Crystal and molecular structure of bis(pentamethylcyclopentadienyl)dicarbonyldicobalt

Comparison of Isoelectronic Heterometallic and Homometallic Binuclear Cyclopentadienylmetal Carbonyls: The Iron–Nickel vs. the Dicobalt Systems

“…Even for the less complicated homoleptic analogue Fe 2 -(CO) 9 , detailed studies [50] do not provide clear and definitive insight into this question.…”

“…A variety of unsaturated homonuclear cyclopentadienylmetal carbonyl compounds have been prepared since the original report [1] of (η 5 -Me 5 C 5 ) 2 Mo 2 (CO) 4 in 1967, including Cp 2 V 2 (CO) 5 , [2] Cp 2 M 2 (CO) 4 (M = Cr, [3] Mo [4] ), and Cp 2 MЈ 2 (CO) 3 (MЈ = Mn, [5] Re [6] ) with formal MϵM triple bonds and Cp 2 Re 2 (CO) 4 , [7] Cp 2 Fe 2 (CO) 3 , [8] and Cp 2 M" 2 (CO) 2 (MЈЈ = Co, [9] Rh [10] ) with formal M=M double bonds (Cp = η 5 -C 5 H 5 or substitution product thereof). In addition, a variety of heteronuclear cyclopentadienylmetal carbonyl compounds are known with heteronuclear metal-metal single bonds.…”

“…(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) metal carbonyl derivatives containing either multiple ironnickel bonds or open-shell iron-nickel pairs. The ironnickel system was chosen for this initial study for the following reasons: (1) The "saturated" derivative Cp 2 FeNi(CO) 3 has been known since 1960 [12,13] as well as its phosphane substitution products of the type (η 5 -C 5 H 5 ) 2 FeNi(CO) 2 L [L = PPh 3 , PPh 2 CH 2 , PPh(CH 3 ) 2 , P(CH 3 ) 3 and P(OPh) 3 ]; [14,15] (2) The isoelectronic dicobalt derivatives are well-characterized experimentally with the isolation and structural characterization of both Cp 2 Co 2 (CO) 3 [16] and Cp 2 Co 2 -(CO) 2 , [9] with formal Co-Co single and Co = Co double bonds, respectively, as well as theoretically using DFT methods. [17] Furthermore, Cp 2 Co 2 (CO), with a formal CoϵCo triple bond, is a probable intermediate in the formation of its dimer, namely Cp 4 Co 4 (µ 3 -CO) 2 , in the pyrolysis of Cp 3 Co 3 (CO) 3 .…”

Five-electron donor versus seven-electron donor bridging phospholyl rings in binuclear cobalt carbonyl derivatives

“…Thus the h 5 -phospholyl manganese carbonyl (h 5 -C 4 H 4 P)Mn(CO) 3 (phosphacymantrene) as well as its more readily available 3,4-dimethyl derivative (h 5 -3,4-C 4 H 2 Me 2 P)Mn(CO) 3 (Fig. 1) were synthesized by Mathey et al [5,6] in 1976 using thermal reactions of the corresponding P-phenylphosphole with Mn 2 (CO) 10 . Such reactions resulted in cleavage of the PeC 6 H 5 bond in the original phosphole.…”

“…In order to see whether this is a general phenomenon, the phospholylcobalt derivatives (C 4 H 4 P) 2 Co 2 (CO) n (n ¼ 3, 2, 1) have now been investigated by related theoretical methods. These binuclear cobalt systems were chosen for this research because two of the analogous binuclear cyclopentadienylcobalt carbonyls [9] (h 5 -C 5 H 5 ) 2 Co 2 (CO) n (n ¼ 3, 2) are known and the permethyl derivative (h 5 -Me 5 C 5 ) 2 Co 2 (m-CO) 2 with a formal Co]Co double bond has been structurally characterized by X-ray crystallography [10]. Although phospholylcobalt carbonyls have not yet been synthesized, they are potentially accessible by reactions of a phospholyl anion with Co 2 (CO) 8 or Co(CO) 4 I with elimination of Co(CO) 4 À or I À , respectively.…”