Synthesis of [AsPh4][Fe3(CO)9(.mu.-CO)(.mu.3-HBCl)] by Oxidative Chloride Substitution of [Fe3(CO)9(.mu.3-HBCO)]2-

Abstract

The deprotonation of (p-H)Fe3(CO)g(p-CO) (p3-HBH) with n-butyllithium yields the dianionic complex [Li]2[Fe3(C0)9(p3-HBCO)], which has been spectroscopically characterized. In contrast to the facile reprotonation of closely related ferraboranes, protonation of [LiIz[Fe3(CO)g(p3-HBCO)] leads to decomposition. On the other hand, reaction of this dianionic complex with 2 equiv of FeCl3 gives a good yield of [Li] [ F~~( C O )~( C~-C O ) (~~-H B C~) . Metathesis with [AsPhJ-[Cl] yields [AsPh] [ F~~( C O ) S (~-C O ) (~~-H B C~) ], which has been crystallographically characterized (triclinic, Pi, a = 9.534(3) A, b = 13.305(4) A, c = 15.225(4) A, a = 104.39(2)', /? = 103.56(2)', y = 99.23(2)', V = 1768.7(8) A3, 2 = 2). Comparison with the analogous osmium clusters, as well as isoelectronic organometallic clusters, reveals relationships among their structures, properties, and energetics.

Substitution on Metallaboranes at Boron. Syntheses of closo-1-X-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2H], X = Cl and OH, and closo-1,5-Cl2-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2] from closo-[2,3,4-(η5-C5Me5)3(μ-H)2Co3B2H2]

“…The low field chemical shift of the boron atom of the parent compound is consistent with its highly metallic environment , The other boron atom of 2 experiences a large shift of −43 ppm, which may be attributed to an antipodal effect. , The existence of an antipodal effect for Cl in this closed metallaborane cage, despite no direct bonding between the boron atoms, shows that the B 2 Co 3 core possesses an essential property of a B n cage. Curiously, the antipodal upfield shift in 2 is considerably larger than the −9.3 ppm shift observed for the main group cage 2-Cl-1,6-C 2 B 4 H 5 . , As expected, the chemical shift observed for 3 is very similar to that observed for the substituted boron of 2 .…”

“…That is, the substituent strongly affects the chemical shift of the substituted boron atom but not the framework hydrogens. We have previously observed for [Fe 3 (CO) 10 (HBX)] - that δ Fe-H-B = −11.1 and −9.3 for X = H, Cl, respectively, thereby showing that a true bridging hydrogen is measurably affected by Cl substitution in a geminal position. , Thus, these new observations on derivatives of 1 point toward a fluxional edge-bridged structure (Chart c) as a better representation of the actual situation. Whether these framework hydrogens lie in or out of the Co 3 plane is a moot point.…”

“…The first example of chlorination of a metallaborane by a metal chloride from our laboratory arose from an investigation of the oxidative coupling of [Fe 3 (CO) 9 BCO] 2- using FeCl 2 /FeCl 3 as the coupling agents. In the course of this work we found that the dianion reacts cleanly with FeCl 3 alone in a 1:2 mole ratio to yield [Fe 3 (CO) 10 (HBCl)] - …”

“…Thus, we suggested edge-bridging positions in the communication (Chart a). Subsequently, the B−H bridge coupling was judged too small for this hydrogen to be Co-B edge-bridging in that [Fe 3 (CO) 10 (HBCl)] - exhibits J FeHB = 60 Hz . Thus, we settled on face-bridging positions in the full publication of the synthetic work (Chart b).…”

Synthesis of B2H5FeCo(CO)6, Fe2Co(CO)9(μ-CO)BH2, FeCo2(CO)9(μ-CO)BH, FeCo2(CO)9(BH)2, and HFe3Co(CO)12BH. Co(CO)3Fragment Addition and Fragment Exchange in Ferraborane Clusters

“…The IR spectrum is very similar to that of HFe 3 (CO) 10 BH 2 (Figure a) and is distinguished by the presence of a strong absorption due to a bridging CO ligand. It has the same number of hydrogen atoms as [Fe 3 (CO) 10 BH 2 ] - , the structure of which has been verified by a crystal structure of [Fe 3 (CO) 10 HBCl] - …”