Phosphorus-Phosphorus Coupling Constants in Mixed-Phosphine Tricarbonyl Iron Complexes, Fe(CO)3LL'. Crystal Structure of trans-Fe(CO)3(PEt3)(PPh3)
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- 作者：Richard L. Keiter ; John William Benson ; Ellen A. Keiter ; Travis A. Harris ; Matthew W. Hayner ; Laura L. Mosimann ; Eric E. Karch ; Carol A. Boecker ; Donna M. Olson ; Jennaver VanderVeen ; Douglas E. Brandt
- 刊名：Organometallics
- 出版年：1997
- 出版时间：May 27, 1997
- 年：1997
- 卷：16
- 期：11
- 页码：2246 - 2253
- 全文大小：253K
- 年卷期：v.16,no.11(May 27, 1997)
- ISSN：1520-6041
文摘
Mixed-ligand complexes,trans-Fe(CO)3LL' (L = PPh3,L' = PPh2Me, PPhMe2, PMe3,PPh2Et, PEt3, PPh2CH=CH2,PPh2H, AsPh3, P(OPh)3; L =PMe3, L' = PEt3, PPh2Et,PCy3,PPh2Me, PPhMe; L = PEt3, L' =PPh2Me; L = PPh2H, L' =PPh2CH=CH2, PPh2Et; L=AsPh3, L' = PPhMe2, P(OPh)3,P(OMe)3, P(OEt)3), have been obtained from thestepwisereaction of phosphines with Fe(CO)3(BDA) (BDA =benzylideneacetone) orFe(CO)3(AsPh3)2and from the reaction of phosphine withFe(CO)4PPh3 in the presence of base.A strongnegative correlation exists between2JPP coupling constant values andthe sum of thephosphine pKa values. By application ofquantitative analysis of ligand effects, it has beenshown that 2JPP for the mixed-ligandcomplexes correlates strongly with both 
andEar, butnot with 
. Although a near perfect fit is obtained from thethree-parameter equation, astatistical analysis suggests that for this small data set there are nopredictive advantagesover the one-parameter pKa model. It ispossible to calculate reliable 2JPPvalues for trans-Fe(CO)3L2 complexes with either model.An X-ray structure of solid-statetrans-Fe(CO)3(PEt3)(PPh3) shows equalFe-PEt3 and Fe-PPh3 bond distances,implying that bond strengthequalization may occur when two rather different phosphines occupytrans coordination sites.
andEar, butnot with . Although a near perfect fit is obtained from thethree-parameter equation, astatistical analysis suggests that for this small data set there are nopredictive advantagesover the one-parameter pKa model. It ispossible to calculate reliable 2JPPvalues for trans-Fe(CO)3L2 complexes with either model.An X-ray structure of solid-statetrans-Fe(CO)3(PEt3)(PPh3) shows equalFe-PEt3 and Fe-PPh3 bond distances,implying that bond strengthequalization may occur when two rather different phosphines occupytrans coordination sites.