TY - JOUR
T1 - Small Heteroborane Cluster Systems. 6. Mössbauer Effect Study of Iron Substituted Small Metallaborane Clusters
AU - Goodreau, Bruce H.
AU - Orlando, Lianna R.
AU - Long, Gary J.
AU - Spencer, James T.
PY - 1996
Y1 - 1996
N2 - The Mössbauer effect spectra for a series of small [Fe(η5-C5H5)(CO)x] substituted metallaborane complexes are reported, where x = 1 or 2. The pentaborane cage in compounds [Fe(η5-C5H5)(CO)2B 5H7P(C6H5)2] (1), [Feη5-C5H5)(CO)2B 5H8] (2), and [(Fe(η5-C5H5)(CO)2) 2B5H7] (3) was found to act as a significantly better donor ligand than the ligands in a comparison group of previously reported [Fe(η5-C5H5)(CO)LX] complexes, where L = CO or PPh3 and X = halide, pseudohalide, or alkyl ligands. These metallaborane complexes were found to most resemble their silyl analogues in Mössbauer spectral parameters and the electronic distribution around the iron centers. In addition, the Mössbauer data showed that the [η-2,3-(P(C6H5)2B5H 7]- ligand was a superior donor to the corresponding unsubstituted [B5H8]- ligand. The Mössbauer spectral results for the metallaborane complexes studied were found to be in general agreement with the anticipated donor and accepting bonding considerations for the cage ligands based upon their infrared and 11B NMR spectra and X-ray structural features. The Mössbauer data for the [Fe(η5-C5H5)(CO)B4H 6(P(C6H5)2)] (4) and [Fe(η5M-C5H5)(CO)B3H 7(P(C6H5)2)] (5) complexes, in comparison with compound 1, showed that as the borane cage becomes progressively smaller, it becomes a poorer donor ligand. A qualitative relationship was found between the observed Mössbauer isomer shift data and the number of boron cage vertices for the structurally related [Fe(η5-C5H5)(CO)xB yHzP(C6H5)2] complexes, where x = 1 or 2, y = 3-5, and z = 6 or 7. The X-ray crystallographic data for compounds 1, 2, 5, and [Fe(η5-C5H5)-(CO)B5H 8] (6) were also found to agree with the trends observed in the Mössbauer spectra which showed that the s-electron density on the iron nucleus increases in the order 5 < 6 < 2 < 1. The X-ray crystal structure of complex 2 is also reported. Crystallographic data for 2: space group P21/c (No. 14, monoclinic), a = 6.084(3) Å, b = 15.045(8) Å,c= 13.449(7) Å, β= 99.69(5)°, V = 1213(1) Å3, Z = 4 molecules/cell.
AB - The Mössbauer effect spectra for a series of small [Fe(η5-C5H5)(CO)x] substituted metallaborane complexes are reported, where x = 1 or 2. The pentaborane cage in compounds [Fe(η5-C5H5)(CO)2B 5H7P(C6H5)2] (1), [Feη5-C5H5)(CO)2B 5H8] (2), and [(Fe(η5-C5H5)(CO)2) 2B5H7] (3) was found to act as a significantly better donor ligand than the ligands in a comparison group of previously reported [Fe(η5-C5H5)(CO)LX] complexes, where L = CO or PPh3 and X = halide, pseudohalide, or alkyl ligands. These metallaborane complexes were found to most resemble their silyl analogues in Mössbauer spectral parameters and the electronic distribution around the iron centers. In addition, the Mössbauer data showed that the [η-2,3-(P(C6H5)2B5H 7]- ligand was a superior donor to the corresponding unsubstituted [B5H8]- ligand. The Mössbauer spectral results for the metallaborane complexes studied were found to be in general agreement with the anticipated donor and accepting bonding considerations for the cage ligands based upon their infrared and 11B NMR spectra and X-ray structural features. The Mössbauer data for the [Fe(η5-C5H5)(CO)B4H 6(P(C6H5)2)] (4) and [Fe(η5M-C5H5)(CO)B3H 7(P(C6H5)2)] (5) complexes, in comparison with compound 1, showed that as the borane cage becomes progressively smaller, it becomes a poorer donor ligand. A qualitative relationship was found between the observed Mössbauer isomer shift data and the number of boron cage vertices for the structurally related [Fe(η5-C5H5)(CO)xB yHzP(C6H5)2] complexes, where x = 1 or 2, y = 3-5, and z = 6 or 7. The X-ray crystallographic data for compounds 1, 2, 5, and [Fe(η5-C5H5)-(CO)B5H 8] (6) were also found to agree with the trends observed in the Mössbauer spectra which showed that the s-electron density on the iron nucleus increases in the order 5 < 6 < 2 < 1. The X-ray crystal structure of complex 2 is also reported. Crystallographic data for 2: space group P21/c (No. 14, monoclinic), a = 6.084(3) Å, b = 15.045(8) Å,c= 13.449(7) Å, β= 99.69(5)°, V = 1213(1) Å3, Z = 4 molecules/cell.
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U2 - 10.1021/ic9605478
DO - 10.1021/ic9605478
M3 - Article
AN - SCOPUS:0000725738
SN - 0020-1669
VL - 35
SP - 6579
EP - 6585
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 22
ER -