Protonation of magnesium and sodium complexes containing dianionic diimine ligands. Molecular structures of 1,2-bis{(2,6-diisopropylphenyl)imino}acenaphthene (dpp-BIAN), [(dph-BIAN)H2(Et2O)], and [(dpp-BIAN)HNa(Et2O)]

Abstract

Hydrolysis of magnesium complexes containing the dianionic acenaphthenediimine ligands, (dpp BIAN)Mg(thf) 3 (1), (dph BIAN)Mg(thf) 3 (2), and (dtb BIAN)Mg(thf) 2 (3) (dpp BIAN is 1,2 bis{(2,6 diisopropylphenyl)imino}acenaphthene; dph BIAN is 1,2 bis{(2 diphe nyl)imino}acenaphthene; dtb BIAN is 1,2 bis{(2,5 di tert butylphenyl)imino}acenaphthene), affords the corresponding diamines (dpp BIAN)H 2 (4), (dph BIAN)H 2 (Et 2 O) (5), and (dtb BIAN)H 2 (6). Compounds 4 and 5 were isolated in the crystalline state and characterized by UV-Vis, IR, and 1 H NMR spectroscopy. Partial hydrolysis of (dpp BIAN)Na 2 (Et 2 O) 3 gave the crystalline (dpp BIAN)HNa(Et 2 O) 2 complex (7), which was also characterized by spectroscopic methods. The structures of compounds 5 and 7 and free diimine dpp BIAN were established by X ray diffraction analysis.Recently, 1,2 we have synthesized alkali and alkaline earth metal complexes with various reduced forms of 1,2 bis[(2,6 diisopropylphenyl)imino]acenaphthene (dpp BIAN). In solvating solvents, alkali metals (Li, Na) successively reduce dpp BIAN to the mono , di , tri , and tetraanions M + n (dpp BIAN) n-(M = Li, Na; n = 1, 2, 3, or 4). Reduction of dpp BIAN with metallic mag nesium or calcium in THF affords exclusively com plexes with the dpp BIAN dianion of composition (dpp BIAN) 2-M 2+ (thf) n (M = Mg, n = 3; M = Ca, n = 4). 3 We have also synthesized 4 two new ligands of this type, viz., 1,2 bis[(2,5 di tert butylphenyl)imino]ace naphthene (dtb BIAN) and 1,2 bis[(2 diphenyl)imi no]acenaphthene (dph BIAN), as well as their magne sium and calcium derivatives (dtb BIAN) 2-Mg 2+ (thf) 2 and (dph BIAN) 2-M 2+ L n (M = Mg, L = DME, n = 2; M = Ca, L = thf, n = 3).Investigation of the reactions of the (dpp BIAN)Mg(thf) 3 complex (1) with a series of organic compounds revealed their specific reactivity. For example, compound 1 reduces diphenyl ketone, resulting in oxida tion of the dpp BIAN dication to the radical anion and the formation of pinacolate [(dpp BIAN)Mg(thf)] 2 [µ O 2 C 2 Ph 4 ], whereas the reaction of 1 with 9(10H ) anthra cenone is accompanied by deprotonation of the phenol tautomer to form the anthryl 9 oxy derivative (dpp BIAN)Mg(OC 14 H 9 )(thf) 2 . 5 The reactions of com plex 1 with halogen containing inorganic (CuCl, SiCl 4 , I 2 ) and organic (Ph 3 SnCl, 1,2 dibromo 1,2 diphenylethane) compounds also lead to oxidation of the dpp BIAN dianion to the radical anion and the formation of the unsymmetrical [(dpp BIAN)Mg(µ X)(thf)] 2 (X = Cl, Br) and (dpp BIAN)MgI(DME) complexes. 6 The reactions of complex 1 with Me 3 SiCl and Me 2 NCH 2 CH 2 Cl re

Sodium Cation Migration Above the Diimine π‐System of Solvent Coordinated dpp‐BIAN Sodium Aluminum Complexes (dpp‐BIAN=1,2‐Bis[(2,6‐diisopropylphenyl)imino]acenaphthene)

“…Fur- (4) 2.914(6) 2.793(5) Na(1)ÀC (5) 2.871(5) 2.832(5) Na(1)ÀC (6) 3.013(4) 2.792(6) 2.847(5) Na(1)ÀC (7) 2.785(4) 2.729(6) 2.832(5) Na(1)ÀC (8) 2.910(4) 2.795(11) 2.793(5) Na(1)ÀC (16) 2.728(4) Na(1)ÀO (1) 2.325(4) 2.230(3) Na(1)ÀO (2) 2.308(4) Na (1) bonds in free dpp-BIAN (both C À N 1.282(4), C(1) À C(2) 1.534(6) ). [15] 3) In all five complexes different Al À CH 3 distances are observed. We suggest that the elongation of the C(37)ÀAl bond (1: 1.991(4); 2: 2.004(4); 3: 2.000(4); 4: 1.990(3); 5: 2.010(4) ) relative to the C(38)ÀAl bond (1: 1.977(4); 2: 1.947(4); 3: 1.962(4); 4: 1.951(4); 5: 1.959(4) ) is caused by interaction of the C(37) atoms with sodium cations.…”

Electron Release and Proton Acceptance Reactions of (dpp-BIAN)Mg(THF)3

“…On the other hand, the C(1)-C(2) bond length should decrease in the same order. In agreement with the expectations, the C-N bonds of 2 (C (1)-N(1) 1.340(6), C(2)-N(2) 1.332(5)Å) and 4 (C (1)-N(1) 1.337(3), C(2)-N(2) 1.336(3), C(37)-N(3) 1.338(3), C(38)-N(4) 1.339(3)Å) containing radical anionic dpp-BIAN are longer than in free dpp-BIAN (both 1.282(4)Å) [14], but shorter than in 1 (1.401(6) and 1.378(7)Å) [4]. Concerning the C-C bonds within the metallacycles it is to note that the C(1)-C(2) bond in 3 (1.403(3)Å) is shortened compared to the corresponding bonds in 2 (1.441(3)Å) and 4 (1.440(3) and 1.448(3)Å) showing a value close to that of the dpp-BIAN dianion in 1 (1.389 (7) …”

Aluminum complexes with mono-and dianionic diimine ligands

“…24 The IR spectrum of compound 1 shows absorption bands of coordinated tetrahydrofuran (1025 and 874 cm -1 ), which is eliminated upon heating to 105 °C. Dissolution of compound 1, which was isolated in the crystalline state, in THF or benzene results in its decomposition to form unidentified products.…”