An easy and direct access to POP-type osmium(II) and osmium(IV) complexes, including OsH 4 {dbf(P i Pr 2 ) 2 } (dbf(P i Pr 2 ) 2 = 4,6bis(diisopropylphosphine)dibenzofuran), is reported. This tetrahydride derivative is an efficient catalyst for the selective formation of imines from alcohols and amines with liberation of H 2 , proving that osmium is a promising alternative to ruthenium for catalysis.

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A bimetallic [Ir(3+)]2 complex was synthesized based on a bridging 1,2,3-triazole ligand that coordinates to one Cp*Ir unit as N,N-bidentate chelate, and to the other as a C,C-bidentate ligand. When compared to monometallic homologues, the bimetallic complex shows greatly enhanced product selectivity for the acceptorless dehydrogenation of alcohols; spectroscopic and electrochemical analysis suggest significant alteration of the metal properties in the bimetallic system compared to the monometallic species, which offers a rationale for the observed high selectivity.

Complexes OsCl(3){dbf(P(i)Pr(2))(2)} [1; dbf(P(i)Pr(2))(2) = 4,6-bis(diisopropylphosphino)dibenzofuran], OsCl(3){xant(P(i)Pr(2))(2)} [2; xant(P(i)Pr(2))(2) = 9,9-dimethyl-4,5-bis(diisopropylphosphino)xanthene], and OsCl(3){xant(PPh(2))(2)} [3; xant(PPh(2))(2) = 9,9-dimethyl-4,5-bis(diphenylphosphino)xanthene] have been obtained in high yield by the reaction of the corresponding diphosphine with OsCl(3)·3H(2)O. The ruthenium(III) counterparts RuCl(3){dbf(P(i)Pr(2))(2)} (4), RuCl(3){xant(P(i)Pr(2))(2)} (5), and RuCl(3){xant(PPh(2))(2)} (6) are similarly obtained from RuCl(3)·3H(2)O in moderate yields. The X-ray structures of dbf(P(i)Pr(2))(2) and complexes 1-3 are also reported.