Synthesis and Chemistry of Dihydridoborate Group 7 Metal Complexes with Varied N,E-Chelated Ligands (E = O, NH, or S).

Several dihydridoborate group 7 metal complexes have been synthesized and their structural aspects have been described from various N,S-, N,N-, and N,O-chelated borate species, such as Na[(HB)mp] (mp = 2-mercaptopyridyl), Na[(HB)amt] (amt = 2-amino-5-mercapto-1,3,4-thiadiazolyl), Na[(HB)hp] (hp = 2-hydroxypyridyl), Na[(HB)bap] (bap = bis(2-aminopyridyl)), and Na[(HB)bdap] (bdap = bis(2,6-diaminopyridyl)). Room temperature photolysis of [M(CO)] (M = Mn or Re) with these borate species afforded dihydridoborate complexes [(CO)M(μ-H)BHL] - (, M = Mn, L = mp; , M = Re, L = mp; , M = Mn, L = amt; , M = Mn, L = hp; , M = Mn, L = ap; , M = Mn, L = dap, ap = 2-aminopyridyl, dap = 2,6-diaminopyridyl). In complexes -, the corresponding (HBHL) units are coordinated to the metal centers through the (κ-H,H,S) mode. However, in complexes and (or ), the connection is via (κ-H,H,O) and (κ-H,H,N) modes of coordination, respectively. Complexes and underwent hydroboration reactions with terminal alkynes that yielded -hydroborated species [Mn(CO)(μ-H)(NCHE)B(PhC═CH)] (, E = S; , E = NH). Density functional theory (DFT) calculations have been carried out to investigate the electronic structures of these dihydridoborate species as well as the nature of bonding in them.