Heterobimetallic Metal–Amidinate Complexes by Stepwise Metalation of Methanetrisamidines

Abstract

The acidity of the four N–H groups in methanetrisamidine 1c differs significantly, thereby allowing stepwise metalation by metal organic compounds such as ZnMe2, AlMe3, and GaMe3. Dinuclear complexes 3a–c were formed under kinetic control in the reactions of 1c with 2 equiv. of the metal organic compounds at low temperatures, whereas prolonged reaction times at elevated temperature (100 °C) with 4 equiv. of ZnMe2, AlMe3, and GaMe3 yielded the corresponding tetranuclear complexes 4a–c. The different acidity of the four N–H groups also allowed the stepwise metalation of 1c by two different metal organic complexes with the formation of the heterobimetallic complexes 5a and 5b. In addition, transmetalation by Zn/Al exchange was observed in the reaction of 3c with AlMe3, yielding the corresponding dinuclear aluminium complex 3a. The complexes were characterized by NMR and IR spectroscopy and single‐crystal X‐ray diffraction (3a, 4b, 5a).

Organo-Aluminum and Zinc Acetamidinates: Preparation, Coordination Ability, and Ring-Opening Polymerization Processes of Cyclic Esters

“…As far as we know, only one example of this class of this high extended π-HN–C 2 –N′(sp 2 ) has been described by Schulz et al . Two additional methyl groups occupy the final positions around the aluminum atom, with almost equivalent Al–C bond distances [1.958(3)–1.959(3) Å].…”

Syntheses and Structures of Bis-Amidinate–Alane Complexes

“…Very recently, we synthesized methanetrisamidines of type VII [13] by hydrolysis of the corresponding tetranuclear zinc amidinate complexes {C[C(NR) 2 ZnMe] 4 } [14] and reported on their capability to form dinuclear, trinuclear and tetranuclear homometallic complexes as well as heterobimetallic tetranuclear complexes in metalation reactions with ZnMe 2 , AlMe 3 , GaMe 3 and i-Bu 2 AlH, respectively. [13,15] This document is the Accepted Manuscript version of a Published Work that appeared in final form in: Organometallics 2014, 33, 8, 2080-2087, copyright © American Chemical Society after peer review and technical editing by the publisher.…”

“…Very recently, we synthesized methanetris-amidines of type VII 13 by hydrolysis of the corresponding tetranuclear zinc amidinate complexes {C[C-(NR) 2 ZnMe] 4 } 14 and reported on their capability to form dinuclear, trinuclear, and tetranuclear homometallic complexes as well as heterobimetallic tetranuclear complexes in metalation reactions with ZnMe 2 , AlMe 3 , GaMe 3 , and i-Bu 2 AlH, respectively. 13,15 C x H 2x -bridged α,ω-bis-carbodiimides RNCN−X n −NCNR (X n = C 2 H 4 , C 3 H 6 , ...) of type VIII are of potential interest for the formation of tethered bimetallic bis-amidinate complexes, since they are more flexible in comparison to the CH 2 -and SiMe 2 -bridged systems, which is expected to be a prerequisite for cooperative effects between two metal centers.…”

Methanetrisamidines in coordination chemistry – syntheses, structures and CH–NH tautomerism

“…The capability of the C3-symmetric ligands 1a and 1b as well as that of 1c to react with metal alkyl complexes MRn and alkyl 45 metal hydrides HMRn with alkane or hydrogen elimination was demonstrated and several homometallic tri-and tetranuclear complexes such as {CH [C(Ni-Pr)2AlR2]3} (R = Me, i-Bu) were structurally characterized. [9] In addition, 1c was found to undergo stepwise deprotonation reactions with two different metal alkyl 50 complexes at different reaction temperatures, which was successfully used for the synthesis of heterometallic tetranuclear [10] Herein we report on our studies concerning the formation of coordination complexes utilizing the multiple 55 coordinative imino sites of the neutral methanetrisamidines.…”

“…9 In addition, 1c was found to undergo stepwise deprotonation reactions with two different metal alkyl complexes at different reaction temperatures, which was successfully used for the synthesis of heterometallic tetranuclear complexes {C[C(N(η 3 -Ph))N(Ph)ZnMe] 2 -[C(N(Ph)MMe 2 ) 2 ]} (M = Al, Ga). 10 Herein we report on our studies on the formation of coordination complexes utilizing the multiple coordinative imino sites of neutral methanetrisamidines.…”