Intramolecular proton-hydride interactions in iridium complexes, a new type of hydrogen bond

grantor: University of TorontoSeven cationic hydrido pyridinethione (SpyH) complexes containing either PCy3 or PPh3 co-donor ligands have been prepared from iridium polyhydride complexes. These include three PCy3 complexes [IrH2([eta]1-SpyH)2(PCy3) 2](BF4) 1, [IrH([eta]1-SpyH) 4(PCy3)](BF4)2 4, [IrH([eta] 1-SpyH)2([eta]2-Spy)(PCy3)](BF 4) 5 and four PPh3 complexes [IrH([eta] 1-SpyH)([eta]2-Spy)(PPh3)2](BF 4) 9, [IrH2([eta]1-SpyH)(PPh 3)3](BF4) 10, [IrH2([eta] 1-SpyH)2(PPh3)2](BF4) 11 and [IrH(CO)([eta]1-SpyH)2(PPh3) 2](BF4)2 12. All contain NH &cdots; HIr proton-hydride bonding units in the solid state {d(HH): 1.8 to 2.1 Å, X-ray analysis). The proton-hydride bonds in these complexes are maintained in CH2Cl2. Stronger proton-hydride bonds are formed in complexes with PCy3 co-donor ligands vs complexes with PPh3 co-donor ligands. The strength of proton-hydride bonds is decreased in complexes containing more PPh3 or CO ligands. The strength of the proton-hydride bonds in solution is probed for 1, 4 and 5 by introducing a conventional H-bond acceptor (THF-d8 or OPPh3). The H &cdots; H interactions in 1 are disrupted but remain intact in 4 and 5. Four chloro SpyH complexes 'cis'-IrH2Cl([eta] 1-SpyH)(PCy3)2 13, IrHCl2 ([eta]1-SpyH)(PCy3)2 14a , IrCl2([eta]1-SpyH)([eta]2-Spy)(PCy 3) 15 and [IrCl([eta]1-SpyH)2([eta] 2-Spy)(PCy3)](BF4) 16 have been prepared from iridium polyhydride complexes. 13 and 14a contain NH &cdots; ClIr hydrogen bonds over NH &cdots; HIr bonds {d(H &cdots; Cl): 2.15(7) Å, 15}. 16 possesses an N-H &cdots; Cl(Ir) &cdots; H-N hydrogen bonded network {d(N &cdots; Cl): 3.137, 3.045 Å}. Ligands other than HSpy used in the reaction with IrH5(PCy 3)2 include pyrazole, acetaldoxime and dimethylglyoxime. The products of these reactions are iridium(III) dihydrides containing conventional Y-H &cdots; X hydrogen bonding units, Y, X = N, O. An 18 electron Ir(III) complex containing Ir &cdots; FBF3 and agostic Ir &cdots; H-C bonds is formed in the reaction of IrH5(PCy3) 2 with HBF4 in benzene {d(Ir &cdots; H): 2.04(5) Å and d(Ir &cdots; F): 2.272(3) Å}.Ph.D