Cyclometalated [Cp*M(C^X)] (M = Ir, Rh; X = N, C, O, P) complexes

Abstract

Half-sandwich Cp*Ir and Cp*Rh metalacycles have been successfully applied in traditional domains encompassing organic transformations and catalysis in recent years, especially the catalytic activation of C-H bonds. Cyclometalation has proven to be a highly attractive and versatile synthetic method for the formation of organometallic metalacycles. This review intends to describe isolated and well-defined cyclometalated iridium/rhodium complexes that contain a Cp*M-C (M = Ir, Rh) bond stabilised by the intramolecular coordination of neutral donor atoms (N, C, O or P). The formation of metalamacrocycles and cages employing cyclometalated approaches is discussed. In focusing on selected mechanistic insights garnered from iridium/rhodium-catalysed functionalisation of C-H bonds involving cyclometalated complexes, a limited number of substrates will be discussed, but a broad range of mechanistic features is highlighted.

Formation of 5-membered metallacycles at iPrPCPIr by C–H, O–H, and C–CO bond cleavage

“…For example, metallacycles have been determined as key intermediates in olefin metathesis reactions [3,4], a number of C-H functionalization reactions [5][6][7][8][9], and alkyne trimerisation [10,11]. The chemistry of iridacycles is quite diverse [12][13][14]. Complexes containing iridium metallacycles have been used for OLED applications [15], the hydrogenation of imines [16], the conversion of ethanol to butanol [17], and have even shown anti-cancer activity [18].…”

Rh(III)- and Ir(III)-Catalyzed C–C Bond Cross Couplings from C–H Bonds

“…bond formations. In contrast, although the [Cp*IrCl 2 ] 2 precatalyst is recognized to be a more efficient metalating agent than the Rh congener [14,21], the use of this high-oxidation-state third-row transition metal catalyst to construct C-C bonds is clearly less documented [22]. The limited potential of the [IrCp*Cl 2 ] 2 precatalyst in C-C bond forming reactions might be due to the high stability of the metallacyclic intermediates and the unfavorable final product formation (e.g., by means of an oxidative coupling of the C-N bond) which might compromise an efficient catalytic turnover [23].…”

“…Following this ambitious goal, Glorius endeavored on designing such CDCs between two structurally similar heterocyclic scaffolds [146]. The desired cross coupling reaction could be achieved by carefully selecting both coupling partners (typically furans and (benzo)thiophenes), and after an intensive optimization study, the desired transformation delivered a panel of biheteroaryls (14).…”

“…was undertaken. Rapidly, it was proved unequivocally that such late transition metals, in the presence of sodium acetate as additive, are particularly potent catalysts for C-H activation affording cyclometalated complexes termed [Cp*M(C^X)] (M¼Rh, Ir) [14]. Importantly, these Ir-and Rh-cyclometalated species could be frequently prepared with high efficiency and under relatively mild reaction conditions [15].…”

Synthesis and crystal structure of 1D Cd-amine coordination polymer and its luminescent properties

“…It is may be due to that the weak or non-polar solvent could not influence the electronic density of a conjugated system and is unable to result in the bathochromic or hypsochromic shift of the absorption band. The coordination polymers of d 10 metal centre have been investigated for fluorescence properties owning to their potential application in photoactive materials [35][36][37][38][39][40][41] . The photoluminescence properties of compound 1 were studied in DMSO, CH 3 CN, CH 3 OH, CHCl 3 , toluene solvents at the same concentration(1.0×10 −5 mol/L) (Fig.4).…”