Joseph Edwin

Diboryläthylenverbindungen als liganden in metallkomplexen ☆: V. Thiadiborolen-tricarbonyleisen-komplexe: darstellung, struktur- und bindungsverhältnisse

Abstract 3,4-Diethyl-1,2,5-thiadiborolenes (Ia—g, k) and Fe 2 (CO) 9 react to give stable thiadiborolenetricarbonyliron complexes (IIa—g, k). In IIa the BI function can be substituted by Me 2 NH, Et 2 O, AsF 3 and LiBH 4 to yield IIe, f, h and IIi, which leads to the synthesis of the unstable ligands 2,5-dihydro- and 2-fluoro-5-iodo 1,2,5-thiadiborolene in IIh and IIi. Rapid oxidation of IIe occurs with iodine liberating 2,5-bis(methylthio)-1,2,5-thiadiborolene, whereas IIa is only slowly attacked. From nuclear magnetic resonance ( 1 H, 11 B) and infrared spectroscopic data it is shown that the bonding situation between the ligand and the Fe(CO) 3 fragment is characteristically influenced by the Lewis acidity of the boryl group. The ligand acts as a two-electron acceptor, the complexation is accompanied by the formation of the thiadiborolene dianion. The X-ray structural-analyses of Ie and IIe exhibit a significant shortening of the BC-bond distances (0.04 A) Upon complexation of the planar 2,5-bis(dimethylamino)-1,2,5-thiadiborolene (Ie). Ie crystallizes in the space group Pccn with a = 5.6274(4) b = 14.9824(9), c = 15.921(1) A and four molecules per unit cell. The tricarbonyliron complex IIe crystallizes in the space group. P 1 with a = 9.0310(8), b = 9.7214(8), c = 11.0198(8) A, a = 74.598(8), β = 89.658(9), γ = 74.744°, and two molecules per unit cell.

Structural rearrangements in the two-electron oxidations of dimetal cyclooctatetraene compounds: structure of the 34-electron triple-decker dication

Etude faite sur les complexes (η 5 -C 5 (CH 3 ) 5 Co) 2 (cot) et (η 5 -C 3 H 5 Rh) 2 (cot) avec cot=cyclooctatetraene

Diboraethene compounds as ligands in metal complexes: XIV. Synthesis and crystal structure of bis(η5-3,4-diethyl-2,5-dimethyl-1,2,5-thiadiborolene)monocarbonyliron☆

Irradiation of a 2:1 mixture of 3,4-diethyl-2,5-dimethyl-1,2,5-thiadiborolene (I) and Fe(CO)5 produces red-violet bis(1,2,5-thiadiborolene)monocarbonyliron (V). An X-ray diffraction study shows that the latter involves a tetragonal pyramidal arrangement of the sulfur atoms (Fe-S 2.328; 2.329 A) and the groups (Fe-C 2.237, 2.241; 2.198, 2.176 A) of the non-parallel thiadiborolene rings with CO in the vertex position; the structure resembles that of bis(η4-1,3-cyclohexadiene)monocarbonyliron. The ring atom distances are B-S 1.866(4), B-C 1.531(6), and C-C 1.419(3) A. The complex crystallizes in the space group P21/n with the cell parameters a 14.877(1), b 8.9209(8), c 16.739(1) A, β 87.514(5)° and four molecules in the unit cell. Reactions of V with carbonylmetal compounds did not lead to tetra-decker complexes but to 1,2,5-thiadiborolene-tricarbonyliron (II), sandwich and triple-decker complexes. Removal of CO from V with formation of the bis(1,2,5- thiadiborolene)iron (VII) was unsuccessful.

An unusual reaction product from a 1,3-diborolene and tetracarbonylnickel. Structure of a bis(allyl)nickel complex

Abstract The bis(allyl)nickel complex (η3-3-vinyl-2,4,5,6-tetraethyl-1-oxa-2,6-diboracyclohexenyl)(η3-2,3,4,5,6-pentaethyl-1-oxa-2,6-diboracyclohexenyl)nickel(IV) is formed by initial insertion of CO from Ni(CO)4 into the five-membered 1,3-diborolene I, to give a six-membered ring. Subsequent exchange of the CHCH3 group of I for the oxygen atom of the inserted CO and migration of a hydrogen atom from the group of one ring to that of the other results in formation of the bis[1-oxa-2,6-diboracyclohexenyl]nickel, IV, having one vinyl and nine ethyl substituents. An X-ray structural analysis of IV shows the non-planarity of the C3B2O rings; the boron and oxygen atoms lie 0.4 and 0.7 A, respectively, away from the best plane through the allyl carbon atoms. IV crystallizes in the space group P21/n with a = 9.065(2), b = 16.264(3), c = 10.187(2) A, β = 104.28(1)°, and Z = 2.

Darstellung, Eigenschaften und Struktur des Cyclopentadienyl(1.3-diborolenyl)nickel-Sandwiehs [1] / Synthesis, Properties and Structure of the Cyclopentadienyl(1,3-diborolenyl)nickel Sandwich [1]

Abstract 1,3,4,5-Tetraethyl-2-methyl-1,3-diborolene (5) reacts with nickelocene and dimeric cyclopentadienylcarbonylnickel, yielding orange red 4 a, a diamagnetic nickelocene analogue. 1H and 11B NMR data indicate a sandwich structure, which is confirmed by X-ray structure analysis. The title compound crystallizes in the space group Pnma with a = 9.265(I), b = 15.1343(9), c = 12.777(2) Å and four molecules in the unit cell. All metal carbon distances are similar to those of the isoelectronic ferrocene.

Triple-decker complexes XIV. Reactions of iron carbonyls with the triple-decker sandwich complexes (η5-C5H5)Ni(μ,η5-C2B2C)M(η5-C5H5), (M = Co, Ni). Replacement of (η5-C5H5)Ni by and insertion of the Fe(CO)3 fragment into the (η5-C5H5)Ni bond☆☆☆

Abstract The reactions of Fe 2 (CO) 9 with triple-decker sandwich complexes containing the 2-methyl-1,3,4,5-tetraethyl or the 4,5-diethyl-1,3-dimethyl derivatives of the 2,3-dihydro-1,3-diborole heterocycle C 2 B 2 C ( 4a,b ) as a bridging ligand have been investigated. The paramagnetic triple-deckers, 32 valence electron (VE) [(η 5 -C 5 H 5 )-Ni(μ,η 5 -C 2 B 2 C)Co(η 5 -C 5 H 5 )] ( 8a ) and 33 VE [(η 5 -C 5 H 5 )Ni(μ,η 5 -C 2 B 2 C)Ni(η 5 -C 5 H 5 )] ( 9b ) react with Fe 2 (CO) 9 to give products resulting either from replacement of a (η 5 -C 5 H 5 )Ni fragment by Fe(CO) 3 , or insertion of Fe(CO) 3 into the (η 5 -C 5 H 5 )Ni bond. Thus, reaction of 8a with Fe 2 (CO) 9 proceeds via Fe(CO) 3 insertion into the (η 5 -C 5 H 5 )Ni bond to yield the trinuclear carbonyl-bridged complex [(η 5 -C 5 H 5 )FeCO(μ-CO) 2 Ni(μ,η 5 -C 2 B 2 C)Co(η 5 -C 5 H 5 )] ( 10a ), and subsequently the tetranuclear [{(η 5 -C 5 H 5 )Co(μ,η 5 -C 2 B 2 C)Ni(μ-CO)} 2 ] ( 12a ), and also via replacement of (η 5 -C 5 H 5 )Ni to give the triple-decker [(η 5 -C 5 H 5 )Co(μ,η 5 -C 2 B 2 C)Fe(CO) 3 ] ( 13a ). 33 VE 9b reacts with Fe 2 (CO) 9 to give initially [(η 5 -C 5 H 5 )Ni(μ,η 5 -C 2 B 2 C)Fe(CO) 3 ] ( 14b ); subsequent reactions lead to the carbonyl-bridged [(η 5 -C 5 H 5 )Fe(CO)(μ-CO) 2 Ni(μ,η 5 -C 2 B 2 C)Fe(CO) 3 ] ( 15b ), the tetra-decker [{(CO) 3 Fe(μ,η 5 -C 2 B 2 C)} 2 Ni] ( 16b ), and the triple-decker [(η 5 -C 5 H 5 )Fe(μ,η 5 -C 2 B 2 C)Fe(CO) 3 ] ( 17b ). The unsymmetrical triple-decker complexes 14a and 14b have been made independently by stacking the Ni-sandwich complexes 20a and 20b with an Fe(CO) 3 fragment. A close chemical relationship between 32 VE 8a and 20 VE nickelocene has been established, and may be rationalised by consideration of electronic structures.