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The efficiency of various gold compounds containing bis(phosphino)ferrocene ligands for catalyzing ring-closing reactions was examined. Six commercially available bis(phosphino)ferrocene ligands: 1,1′-bis(ditert-butylphosphino)ferrocene (dtbpf), 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(dicylohexylphosphino)ferrocene (dcpf), 1,1′-bis(diiso-propylphosphino)ferrocene (dippf), 1-diphenylphosphino-1′-di-tert-butylphosphinoferrocene (dppdtbpf) and 1,1′-bis(5-methyl-2-furanylphosphino)ferrocene (dfurpf) were employed in this study. In addition to the previously reported [Au2Cl2(μ-PP)] (PP = dtbpf, dppf, dcpf, dippf or dppdtbpf) compounds, [Au2Cl2(μ-dfurpf)] was synthesized and characterized by NMR spectroscopy, cyclic voltammetry and X-ray crystallography. All of these gold compounds react with Na[BArF24] (BArF24 = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) to remove a chloride and yield the cationic monochlorides, [Au2(μ-Cl)(μ-PP)]+. The effectiveness of the [Au2Cl2(μ-PP)] and [Au2(μ-Cl)(μ-PP)][BArF24], either pre-formed or generated in situ, compounds for the catalytic intramolecular alkyne hydroalkoxylation of (Z)-3-methylpent-2-en-4-yn-1-ol was examined in CDCl3 and toluene-d8. The ring-closing of N-(prop-2-yn-1-yl)benzamide was also examined and was efficiently carried out in toluene-d8 using [Au2(μ-Cl)(μ-PP)][BArF24] (PP = dtbpf, dppf, dcpf, dippf, dppdtbpf or dfurpf). In addition, [Au2Cl2(μ-dppe)] and [Au2(μ-Cl)(μ-dppe)][BArF24] were examined as catalysts for these ring-closing reactions in order to determine if the ferrocene backbone of the bis(phosphino)ferrocene ligands was important for catalysis.

Ferrocene and ferrocene-derived ligands are capable of a wide variety of coordination modes. The flexible coordination exhibited by these compounds leads to a range of interesting structures ranging from small molecules to large coordination polymers. These compounds are used in a variety of applications ranging from photosensors to catalysts. This chapter presents some of the interesting developments in coordination compounds of ferrocene-based ligands from 2003 to 2018.

Three new [Pd(κ2-PP)MeCl] (PP = 1,1′-bis(dicyclohexylphosphino)ferrocene (dcpf), 1-diphenylphosphino-1′-ditert-butylphosphinoferrocene (dppdtbpf) or 1,1ʹ-bis(5-methyl-2-furanylphosphino)ferrocene (dfurpf)) compounds were prepared and characterized. The X-ray crystal structure of [Pd(dppdtbpf)MeCl] was obtained which allowed for unambiguous determination of the cis/trans- relationship between the methyl and chloride ligands with respect to the different phosphine groups. The oxidative electrochemistry of the three new compounds as well as that of the reported [Pd(κ2-PP)MeCl] (PP = 1,1′-bis(diphenylphosphino)ferrocene (dppf), or 1,1′-bis(diiso-propylphosphino)ferrocene (dippf)) and [Pd(κ3-dtbpf)Me]Cl (dtbpf = 1,1′- bis(ditert-butylphosphino)ferrocene) was examined. The compounds with the κ2-bis(phosphino)ferrocene ligands react with sodium tetrakis(3,5-bis(trifluoromethyl)phenylborate) to lose a chloride ligand and the catalytic activity of these compounds was investigated for the polymerization of phenylacetylene.

The ligand 1,1′-bis(diphenylphosphino)ferrocene (dppf) is commonly employed in a variety of catalytic systems. There are a variety of coordination modes known for dppf, the least studied being the κ3 coordination mode, in which both phosphorus atoms and the iron atom of dppf interact with another metal center. One such compound is the previously reported [Pd(κ3-dppf)(PPh3)]2+. A series of related compounds, [Pd(κ3-dppf)(P(p-C6H4R)3)]2+ (R = OCH3, CH3, F and CF3), has been synthesized and characterized. The X-ray crystal structure of [Pd(dppf)(P(p-C6H4F)3)][BF4]2 was determined. Electrochemical and computational studies indicate that the electron donor ability of the P(p-C6H4R)3 ligands influences the properties of these compounds. Substitution reactions of the P(p-C6H4R)3 ligands have been examined, and, in general, the more electron donating P(p-C6H4R)3 ligands completely replace the less electron donating ones. The kinetics of the reaction of [Pd(κ3-dppf)(P(p-C6H4F)3)]2+ with P(p-C6H4OCH3)3 indicate that the reaction proceeds through a dissociative mechanism, contrary to the associative substitutions prevalent in square planar palladium(II) chemistry.

The synthesis of several new zinc compounds with 1,1ʹ-bis(phosphino)ferrocene ligands and their phosphine chalcogenide derivatives are reported. X-ray crystal structures of [Zn(dppdtbpf)Cl2] (dppdtbpf = 1-diphenylphosphino-1ʹ-di-tert-butylphosphino ferrocene), [Zn(dippfO2)Cl2] (dippf = 1,1ʹ-bis(di-iso-propylphosphino)ferrocene), [Zn(dtbpfO2)Cl2] (dtbpf = 1,1ʹ-bis(di-tert-butylphosphino)ferrocene) and [Zn(dppdtbSf)Cl2] were determined. The oxidative electrochemistry of the zinc compounds was examined and typically gave rise to irreversible oxidations. The reaction of [(AuCl)2(PP)] (PP = 1,1ʹ-bis(diphenylphosphino)ferrocene (dppf), dtbpf or dppdtbpf) with [N(p-C6H4Br)3][B(C6F5)4] results in loss of a chloride forming [Au2(μ-Cl)(PP)][B(C6F5)4]. The structures of [(AuCl)2(dtbpf)] and [Au2(μ-Cl)(dtbpf)][B(C6F5)4] have been determined and [Au2(μ-Cl)(dtbpf)]+ displays a weak Au-Au interaction that is not present in [(AuCl)2(dtbpf)]. The oxidative electrochemistry of [Au2(μ-Cl)(PP)]+ displays two reversible waves, the first occuring at potentials similar to that of the corresponding [(AuCl)2(PP)] species.

The reactions of Na[BArF] (BArF = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) with a series of [Pd(dpEMc)Cl 2 ] (dpEMc = 1,1′-bis(diphenylphosphino)ruthenocene (dppr), 1,1′-bis(diphenylphosphino)osmocene (dppo) or 1,1′-bis(diphenylarsino)ferrocene (dpaf)) compounds were examined. The reaction of Na[BArF] with [Pd(dppMc)Cl 2 ] (dppMc = dppr or dppo) resulted in the formation of the corresponding chloride-bridged dimers, [Pd(dppMc)(μ-Cl)] 2 2+ , which were structurally characterized. However, these dimers appear to be unstable in CH 2 Cl 2 and partially (Ru) or fully (Os) convert into the corresponding monomers, [Pd(dppMc)Cl] + , which are proposed to have a weak, non-covalent M–Pd (M = Ru or Os) interaction. Similar compounds, [Pd(dppo)PPh 3 ] 2+ and [Pt(dppMc)PPh 3 ] 2+ (M = Fe (1,1′-bis(diphenylphosphino)ferrocene (dppf)) or Os (dppo)), were also prepared and structurally characterized. These compound also exhibit weak, non-covalent M–Pd/Pt interactions. In addition, the electrochemical properties of these compounds were examined by cyclic voltammetry.

vii GENERAL INTRODUCTION 1 Dissertation Organization 1 PROTONATION OF METAL-METAL BONDS IN BIMETALLIC ORGANOMETALLIC COMPLEXES 2 Introduction 2 Protonation of Metal-Metal Bonds 2 References 19 CYCLOPENTADffiNYL LIGAND EFFECTS ON ENTHALPIES OF PROTONATION OF THE Ru-Ru BOND IN Cp'.RUoCCO)^ COMPLEXES 23 Abstract 23 Introduction 24 Experimental Section 26 Results 32 Discussion 35 Conclusions 41 Acknowledgments 43 References 4323 Introduction 24 Experimental Section 26 Results 32 Discussion 35 Conclusions 41 Acknowledgments 43 References 43

The reaction of [Pd(dtbpf)Cl2] (dtbpf = 1,1′-bis(di-tert-butylphosphino)ferrocene) with sodium bromide yields [Pd(dtbpf)Br][Br], which displays an interaction between the iron and palladium atoms. The structure of this compound has been obtained and is compared to those of the previously reported [Pd(dtbpf)X]+ (X = Cl, I) analogues. Similar to [Pd(dtbpf)Cl]+, [Pd(dtbpf)Br]+ appears to undergo a solid-state isomerization at low temperature to a species in which the Fe–Pd interaction is disrupted. In addition to 1H and 31P{1H} NMR and visible spectroscopy, the [Pd(dtbpf)X]+ (X = Cl, Br) compounds were also characterized by zero-field 57Fe Mossbauer spectroscopy. DFT calculations on [Pd(dtbpf)X]+ (X = Cl, Br, I) show that the Fe–Pd interaction is weak and noncovalent and that the strength of the interaction decreases as the halide becomes larger. A related trend is noted in the potential at which oxidation of the iron center occurs; the larger the halide, the less positive the potential at which oxidation oc...

1,1′-bis(phosphino)ferrocene ligands are commonly employed in a variety of catalytic systems. These ligands are of particular interest as the steric and electronic properties of the phosphorus donor atoms can be altered by changing the substituents of the phosphines. In addition, the ferrocene backbone of the ligands provides unique electronic and conformational flexibility to these ligands. Previous investigations in this lab have examined catalytic ring closing reactions using a series of gold compounds with bis(phosphino)ferrocene ligands, [Au2Cl2(μ-PP)]. These gold compounds were shown to react with sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate, Na[BArF24], to generate a cationic species with the general formula [Au2(μ-Cl)(μ-PP)][BArF24] that are much more efficient catalysts than the [Au2Cl2(μ-PP)] compounds. In this study, a series of [Au2Cl2(μ-PP)] (μ-PP = 1,1′-bis(diphenylphosphino)ferrocene (dppf), 1,1′-bis(diiso-propylphosphino)ferrocene (dippf), 1,1′-bis(dicyclohexylphosphino)ferrocene (dcpf), 1,1′-bis(ditert-butylphosphino)ferrocene (dtbpf), 1-diphenylphosphino-1′-ditert-butylphosphinoferrocene (dppdtbpf) or 1,1ʹ-bis(5-methyl-2-furanylphosphino)ferrocene (dfurpf)) compounds were examined as catalysts for the intramolecular ring-closing hydroamination of 3-(vinyloxy)propan-1-amine and the intermolecular hydroamination of phenylacetylene with a variety of phenylamine reagents. The catalytic activity of the corresponding [Au2(μ-Cl)(μ-PP)][BArF24] compounds that were generated in situ was also explored. Two new [Au2Cl2(μ-PP)] compounds with chiral bis(phosphino)ferrocene ligands (PP = 1,1′-bis(2R,5R-dimethylphospholanyl)ferrocene (R-dMeplf) or 1,1′-bis(2S,5S-dimethylphospholanyl)ferrocene (S-dMeplf)) were prepared, characterized spectroscopically and electrochemically, and evaluated as catalysts in the ring-closing hydroamination reaction. In addition, the X-ray structures of [Au2Cl2(μ-PP)] (PP = dppdtbpf, R-dMeplf and S-dMeplf) were determined.

A variety of mono- and bisphosphine sulfides and selenides were synthesized and structurally characterized by NMR spectroscopy. In addition, the X-ray crystal structures were determined for eleven of these compounds. The percent buried volume was determined from the X-ray structures and the use of this measurement in estimating the steric bulk in phosphine sulfides and selenides was further developed. The oxidation of the mono- and bisphosphine chalcogenides was examined using cyclic voltammetry in methylene chloride and acetonitrile. The solvent had little effect on the observed trends in the potentials at which oxidation occurred. Both the mono- and bisphosphine chalcogenides display an irreversible oxidative wave. Many of the phosphine selenides also display a follow-up, irreversible reductive wave indicative of the formation of a Se–Se bond upon oxidation. However, the products for the oxidation of the phosphine selenides could not be isolated by chemical oxidation. The potential at which oxidation of the phosphine sulfides occurs is more positive than the analogous phosphine selenides.

Two new 1,1′-disubstituted cobaltocenium compounds, [(C5H4CHEt2)2Co][PF6] and [(C5H4SiMe3)2Co][PF6], were synthesized and the X-ray crystal structures were determined. The electrochemistry of seven 1,1′-disubstituted cobaltocenium compounds and the analogous ferrocene compounds was studied in methylene chloride using cyclic voltammetry. The affect of the various substituents on the redox potentials of these compounds was examined and trends in the electrochemical data were explored.

The reaction of [Pd(dtbpf)Cl2] (dtbpf = 1,1′-bis(di-tert-butylphosphino)ferrocene) with a chemical oxidant led unexpectedly to the formation of [Pd(dtbpf)Cl]+. Further study found that a variety of reagents could be used to abstract a chloride ligand from [Pd(dtbpf)Cl2] to yield [Pd(dtbpf)Cl]+. The solid-state structure suggests the formation of an Fe–Pd interaction. The presence of the bulky tert-butyl groups is essential, as similar reactions with [Pd(PP)Cl2] (PP = other 1,1′-bis(phosphino)ferrocene ligands) results in the formation of [Pd(PP)(μ-Cl)]22+. The analogous platinum compounds have also been investigated and appear to behave in a similar manner. Similar compounds of the type [M′(PP)(PR3)]2+ (M′ = Pd, Pt, R = Ph, Me) have been prepared, and a metal–metal interaction has also been observed. Steric and electronic effects dictate the formation of these compounds. X-ray crystal structures were obtained for eight of these compounds and were used as the basis for a computational analysis of the metal...

While the redox active backbone of bis(phosphino)ferrocene ligands is often cited as an important feature of these ligands in catalytic studies, the structural parameters of oxidized bis(phosphino)ferrocene ligands have not been thoroughly studied. The reaction of [Re(CO)3(dippf)Br] (dippf = 1,1′-bis(diiso-propylphosphino)ferrocene) and [NO][BF4] in methylene chloride yields the oxidized compound, [Re(CO)3(dippf)Br][BF4]. The oxidized species, [Re(CO)3(dippf)Br][BF4], and the neutral species, [Re(CO)3(dippf)Br], are compared using X-ray crystallography, cyclic voltammetry, visible spectroscopy, IR spectroscopy and zero-field 57Fe Mössbauer spectroscopy. In addition, the magnetic moment of the paramagnetic [Re(CO)3(dippf)Br][BF4] was measured in the solid state using SQUID magnetometry and in solution by the Evans method. The electron transfer reaction of [Re(CO)3(dippf)Br][BF4] with acetylferrocene was also examined. For additional comparison, the cationic compound, [Re(CO)3(dippc)Br][PF6] (dippc = 1,1′-bis(diiso-propylphosphino)cobaltocenium), was prepared and characterized by cyclic voltammetry, X-ray crystallography, and NMR, IR and visible spectroscopies. Finally, DFT was employed to examine the oxidized dippf ligand and the oxidized rhenium complex, [Re(CO)3(dippf)Br]+.

The oxidative electrochemistry of group VI and group VII metal carbonyl compounds containing 1,1′-bis(phosphino)ferrocene ligands with the general formula [M(CO)4(P∩P)] (M = Cr, Mo, or W, P∩P = 1,1′-bis(diisopropylphosphino)ferrocene (dippf) or 1,1′-bis(dicyclohexylphosphino)ferrocene (dcpf)) and [M(CO)3Br(P∩P)] (M = Mn, P∩P = 1,1′-bis(diphenylphosphino)ferrocene (dppf) or dippf; M = Re, P∩P = dppf, dippf or dcpf) was investigated. Two reversible waves were observed in the electrochemistry of the Cr compounds, while the other compounds exhibited one wave with varying reversibility. The compounds were examined using spectroelectrochemistry, which was particularly useful in assigning the two waves in the Cr species. In addition, the X-ray structures of [Cr(CO)4(dippf)], [Cr(CO)4(dcpf)] and [Mn(CO)3Br(dippf)] were determined. The %Vbur values for dippf, dcpf and other bidentate phosphines have been calculated for these pseudo-octahedral Cr and Mn compounds and these structural studies have been supplemented by DFT optimized geometries for the Cr complexes.

The electrochemistry of 1,1′-bis(diphenylphosphino)cobaltocenium hexafluorophosphate ([dppc][PF6]), 1,1′-bis(dicyclohexylphosphino)cobaltocenium hexafluorophosphate ([dcpc][PF6]), 1,1′-bis(di-iso-propylphosphino)cobaltocenium hexafluorophosphate ([dippc][PF6]), and 1-(di-tert-butylphosphino)cobaltocenium hexafluorophosphate ([1-dtbpc][PF6]) was examined in methylene chloride with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. A reversible reductive wave followed by an irreversible wave at more negative potentials was observed. Ten new phosphinothioyl ([dppcS2][PF6], [dcpcS2][PF6], [dippcS2][PF6], [1-dtbpcS][PF6], and 1,1′-bis(dicyclohexylphosphinothioyl)ferrocene) and phosphinoselenoyl derivatives ([dppcSe2][PF6], [dcpcSe2][PF6], [dippcSe2][PF6], [1-dtbpcSe][PF6], and 1,1′-bis(dicyclohexylphosphinoselenoyl)ferrocene) were prepared and characterized, and the structures of eight of these compounds were determined. The electrochemistry of these phosphinochalcogenyl cobaltocenium compounds, as well as the previously prepared [dppcO2][PF6], displayed two reversible reductive waves at potentials less negative than that of the free phosphines. A correlation was found to exist between the Hammett substituent constant σp and the reduction potentials of these compounds. In addition, the phosphinoselenoyl [dppcSe2][PF6], [dcpcSe2][PF6], and [dippcSe2][PF6] displayed an electrochemically irreversible oxidative wave, potentially indicating an intramolecular Se–Se bonded trication. The electrochemistry of three new and five previously reported transition metal complexes of the general formula [MnCl2(P∩P)][PF6] (M = Pd or Pt, n = 1, P∩P = dppc, dcpc or dippc; M = Au, n = 2, P∩P = dppc or dcpc)) was also examined displaying at least two reductive waves at potentials less negative than that of the free phosphines. Comparison of the electrochemical data with that previously obtained for analogous ferrocenes indicates that a correlation exists between the reduction potentials of the cobaltocenium phosphines and the potentials at which oxidation of the ferrocene phosphines occurs. In addition, the structure of [Au2Cl2(dppc)][PF6] was determined.

New compounds containing the 1,1′-bis(dialkylaminophosphino)ferrocene ligands 1,1′-bis(dimethylaminophosphino)ferrocene (dmapf) and 1,1′-bis(diethylaminophosphino)ferrocene (deapf) were prepared and characterized by NMR. The oxidative electrochemistries of these compounds were examined in methylene chloride. The transition metal compounds M n Cl 2 (P–P) (M = Pd or Pt, n = 1, P–P = dmapf or deapf; M = Au, n = 2, P–P = dmapf) displayed one-electron, Nernstian waves. The corresponding selenides were prepared and the oxidative electrochemistries, along with those of the previously prepared 1,1′-bis(alkylaminophosphine sulfide)ferrocene, were examined. The sulfides displayed one-electron, Nernstian oxidations. The selenides displayed electrochemically irreversible two-electron waves. The X-ray structures of the sulfides and selenides as well as that of the transition metal compounds [(AuCl) 2 (dmapf)] and [PtCl 2 (dmapf)] were determined.

The oxidative electrochemistries of a series of chiral bisphosphinoferrocene ligands, 1,1'-bis(2,4-dialkylphosphetanyl)ferrocene (FerroTANE) and 1,1'-bis(2,5-dialkylphospholanyl)ferrocene (FerroLANE), were examined. The reversibility of the oxidation is sensitive to the steric bulk of the alkyl groups. New transition metal compounds and phosphine chalcogenides of these ligands were prepared and characterized. X-ray crystal structures of 10 of these compounds are reported. The percent buried volume (%V(bur)) is a recently developed measurement based on crystallographic data that examines the steric bulk of N-heterocyclic carbene and phosphine ligands. The %V(bur) for the FerroTANE and FerroLANE structures with methyl or ethyl substituents suggests these ligands are similar in steric properties to 1,1'-bis(diphenylphosphino)ferrocene (dppf). In addition the %V(bur) has been found to correlate well with the Tolman cone angle for phosphine chalcogenides. The oxidative electrochemistries of the transition metal complexes occur at more positive potentials than the free ligands. While a similar positive shift is seen for the oxidative electrochemistries of the phosphine chalcogenides, the oxidation of the phosphine selenides does not occur at the iron center, but rather oxidation occurs at the selenium atoms.

The characterization of 1-methyl-1-vinyl-3,3,5,5-tetraphenylcyclotrisiloxane by NMR(1H,13C,29Si) and X-ray crystallography is reported. The central siloxane ring is planar with Si–O bond lengths and angles which are similar to those found in the structures of other cyclotrisiloxanes. There is significant thermal motion of the methyl and vinyl groups. Very low incorporation of the siloxane is observed in the radical catalyzed copolymerization of the siloxane with styrene.

The bimetallic complexes CpRu(P−P)X [Cp = η5-C5H5; X = Cl, H; P−P = dppf (1,1′-bis(diphenylphosphino)ferrocene), dppr (1,1′-bis(diphenylphosphino)ruthenocene), dppo (1,1′-bis(diphenylphosphino)-osmocene), dippf (1,1′-bis(diisopropylphosphino)ferrocene), dcpf (1,1′-bis(dicyclohexylphosphino)ferrocene)], Cp*Ru(P−P)X [Cp* = η5-C5Me5; X = Cl, H; P−P = dppf, dippf, dppomf (1,1′-bis(diphenylphosphino)octamethylferrocene), dppc (1,1′-bis(diphenylphosphino)cobaltocene)], [Cp*Ru(P−P)X]+ (X = H, CCPh; P−P = dppc+), and [Cp*Ru(P−P)L]2+ (L = CH3CN, t-BuCN; P−P = dppc+) have been synthesized. Most of the chloride and hydride complexes have been studied by cyclic voltammetry. The X-ray structures of [Cp*Ru(dppc)CH3CN][PF6]2 and [Cp*Ru(dppc)CCPh][PF6] have been determined. Protonation of [Cp*Ru(dppc)CCPh]+ gives the vinylidene complex [Cp*Ru(dppc)CCHPh]2+. The Co(III/II) potential of the dppc+ ligand undergoes a cathodic shift upon coordination in [Cp*Ru-(dppc)H]+ and an anodic shift upon coordination in [Cp*Ru(dppc)CH3...

The anodic electrochemistry of 1-di-tert-butylphosphino-1′-diphenylphosphinoferrocene (dppdtbpf) was performed in methylene chloride with tetrabutlylammonium hexafluorophosphate as the supporting electrolyte. The electrochemistry is complicated by a chemical reaction after the oxidation. Three new transition metal complexes of dppdtbpf ([NiCl2(dppdtbpf)], [PtCl2(dppdtbpf)], and [Au2Cl2(dppdtbpf)]) were prepared and characterized. The electrochemistry of the three new compounds and one previously prepared compound ([PdCl2(dppdtbpf)]) was examined. In addition, the reaction of dppdtbpf with sulfur and/or selenium afforded a series of compounds containing a phosphine sulfide (dppSdtbpSf or dppdtbpSf), a phosphine selenide (dppSedtbpSef or dppdtbpSef), or both a phosphine sulfide and a phosphine selenide (dppSedtbpSf or dppSdtbpSef). These compounds were characterized by NMR, and the structures of three of the compounds were determined. Two of the structures are of the isomeric compounds, dppSdtbpSef and dppS...

The oxidative electrochemistry of chiral, bidentate ferrocenylphosphines, five Taniaphos and seven Walphos ligands, was studied in methylene chloride. In general, two waves of varying reversibility were observed. Complexes of the general type [(phosphine)MCl2] (phosphine = Taniaphos or Walphos; M = Pd or Pt) were prepared and characterized by NMR. Upon coordination, the oxidative electrochemistry of the ligands was greatly simplified. The X-ray structures of a Taniaphos platinum complex as well as a palladium and a platinum complex with a Walphos ligand were determined.

The oxidative electrochemistry of 11 chiral bis-phosphinoferrocene ligands, all within the Josiphos class of ligands, was examined in methylene chloride. The oxidation of these ligands displays multiple waves of varying chemical reversibility. Palladium(II) and platinum(II) complexes with the general formula [MCl2(P–P)] (M = Pd or Pt; P–P = Josiphos) were prepared, characterized by NMR and cyclic voltammetry. The electrochemistry simplifies greatly upon coordination of the Josiphos ligands. The X-ray structures of a palladium(II) and platinum(II) complex of the same Josiphos ligand are reported.

The electrochemistry of 1,1′-bis(dicyclohexylylphosphino)ferrocene (dcpf) was examined in methylene chloride with tetrabutylammonium hexafluorophosphate or tetrabutylammonium tetrakis(pentafluorophenyl)borate as the supporting electrolyte. The oxidation of dcpf is complicated by a follow-up reaction. Seven new complexes containing dcpf and one new compound containing 1,1′-bis(di-tert-butylphosphino)ferrocene (dtbpf) were prepared and characterized. The new complexes were analyzed by cyclic voltammetry and the oxidation of these complexes occurred at a more positive potential than the free ligand. In addition, the X-ray structure of [PdCl2(dcpf)] was determined and compared to other palladium complexes containing bisphosphinometallocene ligands. Five different palladium complexes containing bisphosphinometallocene ligands were examined as catalyst precursors in Buchwald–Hartwig catalysis.

The electrochemistry of 1,1‘-bis(di-tert-butylphosphino)ferrocene (dtbpf) was examined in methylene chloride with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. Two new complexes in which dtbpf was bound to a transition metal were prepared and characterized. The two new complexes as well as two previously reported complexes were analyzed by cyclic voltammetry. In addition, the chalcogenids, dtbpfS2 and dtbpfSe2, were prepared and characterized by NMR and the structure of dtbpfSe2 was determined. The oxidation of dtbpfS2 is a simple one-electron process due to the presence of the iron center. In contrast, the oxidation of dtbpfSe2 is electrochemically irreversible and appears to proceed by an EE mechanism. Chemical oxidation of dtbpfSe2 resulted in the formation of [dtbpfSe2][BF4]2, in which a Se−Se bond formed. This compound was characterized by 31P NMR and X-ray crystallography. A detailed analysis of the electrochemistry suggests that the oxidation of dtbpfSe2 occurs by two separa...

The oxidative electrochemistry of 1,1′-bis(diphenylphosphino)osmocene (dppo) and 1,1′-bis(diphenylarsino)ferrocene (dpaf) was studied in dichloromethane with tetrabutylammonium hexafluorophosphate as the supporting electrolyte. The [MCl2(P∩P)] (M = Pd or Pt; P∩P = dppo or 1,1′-bis(diphenylphosphinoindenyl)iron) complexes were prepared, studied electrochemically and the X-ray structures of dppo and [PdCl2(dppo)] were determined.

The oxidative electrochemistries of two chiral metallocene phosphine-aminophosphine (BoPhoz) ligands, R-Methyl BoPhoz ((R)-N-diphenylphosphino-N-methyl-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine) and R-Pcyco BoPhoz ((R)-N-dicyclohexylphosphino-N-methyl-[(S)-2-(diphenylphosphino)ferrocenyl]ethylamine)), were examined in methylene chloride. In addition the platinum(II) and palladium(II) complexes with a general formula [MCl2(P−P)] (M = Pd or Pt; P−P = R-Methyl BoPhoz or R-Pcyco BoPhoz) were prepared and characterized by NMR and cyclic voltammetry; the X-ray structures of the palladium complexes are reported.

The anodic electrochemistry of a series of bidentate phosphine chalcogenides and bidentate phosphine Lewis acid adducts, both with a metallocene backbone, was examined in dichloromethane containing [NBu 4 ][PF 6 ]. Oxidation of the ferrocene compounds dppfE 2 and dippfE 2 (E = O, S, BH 3 , CH 3 + ) was reversible on the cyclic voltammetric (CV) time scale, while the oxidation of the dpprE 2 compounds (E = O, S, BH 3 ) was irreversible; however, the oxidation of dppfSe 2 , dippfSe 2 , and dpprSe 2 displayed an irreversible wave and the reduction of a follow-up product.

The oxidative electrochemistry of 1-di-tert-butylphosphino-1′,2′,3′,4′,5′-pentaphenylferrocene (Q-phos), 1-di-tert-butylphosphino-1′,2′,3′,4′,5′-penta(4-trifluoromethylphenyl)ferrocene (Q-phos-CF3), 1-di-tert-butylphosphino-1′,2′,3′,4′,5′-penta(4-methoxyphenyl)ferrocene (Q-phos-OMe) and 1-di-tert-butylphosphino-1′,2′,3′,4′,5′-penta(4-methylphenyl)ferrocene (Q-phos-Me) was explored. All of the compounds undergo a reversible oxidation, and the formal potentials are sensitive to the R groups on the phenyl rings.

The oxidative electrochemistry of a variety of homo- and bimetallic group VI metal carbonyl compounds containing 1,1‘-bis(diphenylphosphino)ferrocene (dppf) with the general formulas M(CO)5(dppf) (1a−c), M(CO)4(dppf) (2a−c), and (CO)5M(dppf)M‘(CO)5 (3a−f) (M, M‘ = Cr, Mo, W) was investigated. The effect of the group VI metal and the coordination mode of the dppf ligand on the potential at which the oxidation of the group VI metals and the ferrocene backbone of dppf occurred was examined.

The heat of protonation for 1,1‘-bis(diphenylphosphino)ferrocene (dppf) and 1,1‘-bis(diphenylphosphino)ruthenocene (dppr) was determined by titration calorimetry using CF3SO3H in 1,2-dichloroethane. The −ΔHHP values are 18.8(2) kcal/mol for dppf and 19.5(3) kcal/mol for dppr. The basicity of these phosphines is lower than other bidentate phosphines. In comparison to a phenyl group, the cyclopentadienyl rings of a ferrocenyl group are more π-accepting, and therefore, the basicity of dppf and dppr is lower than that of PPh3. In addition, the heat of protonation of dppr is not significantly different from that of dppf.

The chemically reversible oxidation of 1,1‘-bis(diisopropylphosphino)ferrocene (dippf) was investigated using cyclic voltammetry. In addition, seven new compounds with general formulas of [(MCln)m(...

The electrochemistry of 1,1′-bis(diphenylphosphino)ferrocene (dppf) derivatives of Ru3(CO)12 was investigated. Two known compounds [Ru3(CO)8(μ-dppf)2 (1) and Ru3(CO)10dppf (2)] and a new compound [Ru3(CO)11(μ-dppf)Ru3(CO)11 (3)] were prepared. Compound 3 was characterized spectroscopically and an X-ray crystal structure was obtained. The reductive electrochemistry of 1 and 2 showed an irreversible reduction and a follow-up oxidation, similar to Ru3(CO)12. The electrochemistry of compound 3 showed two irreversible waves and a follow-up oxidation. A trend in the reduction potential vs. the number of coordinated phosphorus atoms was noted. The oxidative electrochemistry of 1–3 showed a dppf-based chemically reversible wave, and an irreversible wave similar to that of Ru3(CO)12. Trends were also noted between the oxidation potential and the number of coordinated phosphorus atoms.

The oxidative electrochemistry of 1,1′-bis(diphenylphosphino)ferrocene (dppf) and 1,1′-bis(diphenylphosphino)ruthenocene (dppr) was investigated at a variety of temperatures and concentrations. In addition, the oxidative electrochemistry of [NiCl2(dppf)] and [MCl2(dppr)] (M=Ni, Pd or Pt) compounds was studied. During the preparation of the dppr compounds, crystals of [NiCl2(dppr)] and [(PdCl2(dppr)]·CH2Cl2 were obtained and the structures were determined. With the previously determined structures of [MCl2(dppf)] (M=Ni, Pd or Pt) and [PtCl2(dppr)], a thorough examination of the binding of dppf and dppr to Group 10 metals was performed.

The preparation of 1-ferrocenyl-2-propanol (5) from lithioferrocene and propylene oxide is described. The reaction of lithium diisopropylamide with 2-ferrocenylethanol (3) or 1-ferrocenyl-2-propanol (5), followed by the addition to hexachlorocyclotriphosphazane (1) provides N3P3Cl6−n (OCHRCH2C5H4FeCp)n [R=H, n=1 (3) or 2 (4); R=CH3, n=1 (6)]. The corresponding reactions with ferrocenylmethanol lead to degradation products via a phosphazene–phosphazene rearrangement. The substitution pattern observed for N3P3C14(OCH2CH2C5H4FeCp)2 (4) suggests that the reaction follows a predominantly cis-non-geminal pathway. The substituted phosphazene derivatives were characterized by standard means including 31P-NMR, mass spectrometry, elemental analysis and cyclic voltammetry. An X-ray crystal structure of N3P3C15(OCH2CH2C5H4FeCp) (3) was obtained.

The compound benzo-3,4-[18-crown-6]-diphenylphosphine was characterized by 31 P, 13 C and 1 H NMR in CDCl 3 and CD 3 CN and by cyclic voltammetry in CH 2 Cl 2 and CH 3 CN. The phosphine crown ether was found to be similar to triphenylphosphine in electrochemical and spectroscopic properties. Addition of M + PF 6 − (M + =Li + , Na + , or K + ) to the samples resulted in minimal changes in the observed 31 P spectra but significant differences in the electrochemistry. This suggests that binding a metal cation to the crown ether can be monitored electrochemically.

The preparation of 1,1′-bis(β-hydroxyethyl)ferrocene (1) by oxidation of 1,1′-divinylferrocene is described. Compound 1 has been characterized by 1H and 13C{1H} NMR, and cyclic voltammetry. The electrochemical data are compared to ferrocene and the closely related 2-ferrocenylethanol, 2.

Basicities of the cyanide ligands in a series of Cp{prime}M(L){sub 2}CN complexes were investigated by measuring their heats of protonation ({minus}{Delta}H{sub CNH}) by CF{sub 3}SO{sub 3}H in 1,2-dichloroethane solution at 25 C to give Cp{prime}M(L){sub 2}(CNH){sup +}CF{sub 3}SO{sub 3}{sup {minus}}, in which the N-H{sup +} group is probably hydrogen-bonded to the CF{sub 3}SO{sub 3}{sup {minus}} anion. Basicities ({minus}H{sub CNH}) of the CpRu(PR{sub 3}){sub 2}CN complexes increase from 20.5 (PPh{sub 3}) to 22.4 (PMe{sub 3}) kcal/mol with increasing donor abilities of the phosphine ligands. Basicities of all the Cp{prime}Ru(PR{sub 3}){sub 2}CN complexes, where Cp{prime} = Cp or Cp*, are linearly correlated with their vCN values; the nonphosphine complexes, CpRu(1,10-phen)CN and CpRu(COD)CN, do not follow the same correlation. For a large number of Cp{prime}M(L){sub 2}CN complexes (M = Ru, Fe, L{sub 2} = mono- and bidentate phosphines, CO, 1,10-phen, and COD), their vCN values parallel vCN values of their protonated Cp{prime}M(L){sub 2}(CNH){sup +} analogues. Also, {sup 31}P NMR chemical shifts of the unprotonated Cp{prime}M(PR{sub 3}){sub 2}-CN and protonated CpM(PR{sub 3}){sub 2}(CNH){sup +} complexes are linearly related. Despite the high basicity of Ru in Cp*Ru-(PMe{sub 3}){sub 2}Cl (30.2 kcal/mol), the CN{sup {minus}} in Cp*Ru(PMe{sub 3}){sub 2}CN (25 kcal/mol) is the site of protonation;more » factors that determine whether protonation occurs at the Ru or the CN{sup {minus}} are discussed.« less

Basicities of a series of Cp'(2)Ru(2)(CO)(4) complexes were established by measuring the heats evolved (DeltaH(MHM)) when the complexes were protonated by CF(3)SO(3)H in 1,2-dichloroethane at 25.0 degrees C. Spectroscopic studies show that the protonation occurs at the metal-metal bond to form [Cp'(2)Ru(2)(CO)(4)(mgr;-H)](+)CF(3)SO(3)(-), in which all of the CO ligands are terminal. The basicities (-DeltaH(MHM)) increase with the Cp'(2) ligands in the following order: (C(5)Me(4)CF(3))(2)(C(9)H(7))(2)C(5)H(4)C(5)H(4)C(5)H(4)CH(2)CH(2)C(5)H(4)(C(5)H(5))(2)(C(5)Me(5))(2)C(5)H(4)CH(2)C(5)H(4). This trend can be understood in part by considering that more strongly donating Cp' ligands increase the basicity of the Ru-Ru bond. Another important factor is the CO-bridging or nonbridging form of each Cp'(2)Ru(2)(CO)(4) complex. A dimer with bridging CO groups is significantly less basic than another dimer with only terminal CO groups although the donor abilities of their Cp' ligands are nearly equal. The Ru-Ru bond in Cp(2)Ru(2)(CO)(4) is substantially more basic than the Ru in the related mononuclear CpRu(CO)(2)H. Molecular structures of [Cp(2)Ru(2)(CO)(4)(mgr;-H)](+)CF(3)SO(3)(-), [(C(5)H(4)CH(2)C(5)H(4))Ru(2)(CO)(4)(mgr;-H)](+)CF(3)SO(3)(-), and (C(5)H(4)CH(2)CH(2)C(5)H(4))Ru(2)(CO)(4) as determined by X-ray diffraction studies are also presented.

Ferrocenylethanol has been prepared and characterized by 1 H and 13 C NMR, cyclic voltammetry and X-ray crystallography. The electrochemical data were compared to ferrocene and related compounds. The lattice constants for ferrocenylethanol (C 12 H 14 FeO) are a =17.291(2) A and α =118.590(0)°. The crystal exists in R3 and there are six formula units per rhombohedral unit cell.

Learning synthetic techniques is an important component of the inorganic laboratory experience. However, if a lab only requires students to prepare a compound, they can be left questioning if the compound they made serves any useful purpose. In this lab, the ligand 1,1'-bis(diphenylphosphino)ferrocene (dppf) can either be prepared as part of a previous laboratory or purchased. A variety of transition-metal complexes are prepared and characterized by NMR and UV–visible spectroscopy. While 1H NMR will be useful in characterizing the complexes, 31P{1H} NMR will be essential for characterization. By varying the metal centers, instructors will be able to introduce crystal field theory, the Evans method, and the effect of NMR active nuclei that are not 100% abundant. In addition, students can examine the electrochemistry of their compounds to determine the effect of the metal on the potential at which oxidation of their ligands occurs.