Estimate of Electrochemical Ligand Parameters in Iron(II) Adducts of [FeH(CN)(dppe)2]

Characterization of Coordination Compounds by Electrochemical Parameters

“…-0.7 to -0.9 [16] O 2----1.8 [73] [a] Ordered generally from higher to lower Isocyanides show P L values that are spread over a wide range, from +0.2 to -0.4 V ( Table 1): benzoyl isocyanide [30] Ͼ bent isocyanides [24,25,34,35] Ͼ ferricinium isocyanides [38,39] Ͼ phosphonium isocyanides [41] Ն linear isocyanides. [24,25,34,43] Metallo-cyanide adducts and other cyano adducts are quite sensitive to the Lewis acid but are always stronger net electron acceptors than cyanide: CNBF 3 - - [40] Ͼ CN -.…”

“…-1.00 [10] 0.02 [13] -0.74 [30] -0.26 [30] Hydrotris(3,5-dimethylpyrazolyl)borate ---0.23 [64] [HB(Me 2 pz) 3 -] Bis(pyrazolyl)borate (H 2 Bpz 2 -) ---0.24 [64] Pyrazolate -1.14 [36] -0.24 [13] 2-Pyridinecarboxylate (2-pyCOO -)…”

“…1.2 [36] Benzoyl isocyanide (CϵNCOPh) 0.20 [30] 0.16 [30] PF 3 0.14 [32] --Aminocarbyne (=CNH 2 + ) 0.09 [31] ca. 1.1 [36] CO 0 [10] 0.99 [13] η 1 -Phosphaalkyne (η 1 -PϵCtBu) -0.04 [33] --N 2 -0.07 [10] --Isocyanides (bent) (CϵNR) [b] -0.07 to -0.18 [24,25,34,35] --Hydrazinium (NH 2 NH 3 + ) --0.80 [57] Ethylene (CH 2 =CH 2 ) --0.76 [13] N-Pyrrolylphosphanes --0.69 to 0.53 [28] PPh n (NC 4 H 4 ) 3-n (n = 0-3) Vinylidenes (=C=CHR) 0 to -0.6 [29,36] 0.7 to 0.2 [36] P(OPh) 3 -0.18 [10] 0.58 [13] η 2 -Allene (η 2 -CH 2 =C=CHPh) -0.21 [31] 0.56 [36] Metallo-dinitriles (NϵC-X-CϵN-ML n-1 ) -0.18 to -0.40 [37] 0.58 to 0.39 [36] Ferricinium isocyanides -0.22 to -0.28 [38,39] 0.55 to 0.50 [36] Nitriles (NϵCR) -0.23 to -0.58 [10,27] 0.49 to 0.33 [13] CϵN-BF 3 --0.24 [30] 0.20 [30] Metallo-cyanides (CϵN-ML n-1 -) -0.25 to -0.61 [30,40] 0.50 to 0.21 [36] Phosphonium isocyanides -0.28 to -0.36 [41] 0.50 to 0.43 [41] Allenylidenes (=C=C=CR 2 ) 0 t o -0.8 [36,42] 0.8 to 0 [36] Me 2 SO (S-coordinated) -0.19 <...>…”

“…[24,25,34,43] Metallo-cyanide adducts and other cyano adducts are quite sensitive to the Lewis acid but are always stronger net electron acceptors than cyanide: CNBF 3 - - [40] Ͼ CN -. [10,30] Carbenes and related ligands are spread over an even wider window of P L values (from 0 to -1.7 V): vinylidenes C=CHR [29,36] Ն allenylidenes C=C=CR 2 [36,42] Ͼ bithiophene-carbenes [44] [5,36] ferrocenyl-oxocarbenes [36] Ն phosphoylide-aminocarbenes [41] Ͼ ferrocenyl-aminocarbenes [36] Ͼ anionic oxycarbenes C(O -)Y.…”

“…The strongest net π-electron acceptors exhibit the highest P L values (Ն0), namely NO + (+1.40 V) [10] Ͼ carbynes (+0.24 to +0.21 V) [29] Ͼ η 2 -vinyl (+0.22 V) [31] Ͼ benzoyl isocyanide (+0.20 V) [30] Ͼ PF 3 (+0.14 V) [32] Ͼ aminocarbyne (=CNH 2 + ) (+0.09 V) [31] Ͼ CO (0 V). Dinitrogen and the phosphaalkyne PϵCtBu, coordinated in the η 1 -mode, have P L values (-0.07 [10] and -0.04 [33] V, respectively) close to that of CO (0 V), but this is accounted for by the limited σ-donor and π-acceptor abilities of the former ligands.…”