Metallaborane Heteroatom Incorporation Reactions:  Enyne Insertion into arachno-[(CO)(PMe₃)₂HIrB₈H₁₂]

Abstract

arachno-[(CO)(PMe3)2HIrB8H12] (1) reacts with HC⋮C−C(CH3)CH2 in xylene at 138 °C to afford [7-{C(CH3)CH2}-9,9,9-(CO)(PMe3)2-nido-9,7,8-IrC2B8H10] (2; 10%) together with traces of [5,5,5-(CO)(PMe3)2-μ-6,7-{CHC(CH3)CH2}-nido-5,6-IrCB8H11] (3, <1%). Compound 2 is a conventional nido 11-vertex metallacarborane with the {C2Ir} three-atom string in the open face of the cluster, whereas compound 3 is based on a nido 10-vertex {5,6-IrCB8} skeleton with C(2) of the original butyne bridging adjacent B(7) and C(6) cluster open-face positions. Compounds 2 and 3 are characterized by 1H, 31P, and 11B NMR spectroscopy and by single-crystal X-ray diffraction analysis.

Metallaborane reaction chemistry. Part 10. Phenylacetylene incorporation via [4,4-(PMe2Ph)2-arachno-4-PtCB8H12] in a ‘converse’ metalladicarbaborane synthesis of [7,7-(PMe2Ph)2-isonido-7,6,8-PtC2B6H7-6-Ph]

“…In cluster electron-counting terms, a closo cluster for 2 would require the {Pt(PMe 2 Ph) 2 } centre to contribute two electrons to the cluster bonding scheme, and thereby act as platinum(II). However, the square-planar coordination tendencies of platinum(II) restrict its principal orbital involvement with the cluster to less than the three that would be required for the BH-vertex equivalence that would be required for classical closo, and it directs the two platinum(II) bonding vectors towards the more electronegative and more electron-rich C(6) and C (8) positions that are transoid to the two phosphines, with P(1)Pt(7)C(8) and P(2)Pt(7)C(6) both approximately linear at 173.76 (14)°and 164.74(13)°, respectively. This minimises the bonding from Pt (7) to the B(1)B(3)B(4) region, and also to B(9), and thence engenders the much more open configuration VIII.…”

“…More recently, we and others became interested in these types of Ôconverse reactionsÕ of acetylenes with boron-containing clusters, using both metallaborane and heteroborane substrates [5][6][7][8][9][10][11]. It was found, for example, that the incorporation of HC"CH into the arachno nine-vertex [4,4,4,4-(CO)(PPh 3 ) 2 H-4-IrB 8 H 12 ] cluster gives an 11-vertex {IrC 2 B 8 } species, and that HC"CAC(Me)@CH 2 gives both 10-vertex {IrCB 8 } and 11-vertex {IrC 2 B 8 } species [7,8]. We also found 1387-7003/$ -see front matter Ó…”

“…Of the few examples, it had been shown that addition of alkynes, accompanied by boron-vertex loss, to [2-(C 5 H 5 )-nido-2-CoB 4 H 8 ] gives [1-(C 5 H 5 )-nido-1,2,3-CoC 2 B 3 H 7 ] and Csubstituted derivatives [3], and that the addition of MeC"CMe into [1,1,1-(CO) 3 [4]. More recently, we and others became interested in these types of Ôconverse reactionsÕ of acetylenes with boron-containing clusters, using both metallaborane and heteroborane substrates [5][6][7][8][9][10][11]. It was found, for example, that the incorporation of HC"CH into the arachno nine-vertex [4,4,4,4- [7,8].…”

“…More recently, we and others became interested in these types of Ôconverse reactionsÕ of acetylenes with boron-containing clusters, using both metallaborane and heteroborane substrates [5][6][7][8][9][10][11]. It was found, for example, that the incorporation of HC"CH into the arachno nine-vertex [4,4,4,4- [7,8]. We also found skeletal assimilation of phenyl acetylene, PhC"CH, into nine-vertex hypho-type azaboranes [(RNH 2 )B 8 H 11 NHR] to give 11-vertex {NC 2 B 8 } azadicarbaborane cluster species [11].…”

Reaction of 2-Butyne withnido-[1,2-(Cp*RuH)2B3H7]: Improved Kinetic Control Leads to Metallacarboranes of Novel Composition and Structure

“…[7] The key step, a stereospecific tris-Curtius rearrangement of triazide (purified chromatographically with CHCl 3 ), proceeded with high yield in refluxing dioxane or toluene (caution!). [8] The resulting triisocyanate was hydrolyzed under harsh conditions (37 % HCl/THF), from which the trihydrochloride salt precipitated. Treatment with an ion-exchange resin released the free triamine l (m.p.…”