Mono- and Dianionic Guanidinate Ligands. Reactivity of [ⁱPrNC(NⁱPr)₂]Ta(NMe₂)₃ and [(ⁱPrNH)C(NⁱPr)₂]TaCl(NMe₂)₃ with Me₃SiCl and ArNC (Ar = 2,6-Me₂C₆H₄)

Abstract

Reactivities of the dianionic guanidinate complex of [ i PrNdC(N i Pr) 2 ]Ta(NMe 2 ) 3 (1) and the monoanionic guanidinate complex Ta(NMe 2 ) 3 Cl[( i PrN) 2 CN(H) i Pr] (4) have been investigated. Reaction of 1 with Me 3 SiCl produced compound 2, Ta(NMe 2 ) 3 Cl[( i PrN) 2 CN-(SiMe 3 ) i Pr], which is proposed to arise from the addition of the Si-Cl bond across a Ta-N(guanidinate) bond of the starting material rather than one of the Ta-NMe 2 bonds. Complex 2 is the analogue of 4 in which H has been replaced by SiMe 3 . Derivatization of 2 was achieved by reaction with PhCH 2 MgCl to produce Ta(NMe 2 ) 3 (CH 2 Ph)[( i PrN) 2 CN-(SiMe 3 ) i Pr] (3). The single-crystal X-ray-determined structural features of 3 are reported and support the spectroscopic characterization of 3, and indirectly that of 2, by revealing a bidentate tetrasubstituted guanidinate monoanion and an η 1 -benzyl group. Complexes 1 and 4 insert 2,6-dimethylphenyl isocyanide (ArNC) to yield the structurally characterized complex Ta(NMe 5), which possesses one dianionic bidentate guanidinate ligand and two η 2 -iminocarbamoyl ligands derived from the insertion of ArNC into two of the Ta-NMe 2 bonds of the starting materials. The formally sevencoordinate Ta(V) center of 5 can be viewed as pseudo trigonal bipyramidal, with each of the η 2 -CdN linkages occupying a single coordination site. In the case of 4, the transformation of the guanidinate anion into its dianionic form was concomitant with insertion of ArNC. The sources of base for the deprotonation of the guanidinate ligand are likely the amido groups of a portion of the starting material.Supporting Information Available: Figures giving selected 1 H NMR spectra for 3 and X-ray diffraction data, including tables of atomic positions, thermal parameters, crystallographic data, and bond distances and angles and ORTEP drawings, for compounds 3 and 5. This material is available free of charge via the Internet at http://pubs.acs.org. OM991010F

New Tantalum Amido Complexes with Chelate Ligands as Metalorganic (MO) Precursors for Chemical Vapor Deposition (CVD) of Tantalum Nitride Thin Films

“…The single-crystal X-ray diffraction results (Figures 1 and 2) confirm the monomeric nature of compound 5 and its highly disordered isomer 6, and reveal distorted octahedral coordination geometries for tantalum centers with two nitrogens (N5 and N6 in 5, N1 and N1A in 6) from the chelate guanidinate ligands and two nitrogens (N2 and 35 ) were also used to conclude the absence of the potential π conjugations between the p orbital of the exocyclic nitrogens and chelate NCN fragments. However, the corresponding dihedral angle (between planes of N1;C1;N1A and C9;N5;C9 0 A) in 6 could not be accurately determined due to the presence of the extreme disorder in this structure.…”

Heterobimetallic complexes of lanthanide and lithium metals with dianionic guanidinate ligands: Syntheses, structures and catalytic activity for amidation of aldehydes with amines

“…Considering the ability to generate dianionic species by deprotonating of a second N-H bond which provides the possibility to construct a new kind of heterobimetallic complex [37], the N,N 0 ,N 00 -trialyl guanidinato ligands were chosen. While various complexes of d-block transition metals and s-block main metals with dianionic N,N 0 ,N 00 -trialyl guanidinates ligands were synthesized [37][38][39][40][41][42][43][44], no example of lanthanide metals has been reported up to date. Here we report the syntheses and molecular structures of the first heterobimetallic complexes of lanthanide and lithium metals with dianionic guanidinate ligands…”

Synthesis and Characterization of Lanthanide(III) Bis(guanidinate) Derivatives and the Catalytic Activity of Methyllanthanide Bis(guanidinate) Complexes for the Polymerization of ϵ‐Caprolactone and Methyl Methacrylate

“…As a result, guanidinates have attracted increasing attention as ancillary ligands in the coordination and organometallic chemistry of main group and transition metals,1 and some of these complexes have been reported to exhibit interesting reactivity. For example, neutral and cationic Zr IV bis(guanidinate) complexes are catalysts for the polymerization of α‐olefins,2 and mono‐ and dianionic guanidinate complexes of Ta IV and (hydrocarbyl)Zr IV bis(guanidinate) complexes react with Me 3 SiCl, ArNC,3 and 2,6‐dimethylphenyl isocyanide,4 respectively. However, the application of guanidinate ligands in organolanthanide chemistry has been quite limited; to date, only three papers concerning the synthesis and characterization of lanthanide guanidinate complexes have been published,5−7 with one of these discussing the catalytic activity of La[CyNC{N(SiMe 3 ) 2 }NCy](OC 6 H 3 t Bu 2 ‐2,6) 2 complexes for the ring‐opening polymerization of D , L ‐lactide 7…”