Synthesis and molecular structure of [Re2(μ:η6-C24H18N4)(CO)6] containing the rtct-tetrakis(2-pyridyl)cyclobutandiyl ligand, derived from the reaction of [Re2(CO)8(MeCN)2] and 1,2-bis(2-pyridyl)ethene

Dirhenium carbonyl complexes bearing 2-vinylpyridine, morpholine and 1-methylimidazole ligands

“…An asymmetric triangle is formed by C(9), C(10) and Re(2) atoms [Re(2)-C(9) = 2.325(5), Re(2)-C(10) = 2.287(4) Å ], and as a consequence of the g 2 -coordination of the ethylenic moiety; the distance C(9)-C(10) [1.418(6) Å ] closely resembles to that observed for the corresponding distance of 1.38(2) Å in [Re 2 (CO) 8 (l-g 3 -C 12 H 10 N 2 )] and is longer than an uncoordinated C-C double bond lengths [4]. The formation of 1 from [Re 2 (CO) 8 (MeCN) 2 ] and 2-vinylpyridine simply requires displacement of the two acetonitrile ligands.…”

“…The two morpholine ligands are coordinated through the ''amino'' nitrogen atoms and occupy equatorial coordination sites. The Re-N bond distance {2.278(2) Å } is longer compared to the Re-N bond distances in previously reported g 1 -coordinated aromatic nitrogen heterocycles [4,30]. This is due to the fact that the ''amino'' nitrogen atoms possess sp 3 hybridization rather than sp 2 hybridization observed for ''imino'' nitrogen atoms and thus the presence of hydrogen atoms cause steric hindrance to push the nitrogen atoms away from the rhenium atoms.…”

“…2-mercapto-1-methylimidazolyl) [30] and 2.211(6) Å in [Re 2 (CO) 8 (l-g 3 -C 12 H 10 N 2 )] [4]. An asymmetric triangle is formed by C(9), C(10) and Re(2) atoms [Re(2)-C(9) = 2.325(5), Re(2)-C(10) = 2.287(4) Å ], and as a consequence of the g 2 -coordination of the ethylenic moiety; the distance C(9)-C(10) [1.418(6) Å ] closely resembles to that observed for the corresponding distance of 1.38(2) Å in [Re 2 (CO) 8 (l-g 3 -C 12 H 10 N 2 )] and is longer than an uncoordinated C-C double bond lengths [4].…”

“…The synthesis and reactivity of the dirheniumpyridyl compound [Re 2 (CO) 8 (l-g 2 -C 5 H 4 N)-(l-H)] were investigated by Brown and co-workers in 1982 [7]. Arce et al [4] reported the bipyridyldirhenium complexes [Re 2 (CO) 8 (l-g 3 -C 12 H 10 N 2 )], [Re 2 (CO) 7 (l-g 3 -C 12 H 9 N 2 )-(l-H)], [Re 2 (CO) 6 (l-g 4 -C 12 H 9 N 2 )(l-H)], [Re 2 (CO) 8 (l-g 4 -C 12 H 10 N 2 )] and [Re 2 (CO) 6 (l-g 6 -C 24 8 (MeCN) 2 ] with thiazole and 4-methylthiazole [8].…”

Reactivity of 2,3-bis(2-pyridyl)pyrazine with [Re2(CO)8(CH3CN)2]: Molecular structures of [Re2(CO)8(C14H10N4)] and [Re2(CO)8(C14H10N4)Re2(CO)8]

“…Unlike 1, the IR carbonyl spectrum of 4 in CH 2 Cl 2 shows a very simple band pattern similar to the one observed for [Re 2 (l:g 6 -C 24 H 18 N 4 )(CO) 6 ] [21], [Re 2 -(CO) 6 (OX) 2 ] (X = 8-quinolinate) [22] and [Re(CO) 3 -(C 12 H 8 N 2 )Cl] 2 [23], as pseudo-octahedral rhenium complexes with only facial CO ligands usually display three bands in the carbonyl stretching region [24]. The 1 H NMR spectrum of 4 in the aromatic region contains eight different signals associated to two non-equivalent pyridinic systems and two different signals for the four pyrazinic protons, so the ligand symmetry is lost.…”