Syntheses and Structures of Trimethylphosphine-complexed Primary Boryl Complexes of Group 8 Metals, Cp*M(CO)2(BH2·PMe3) (M = Fe, Ru)

Abstract

Photolysis of Cp*Fe(CO)2Me in the presence of BH3·PMe3 (1) produced a boryliron complex Cp*Fe(CO)2(BH2·PMe3) (2a). Complex 2a and the ruthenium analogue Cp*Ru(CO)2(BH2·PMe3) (3) were accessible by the salt-elimination reaction between K[Cp*M(CO)2] (M = Fe, Ru) and BH2Cl·PMe3.

Ruthenium (II) complexes of the chelating phosphine borane H2ClB·dppm

“…than in II [2.141(2) and 2.180(2) Å , respectively]. However, both these Ru-B distances are short, being comparable to that found in complexes with direct Ru-B r-bonds [14]. Calculations on II [9] and related ruthenium hydridoborates [15] do indeed indicate a small, but significant, interaction between ruthenium and boron.…”

Transition‐Metal Complexes of Boron—New Insights and Novel Coordination Modes

“…The phosphine adduct 64 , obtained from reaction of CoCl 2 with NaBH 4 in the presence of CO and dppm, proved to be more stable and could be structurally characterized by X‐ray diffraction methods 41. A more general synthetic route to base‐stabilized boryl complexes is represented by photolytic reactions of BH 3 ⋅PMe 3 with half‐sandwich methyl complexes of molybdenum, tungsten, and iron (Scheme ) 42a,b…”

“…The analogous cyclopentadienyl derivatives were observed in solution during photolysis, but turned out to be too unstable to be isolated. Alternatively, complex 67 and its ruthenium analogue 68 could be prepared in slightly better yields by salt‐elimination reactions according to Scheme 42b…”

Base‐Stabilized Boryl and Cationic Haloborylene Complexes of Iron

“…Base‐stabilized dihydroboryl complexes are exceedingly rare, and their free analogues have not been isolated to date 6. 10 This reaction, as depicted in Scheme a, is comparable to the synthesis of the phosphine‐stabilized boryl complex [(η 5 ‐C 5 Me 5 )Fe(CO) 2 (BH 2 ⋅ PMe 3 )] by Shimoi and co‐workers in 2000 6b. This complex was isolated in quite low yields (14 %), which is in contrast to the fairly good yield of 2 (73 %).…”

“…Although the BC3 bond length of 1.590(3) Å is comparable to other NHC–boron adducts,9 the FeB bond is the longest of structurally authenticated iron(II)–boryl complexes 1. It is longer than the FeB bond in [(η 5 ‐C 5 Me 5 )Fe(CO) 2 (BH 2 ⋅ PMe 3 )] (2.195(14) Å)6b and significantly elongated with respect to complexes with tricoordinate boryl ligands. This elongation is most likely due to the coordination of the NHC, which leads to the occupation of the former vacant p orbital at boron.…”