Synthesis and characterization of Co and Ni complexes stabilized by keto- and acetamide-derived P,O-type phosphine ligands

Abstract

The coordination properties of the beta-keto phosphine ligands R(2)PCH(2)C(O)Ph (, R = i-Pr; , R = Ph), of the new acetamide-derived phosphine ligand (i-Pr)(2)PNHC(O)Me () and of Ph(2)PNHC(O)Me () have been examined towards Ni(ii) complexes. Comparisons are made between systems in which the PCH(2) function of the ketophosphine has been replaced with an isoelectronic PNH group in amide-derived ligands, or the PCH functionality of phosphinoenolates with a PN group in phosphinoiminolate complexes. Furthermore, ligands and reacted with [(eta(5)-C(5)H(5))CoI(2)(CO)] to afford the phosphine mono-adducts [(eta(5)-C(5)H(5))CoI(2){Ph(2)PCH(2)C(O)Ph}] () and [(eta(5)-C(5)H(5))CoI(2){Ph(2)PNHC(O)Me}] (), respectively, which upon reaction with excess NEt(3) yielded the phosphinoenolate complex [(eta(5)-C(5)H(5))[upper bond 1 start]CoI{Ph(2)PCH[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Ph}] () and the phosphinoiminolate complex [(eta(5)-C(5)H(5))[upper bond 1 start]CoI{Ph(2)PN[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Me}] (), respectively. The complexes cis-[[upper bond 1 start]Ni{(i-Pr)(2)PN[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Me}(2)] () and cis-[[upper bond 1 start]Ni{Ph(2)PN[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Me}(2)] () were obtained similarly from NiCl(2) and (3) and (4), respectively, in the presence of a base. The phosphinoenolate complex [[upper bond 1 start]Ni{(i-Pr)(2)PCH[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Ph}(2)] () exists in ethanol as a mixture of the cis and trans isomers, in contrast to cis-[[upper bond 1 start]Ni{(Ph(2)PCH[horiz bar, triple dot above]C([horiz bar, triple dot above]O[upper bond 1 end])Ph}(2)], and the solid-state structure of the trans isomer of was established by X-ray diffraction. The structures of the ligand (3) and of the complexes , in .3/2CH(2)Cl(2), , and have also been determined by X-ray diffraction and are compared with those of related complexes. Complexes , and contain a five-membered heteroatomic metallocyclic moiety, which is constituted by five different chemical elements. The structural consequences of the steric bulk of the P substituents and of the electronic characteristics of the P,O chelates are discussed.

Ruthenium complexes of diphenylphosphino derivatives of carboxylic amides: Synthesis and characterization of bidentate P,N- and P,O-chelate ligands and their reactivity towards [RuCl2(PPh3)3]

“…This compound has already been characterized crystallographically [26] and in the solid state each Ru atom carries two chemically different 7.53 (m, aryl, 2H). 13 1c: This compound was synthesized according to a procedure of Opatz et al [12] (modified procedure). To a solution of 2-hydroxypyridine (2.00 g, 21.0 mmol) and triethylamine (2.14 g, 21.0 mmol) in THF (30 mL) at 40°C chlorodiphenylphosphine (4.65 g, 21.0 mmol) was added with stirring.…”

“…Moreover, phosphino-functionalized carboxylic amides, which still bear an acidic proton (N−H moiety) can be utilized as mono-anionic bidentate chelators upon deprotonation, and their coordination chemistry has been studied with a variety of transition metal compounds (some examples are shown in Scheme 1, C, D and E) [13,14]. Phosphino-functionalized carboxylic amides devoid of this acidic N−H feature (or in general lacking the capability of forming the corresponding anion) can thus only serve as neutral chelators, hence lacking some electrostatic binding force, which should render these ligands more labile.…”

“…In general, the P,N [7] and P, O [8] bidentate donor sets may exhibit mono-vs. bidentate ligand characteristics, and in combination with rather soft transition metal atoms the phosphorus atom represents the superior σ-donor over the N or O atom in case of monodentate binding in the transition metal coordination sphere (A, B and C in Scheme 1). This hemilabile property is supportive in many catalytic processes like oligo-and polymerization, carbonylation as well as hydro-and dehydrogenation [8][9][10][11][12].Moreover, phosphino-functionalized carboxylic amides, which still bear an acidic proton (N−H moiety) can be utilized as mono-anionic bidentate chelators upon deprotonation, and their coordination chemistry has been studied with a variety of transition metal compounds (some examples are shown in Scheme 1, C, D and E) [13,14]. Phosphino-functionalized carboxylic amides devoid of this acidic N−H feature (or in general lacking the capability of forming the corresponding anion) can thus only serve as neutral chelators, hence lacking some electrostatic binding force, which should render these ligands more labile.…”

“…91-6.96 (m, aryl, 2H), 7.34-7.41 (m, aryl, 6H), 7.58-7.65 (m, aryl, 5H), 8.19 (m, aryl, 1H). 13 C{ 1 H} NMR (CDCl 3 , δ ppm): 112.3 (s, C3, PyO), 118.0 (s, C5, PyO), 128.4 (d, J = 17.2 Hz, meta-Ph), 129.6 (s, para-Ph), 130.9 (d, J = 23.4 Hz, ortho-Ph), 139.1 (s, C4, PyO), 140.7 (d, J = 18.9 Hz, ipso-Ph), 147.6 (s, C6, PyO),162.5 (d, J = 6.9 Hz, C2, PyO). 31 P{ 1 H} NMR (CDCl 3 , δ ppm): 100.6 (s).…”

Synthesis of neutral and zwitterionic phosphinomethylpyrrolato complexes of nickel

“…Nickel P-O chelates form the basis of the Shell Higher Olefins Process (SHOP) [1][2][3]. Some nickel allyl and benzyl chelate complexes show also good polymerisation activity [4,5].…”