Novel Copper(I) Complexes Containing 1,1‘-Bis(diphenylphosphino)ferrocene (dppf) as a Chelate and Bridging Ligand:  Synthesis of Tetrabridged Dicopper(I) Complexes [Cu₂(μ-η¹-C⋮R)₂(μ-dppf)₂] and X-ray Crystal Structure of [Cu₂(μ-η¹-C⋮CC₆H₄CH₃-4)₂(μ-dppf)₂]

Abstract

Binuclear copper(I) complexes [Cu(κ2-P,P-dppf)(CH3CN)2][BF4] (1), [Cu(κ2-P,P-dppf)(bipy)][BF4] (2) containing the chelating dppf ligand (dppf = 1,1‘-bis(diphenylphosphino)ferrocene) have been prepared by substitution reactions of the acetonitrile ligands from the complexes [Cu(CH3CN)4][BF4] and (1) with dppf and bipy, respectively. Similarly, the treatment of the complex [Cu2(μ-dppm)2(CH3CN)2][BF4]2 with dppf in CH2Cl2 at room temperature gives the tetranuclear complex [Cu2(μ-dppm)2(κ2-P,P-dppf)2][BF4]2 (3). The analogous bridging chloride tetranuclear complex [Cu2(μ-Cl)2(κ2-P,P-dppf)2] (4) has been also prepared by the addition of dppf to a solution in THF containing an equimolar mixture of CuCl and tetramethylethylenediamine. Complex 4 has been used as a precursor for μ-η1-alkynyl bridging dicopper(I) complexes containing the framework [Cu2(μ-dppf)2]. Complexes [Cu2(μ-η1-C⋮CR)2(μ-dppf)2] (R = C6H4CH3-4 (5), C6H5 (6), CH2OCH3 (7), CH2CH2CH3 (8), (η5-C5H4)Fe(η5-C5H5) (9)) are obtained by the treatment of complex 4 with an excess of LiC⋮CR in THF. Complexes 5−9 can also be prepared from the reaction of an equimolar mixture of [Cu(C⋮CR)] n and dppf in toluene at room temperature. The crystal structure of complex 5 has been determined by X-ray diffraction. The crystallographic asymmetric unit consists of three molecules of 5, all with related stereochemistries at their centers. The complex consists of two copper atoms linked by two bridging dppf ligands and two bridging alkynyl groups in a μ-η1 bonding arrangement with an almost planar [Cu2(μ-η1-C⋮CR)2] framework. The arylethynyl groups are nearly linear (C⋮C−C angles 174(2)−175(2)°), and the C⋮C distances (1.20(2)−1.21(2) Å) are typical for cases of metal−acetylide σ-bonding. Both bridging dppf ligands are twisted from the eclipsed conformation (mean value 77(2)°) and also show a relatively large value of the angle (mean value 56.8(6)°) formed by the projection of the Cp···Cp axis of dppf onto the Cu···Cu axis. This seems to indicate that the molecular core [Cu2(μ-η1-C⋮CC6H4CH3-4)2] is a sterically demanding system that forces the dppf ligand to adopt a relatively strained conformation.

The Mechanism of CX (X=F, Cl, Br, and I) Bond Activation in CX4 by a Stabilized Dialkylsilylene

“…Synthesis and structure : The compounds from Scheme were straightforwardly obtained using the corresponding dqp derivative and [Cu(dppf)(CH 3 CN) 2 ][BF 4 ] or [Cu(dppf)(CH 3 CN) 2 ][PF 6 ] 17. Elemental analyses, mass spectrometry, and 31 P, 19 F and 1 H NMR spectroscopy confirmed the composition, the (dqp) 0 , Fe II , and Cu I oxidation states, and the trigonal spectroscopic symmetry of [(μ 3 ‐dqp){Cu(dppf)} 3 ] 3+ .…”

“…General : The ligands diquinoxaline[2,3‐ a :2′,3′‐ c ]phenazine (L 1 ),25 2,3,8,9,14,15‐hexachlorodiquinoxaline[2,3‐ a :2′,3′‐ c ]phenazine (L 2 )26 and 2,3,8,9,14,15‐hexamethyldiquinoxaline[2,3‐ a :2′,3′‐ c ]phenazine (L 3 )27 (Scheme ) were synthesized by following the literature procedure. The precursor complexes [Cu(dppf)(CH 3 CN) 2 ]BF 4 and [Cu(dppf)(CH 3 CN) 2 ]PF 6 were obtained by reacting dppf with [Cu(CH 3 CN) 4 ]BF 4 or [Cu(CH 3 CN) 4 ]PF 6 , respectively 17. Chemicals and solvents were reagent grade and were used as received.…”

Invariant Oxidation State of Copper but not of Ruthenium in Complexes with Noninnocent N‐(2‐Methyl‐5,8‐dioxo‐5,8‐dihydroquinolin‐7‐yl)acetamide: A Combined Structural, Electrochemical and Spectroelectrochemical Investigation

“…General Considerations: The complexes cis-Ru(acac) 2 (CH 3 CN) 2 , [38] [(dppf)Cu(CH 3 CN) 2 ](BF 4 ) [39] and the ligand (L) [40] were synthesized according to reported procedures. RuCl 3 ·nH 2 O was purchased from Merck, CuCl from Strem, and 1,1Ј-bis(diphenylphosphanyl)ferrocene from Alfa Aesar.…”

Isomerism and dynamic behavior of bridging phosphaalkynes bound to a dicopper complex

“…12 Many multicopper assemblies bind substrates through a combination of these modes, and unsaturated molecules more oen bind in a canted m-h 1 :h 1 or m-h 1 :h 2 fashion, rather than in a symmetrical mode through one bridging atom (m-h 1 :h 1 ). 10,[13][14][15][16][17][18][19][20] Moreover, the observed binding modes are oen found to be substrate-specic rather than examples of a broader structural class. [21][22][23] One system that notably exhibits a high tendency toward symmetrical m-h 1 :h 1 binding is the naphthyridine-supported dicopper (I) core reported by this laboratory, which binds nitriles, isonitriles, carbon monoxide, as well as phenyl and terminal alkynyl anions exclusively in a symmetrical m-h 1 :h 1 fashion.…”