The platinum(0) monocarbonyl complex, [(Cy(3)P)(2)Pt(CO)], was synthesized by reaction of [(Cy(3)P)(2)Pt] with [(η(5)-C(5)Me(5))Ir(CO)(2)] and subsequent irradiation. X-ray structure analysis was performed and represents the first structural evidence of a platinum(0) monocarbonyl complex bearing two free phosphine ligands. Its corresponding dicarbonyl complex [(Cy(3)P)(2)Pt(CO)(2)] was synthesized by treatment of [(Cy(3)P)(2)Pt] with CO at -40 °C and confirmed by X-ray structure analysis.

The incorporation of subvalent Group 13 ligands into the coordination sphere of transition metals has always been a challenging task, particularly in the formation of homoleptic complexes. Although metastable or sterically protected subvalent E I (E = Al, Ga, In) precursors have become accessible during the last few decades, [1] for example, E I halides, [1, 2] [{Cp*E} n ] (Cp* = h 5 -C 5 Me 5 ), [1, 3] and [{EC(SiMe 3 ) 3 } n ], [1, 4] stable and isolable boron congeners have still not been prepared. For this reason, only homoleptic transition-metal complexes with Al-, Ga-, and In-based ligands have so far been realized, for example, mononuclear [Ni(ECp*) 4 ] (A; E = Al, Ga) [5,6] and [Ni{EC(SiMe 3 ) 3 } 4 ] (B; E = Ga, In), [7,8] as well as numerous heteroleptic examples with two or more E I ligands. [9] The corresponding subvalent boron ligands, that is, borylenes, have only been generated directly in the coordination sphere of transition metals [10] to form species such as [(OC) 5 M=BN(SiMe 3 ) 2 ] (C; M = Cr, Mo, W).[11] To date, both mononuclear borylene complexes containing more than one borylene substituent as well as homoleptic borylene species have continuously resisted isolation. Nonetheless, borylene complexes have sparked increasing interest in fundamental organometallic research because of their close relationship with important organometallic compounds such as carbene, carbyne, and vinylidene complexes, and the similarity of the bonding properties of borylene and carbonyl ligands. Numerous experimental and computational studies have previously examined these bonding properties in detail.[10] It was thus shown that BR has stronger s-donor and p-acceptor properties than CO, which makes the M À BR bond even more stable with respect to homolytic dissociation than the M À CO bond, but in turn it is kinetically labile due to the high polarity. Getting back to the series of related ligands mentioned above, the predominance of the CO and carbene ligands in organometallic chemistry is also manifested by the fact that homoleptic complexes have only been accessible with these two ligands. By contrast, the incorporation of two borylene or carbyne ligands into a mononuclear transition-metal complex has always proven problematic. While in the former case a suitable synthetic approach is still lacking, [12] the synthesis of bis(carbyne) species is further hampered by reductive coupling to form acetylenes, particularly with alkyl-substituted carbynes.[13] It has not yet been elucidated whether bis-(borylene) complexes are resistant towards reductive coupling. In any case, it would require the availability of experimental data before this question could be clarified. We have been studying borylene complexes for more than a decade now, but all our efforts to synthesize a complex with more than one terminal borylene have so far failed.Herein, we describe the successful generation and isolation of a long-sought after mononuclear, terminal bis-(borylene) complex derived from the [Cp*Ir] half-sandwich fragment,...

New metal-only Lewis pairs (MOLPs: Ru→Cr and Os→Cr) are prepared by the insertion of a zerovalent ruthenium or osmium complex into chromium-boron double bonds of borylene complexes. The reaction creates new borylene complexes (the first ever for osmium), and is crystallization-controlled; re-dissolving the complexes results in regeneration of the starting materials. A mechanism is proposed based on DFT calculations, along with a computational study of the unusual MOLPs.

Mono‐ and dinuclear hydridoborylene complexes were prepared by intermetallic borylene transfer from Group VI borylene or metalloborylene reagents. The hydride and borylene ligands were found to interact with each other significantly, although the boron ligand retains much of its former borylene character. Zero‐valent platinum fragments were successively added to the dinuclear hydridoborylene complexes, resulting in tri‐ and tetranuclear borido complexes, in which the BH interaction has been lost, and the hydride ligands now bridge two metal centers. The complexes were studied spectroscopically, crystallographically, and by DFT methods, and the unusual bonding situation in the MBH triangles of hydridoborylene complexes were evaluated.