Phosphine induced migratory CO insertion into the Fe–CH2 bond of the organometallic polymer -[(η5-C5H4)Fe(CO)2CH2SiMe2]n- and characterization of model iron complexes

Abstract

Thermal and photochemical treatment of 1-sila-3-ferracyclobutane, (eta(5)C(5)H(4))Fe(CO)(2)CH(2)SiMe(2) (1) results in ring-opening polymerization (ROP). Phosphine-induced migratory CO insertion into the Fe-CH(2) bond of the preformed polymer, -[(eta(5)-C(5)H(4))Fe(CO)(2)CH(2)SiMe(2)](n)- (2) results in either linear polymers, -[(eta(5)-C(5)H(4))Fe(CO)(PR(3))C(O)CH(2)SiMe(2)](n)- [R(3) = Me(2)Ph (3), Ph(3) (4)] or diphosphine bridged polymers, -{[(eta(5)-C(5)H(4))Fe(CO)C(O)CH(2)SiMe(2)](2)(P-P)}(n)- [P-P = dppe (5), dppp (6), dppb (7), trans-dppen (8), dmpe (9); dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,2-bis(diphenylphosphino)propane, dppb = 1,2-bis(diphenylphosphino)butane, cis-dppen = cis-1,2-bis(diphenylphosphino)ethylene, dmpe = 1,2-bis(dimethylphosphino)ethane]. The analogous model complexes, {[(eta(5)-C(5)H(5))Fe(CO)C(O)CH(3)](2)P-P} [P-P = dppp (10), dppb (11), trans-dppen (12), dmpe (13)] were synthesized and characterized as models of the acylated polymers. The X-ray crystal structure of 11 and 13 were determined to establish the bridging nature of the diphosphines in the model complexes and to get insight of the crystal packing.

Synthesis and migration insertion polymerization (MIP) of CpFe(CO)2(CH2)6PPh2(FpC6P) for PFpC6P: macromolecule stability, degradability and redox activity

“…As shown in Fig. 35 This result indicates that the proton signals for CH 2 -P overlap with one peak for the diastereotopic protons at 2.3 ppm, which is confirmed by the integration ratio (1 : 3) of the signals at 2.7 and 2.3 ppm. 4).…”

“…The resulting brown solution was slowly added to hexane to precipitate the polymer. These two frequencies are known for terminal and acyl CO absorptions commonly observed from iron acyl complexes, 29,35 suggesting that MIP occurred. NMR and IR were used to characterize the polymers.…”

“…44,45 Half-sandwich iron-carbonyl complexes usually have less electrochemical stability when compared to ferrocene. 47 The cyclic voltammetry (CV) experiment for this polymer shows an irreversible redox cycle with oxidations at 0.59 V and 0.62 V (relative to Ag/AgCl). 47 The cyclic voltammetry (CV) experiment for this polymer shows an irreversible redox cycle with oxidations at 0.59 V and 0.62 V (relative to Ag/AgCl).…”

“…Both IR and 13 C NMR provided evidence that MIP occurred. 29,35 The 31 P NMR spectrum is illustrated in Fig. 2a).…”

“…28,46 -[CpFe(CO)(PR 3 )C(O)CH 2 SiMe 2 ] nis a type of MCP that contains a half-sandwich iron-acyl complex similar to the coordination structure of the FpC6P repeat units, but the phosphine ligands are not involved in the polymer backbone. 47 We performed CV experiments for FpC6P in DMF. 47 We performed CV experiments for FpC6P in DMF.…”