<Tr> <Td> HCo (CO) (PPh) </Td> <Td> 7.0 </Td> </Tr> <Tr> <Td> HMn (CO) </Td> <Td> 7.1 </Td> </Tr> <Tr> <Td> H Fe (CO) </Td> <Td> 4.4, 14 </Td> </Tr> <P> Metal carbonyls are relatively distinctive in forming complexes with negative oxidation states . Examples include the anions discussed above . These anions can be protonated to give the corresponding metal carbonyl hydrides . The neutral metal carbonyl hydrides are often volatile and can be quite acidic . </P>

The metal carbonyl that can obey ean rule