Heats of Formation of Co(CO)₂NOPR₃, R = CH₃ and C₂H₅, and Its Ionic Fragments

Abstract

A joint threshold photoelectron photoion coincidence spectrometry (TPEPICO) and collision-induced dissociation (CID) study on the thermochemistry of Co(CO)(2)NOPR(3), R = CH(3) (Me) and C(2)H(5) (Et), complexes is presented. Adiabatic ionization energies of 7.36 +/- 0.04 and 7.24 +/- 0.04 eV, respectively, were extracted from scans of the total ion and threshold electron signals. In the TPEPICO study, the following 0 K onsets were determined for the various fragment ions: CoCONOPMe(3)(+), 8.30 +/- 0.05 eV; CoNOPMe(3)(+), 9.11 +/- 0.05 eV; CoPMe(3)(+) 10.80 +/- 0.05 eV; CoCONOPEt(3)(+), 8.14 +/- 0.05 eV; CoNOPEt(3)(+), 8.92 +/- 0.05 eV; and CoPEt(3)(+), 10.66 +/- 0.05 eV. These onsets were combined with the Co(+)-PR(3) (R = CH(3) and C(2)H(5)) bond dissociation energies of 2.88 +/- 0.11 and 3.51 +/- 0.17 eV, obtained from the TCID experiments, to derive the heats of formation of the neutral and ionic species. Thus, the Co(CO)(2)NOPR(3) (R = CH(3) and C(2)H(5)) 0 K heats of formation were found to be -350 +/- 13 and -376 +/- 18 kJ x mol(-)(1), respectively. These heats of formation were combined with the published heat of formation of Co(CO)(3)NO to determine the substitution enthalpies of the carbonyl to phosphine substitution reactions. Room-temperature values of the heats of formation are also given using the calculated harmonic vibrational frequencies. Analysis of the TCID experimental results provides indirectly the adiabatic ionization energies of the free phosphine ligands, P(CH(3))(3) and P(C(2)H(5))(3), of 7.83 +/- 0.03 and 7.50 +/- 0.03 eV, respectively.

Modeling unimolecular reactions in photoelectron photoion coincidence experiments

“… Parallel dissociations ICH 2 CN,63 C 3 H 4 O (acrolein),64 (C 6 H 5 ) 3 COH,65 CH 2 BrI, CH 2 ICl, CH 2 Cl 2 , CH 2 ClBr,51 C 2 H 5 COCH 3 , C 2 H 5 COCOCH 3 ,66 P(CH 3 ) 3 ,67 Ge(CH 3 ) 3 Cl, Ge(CH 3 ) 3 Br,56 neo ‐C 5 H 11 NH 2 ,68 CHCl 2 Br, CHClBr 2 ,54 C 2 H 3 Cl,61 C 3 H 6 ,28 Si 2 Cl 6 , SiCl 3 C 2 H 5 , SiCl 3 C 2 H 3 ,27 (CH 3 ) 4 C,24 t ‐C 4 H 9 OO t ‐C 4 H 9 , t ‐C 4 H 9 NN t ‐C 4 H 9 ,23 (CH 3 ) 2 NNH 2 ,30 Cp 2 Ni, Cp 2 Co, Cp 2 Cr 31 Consecutive dissociations CpCo(CO) 2 ,69 CpMn(CO) 3 ,70 BzCr(CO) 3 ,71 Bz 2 Cr,72 Co(CO) 2 NOP(CH 3 ) 3 , Co(CO) 2 NOP(C 2 H 5 ) 3 ,73 CpMn(CO) 2 CS, CpMn(CO) 2 CSe,74 C 2 H 3 Br 3 ,52 (CH 3 ) 6 Si 2 , (CH 3 ) 3 SiBr,55 HP(C 2 H 5 ) 2 ,60 t ‐C 4 H 9 NCCo(CO) 2 NO,75 S 2 Cl 2 , SOCl 2 62 Parallel and consecutive dissociations Co(CO) 3 NO,76 C 3 H 8 COCH 3 ,66 P(C 2 H 5 ) 3 60…”

“…CpCo(CO) 2 ,69 CpMn(CO) 3 ,70 BzCr(CO) 3 ,71 Bz 2 Cr,72 Co(CO) 2 NOP(CH 3 ) 3 , Co(CO) 2 NOP(C 2 H 5 ) 3 ,73 CpMn(CO) 2 CS, CpMn(CO) 2 CSe,74 C 2 H 3 Br 3 ,52 (CH 3 ) 6 Si 2 , (CH 3 ) 3 SiBr,55 HP(C 2 H 5 ) 2 ,60 t ‐C 4 H 9 NCCo(CO) 2 NO,75 S 2 Cl 2 , SOCl 2 62…”

Bonding in a Borylene Complex Investigated by Photoionization and Dissociative Photoionization

“…A value of (7.30 AE 0.05) eV was obtained for [(C 6 H 6 )Cr(CO) 3 ], [29] (7.69 AE 0.02) eV for [CpMn(CO) 3 ], [6] and (7.24 AE 0.04) eV for [Co(CO) 2 NOPEt 3 ]. [30] However, ionization energies above 8 eV were reported for [Cr(CO) 6 ], [4b] which is about 1 eV higher. Therefore, the boron-containing group has a significant influence on the ionization energy of a metal carbonyl, but the influence is comparable to that of organic ligands, such as C 6 H 6 , Cp or PA C H T U N G T R E N N U N G (C 2 H 5 ) 3 .…”

Unimolecular Reaction Mechanism of an Imidazolin‐2‐ylidene: An iPEPICO Study on the Complex Dissociation of an Arduengo‐Type Carbene

“…This provides a robust route to thermochemical quantities, such as bond energies or proton affinities through the ion cycle 52. Several volatile organometallic complexes have been investigated so far, for example, the binary iron pentacarbonyl, [Fe(CO) 5 ],53, 54 chromium hexacarbonyl [Cr(CO) 6 ],55 the cyclopentadienyl half‐sandwich complex [C 5 H 5 Mn(CO) 3 ],56 the sandwich complexes [(η 5 ‐C 5 H 5 ) 2 M] (M=Cr, Co, Ni),57 and several tricarbonylnitrosyl compounds of the type [Co(CO) 2 (NO)(PR 3 )] 58. The measured bond‐dissociation energies and heats of formation shed more light on the ligand‐to‐metal bond 59.…”

“…[52] Several volatile organometallic complexes have been investigated so far, for example, the binary iron pentacarbonyl, [Fe(CO) 5 ], [53,54] chromium hexacarbonyl [Cr(CO) 6 ], [55] the cyclopentadienyl half-sandwich complex [C 5 H 5 Mn(CO) 3 ], [56] the sandwich complexes [(h 5 -C 5 H 5 ) 2 M] (M = Cr, Co, Ni), [57] and several tricarbonylnitrosyl compounds of the type [Co(CO) 2 (NO)A C H T U N G T R E N N U N G (PR 3 )]. [58] The measured bond-dissociation energies and heats of formation shed more light on the ligand-to-metal bond. [59] In order to understand how the transition-metal bond influences the PR 3 ligand chemistry, Kercher et al investigated the uncoordinated tri-, di-, and monoethylphosphines, [60] and verified their results by isodesmic reaction energy calculations.…”