carbon atom inserted between the two metals (7 a: d 280.8; 7 b: d 275.9), and the clean set of resonances attributable to the relevant molecular fragments indicate its selective formation.…”

Section: Resultsmentioning

confidence: 99%

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Cooperative Reactivity of Early-Late Heterodinuclear Transition Metal Complexes with Polar Organic Substrates

et al. 2000

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A comprehensive investigation into the cooperative reactivity of two chemically complementary metal-complex fragments in early-late heterodinuclear complexes has been carried out. Reaction of the partially fluorinated tripodal amidozirconium complexes [HC-(SiMe2NR)3Zr(mu-Cl)2Li(OEt2)2] (R = 2-FC6H4: 2a, 2,3,4-F3C6H4: 2b) with K[CpM(CO)2] (M=Fe, Ru) afforded the stable metal-metal bonded heterodinuclear complexes [HC[SiMe2NR]3-Zr-MCp(CO)2] (3-6). Reaction of the dinuclear complexes with methyl isonitrile as well as the heteroallenes CO2, CS2, RNCO and RNCS led to insertion into the polar metal-metal bond. Two of these complexes, [HC[SiMe2N(2-FC6-H4)]3Zr(S2C)Fe(CO)2Cp] (9a) and [HC-[SiMe2N(2-FC2H4)]3Zr-(SCNPh)Fe(CO)2-Cp] (12), have been structurally characterized by a single crystal X-ray structure analysis, proving the structural situation of the inserted substrate as a bridging ligand between the early and late transition metal centre. The reactivity towards organic carbonyl derivatives proved to be varied. Reaction of the heterobimetallic complexes with benzyl and ethylbenzoate led to the cleavage of the ester generating the respective alkoxozirconium complexes [HC[SiMe2N(2-FC6H4)]3ZrOR] (R = Ph-CH2: 13a, Et: 13b) along with [CpFe-[C(O)Ph](CO)2], whereas the analogous reaction with ethyl formate gave 13b along with [CpFeH(CO)2]; this latter complex results from the instability of the formyliron species initially formed. Aryl aldehydes were found to react with the Zr-M complexes according to a Cannizzaro disproportionation pattern yielding the aroyliron and ruthenium complexes along with the respective benzoxyzirconium species. The transfer of the aldehyde hydrogen atom in the course of the reaction was established in a deuteriation experiment. [HC[SiMe2-N(2-FC6H4)]3Zr-M(CO)2Cp] reacted with lactones to give the ring-opened species containing an alkoxozirconium and an acyliron or acylruthenium fragment; the latter binds to the early transition metal centre through the acyl oxygen atom, as evidenced from the unusuallly low-field shifted 13C NMR resonances of the RC(O)M units. Ketones containing a-CH units react with the Zr-Fe complexes cooperatively to yield the aldol coupling products coordinated to the zirconium complex fragment along with the hydridoiron compound [CpFeH(CO)2], whereas 1,2-diphenylcyclopropenone underwent an oxygen transfer from the keto group to a CO ligand to give a linking CO2 unit and a cyclopropenylidene ligand coordinated to the iron fragment in [HC-[Si(CH3)2N(2,3,4-F3C6H2)]3Zr(mu-O2C)-Fe(CO)[C3Ph2)Cp] (19). The atom transfer was established by 17O and 13C labelling studies. Similar oxygen-transfer processes were observed in the reactions with pyridine N-oxide, dimethylsulfoxide and methylphenylsulfoxide.

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 55%

Section: Resultsmentioning

confidence: 71%