Synthesis and Structure of an N₂Sb₂ Ring with Different Types of Coordination for Antimony Atoms

Abstract

18PScheme 2. Proposed binding modes for the complexation of N-CBz-gly-gly-NHBn (14) by 3c.

Dissociation of 2,4-Bis(2,4,6-tri-tert-butylphenyl)-cyclo-1,3-dipnicta-2,4-diazanes (pnict = P, As, Sb) Imposed by Substituent Steric Strain: A Cyclobutane/Olefin Analogy

“…The structural features for the new derivatives of 2 are predictably different from those N 2 P 2 heterocycles, 24 N 2 As 2 heterocycles 32,33 and N 2 Sb 2 heterocycles [34][35][36][37][38][39][40][41] involving higher coordination numbers for the pnictogen center, but are consistent with those of cyclo-1,3-diphospha(III)-2,4-diazanes, 24 cyclo-1,3-diarsa(III)-2,4-diazanes, 21,42-45 and cyclo-1,3-distiba(III)-2,4-diazanes, 21,46-51 respectively. The struc-tural features (Table 2) of all three new derivatives are surprisingly similar.…”

“…mp: 60-65 °C. FT-IR: 3520 (33), 3453(30), 3406sh-(21), 3386(11), 3095 (25), 3032(16), 2744 (29), 1768 (28), 1620(23), 1598(13), 1558 (26), 1434sh(8), 1420(4), 1393, 1361(1), 1286(14), 1265(15), 1240(6), 1216(3), 1201sh(10), 1190sh(12), 1022 (32), 928- (31), 913 (34), 880(5), 843(9), 816(19), 792(22), 769 (27), 757(18), 723 (35), 642(20), 547 (36), 466(24), 361(2), 332sh( 7 2AsCl. NEt 3 (10 mL) in Et 2 O (15 mL) was added to Mes*(H)-NAsCl 2 (1.36 g, 3.34 mmol) in Et 2 O (15 mL), producing a dark purple solution and a white precipitate.…”

“…mp: 159-164 °C (color change to red at 105 °C). FT-IR: 2624(29), 2606 (28), 2533 (43), 2499 (38), 1597(24), 1409(9), 1398(7), 1392(10), 1363(3), 1291-(22), 1262(16), 1241(14), 1201(6), 1188(12), 1175(5), 1141 (31), 1104(1), 1037 (33), 1027 (34), 947 (44), 933 (37), 912(18), 879(11), 847(2), 819 (27), 801(4), 756(17), 751(20), 731(8), 650 (39), 635-(19), 591 (32), 548(23), 539 (36), 482(21), 458 (42), 412 (35), 370-(15), 321(13), 303 (40), 293 (26), 291 (25). NMR (δ): 1 H (CD 2 Cl 2 ) 1.31 (s, 9H, p-t Bu), 1.62 (s, 18H, o-t Bu), 7.37 (s, 2H, Ar-H).…”

“…mp: remains solid above 360 °C. FT-IR: 1599-( 22), 1588 (27), 1568 (37), 1515 (33), 1424(13), 1398(18), 1367(12), 1363(11), 1312(10), 1295(6), 1269(4), 1245(5), 1229(1), 1186(7), 1182(8), 1157(0), 1109(14), 1078 (29), 1022(2), 964 (26), 942 (25), 915 (30), 879(20), 856(17), 821 (35), 804 (34), 784 (36), 765(21), 756-(23), 733(19), 704 (28), 694 (31), 670 (32), 646(16), 635(3), 576-(24), 519(15), 470 (28), 353 (39). NMR (δ): 1 H (CD 2 Cl 2 ) 1.30 (s, 9H, p-t Bu), 1.65 (s, 18H, o-t Bu), 7.41 (s, 2H, Ar-H).…”