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This work centers around the nickel complexes derived from two tetrahydrosalen-type proligands: N , N ′-bis(2-hydroxybenzyl)- o -phenylenediamine (H 2 salophan) and N , N ′-bis(2-hydroxy-3-methylbenzyl)- o -phenylenediamine (H 2 salophan_Me). The reaction of H 2 salophan with Ni(OAc) 2 ·4H 2 O generates a dinuclear complex Ni 2 (Hsalophan) 2 (OAc) 2 or Na[Ni 2 (salophan) 2 (OAc)] when NaOH is added to assist ligand deprotonation. The reaction of H 2 salophan_Me with Ni(OAc) 2 ·4H 2 O, however, yields a mononuclear complex Ni(Hsalophan_Me) 2 . Unlike the corresponding salen-type nickel complexes, these tetrahydrosalen-type complexes are paramagentic and air sensitive (in solution). Oxidation by O 2 or peroxides results in dehydrogenation of the ligand backbone to form the salen-type complexes. 

HN(CH 2 CH 2 PR 2 ) 2 -ligated copper borohydride complexes, ( R PN H P)Cu(BH 4 ) (R = i Pr, Cy, t Bu), which can be prepared from ( R PN H P)CuBr and NaBH 4 , are capable of catalyzing the hydrogenation of aldehydes in an alcoholic solvent. More active hydrogenation catalysts are ( R PN H P)CuBr mixed with KO t Bu, allowing various aldehydes and ketones to be efficiently reduced to alcohols except those bearing a nitro, N -unprotected pyrrole, pyridine, or an ester group, or those prone to aldol condensation ( e.g. , 1-heptanal). Modifying the catalyst structure by replacing the NH group in ( i Pr PN H P)CuBr with an NMe group results in an inferior catalyst but preserves some catalytic activity. The hexanuclear copper hydride cluster, ( i Pr PN H P) 3 Cu 6 H 6 , is also competent in catalyzing the hydrogenation of aldehydes such as benzaldehyde and N -methyl-2-pyrrolecarboxaldehyde, albeit accompanied by decomposition pathways. The catalytic performance can be enhanced through the addition of a strong base or i Pr PN H P. The three catalytic systems likely share the same catalytically active species, which is proposed to be a mononuclear copper hydride ( R PN H P)CuH with the NH group bound to copper. 

The reaction of 1,3,5-( i Pr 2 PO) 3 C 6 H 3 with Co 2 (CO) 8 leads to the isolation of a POCOP-type mononuclear pincer complex {κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }Co(CO) 2 (1) or a tetranuclear species {κ P -{κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }Co(CO) 2 } 2 Co 2 (CO) 6 (2), depending on the ligand to cobalt ratio employed. The latter compound can be an impurity during the synthesis of {2,6-( i Pr 2 PO) 2 -4-Me 2 N-C 6 H 2 }Co(CO) 2 , when the ligand precursor 5-(dimethylamino)resorcinol is contaminated with phloroglucinol due to incomplete monoamination. Similarly, the reaction of 1,3,5-( i Pr 2 PO) 3 C 6 H 3 with NiCl 2 in the presence of 4-dimethylaminopyridine provides {κ P ,κ C ,κ P -2,4,6-( i Pr 2 PO) 3 C 6 H 2 }NiCl (3) bearing an appended phosphinite group. Structures 1–3 have been studied by X-ray crystallography.