Preparation and X-ray Structures of Alkali-Metal Derivatives of the Ambidentate Anions [^tBuN(E)P(μ-N^tBu)₂P(E)N^tBu]^2- (E = S, Se) and [^tBuN(Se)P(μ-N^tBu)₂PN(H)^tBu)]^-

Abstract

The ambidentate dianions [tBuN(E)P(μ-NtBu)2P(E)NtBu]2- (5a, E = S; 5b, E = Se) are obtained as their disodium and dipotassium salts by the reaction of cis-[tBu(H)N(E)P(μ-NtBu)2P(E)N(H)tBu] (6a, E = S; 6b, E = Se), with 2 equiv of MN(SiMe3)2 (M = Na, K) in THF at 23 °C. The corresponding dilithium derivative is prepared by reacting 6a with 2 equiv of tBuLi in THF at reflux. The X-ray structures of five complexes of the type [(THF) x M]2[tBuN(E)P(μ-NtBu)2P(E)NtBu] (9, M = Li, E = S, x = 2; 11a/11b, M = Na, E = S/Se, x = 2; 12a, M = K, E = S, x = 1; 12b, M = K, E = Se, x = 1.5) have been determined. In the dilithiated derivative 9 the dianion 5a adopts a bis (N,S)-chelated bonding mode involving four-membered LiNPS rings whereas 11a,b and 12a,b display a preference for the formation of six-membered MNPNPN and MEPNPE rings, i.e., (N,N ‘ and E,E ‘)-chelation. The bis-solvated disodium complexes 11a,b and the dilithium complex 9 are monomeric, but the dipotassium complexes 12a,b form dimers with a central K2E2 ring and associate further through weak K···E contacts to give an infinite polymeric network of 20-membered K6E6P4N4 rings. The monoanions [tBu(H)N(E)P(μ-NtBu)2P(E)NtBu)]- (E = S, Se) were obtained as their lithium derivatives 8a and 8b by the reaction of 1 equiv of nBuLi with 6a and 6b, respectively. An X-ray structure of the TMEDA-solvated complex 8a and the 31P NMR spectrum of 8b indicate a N,E coordination mode. The reaction of 6b with excess tBuLi in THF at reflux results in partial deselenation to give the monolithiated P(III)/P(V) complex {(THF)2Li[tBuN(Se)P(μ-NtBu)2PN(H)tBu]} 10, which adopts a (N,Se) bonding mode.

Syntheses and crystal structures of mono- and bi-metallic zinc compounds of symmetrically- and asymmetrically-substituted bis(amino)cyclodiphosph(V)azanes

“…These ambidentate ligands chelate metal moieties as bis(amido) (N ,N 0 ) ligands above the heterocycle (B) [7] as bis(chalcogenido) (E,E 0 ) ligands below the heterocycles (C) [8], or as a combination of both, namely as bis(amido)/bis(chalcogenido) ligands, i.e., N ,N 0 and E,E 0 (D) [9,10]. The, thus far, most common coordination mode observed, however, is one in which the metal ions are coordinated laterally, similar to aminophosphoranes in either a monoanionic (N ,E) (E) [11,12] or a dianionic (N ,E)/ (N 0 ,E 0 ) (F) fashion [10,13].…”

“…These ambidentate ligands chelate metal moieties as bis(amido) (N ,N 0 ) ligands above the heterocycle (B) [7] as bis(chalcogenido) (E,E 0 ) ligands below the heterocycles (C) [8], or as a combination of both, namely as bis(amido)/bis(chalcogenido) ligands, i.e., N ,N 0 and E,E 0 (D) [9,10]. The, thus far, most common coordination mode observed, however, is one in which the metal ions are coordinated laterally, similar to aminophosphoranes in either a monoanionic (N ,E) (E) [11,12] or a dianionic (N ,E)/ (N 0 ,E 0 ) (F) fashion [10,13]. A unique combination of facial and lateral coordination modes was reported by Chivers et al [14,15] for the dilithio salt G. But most of these reactions were done with different cyclodiphosph(V)azanes, in different solvents, at different temperatures and with a variety of metallating agents, even for the same metal, thereby clouding the role of the ligand on the outcomes of these reactions.…”

The Selenium‐Based Hexameric Macrocycle [(Se)P(μ‐NtBu)2P(μ‐Se)]6

“…Evidence of the resulting presence of alternate P III and P V centers within the backbone of 2 is seen in the roomtemperature 31 P{ 1 H} NMR spectrum in toluene, which shows P III (d, d = 206.8 ppm) and P V centers (d, d = 54.4 ppm) that are coupled to each other with a coupling constant that is typical of a P-(m-NR)-P bridge ( 2 J31 P-31 P = 44 Hz). [8] This spectrum can be compared to that of the precursor 1, which shows two singlet resonances in the P V region only, for the cis (d = 22.1 ppm, major) and trans (d = 22.7 ppm, minor) isomers (together with 77 Se satellites attributed to the AA'X isotopomer containing one 77 Se atom (I = 1/2, 7.6 %)).[8] The structural characterization of 1 [9] also strongly supports the presence of isomers in a maximum ratio cis/trans of 7:1 (3:1 according to the relative integration of the 1 H, 31 P, and 77 Se NMR spectra). This situation contrasts with previous studies of the dimers [R(H)N(Se=)P(m-NtBu)] 2 , which show the presence exclusively of the cis isomer.…”

“…[8] This spectrum can be compared to that of the precursor 1, which shows two singlet resonances in the P V region only, for the cis (d = 22.1 ppm, major) and trans (d = 22.7 ppm, minor) isomers (together with 77 Se satellites attributed to the AA'X isotopomer containing one 77 Se atom (I = 1/2, 7.6 %)). [8] The structural characterization of 1…”

“…This situation contrasts with previous studies of the dimers [R(H)N(Se=)P(m-NtBu)] 2 , which show the presence exclusively of the cis isomer. [8] The greater proportion of the cis isomer of 1 over the trans may have an influence on the formation of a macrocyclic (rather than oligomeric or polymeric) product. [1,3,4] Owing to the low solubility of the macrocycle 2 in organic solvents (such as CHCl 3 , toluene, and THF), further elucidation of the chemical environments and bonding of the Se atoms in its macrocyclic backbone using 77 Se NMR spectroscopy was not possible.…”