Formation of Two Isomeric closo‐[(η⁵‐C₅H₅)FePC₂B₈H₁₀] Phosphadicarbaborane Analogues of Ferrocene via Isolable η¹‐Bonded Complexes of the [7‐{(η⁵‐C₅H₅)Fe(CO)₂}‐(η¹‐nido‐PC₂B₈H₁₀)] Type

Abstract

The reaction of nido-[7,8,9-PC(2)B(8)H(11)] (1) with [[CpFe(CO)(2)](2)] (Cp=eta(5)-C(5)H(5) (-)) in benzene (reflux, 3 days) gave an eta(1)-bonded complex [7-Fp-(eta(1)-nido-7,8,9,-PC(2)B(8)H(10))] (2; Fp=CpFe(CO)(2); yield 38 %). A similar reaction at elevated temperatures (xylene, reflux 24 h) gave the isomeric complex [7-Fp-(eta(1)-nido-7,9,10-PC(2)B(8)H(10))] (3; yield 28 %) together with the fully sandwiched complexes [1-Cp-closo-1,2,4,5-FePC(2)B(8)H(10)] 4 a (yield 30%) and [1-Cp-closo-1,2,4,8-FePC(2)B(8)H(10)] 4 b (yield 5%). Compounds 2 and 3 are isolable intermediates along the full eta(5)-complexation pathway of the phosphadicarbaborane cage; their heating (xylene, reflux, 24 h) leads finally to the isolation of compounds 4 a (yields 46 and 52%, respectively) and 4 b (yields 4 and 5%, respectively). Moreover, compound 3 is isolated as a side product from the heating of 2 (yield 10%). The structure of compound 4 a was determined by an X-ray structural analysis and the constitution of all compounds is consistent with the results of mass spectrometry and IR spectroscopy. Multinuclear ((1)H, (11)B, (31)P, and (13)C), two-dimensional [(11)B-(11)B]-COSY, and (1)H[(11)B(selective)] magnetic resonance measurements led to complete assignments of all resonances and are in excellent agreement with the structures proposed.

New Ways to a Series of Parent Representatives of the Eight‐, Nine‐, and Ten‐Vertex Monocarbaborane Family

“…Melting points were measured in sealed capillaries under argon and are uncorrected. Multinuclear ( 1 H, 11 B, and 13 C) NMR spectroscopy was performed essentially with the instrumentation described in other related papers from our laboratories 15. The 11 B and 13 C chemical shifts are given in the following manner: δ(exp.…”

Diphosphacarborane analogues of ferrocene: The synthesis of two isomeric twelve-vertex closo-[(η5-C5H5)FeP2CB8H9] complexes

“…The distances from the metal centre Fe1 to the cluster heteroatoms C5, P2 and P3, at 2.053(6), 2.2616(17) and 2.2633(16) A ˚, respectively, approximate to similar separations found crystallographically for the isostructural complex [1-Cpcloso-1,2,4,5-FePC 2 B 8 H 10 ] (6). 1 The intracluster C-B, P-B, and B-B distances are also in similar ranges to those of 6. The structure determination also confirms the symmetrical arrangement of the iron, carbon and phosphorus heteroatoms within the twelve-vertex closo cage.…”

“…There is current interest in the synthesis and chemistry of closo twelve-vertex ferraphosphacarborane compounds because of their high stabilities and their structural analogies to ferrocene. In this area we have recently reported 1 that the reaction between neutral nido-7,8,9-PC 2 B 8 H 11 2 and [CpFe(CO) 2 ] 2 yields closo complexes [1-Cp-1,2,4,5-FePC 2 B 8 H 10 ] and [1-Cp-1,2,4,8-FePC 2 B 8 H 10 ]. We have also demonstrated that these compounds can form via the isolatable g 1bonded nido intermediates [7-{CpFe(CO) 2 }-7,8,9,-PC 2 B 8 H 10 ] and [7-{CpFe(CO) 2 }-7,9,10-PC 2 B 8 H 10 ].…”

“…We have also demonstrated that these compounds can form via the isolatable g 1bonded nido intermediates [7-{CpFe(CO) 2 }-7,8,9,-PC 2 B 8 H 10 ] and [7-{CpFe(CO) 2 }-7,9,10-PC 2 B 8 H 10 ]. 1 Further, we found that thermal isomerisation of [1-Cp-closo-1,2,4,5-FePC 2 B 8 H 10 ] at 180-350 • C gave another three closo complexes, isomeric with [1-Cp-closo-1,2,4,5-FePC 2 B 8 H 10 ], specifically [1-Cp-1,2,3,8-FePC 2 B 8 H 10 ], [1-Cp-1,10,2,4-FePC 2 B 8 H 10 ], and [1-Cp-1,2,4,10-FePC 2 B 8 H 10 ]. 3 Because of the isolobal parallels between CH and P units as cluster constituents, all of these closo twelve-vertex complexes are analogous to the compounds that constitute the iron(II) tricarbollide family, specifically the parent [CpFeC 3 B 8 H 11 ] isomers themselves, together with amine derivatives of formulation [CpFeC 3 B 8 H 10 (NR 2 )], where R can be hydrogen or an alkyl group.…”

Monocarbaborane Chemistry: Cage Opening of nido‐1‐CB8H12 by Tertiary Bases − an Example of a Straightforward nido → arachno Transformation; Isolation of a New Series of 4‐L‐arachno‐5‐CB8H12 Compounds (L = NMe3, NEt3, and Quinoline)

“…Other chemicals were reagent or analytical grade and were used as purchased. The analytical TLC and column chromatography, melting points, mass spectrometry, and NMR spectroscopy were essentially carried out as described in other work from our laboratories 12…”