John N. Bridson

Synthesis, structure and reactivity of bidentate 2-ketopyrrolyl cobalt(III) phosphonates and phosphinates

Abstract Bidentate N,O complexes (η5-C5R5)Co(R′C(O)-C4H3N)(I) (3) are prepared by treating in situ produced 2-acryl-pyrrolyl anion (R′C(O)-C4H3N−, 2α,β; α (R′H), β (R′ Me)) with ( η 5 - C 5 R 5 ) Co(CO) ( 1 ) 2 (1a,b;a (RH), b (RMe)) in THF. Reaction of 3 with P-donor ligands (PMe3, P(OMe)3 and PPh(OMe)2) results in simple halide substitution to give [(η5-C5R5)Co(R′C(O)-C4H3N) (P-donor)]+I− (4–6). The PMe3 product (4) is readily isolated, however facile Arbuzov dealkylation of the phosphite (5) and phosphonite (6) salts gives dimethyl phosphonates, (η5-C5R5)Co(R′C(O)-C4H3N)(P(O)(OMe)2) (7), and mixtures of diastereomeric methyl phenylphosphinates, (η5-C5R5)(Co(R′C(O)-C4H3N)(P(O)Ph(OMe)) (8), respectively. Intermediate phosphite and phosphonite complexes [(η5-C5R5)Co(R′C(O)-C4H3N)(PR″=OMe, Ph) were directly observed by 1H NMR in acetone-d6 at room temperature in several cases. The molecular structures of complexes 3bβ and 7bβ were determined by X-ray diffraction 3bβ crystallizes in the orthorhombic system with a = 16.809(3), b = 13.755(5), c = 7.535(2) A 3 , Z = 4 . Although the coordination geometry of 3bβ was determined, disorder problems in the selected crystal prevented refinement of the diffraction data to give meaningful structural parameters. 7bβ crystallizes in the monoclinic system, space group P21/c (No. 14) with a = 12.183(1), b = 10.100(2), c = 16.915(2) A , β = 106.559(9)°, V = 1995.1(4) A 3 , Z = 4 and R = 0.036 (R w = 0.039 ) for 2716 reflections with 1 > 3.00σ(1). Conformation preferences for metallophosphonates and phosphinates 7 and 8, determined from solid state and solution (1H nOed) data, are analyzed using molecular modeling (MM+) and extended Huckel calculations.

Synthesis, characterization, crystal structure, and solution conformation of (−)436-(SCo,SC)-(η5-C9H7)Co★(C3F7)I(Ph2PNHC★H(CH3)Ph, an easily resolvable chiral-at-metal complex

Abstract A convenient method for the preparation and resolution of (−) 436 -( S Co ,S C )-(η 5 -C 9 H 7 )Co★(C 3 F 7 )I(Ph 2 PNHC★H(CH) 3 Ph) ( 2a ) from racemic (η 5 -C 9 H 7 )CO★(C 3 F 7 )(CO)I with an optical yield > 99% is described. The absolute configuration of 2a was determined by crystallography. (−) 436 - 2a crystallizes in the space group P 2 1 2 1 2 1 with a = 16.362(1), b = 19.944(4), c = 9.417(2) A, V = 3073.0(8) A 3 , Z = 4, R = 0.071, R w = 0.064.