Flexidentate Coordination Behavior and Chemical Non-Innocence of a Bis(1,3-Diphosphacyclobutadiene) Sandwich Anion

Roedl, Christian and Wolf, Robert (2019) Flexidentate Coordination Behavior and Chemical Non-Innocence of a Bis(1,3-Diphosphacyclobutadiene) Sandwich Anion. CHEMISTRY-A EUROPEAN JOURNAL, 25 (35). pp. 8332-8343. ISSN 0947-6539, 1521-3765

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Abstract

The homoleptic 1,3-diphosphacyclobutadiene sandwich complex [Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)](-) behaved as a versatile and highly flexible metalloligand toward Ni2+, Ru2+, Rh+, and Pd2+ cations, forming a range of unusual oligonuclear compounds. The reaction of [K(thf)(2){Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}] with [Ni2Cp3]BF4 initially afforded the sigma-complex [CpNi{Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}(thf)] (2), which converted into [Co(eta(4)-CpNi{1,3-P(2)C(2)tBu(2)-kappa P,kappa C})(eta(4)-1,3-P(2)C(2)tBu(2))] (3) below room temperature. The structure of 3 contains an unprecedented 1,4-diphospha-2-nickelacyclopentadiene moiety formed by an oxidative addition of a ligand P-C bond onto nickel. At elevated temperatures, 3 isomerized to [Co(eta(4)-CpNi{1,4-P(2)C(2)tBu(2)-kappa P-2,P})(eta(4)-1,3-P(2)C(2)tBu(2))] (4), which features a 1,3-diphospha-2-nickelacyclopentadiene unit. Transmetalation of [K(thf)(2){Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}] with [Cp*RuCl](4) (Cp*=C5Me5) afforded tetranuclear [(Cp*Ru)(3)(mu-Cl)(2){Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}] (5), in which the [Co(eta(4)-1,3-P(2)C(2)tBu(2)](-) anion acts as a chelate ligand toward Ru2+. The diphosphido complex [(Cp*Ru)(2)(mu,eta(2)-P-2)(mu,eta(2)-C(2)tBu(2))] (6) was formed as a byproduct. Pure compound 6 was isolated after prolonged heating of the reaction mixture. The reaction of [K(thf)(2){Co(eta(4)-1,3-P2C2R2)(2)}] (R=tBu; adamantyl, Ad) with [RhCl(cod)](2) (cod=1,5-cyclooctadiene) afforded unprecedented pi-complexes [Rh(cod){Co(eta(4)-1,3-P2C2R2)(2)}] (7: R=tBu; 8: R=Ad), in which one mu:eta(4):eta(4)-P2C2R2 ligand bridges two metal atoms. The pentanuclear complex [Pd-3(PPh3)(2){Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}(2)] (10), featuring a Pd-3 chain and a rare 1,4-diphospha-2-butene ligand, was synthesized by reacting [K(thf)(2){Co(eta(4)-1,3-P(2)C(2)tBu(2))(2)}] with cis-PdCl2(PPh3)(2). The redox properties of selected compounds were analyzed by cyclic voltammetry, whereas DFT calculations gave additional insight into the electronic structures. The results of this study revealed several remarkable and previously unrecognized properties of the [Co(P(2)C(2)tBu(2))(2)](-) anion.

Item Type: Article
Uncontrolled Keywords: PHOSPHORUS-COMPOUNDS; MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURES; BUILDING-BLOCKS; STRUCTURAL-CHARACTERIZATION; RING CONTRACTION; METAL-COMPLEXES; 1ST EXAMPLE; PHOSPHAALKYNES; CHEMISTRY; coordination modes; diphosphacyclobutadienes; heterometallic complexes; sandwich complexes; transition metals
Subjects: 500 Science > 540 Chemistry & allied sciences
Divisions: Chemistry and Pharmacy > Institut für Anorganische Chemie
Chemistry and Pharmacy > Institut für Anorganische Chemie > Arbeitskreis Prof. Dr. Robert Wolf
Depositing User: Dr. Gernot Deinzer
Date Deposited: 06 Apr 2020 08:33
Last Modified: 06 Apr 2020 08:33
URI: https://pred.uni-regensburg.de/id/eprint/26814

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