Photochemistry of (η⁴-diene)Ru(CO)₃Complexes as Precursor Candidates for Photoassisted Chemical Vapor Deposition

Abstract

Solution phase photochemical experiments on (η4-diene)­Ru­(CO)3 complexes (diene = butadiene, isoprene, 1,3-cyclohexadiene, or cyclobutadiene) demonstrated loss of both diene and CO, making them attractive precursors for photoassisted chemical vapor deposition of ruthenium. Pathways including loss of one CO ligand, loss of diene, loss of two CO ligands, and loss of CO plus diene were observed. Quantum yields for loss of a single CO or diene ligand as the primary photoprocess were determined for the (η4-diene)­Ru­(CO)3 complexes and were found to be dependent on the structure of the diene. Subsequent ligand loss was determined to occur from secondary photolysis. Very little luminescence was observed for the compounds, demonstrating that radiative decay of the excited states was not competitive with photochemical ligand loss. Exhaustive photolysis experiments confirmed that all of the dienes, except for cyclobutadiene, were photolytically labile. In the absence of phosphite, the (η4-diene)­Ru­(CO)3 complexes showed evidence for formation of colloidal Ru species following irradiation in hydrocarbon solutions.

Synthesis, Spectroscopy, and Structure of [FeRu(μ-dithiolate)(CN)2(CO)4]2–

“…The complex [Ru(CN) 2 (CO) 3 ] 2− ([1] 2− ) was prepared with [K(18-crown-6)]CN using Ru-(C 2 H 4 )(CO) 4 as a source of Ru(CO) 3 . 23 The ethylene complex was not isolated but was generated in situ by the blue-light (456 nm) irradiation of Ru 3 (CO) 12 in an ethylenesaturated solution pentane. Some initial experiments investigated the utility of Ru(C 2 H 4 ) 2 (CO) 3 , but the preparation of this bis(ethylene) complex was arduous; therefore, we resorted to the methods that required two photochemical steps.…”

“…The complex [Ru­(CN) 2 (CO) 3 ] 2– ([ 1 ] 2– ) was prepared with [K­(18-crown-6)]­CN using Ru­(C 2 H 4 )­(CO) 4 as a source of Ru­(CO) 3 . The ethylene complex was not isolated but was generated in situ by the blue-light (456 nm) irradiation of Ru 3 (CO) 12 in an ethylene-saturated solution pentane.…”

General access to cubanes: ideal bioisosteres of ortho-, meta-, and para-substituted benzenes

“…Under this protocol, a Diels-Alder reaction between cyclobutadiene, generated in situ from cyclobutadieneiron tricarbonyl, and 2,5-dibromobenzoquinone, served to construct the cubane framework in only 3 steps. To date, this synthesis has seen no application in medicinal chemistry, likely owing to the arduous synthesis of the cyclobutadiene precursor cyclobutadieneiron tricarbonyl, which involves 4 steps (9% overall yield 33,34 ) and requires inconvenient reagents such as chlorine gas, benzene, and highly toxic diiron nonacarbonyl. Convenient access to 1,3-cubane precursors would thus require the development of a new, readily accessible cyclobutadiene precursor.…”

“…3, 33-38). Moreover, many functional groups, including the metal-sensitive isoxazole-moiety (33), were tolerated, demonstrating the mildness of the reaction. Under slightly modified conditions, aryl and heteroaryl bromides were also coupled with cubane (39)(40)(41)(42)(43)(44)(45)(46) and synthetically useful functional groups such as cyanides (39) and aryl chlorides (42,44) were preserved.…”

Tridentate κ3-P,P,C iridium complexes: influence of ligand saturation on intramolecular C–H bond activation

“…Equally unusual is the 1,2,3,5-Z 3 ,Z 1 -C 8 H 12 binding motif -which, to our knowledge, is unprecedented; 39 more common is the 1,2,3,6-Z 3 ,Z 1 -C 8 H 12 binding motif, as observed by us and others. 30,[40][41][42][43][44][45] The above qualities are showcased in the solidstate structure of (AE)-3, namely: a -(CH 2 )(CH)Q(CH)-linker arm, with C-C bond lengths of 1.335(9) and 1.49(1) Å and a slight Ir(1)-C(linker) contraction of 2.062(7) Å cf., 2.165(8) and 2.164(3) Å for (AE)-1 and (AE)-2, respectively.…”