Ligand control in multihaptotropic o-indenyl rhenium systems. experimental and theoretical study

The synthesis of a novel class of alcohol- and ether-functionalized indenyl ligands, focusing on the haptotropic rearrangements of the hybrid O-indenyl rhenium species, is herein described, eta(1)-Ind(x)(Ome)Re(CO)(5) (12(x)) and eta(3)-Ind(x)(OMe)Re(CO)(4) (13(x), x = a, d)[Ind(a)(OMe) = C9H6CH2CH(Me)OMe, 1(a); Ind(d)(OMe) = C9H6CH(CH2)(3)CHOMe, 1d(a)] are examples of a and allylic intermediates in the Cp substitution. The tuning of stercoelcctronic effects of the functionalized alkyl chain or the coordinating solvent (MeCN, THF) allows the study of the relative stabilities of the intercepted solvento species eta(5)-Ind(h)(OMe) Re(CO)(2)(NCMe), 14(b), eta(5)-Ind(c)(OMe)Re(CO)(2)(THF), 15(c), or the chelate [eta(5):k(1)-O-Ind(b,c)(O)Re(CO)(2)], 16(b,c{)Ind(b)(OMe) = [C9H6CH2CH(Ph)OMe](-), 4(b); Ind(c)(OMe) = [C9H6CH(Ph)CH2OMe](-), 4(c)}. DFT calculations reported oil some of the Ind(o) systems have been compared with those of smaller (Cp-O) 5(a) or larger (Flu(a)(O)) 10(a) congeners, confirming the experimental findings. As peculiar examples of the underrepresented low-valent rhenium alkoxy species, the isolation of k(1)-O-Hlnd(x)(O)Re(CO)(5) [X = a,b] is also reported.