The Transition Metal Chemistry of PGeP and PSnP Pincer Heavier Tetrylenes

Abstract

This review article collects and discusses the syntheses of the currently known metal‐free heavier tetrylenes having a PEP pincer topology (E = tetrel atom) as well as their transition metal derivative chemistry. To date, only five PGeP germylenes and two PSnP stannylenes have been isolated. These compounds have been successfully synthesized by treating GeCl2(diox) (diox = 1,4‐dioxane), GeCl2(NHC) (NHC = N‐heterocyclic carbene) or SnCl2 with two equivalents of an appropriate lithiated phosphine. Their transition metal chemistry is dominated by processes in which, in addition to the coordination of one or both phosphane groups, the E atom ends inserted into M–M or M–X (X = anionic group) bonds. Only in a few occasions a simple coordination of the tetrylene fragment (as a neutral two‐electron‐donor ligand) has been observed. The structural and bonding characteristics of the metal‐free PEP tetrylenes and of relevant examples of their transition metal derivatives are also surveyed.

Phenyldiquinolinylarsine as a Nitrogen‐Arsenic‐Nitrogen Pincer Ligand

“…For further diversity of pincer ligands, various elements, e.g., boron and silicon, have been introduced so far. Moreover, incorporation of heavy elements is an emerging strategy toward new class of pincer ligands . Germylenes (Figure a) and stannylenes (Figure b), being analogues of carbene, are used for phosphorus‐germanium‐phosphorus and phosphorus‐tin‐phosphorus pincer ligands, respectively.…”

Dipyrromethane‐Based PGeP Pincer Methylgermyl and Methoxidogermyl Nickel and Palladium Complexes

“…The recent availability of metal-free PGeP germylenes (Figure 1) [1][2][3][4][5][6][7][8] has allowed an advance of the coordination chemistry of PGeP pincer complexes. [1] In fact, some of these germylenes have already led to transition metal (TM) complexes containing either PGeP pincer germylene ligands (just by simple coordination) [7,8] or PGeP pincer germyl ligands (by insertion of the Ge atom into an MÀ Cl bond of the metal precursor).…”

“…The recent availability of metal-free PGeP germylenes (Figure 1) [1][2][3][4][5][6][7][8] has allowed an advance of the coordination chemistry of PGeP pincer complexes. [1] In fact, some of these germylenes have already led to transition metal (TM) complexes containing either PGeP pincer germylene ligands (just by simple coordination) [7,8] or PGeP pincer germyl ligands (by insertion of the Ge atom into an MÀ Cl bond of the metal precursor). [2][3][4][8][9][10][11] A few PGeP pincer germyl metal complexes were already known before the appearance of metal-free PGeP germylenes, but the strategy used for their syntheses is not of general applicability because it involves the formation of a GeÀ M bond from a GeÀ C, [12,13] GeÀ H, [13,14] GeÀ Cl [15] or GeÀ F [16] bond of a germane fragment.…”

“…, 47.17; H, 6.85; N, 4.23; found: C, 47.21; H, 6.93; N 4.17. 1 H NMR (C 6 D 6 , 400.1 MHz, 298 K): δ 6.33 (s, 2 H, 2 CH of 2 pyrrole), 6.15 (s, 2 H, 2 CH of 2 pyrrole), 2.95 (d, J H-H = 14.6 Hz, 2 H, 2 CH of 2 CH 2 P), 2.59 (m, 2 H, 2 CH of 2 CHMe 2 ), 2.53 (d, J H-H = 14.6 Hz, 2 H, 2 CH of 2 CH 2 P), 2.21 (m, 2 H, 2 CH of 2 CHMe 2 ), 1.89 (s, 3 H, 1 CH 3 of CMe 2 ), 1.66 (s, 3 H, 1 CH 3 of CMe 2 ),1.32 (dd, J H-P = 14.0 Hz, J H-H = 6.0 Hz, 6 H, 2 CH 3 of 2 CHMe 2 ), 1.13 (dd, J H-P = 14.0 Hz, J H-H = 6.0 Hz, 6 H, 2 CH 3 of CHMe 2 ), 0.98 (s, 3 H, CH 3 of GeMe), 0.88 (dd, J H-P = 14.0 Hz, J H-H = 6.0 Hz, 6 H, 2 CH 3 of 2 CHMe 2 ), 0.77 (dd, J H-P = 14.0 Hz, J H-H = 6.0 Hz, 6 H, 2 CH 3 of 2 CHMe 2 ) ppm 13. C{ 1 H} NMR (C 6 D 6 , 100.6 MHz, 298 K): δ 144.8 (s, 2 C of 2 pyrrole), 109.0 (s, 2 CH of 2 pyrrole), 104.3 (s, 2 CH of 2 pyrrole), 39.6 (s, 1 CH 3 of CMe 2 ), 36.9 (s, CMe 2 ), 27.3 (vt, J C-P = 11.6 Hz, 2 CH of 2 CHMe 2 ), 26.0 (s, 1 CH 3 of CMe 2 ), 24.8 (vt, J C-P = 11.6 Hz, 2 CH of 2 CHMe 2 ), 20.1-19.8 (m, 2 CH 2 P + 4 CH 3 of 4 CHMe 2 ), 18.3 (s, 2 CH 3 of 2 CHMe 2 ), 17.8 (s, 2 CH 3 of 2 CHMe 2 ), 11.3 (t, J C-P = 4.4 Hz, CH 3 of GeMe) ppm.…”

NON‐Ligated N‐Heterocyclic Tetrylenes

“…They showed as well that PEP pincer 2-germaand 2-stannabenzimidazol-2-ylidenes undergo insertion reactions with various group 9-11 metal halides (one example (C) is shown in Scheme 1). [12] The NON ligand (NON = 4,5-bis(2,6-diisopropylphenylamino)-2,7-di-tert-butyl-9,9-dimethylxanthene) has been employed in some actinide, yttrium, and zirconium complexes. [13] In main group chemistry, however, fewer examples are known.…”