The document summarizes research on synthesizing new inorganic complexes by reacting iron carbonyl dianions with an indium tris(3,5-dimethyl)-1-pyrazolylborate moiety. Specifically, reacting [HB(3,5-Me2-pz)3]InCl2·THF with [Fe(C2H4(NH2)2)3][Fe2(CO)8] or [Fe(C2H4(NH2)2)3][Fe3(CO)11] yielded new complexes as shown by IR and NMR spectroscopy, which indicate new indium-iron bonds and coordination of the pyrazolylborate ligand to the
![Abstract The reaction of [HB(3,5-Me 2 -pz) 3 ]InCl 2 •THF (pz=pyrazolyl ring) with [Fe(C 2 H 4 (NH 2 ) 2 ) 3 ][Fe 2 (CO) 8 ] in THF yields [HB(3,5-Me 2 -pz) 3 ]In[Fe 2 (CO) 8 ] •THF in 58.58% yield. The reaction of [HB(3,5-Me 2 -pz) 3 ]InCl 2 •THF with [Fe(C 2 H 4 (NH 2 ) 2 ) 3 ][Fe 3 (CO) 11 ] in THF yields [HB(3,5-Me 2 -pz) 3 ]In[Fe 3 (CO) 11 ]. In 46.30% yield. Infrared spectroscopy monitoring the shifts in the carbonyl regions of these new complexes show results that new indium to iron bonds are taking place as these two complexes coordinate with the Indium tris(3,5-dimethyl)-1 Pyrazolylborate Moiety. In monitoring the shifting IR bands of the CO region of the respective spectra, starting from the neutral parent compounds, to the ethylenediamine dianions 1 , and to the final the coordinated complexes with the Indium Pyrazolylborate Moiety, it has been shown that these multi metal centered carbonyl dianions react with the Indium Pyrazolylborate Moiety forming new inorganic complexes. Iron Carbonyl Dianions Stabilized by the Indium tris(3,5-dimethyl)-1 Pyrazolylborate Moiety Introduction In recent years the pyrazolylborate family of ligands have been used to create compounds that exhibit a number of interesting features. The most interesting feature of the pyrazolylborate ligand is its capability to bond or coordinate to a central metal atom, like indium. In the family of pyrazolylborate stems from research and synthesis done by Trofimenko, et. al at DuPont. 1 More notably known as the scorpinate family of ligands, the pyrazolylborate acts like a scorpion, coordinating to a central metal atom with two of the nitrogens from the first two pyrazolyl rings and the final coordination site is achieved by “stinging” the metal center from the last nitrogen on the last pyrazolyl ring. Reger, et. al. have explored this interesting capability in their class of pyrazolylborate ligand system known collectively as the indium pyrazolylborate family. 2,3.4 Focusing on an indium center, Reger et. al. have designed a ligand system containing the tris(3,5 dimethyl)-1 pyrazolylborate moiety and a indium metal center Research is on going in the field of these six coordinate indium pyrazolylborate complexes. Specifically looking at the indium tris(3,5 dimethyl)-1 pyrazolylborate moiety in providing stability to dianionic metal carbonyl species. Previous dianion metal species have been synthesized, including Collman’s Reagent and others, as reported by Ellis, et. al. 5 In narrowing down the list of dianionic metal carbonyls, the group of iron carbonyl dianions can be synthesized in situ and brought together with the one pot synthesis stated by Reger, et. al. (Equation 1) The results of these reactions look promising in stabilizing the group of iron metal carbonyl dianions stemming originally from Reger, et. al. research completed with Collman’s Reagent. 6 The investigation of this research explores coordinating these multi-iron metal carbonyl dianions to the indium tris( 3,5 dimethyl)-1 pyrazolyl borate moiety [Fe(C 2 H 4 (NH2) 2 ) 3 ][Fe 2 (CO) 8 ] + [Fe(C 2 H 4 (NH2) 2 ) 3 ][Fe 3 (CO) 11 ] + Spectral Analysis The shifts in the IR spectra in the CO region is expected to shift from the synthesis of the neutral parent to the dianion as more electron density is given to the central iron atoms. The CO shifts between the dianion and the iron indium pyrazolylborate complex shifted slightly (comparatively to the dianion and neutral parent) as the two lone pairs (one from each iron) is donated to the central indium atom. The reaction of [Fe(C 2 H 4 (NH 2 ) 2 ) 3 ][Fe 2 (CO) 8 ] with HB[(Me 2 -pz) 3 ]InCl 2 ·THF yielded a major product with carbonyl bands 2011.18 cm -1 , 1971.58 cm -1 ,1928.14 cm -1 ,1891.38 cm -1 . The neutral parent Fe 2 (CO) 9 had carbonyl bands at 2081.52 cm -1 , 2017.95 cm -1 , 1985.92 cm -1 ,1826.57cm -1 . The ethylenediamine dianion complex had carbonyl bands at 2009.83 cm -1 , 1924.24 cm -1 , 1852.04 cm -1 . The 1 HNMR of this compound provided an insight as to the structure of this compound. 1 HNMR (CD 3 SOCD 3 ): δ 5.505, 5.137 ( s,s, 2.87, 2.09; 4-H); 3.388, 2.162 (m-m 18.89, 20.39; THF), 2.706, 1.883, (s-s, 45.84, 44.32 Me), 1.507, 0.869, (s-s, Me 15.89, 8.49). The peaks at 5.505 and 5.137 ppm indicate the 4-H position on the Pyrazolyl rings, the peaks at 3.388 and 2.162 provide that a weakly bound THF solvent ligand is attached, keeping the indium octahedral, the peaks at 2.706 and 1.883 show the two equivalent methyl groups on two of the Pyrazolyl rings and the peaks at 1.507 and 0.869 show the nonequivelent methyl groups on the last Pyrazolyl ring. Comparing these 1 HNMR peaks to the ones for the initial Indium tris(3,5-dimethyl)-1 Pyrazolylborate: 1 HNMR (CDCl 3 ): HB[(Me 2 -pz) 3 ]InCl 2 ·THF δ5.97 (1.23, s, 4-Hpz*); 3.80, 1.90 (1.00, 1.90, m, m; THF); 2.60, 2.95 (7.10, 7.10,s,s; 3,5Me-pz*) the peaks have shifted, indicating that the Indium tris(3,5-dimethyl)-1 Pyrazolylborate has coordinated to the diiron complex . The two lone pair of electrons in the reduced state of the ethylenediamine dianion (one from each iron) has donated them to the central indium atom making a new coordination complex. The reaction of [Fe(C 2 H 4 (NH 2 ) 2 ) 3 ][Fe 3 (CO) 11 ] with HB[(Me 2 -pz) 3 ]InCl 2 ·THF yielded a major product [HB(Me 2 -pz) 3 ]In[Fe 3 (CO) 11 ] with carbonyl bands at 2001.44 cm -1 , 1941.10 cm -1 , 1893.64 cm -1 . The [Fe(C 2 H 4 (NH 2 ) 2 ) 3 ][Fe 3 (CO) 11 ] compound was made from the procedure provided by Heiber, et. al. 7,8 and provides a convenient synthesis and the complex is much more stable and easier to handle both in crystal form and in situ The neutral parent Fe 3 (CO) 12 had carbonyl bands at 2000cm -1 (CO) ; 1826.58cm -1 (CO bridged) and the ethylenediamine dianion complex had carbonyl bands at 2009.83 cm -1 , 1924.24 cm -1 , 1852.04 cm -1 . The shifts in the IR spectra in the CO region is expected to shift from the synthesis of the neutral parent to the dianion as more electron density is given to the central iron atoms. The CO shifts between the dianion and the iron indium pyrazolylborate complex shifted slightly (comparatively to the dianion and neutral parent) as the two lone pairs are donated from the irons to the central indium atom. Brandon M. Alexander, Mount Union College ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Acknowledgements Dr. Scott Mason, Mount Union College, Chemistry Department Dr. Jeffery Draves, Mount Union College, Chemistry Department Dr. Mark Himmelien, Mount Union College, Foreign Languages . Figure 1- 3D Model: Energy (MM2) Minimization (view down the Boron) Figure 1- 3D Model: Energy (MM2) Minimization (view from the Iron Side) L=tris ligand, [HB(Me 2 -pz) 3 ] M = Fe , W L I n C l 2 T H F + N a 2 M ( C O ) x LIn-M(CO) x + 2 NaCl Equation 1—One Pot Synthesis](https://image.slidesharecdn.com/scholardaypresentationposter-12759337215115-phpapp01/85/Scholar-Day-Presentation-Poster-1-320.jpg)
