The Reagent [K(18-crown-6)][RuH(PPh₃)₂(η⁵-7,8-C₂B₉H₁₁)] as a Precursor to New Ruthenacarborane Complexes

Abstract

In ethanol the charge-compensated molecule exo-nido-ruthenacarborane [5,6,10-{RuCl(PPh(3))(2)}-5,6,10-&mgr;-(H)(3)-10-H-7,8-C(2)B(9)H(8)] reacts with KOH to afford the anionic closo-complex [RuH(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))](-) isolated as its K(+) (2a) or [K(18-crown-6)](+) (2b) salt. Treatment of 2a with CO gives [Ru(CO)(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))] (3a) in high yield; its structure was determined by X-ray crystallography. In contrast 2b reacts with CO to yield the salt [K(18-crown-6)][RuH(CO)(PPh(3))(eta(5)-7,8-C(2)B(9)H(11))] (2d). Reaction of 2b with [RuCl(2)(PPh(3))(3)] affords [Ru(2)(&mgr;-H)(H)(PPh(3))(4)(eta(5)-7,8-C(2)B(9)H(11))] (5), which with CO produces [Ru(2)(&mgr;-H)(&mgr;-sigma: eta(5)-7,8-C(2)B(9)H(10))(CO)(4)(PPh(3))(2)] (6), the structure of which was established by X-ray diffraction. The molecule has a metal-metal bond bridged on one side by a hydrido ligand and on the other by a nido-7,8-C(2)B(9)H(10) fragment. The latter is eta(5)-coordinated to a ruthenium atom ligated by a PPh(3) and a CO ligand and is also sigma-bonded to the second ruthenium which carries three CO molecules and a PPh(3) group. The sigma bond utilizes a boron lying in an alpha site with respect to the carbons in the ring coordinated to the Ru(CO)(PPh(3)) moiety. Reactions between 2b or 2d and [CuCl(PPh(3))(3)] and [AuCl(PPh(3))], respectively, afford the bimetal complexes [RuM(&mgr;-H)(L)(PPh(3))(2)(eta(5)-7,8-C(2)B(9)H(11))] [M = Cu, L = PPh(3) (7a), L = CO (7b); M = Au, L = PPh(3) (8a), L = CO (8b)]. X-ray diffraction studies are reported for 7a and 8a, revealing in the case of the former a structure in which an exopolyhedral B-Hright harpoon-up Cu bond supplements the Ru(&mgr;-H)Cu interaction.

Balancing Steric and Electronic Effects in Carbonyl–Phosphine Molybdacarboranes

“…The relative trans influences of CO and PPh 3 in metallacarboranes can be assessed by considering exopolyhedral ligand orientations (ELOs) of structurally characterised literature compounds. When the search is restricted to only {3,1,2‐ closo ‐MC 2 B 9 H 11 } fragments to minimise the possible influence of intramolecular steric crowding on conformation, there is only one [(CO)(PPh 3 ) 2 MC 2 B 9 H 11 ] species, [3‐CO‐3,3‐(PPh 3 ) 2 ‐3,1,2‐ closo ‐RuC 2 B 9 H 11 ] ( BIHQUE ), and one [(CO) 2 (PPh 3 )MC 2 B 9 H 11 ] species, [3,3‐(CO) 2 ‐3‐PPh 3 ‐3,1,2‐ closo ‐FeC 2 B 9 H 11 ] ( KISBIX ), in the Cambridge Structural Database (CSD) . Key ELO data for these, together with those of the closely related species [3‐µ‐(PPh 2 CH 2 PPh 2 )‐{3,3‐(CO) 2 ‐3,1,2‐ closo ‐RuC 2 B 9 H 11 } 2 ] ( HIZQUC ), are presented in Tables and .…”

Facile formation of exo-nido→closo-rearrangement products upon the replacement of PPh3 ligands with bis(diphenylphosphino)alkanes in “three-bridge” ruthenacarborane 5,6,10-[RuCl(PPh3)2]-5,6,10-(µ-H)3-10-H-exo-nido-7,8-C2B9H8

“…The constant 3 J H,H is associated with either the long range spin spin coupling H(Ru)...H(B) through the metal atom or the specific through space coupling interaction between the metal hydride and the hydrogen atom of the BH group, which has been observed earlier for the structurally similar ruthe nium complexes closo 3,3 (PPh 3 ) 2 Although complex 3 was isolated under the above mentioned conditions as the only product, TLC monitor ing of the reaction provided evidence for the formation of an apparent intermediate. The intermediate complex was isolated as a mixture with complex 3 when the reaction was terminated immediately after the disappearance of the starting reagent 1 from the reaction mixture, i.e., after approximately ~2 h. This complex was further identified as 5,6,10 [RuCl(dppb)] 5,6,10 (µ H) 3 10 H exo nido 7,8 C 2 B 9 H 8 (4). In spite of the fact that complex 4 was observed on a silica gel column as an individual band, whose R f differs substantially from that of the final prod uct (3, R f = 0.75; 4, R f = 0.35), this complex appeared to be kinetically unstable since, upon storage in a benzene solution, it is readily transformed into compound 3.…”

Synthesis, isomerism, and catalytic properties of chelate ruthenium copper bimetallacarborane cluster exo-closo-(Ph3P)Cu(μ-H)Ru[Ph2P(CH2)4PPh2](η5-C2B9H11), in radical polymerization of methyl methacrylate

“…This signal would be expected to be relatively broad due to the spin spin coupling of 1 H with the magnetic nuclei 11 B, 10 B, and 63 Cu and, conse quently, would coalesce with the baseline. 15 The expected set of closely spaced signals for the protons of the dppb and PPh 3 ligands, the Ph groups of diphosphines, and the cluster CH groups of both isomers 9a,b is observed in the aliphatic and aromatic regions of the 1 H NMR spectrum; …”