Synthesis of NPN-Coordinated Tantalum Alkyl Complexes and Their Hydrogenolysis: Isolation of a Terminal Tantalum Hydride Incorporating a Doubly Cyclometalated NPN Scaffold.

Title Synthesis of NPN-Coordinated Tantalum Alkyl Complexes and Their Hydrogenolysis: Isolation of a Terminal Tantalum Hydride Incorporating a Doubly Cyclometalated NPN Scaffold.
Authors S. Batke; M. Sietzen; H. Wadepohl; J. Ballmann
Journal Inorg Chem
DOI 10.1021/acs.inorgchem.7b00277
Abstract

The closely related benzylene-linked diaminophosphines PhP(CH2C6H4-o-NHPh)2 (AH2) and PhP(C6H4-o-CH2NHXyl)2 (BH2 with Xyl = 3,5-Me2C6H3) were employed for the synthesis of tantalum(V) alkyls, which were then studied with respect to hydrogenolysis. In the case of AH2, the tantalum trimethyl complex [Ta(A)Me3] (1) and the tantalum hydrocarbyl complex [Ta(A)(CH2SiMe3)(?(2)-EtC?CEt)] (2) were prepared from the ligand's dilithium salt (A)Li2(diox). Upon hydrogenolysis of 1 and 2, the formation of methane and SiMe4, respectively, was observed, but well-defined tantalum hydrides could not be detected. In the case of BH2, the cyclometalated species [Ta(B*)(NMe2)2] (3 with B* = ?(4)-N,P,N,C-(PhP(C6H4-o-CH2NXyl)(C6H4-o-CHNXyl))(3-)) was isolated and converted to the corresponding diiodo species [Ta(B*)I2] (4). Treatment of 4 with LiCH2SiMe3 resulted in the isolation of the corresponding dialkyl complex [Ta(B*)(CH2SiMe3)2] (5), which was converted to the doubly cyclometalated monoalkyl complexes [Ta(B**)(CH2SiMe3)(PMe3)] (6 with B** = ?(5)-C,N,P,N,C-(PhP(C6H4-o-CHNXyl)2)(4-)) and [Ta(B**)(CH2SiMe3)(dmpe)] (7) via reaction with PMe3 and dmpe, respectively. In contrast to 5 and 6, 7 was found to react cleanly with dihydrogen to afford the corresponding terminal tantalum(V) hydride [Ta(B**)(H)(dmpe)] (8). Upon reaction of 7 with D2, the deuteride [Ta(d2-B**)(D)(dmpe)] (9) was obtained and found to contain deuterium atoms in the methine positions of both tantalaaziridine subunits. The partially deuterated derivatives [Ta(B**)(D)(dmpe)] (10) and [Ta(d2-B**)(H)(dmpe)] (11) were generated via reaction of 8 and 9 with PhSiD3 and PhSiH3, respectively. Prior to the addition of gaseous D2 or H2, no H/D scrambling was observed in 10 or 11, indicating that the exchange of the methine positions proceeds via addition of D2 or H2 across the tantalaaziridine Ta-C bonds.

Citation S. Batke; M. Sietzen; H. Wadepohl; J. Ballmann.Synthesis of NPN-Coordinated Tantalum Alkyl Complexes and Their Hydrogenolysis: Isolation of a Terminal Tantalum Hydride Incorporating a Doubly Cyclometalated NPN Scaffold.. Inorg Chem. 2017;56(9):51225134. doi:10.1021/acs.inorgchem.7b00277

Related Elements

Tantalum

See more Tantalum products. Tantalum (atomic symbol: Ta, atomic number: 73) is a Block D, Group 5, Period 6 element with an atomic weight of 180.94788. Tantalum Bohr ModelThe number of electrons in each of tantalum's shells is [2, 8, 18, 32, 11, 2] and its electron configuration is [Xe] 4f14 5d3 6s2. The tantalum atom has a radius of 146 pm and a Van der Waals radius of 217 pm. High Purity (99.999%) Tantalum (Ta) MetalTantalum was first discovered by Anders G. Ekeberg in 1802 in Uppsala, Sweden however, it was not until 1844 when Heinrich Rose first recognized it as a distinct element. In its elemental form, tantalum has a grayish blue appearance. Tantalum is found in the minerals tantalite, microlite, wodginite, euxenite, and polycrase. Due to the close relation of tantalum to niobium in the periodic table, Tantalum's name originates from the Greek word Tantalos meaning Father of Niobe in Greek mythology.

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