Synthesis and Complexation Study of New Aminoalkynyl−amidinate Ligands

Affiliation
Chemisches Institut Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Wang, Sida;
ORCID
0000-0002-4660-1691
Affiliation
Chemisches Institut Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Liebing, Phil;
Affiliation
Chemisches Institut Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Engelhardt, Felix;
Affiliation
Chemisches Institut Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Hilfert, Liane;
Affiliation
Chemisches Institut Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Busse, Sabine;
ORCID
0000-0001-8296-2331
Affiliation
Institut für Physik Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Goldhahn, Rüdiger;
ORCID
0000-0001-5209-0018
Affiliation
Institut für Physik Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany
Edelmann, Frank T.

Abstract The current library of amidinate ligands has been extended by the synthesis of two novel dimethylamino‐substituted alkynylamidinate anions of the composition [Me 2 N−CH 2 −C≡C−C(NR) 2 ] − (R = i Pr, cyclohexyl (Cy)). The unsolvated lithium derivatives Li[Me 2 N−CH 2 −C≡C−C(NR) 2 ] ( 1 : R = i Pr, 2 : R = Cy) were obtained in good yields by treatment of in situ‐ prepared Me 2 N−CH 2 −C≡C−Li with the respective carbodiimides, R−N=C=N−R. Recrystallization of 1 and 2 from THF afforded the crystalline THF adducts Li[Me 2 N−CH 2 −C≡C−C(NR) 2 ] ⋅  n THF ( 1 a : R = i Pr, n =1; 2 a : R = Cy, n =1.5). Precursor 2 was subsequently used to study initial complexation reactions with selected di‐ and trivalent transition metals. The dark red homoleptic vanadium(III) tris(alkynylamidinate) complex V[Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 3 ( 3 ) was prepared by reaction of VCl 3 (THF) 3 with 3 equiv. of 2 (75 % yield). A salt‐metathesis reaction of 2 with anhydrous FeCl 2 in a molar ratio of 2 : 1 afforded the dinuclear homoleptic iron(II) alkynylamidinate complex Fe 2 [Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 4 ( 4 ) in 69 % isolated yield. Similarly, treatment of Mo 2 (OAc) 4 with 3 or 4 equiv. of 2 provided the dinuclear, heteroleptic molybdenum(II) amidinate complex Mo 2 (OAc)[Me 2 N−CH 2 −C≡C−C(NCy) 2 ] 3 ( 5 ; yellow crystals, 50 % isolated yield). The cyclohexyl‐substituted title compounds 2 a , 4 , and 5 were structurally characterized through single‐crystal X‐ray diffraction studies.

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